U.S. patent application number 13/421685 was filed with the patent office on 2012-07-05 for starch foam microparticles for delivery of non-aqueous liquid to bees.
This patent application is currently assigned to The United States of America, as represented by the Secretary of Agriculture. Invention is credited to Gregory M. Glenn, Artur P. Klamczynski.
Application Number | 20120171294 13/421685 |
Document ID | / |
Family ID | 39476108 |
Filed Date | 2012-07-05 |
United States Patent
Application |
20120171294 |
Kind Code |
A1 |
Glenn; Gregory M. ; et
al. |
July 5, 2012 |
STARCH FOAM MICROPARTICLES FOR DELIVERY OF NON-AQUEOUS LIQUID TO
BEES
Abstract
The present invention relates to starch foam microparticles
having a porous structure, and which typically have a diameter of
less than or equal to about 50 microns. The present invention also
relates to novel uses for the starch foam microparticles in
beekeeping and in the pharmaceutical, plastics and fragrance
industries.
Inventors: |
Glenn; Gregory M.; (American
Canyon, CA) ; Klamczynski; Artur P.; (Foster City,
CA) |
Assignee: |
The United States of America, as
represented by the Secretary of Agriculture
Washington
DC
|
Family ID: |
39476108 |
Appl. No.: |
13/421685 |
Filed: |
March 15, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11607714 |
Dec 1, 2006 |
8163309 |
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13421685 |
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Current U.S.
Class: |
424/490 ;
424/745; 424/769 |
Current CPC
Class: |
Y10T 428/2982 20150115;
A61P 33/14 20180101; A01N 25/12 20130101; A01N 25/16 20130101 |
Class at
Publication: |
424/490 ;
424/745; 424/769 |
International
Class: |
A61K 9/14 20060101
A61K009/14; A61K 36/61 20060101 A61K036/61; A61P 33/14 20060101
A61P033/14; A61K 36/53 20060101 A61K036/53 |
Claims
1. A starch foam microparticle wherein: (i) the starch foam
microparticle has a porous structure, and wherein (ii) the starch
foam microparticle has a diameter of less than or equal to about 50
microns (.mu.m) at its widest point.
2. The starch foam microparticle of claim 1, wherein the starch
foam microparticle has a density that is in a range that is between
about 0.14 g/cm.sup.3 and about 0.34 g/cm.sup.3.
3. The starch foam microparticle of claim 1, wherein the starch
foam microparticle has a density that is less than of equal to
about 0.32 g/cm.sup.3.
4. The starch foam microparticle of claim 1, wherein the
microparticle has a diameter at its widest point that is in a range
that is between about 5.0 .mu.m and about 0.1 .mu.m.
5. The starch foam microparticle of claim 1, wherein the starch
foam microparticle has a diameter at its widest point of less than
or equal to about 20 .mu.m.
6. The starch foam microparticle of claim 1, wherein the starch
foam microparticle comprises a starch that is a plant starch.
7. The starch foam microparticle of claim 6, wherein the starch is
a plant starch that is a member selected from the group consisting
of a cereal starch, a tuber starch and a legume starch or a
combination of such members.
8. The starch foam microparticle of claim 6, wherein the plant
starch is member selected from the group consisting of a modified
starch and an unmodified starch or a combination of such
members.
9. The starch foam microparticle of claim 7, wherein the plant
starch is a member selected from the group consisting of corn
starch, wheat starch, potato starch, rice starch and high amylose
corn starch or a combination of such members.
10. The starch foam microparticle of claim 1, wherein the starch
foam microparticle is loaded with a non-aqueous liquid.
11. The starch foam microparticle of claim 10, wherein the
non-aqueous liquid comprises at least one oil.
12. The starch foam microparticle of claim 11, wherein the at least
one oil is an essential oil.
13. The starch foam microparticle of claim 12, wherein the
essential oil has mitocidal properties.
14. The starch foam microparticle of claim 13, wherein the
essential oil is member selected from the group consisting of
cinnamon oil, thyme oil, clove oil, patchouli oil, wintergreen oil
and tea tree oil or a combination of such members.
15. The starch foam microparticle of claim 10, wherein the
non-aqueous liquid comprises a pharmaceutical.
16. The starch foam microparticle of claim 10, wherein the
non-aqueous liquid comprises a fragrance.
17. The starch foam microparticle of claim 10, wherein the
non-aqueous liquid comprises a pheromone.
18. A population of starch foam microparticles having a porous
structure, a density that is in a range that is between about 0.14
g/cm.sup.3 and about 0.34 g/cm.sup.3, and a diameter that is less
than or equal to about 50 .mu.m wherein, (i) the population of
starch foam microparticles is loaded with a non-aqueous liquid by
forming a mixture comprising the non-aqueous liquid and the
population of starch foam microparticles, wherein (ii) the
non-aqueous liquid is present in an amount that is less than or
equal to at least about 25% by weight of the mixture, wherein (iii)
the population of starch foam microparticles absorbs the
non-aqueous liquid thereby forming a loaded population of starch
foam microparticles, and wherein (iv) the loaded population of
starch foam microparticles is a free flowing powder.
19. A population of starch foam microparticles having a porous
structure, a density that is in a range that is between about 0.14
g/cm.sup.3 and about 0.34 g/cm.sup.3, and a diameter that is less
than or equal to about 50 .mu.m wherein: (i) the starch comprising
the population of starch foam microparticles is a an unmodified
plant starch that is a member selected from the group consisting of
corn starch, high amylose corn starch and wheat starch, or a
combination of such members; and (ii) the population of starch foam
microparticles is loaded with an essential oil that is a member
selected from the group consisting of cinnamon oil, thyme oil,
clove oil, patchouli oil, wintergreen oil and tea tree oil or a
combination of such members.
20. The method of claim 19, wherein the essential oil is present in
an amount that is about 25% the weight of the population of starch
foam microparticles.
21. A method for controlling Varroa mites in a bee colony, the
method comprising: (a) loading a mitocidal chemical onto a
population of starch foam microparticles, wherein the starch foam
microparticles comprising the population of starch foam
microparticles have a porous structure, have a density that is in a
range that is between about 0.14 g/cm.sup.3 and about 0.34
g/cm.sup.3, and have a diameter of less than or equal to about 20
.mu.m, and (b) feeding the bees the population of starch foam
microparticles.
22. The method of claim 21, wherein the mitocidal chemical is an
essential oil.
23. The method of claim 21, wherein the essential oil is present in
an amount that is about 25% the weight of the population of starch
foam microparticles.
24. The method of claim 22, wherein the essential oil is selected
from the group consisting of thyme oil and clove oil or a
combination of such members.
25. A plastic composite film comprising starch foam microparticles
wherein the starch foam microparticles: (i) have an porous
structure; and (ii) have a diameter of less than or equal to about
50 .mu.m at their widest point.
26. The plastic composite film of claim 25, wherein the starch foam
microparticles have a density that is in a range that is between
about 0.14 g/cm.sup.3 and about 0.34 g/cm.sup.3.
27. The plastic composite film of claim 25, wherein the starch foam
microparticles have a diameter at their widest point that is less
than or equal to about 25% of the film thickness.
28. The plastic composite film of claim 25, wherein the starch foam
microparticles have a diameter at their widest point that is in a
size rage that is between about 0.1 .mu.m and about 5 .mu.m.
29. The plastic composite film of claim 28, wherein the starch foam
microparticles: (i) have a diameter at their widest point that is
in a range that is between about 100 nm and about 999 nm, and (ii)
are present in the plastic composite film in an amount that is less
than or equal to about 50% on a weight basis.
Description
FIELD OF THE INVENTION
[0001] The invention relates to starch foam microparticles having a
porous structure and having a diameter at their widest point of
less than or equal to about 50 microns (.mu.m).
BACKGROUND OF THE INVENTION
[0002] Powders are a complex mixture of solid particles and/or
granules interspersed with air. The powder form is often useful.
For example, from an application perspective, powders are less
labor intensive to handle and are easier and more accurately
measured than are other forms of solid materials e.g., solid
blocks. Free-flowing powders are easily mixed and blended and
facilitate the handling and packaging of a product on the
commercial scale.
[0003] As is well known in the art, starch, in its native form, is
a free flowing powder. The native starch powder is comprised of
solid particles of starch that are typically of a size that is
between about 4 .mu.m and 100 .mu.m, and have an average density of
about 1.4 g/cm.sup.3. Starch is an abundant, useful, and
inexpensive natural biodegradable material. In the form of a
free-flowing powder, starch is easy to handle and package on a
commercial scale. Free-flowing starch powders can also be easily
mixed and blended with other powders.
[0004] Starch powders are potentially useful carrier agents. As
noted above, starch is edible and biodegradable. Thus, because it
is also abundant and inexpensive, it is ideal for applications that
require a carrier agent to be edible and/or biodegradable.
Unfortunately however, native starch powders have only a limited
ability-to function as carrier agents, particularly for liquid
substances.
[0005] Indeed, only thin film of liquid can be formed around each
individual starch granule when the native starch powder is mixed
with a non-aqueous liquid e.g., an oil. Thus, only a small
percentage of the oil can be loaded onto the starch powder before
the flow properties begin to change. Loading more than about 5% oil
(weight basis) onto native starch powder markedly affects the
flowability and dispersion of the starch. In fact, loading more
than 5% oil leads to agglomeration of the starch granules.
[0006] As noted above, native starch powder typically comprises
particles that are in a size range from about 4 .mu.m to about 100
.mu.m. However, the range of potential applications for which
starch is useful, would be extended if smaller particle sizes were
available. An exemplary application is in the plastics industry.
Another exemplary application is in the beekeeping industry. Other
exemplary applications are found, but not limited to the
pharmaceutical industry and the fragrance industry.
[0007] Thus, there exists a need in the art for free flowing
powders comprising small starch particles and for free flowing
small starch particles loaded with substantial quantities of
non-aqueous liquid. Fortunately, as will be clear from the
following disclosure, the present invention provides for this and
other needs.
SUMMARY OF THE INVENTION
[0008] In one embodiment, the present invention provides a starch
foam microparticle that has a porous structure, and has a diameter
of less than or equal to about 50 microns (.mu.m) at it widest
point. In an exemplary embodiment, starch foam microparticles are
comprised of a plant starch that is a member selected from the
group consisting of cereal starch and tuber starch or a combination
of such members.
[0009] In one exemplary embodiment, the starch foam microparticle
is saturated with a non-aqueous liquid.
[0010] In another exemplary embodiment the invention provides a
method for controlling Varroa mites in bee colonies.
[0011] In another embodiment the invention provides a plastic film
product comprising starch foam microparticles.
[0012] Other features, objects and advantages of the invention will
be apparent from the detailed description which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1. Scanning electron micrographs of corn starch under
different processing conditions. (A)--Native starch granules that
have not been heated in water (Scale bar=10 .mu.m); (B) Native
starch granules heated to about 90.degree. C. for 1 minute. Note
that the starch granules are swelling and leaking out some of the
low molecular weight molecules (amylose). (Scale bar=5 .mu.m).
(C)--A starch sample that has been cooked at 95.degree. C. for 30
minutes. The sample has been sliced in half. Notice the starch
granule envelope and all of the fibrous starch has leaked but of
the granules and formed a porous network. (Scale bar=5 um).
(D)--Even after cooking the starch at 95.degree. C. for 60 minutes,
the starch granule envelope is still visible in the foam matrix
(Scale bar=20 um). (E)--Starch sample cooked at 110.degree. C. for
about 15 minutes. Notice that the starch granule or envelope is
almost completely dissolved. (Scale bar=10 .mu.m). (F) Starch
sample was cooked at 120.degree. C. Notice there is little evidence
of any remaining starch envelope. (Scale bar=3 .mu.m). Thus, heat
dissolves the starch granule remnant/envelope:
[0014] FIG. 2. A starch sphere from corn starch made by spraying
the starch melt into ethanol and then dehydrating and drying the
sample. Note the absence of starch granule remnants or
envelopes.
[0015] FIG. 3 Shows an exemplary pathway by which oils enter the
larval hemolymph.
[0016] FIG. 4 Shows the number of adult mites found on sticky
boards of colonies treated with starch encapsulated clove oil.
[0017] FIG. 5 Shows mite mortality in honey bee colonies treated
with starch foam microparticle encapsulated thymol.
DETAILED DESCRIPTION OF THE INVENTION
Definitions
[0018] As used herein, the term "control" or "controlling" as in
e.g., the phrase: the "control" of Varroa mites, or "controlling"
Varroa mites, or as in the phrase: "controlling" agricultural
pests, refers to any means for preventing infection or infestation,
reducing the population of already infected areas or organisms, or
elimination of the population of pests or mites or other species
whose "control" is desired. Indeed, "controlling" as used herein
refers to any indica of success in prevention, elimination,
reduction or amelioration of a pest population or pest problem.
[0019] The term "starch" as used herein refers to a carbohydrate
compound having the formula (C.sub.6H.sub.10O.sub.5).sub.n, where
the subscript "n" denotes the total number of glucose monomer
units. Typically, starches comprise the polysaccharides amylose and
amylopectin. The amylose polysaccharide is comprised primarily of
glucose monomer units joined to one another in .alpha.-1,4
linkages. Amylose is typically considered a linear molecule,
however some minor branching sometimes is found. Typically, amylose
polymers range in length from between about 500 to about 20,000
glucose monomer units, but any length is possible. Amylopectin is
also comprised of glucose monomer units, but is not usually
considered to be a strictly linear molecule. Instead, the
polysaccharide, comprises .alpha.-1,4 linked glucose monomers
interspersed at intervals with branches formed by glucose monomers
in .alpha.-1,6 linkage (see e.g., Advances in Food and Nutrition
Research, Vol. 41: Starch: Basic Science to Biotechnology, Mirta
Noemi Sivak and Jack Preiss eds. Academic Press (1998) which is
incorporated herein by reference in its entirety).
[0020] The relative content of amylose and amylopectin in starch
can vary. Typically, amylose comprises about 20% to about 25% to
about 30% of the starch, but may be present in higher
concentrations as well. For example "high-amylose corn starch"
(HACS) comprises at least about 46% amylose, and in
some-embodiments comprises about 50%, about 55%, about 60%, about
65%, about 70%, about 75% amylose, and in other embodiments
comprises about 80% amylose or about 85% amylose. Amylopectin on
the other hand, typically comprises about 70% to about 75%, to
about 80% of the starch, but may occur in higher proportions or
lower proportions as well, e.g., waxy corn starch may comprise more
than 99% amylopectin, and HAGS may comprise as little as 15%
amylopectin or less.
[0021] Starch is found in nearly every type of plant tissue
including, but not limited to the fruit, seeds, stems, leaves,
rhizomes and/or tubers. Thus, many starches are plant derived
starches or "plant starch". Typically, starch produced in the USA
is derived from corn, potatoes, rice, and wheat. However, useful
starches can come from any source e.g., arrowroot, tapioca
(cassava), buckwheat, banana, barley, cassava, konjac, kudzu, oca,
sago, sorghum; sweet potato, taro; yams and beans e.g., favas,
lentils and peas.
[0022] The term "starch" as used herein, also refers to "modified
starch" which has been modified by human intervention such that it
differs from the raw, unmodified form as extracted from a plant.
For example, starch can be modified by methods known in the art
such as e.g., by inter alia chemical crosslinking and/of by
stabilization through the introduction of anionic groups to the
starch granule.
[0023] The term "microparticles", "microsphere" or equivalent
expressions refer to a general designation for particles of a
certain size, typically particle, of a size that is less than or
equal to about 50 microns (.mu.m) at the widest point of the
particle. In an exemplary embodiment, microparticles have a size
that is less than or equal to about 45 microns (.mu.m) at the
widest point of the particle. In other exemplary embodiments,
microparticles have a size that is less than or equal to about 40
microns (.mu.m), less than or equal to about 35 microns (.mu.m),
less than or equal to about 30 microns (.mu.m), less than or equal
to about 25 microns (.mu.m ), less than or equal to about 20
microns (.mu.m), less than or equal to about 15 microns (.mu.m ),
less than or equal to about 10 microns (.mu.m), and/or less than or
equal to about 5 microns (.mu.m), at the widest point of the
particle. In still other exemplary embodiments, microparticles have
a size that is less than or equal to about 4 microns (.mu.m), less
than or equal to about 3 microns (.mu.m), less than or equal to
about 2 microns (.mu.m), less than or equal to about 1 micron
(.mu.m), less than or equal to about 0.5 micron (.mu.m), less than
or equal to about 0.4 micron (.mu.m), less than or equal to about
0.3 micron (.mu.m), less than or equal to about 0.2 micron (.mu.m),
and/or less than or equal to about 0.1 micron (.mu.m). Thus, the
term "starch foam microparticles" as used herein, refers to
microparticles comprised of starch foam.
[0024] The term "foam" as used herein, refers to any substance
comprising gas bubbles trapped in a liquid or in a solid. In an
exemplary embodiment, foam is comprised of starch. Hence in an
exemplary embodiment, foam is a starch foam. In one exemplary
embodiment, starch foam is a solid foam. As is known in the art,
solid foam compositions can have an open celled structure, a closed
celled or have a structure that is a mixture of closed and open
cells (see e.g., Glenn, G. M., et al. (1996) Microcellular
Starch-Based Foams. In: G. Fuller, T. A. McKeon, D. D. Bills (Eds.)
Agricultural Materials as Renewable Resources. Pp. 88-106.). Open
cell structured foams comprise pores that are connected to each
other such that the connections form an interconnected network of
pores. Closed cell foams do not have interconnected pores.
[0025] "Starch foam microparticles" have a porous structure that
typically comprises a mostly, though not necessarily completely,
open cell structure with a variety of cells/pores/bubble sizes.
Typically, cells/pores/bubbles comprising a starch foam have a
diameter that is less than or equal to about 10 microns (.mu.m). In
an exemplary embodiment, cells/pores/bubble sizes have a diameter
that is in a size range that is between about 0.01 micron (.mu.m)
and about 2 microns (.mu.m).
[0026] "Starch foam microparticles" can be spherical, or almost
spherical or angular in shape. Populations of particles may
comprise spherical starch foam microparticles, almost spherical
starch foam microparticles, angular starch foam microparticles, or
may be combinations of spherical, almost spherical and angular
starch foam microparticles. Typically, the shape of starch foam
microparticles depends on the method used for their manufacture.
For example, spherical and/or almost spherical starch foam
microparticles are formed when a starch melt is sprayed into a
chamber containing ethanol. Angular starch particles are made by
shearing a starch gel or starch melt in an ethanol solution using a
high speed mixer.
[0027] The term "powder" as used herein, refers to a solid
substance in the form of fine loose particles or granules.
Typically powders comprise particles that are in a size range of
between about 1 nm to about 1 mm. Starch foam microparticles
comprising powders typically have a particle size that is less than
or equal to about 50 microns (.mu.m) and equal to or greater than
about 0.1 micron. In an exemplary embodiment, starch foam
microparticles comprising powders have a particle size that is less
than of equal to about 20 microns (.mu.m ).
[0028] The expression "free-flowing powder" as used herein refers
to a powder of which the particles do not adhere significantly to
one another and therefore the particles are able to move past one
another essentially without restriction. Particles comprising a
"free-flowing powder" do not clump together or otherwise
agglomerate. Thus, a free flowing powder is one that flows
consistently with minimal energy input. The inherent flowability of
a powder is readily determined by methods known in the art (see
e.g., U.S. Pat. No. 6,065,330, U.S. Patent Application Publication
No. 20060070428, and A Laboratory Handbook of Rheology, Chapter
III, Van Wazer et al., Interscience (1966)). Free-flowing powders
comprising starch foam microparticles are readily mixed with other
powders to make a homogenous mixture with other materials.
[0029] The expression "nonaqueous liquid" as used herein refers to
a liquid substantially comprised of a nonaqueous solvent or
mixtures of nonaqueous solvents. In an exemplary embodiment, the
nonaqueous liquid comprises one or more polar solvents e.g., an
alcohol, an ester, a ketone and/or an ether. In another exemplary
embodiment, the nonaqueous liquid comprises one or more non-polar
solvents e.g., toluene, xylene, benzene, acetone, hexane, octane,
chloroform, and/or methylene chloride. In another exemplary
embodiment, the nonaqueous liquid comprises at least one each of
both polar and non-polar solvents.
[0030] In some exemplary embodiments, non-aqueous liquids also
comprise water. In general, the water content of a nonaqueous
liquid is less than the amount necessary to begin noticeably
softening or dissolving the starch foam microparticles. Thus, in an
exemplary embodiment, the amount of water present in a nonaqueous
liquid is less than or equal to about 40% by weight based on the
total weight of the nonaqueous liquid. For example, in some
exemplary embodiments starch foam microparticles are equilibrated
in a solution of 60% ethanol. In other exemplary embodiments, the
water content of a nonaqueous liquid is less than or equal to about
30% by weight; less than or equal to about 20% by weight; less than
or equal to about 10% by weight; less than or equal to about 5% by
weight; and/or less than of equal to about 1% by weight. The exact
amount of water present in a nonaqueous liquid is dependent on
inter alia the nonaqueous liquid itself, the particular application
for which the starch foam microparticles are being used, and on the
nature and composition of the starch comprising the starch foam
microparticles e.g., whether the starch foam microparticles
comprise unmodified starch, high amylose starch, or modified starch
and/or the combination of modified and unmodified starches. Thus,
having available the knowledge in the art and reference to the
present disclosure, the exact amount of water in a nonaqueous
liquid is readily determined by one of skill in the art.
[0031] The term "pharmaceutical" as used herein, refers to a
medication e.g., a licensed drug, or substance taken for the
purpose of curing, preventing or ameliorating symptoms of an
illness or medical condition. The term "ameliorating" or
"ameliorate" refers to any indicia of success in the treatment of a
pathology or condition, including any objective or subjective
parameter such as abatement, remission or diminishing of symptoms,
making the condition more tolerable to the patient; making the
final point of degeneration less debilitating, and/or an
improvement in a patient's physical or mental well-being.
Amelioration of symptoms can be based on objective or subjective
parameters; including the results of a physical examination and/or
a psychiatric evaluation.
[0032] The term "bee colony" or "honeybee colony" as used herein,
refers to a social unit of bees, e.g., honeybees comprising a
colony. The social unit can be any system of organization utilized
by bees. Typically, colonies facilitate survival of the group.
Thus, typically, a "bee colony" consists of groups of bees that
cooperate in nest building, food collection, and brood rearing.
Each member of a "bee colony" has a task to perform, and the
combined efforts of the entire colony are directed to survival and
reproduction. A colony typically has a single queen, thousands of
workers, and hundreds of drones. Typically, the social structure of
the colony is maintained by the queen, and workers through an
effective system of communication.
[0033] Domesticated honeybees are cultivated in "beehives" or
"honeybee hives". Thus, the term "beehive" or "honeybee hive"
refers to a structure that functions as a habitation for a colony
of bees, e.g., a colony of honeybees.
[0034] The term "behavior modifying compound" as used herein refers
to any substance or compound which influences the behavior or
development of ah organism e.g. stimulates a mating dance, and/or
helps the organism find food, escape enemies and/or find a mate.
Such substances can be naturally occurring or synthetically made.
For example, "behavior-modifying compounds" include, but are not
limited to e.g., semiochemicals such as e.g., pheromones,
allomones, and kairomones.
[0035] The term "pheromone" as used herein, refers to a substance
or mixture of substances which are secreted and released by an
organism for detection and response by another organism of the same
species. Pheromones mediate a variety of interactions between
organisms. Thus, pheromones are typically classified by the
interaction that they most strongly influence e.g., alarm
aggregation or sex pheromone.
[0036] As is known in the art, "pheromones" belong to the larger
class of chemical compounds referred to as semiochemicals. The term
"semiochemical" as used herein refers to chemicals that mediate
interactions between organisms. Semiochemicals include
allelochemicals and pheromones depending on whether the
interactions are interspecific or intraspecific, respectively. As
used herein the term "allelochemical" refers to chemical substances
that induce a response in the receiver of the signal that is either
adaptively favorable to the emitter but not the receiver
(allomones), or that is favorable to the receiver but not the
emitter (kairomones) or is favorable to both emitter and receiver
(synomones). Allelochemicals and pheromones are useful e.g. as
arrestants, attractants, repellents, deterrents, and/or
stimulants.
[0037] The term "2-heptanone" or "heptane-2-one" as used herein,
refers to a ketone that in its natural state is a component of the
honey bee mandibular gland pheromone. 2-Heptanone is known in the
art (see e.g., U.S. Pat. No. 6,843,985 which is incorporated herein
by reference). In honey bees 2-Heptanone is a pheromone produced by
the mandibular glands of adult worker honey bees, Apis mellifera
and Apis cerana older than 8-10 days (see e.g., Vallet et al., J.
Insect Physiol. 37 (11):789-804 (1991); and Sakamoto et al.,
Journal of Apiculture Research 29 (4):199-205 (1990) each of which
are incorporated herein by reference).
[0038] The term "essential oil" as used herein refers to natural
substances made by plants. Essential oils are found in many
aromatic plants-herbs, flowers, and trees and are present in
various parts of the plant including, but not limited to, leaves,
seeds, flowers, wood and bark. Typically, essential oils give the
plant its particular, signature scent. For example, oils such as
lemon, orange, mustard, and anise give fruits and seeds their
characteristic odor and taste. In Nature, the essential oils of
plants have numerous functions for the plant which include, but are
not limited to e.g., attracting bees for pollination, repelling
insects, and/of protecting the plant from disease. Humans have
invented many uses for essential oils, including, but not limited
to e.g., pesticides e.g., neem oil; insect and animal repellents
e.g., citronella oil; food flavorings e.g., methyl salicylate (oil
of wintergreen); and therapeutics e.g., lavender oil.
[0039] The term "biodegradable" as used herein refers to a
composition or substance that decays and becomes absorbed by the
environment. A biodegradable substance is capable of decaying
through the action of living organisms typically, through the
action of living organisms such as bacteria and fungi.
Biodegradation of biodegradable substances such as food and sewage,
typically leads to compaction and liquefaction, and to the release
of nutrients that are then recycled by the ecosystem.
I. Introduction: Starch Foam Microparticles
[0040] In an exemplary embodiment the invention provides starch
foam microparticles having a porous microcellular structure and a
diameter at their largest point of less than or equal to about 50
.mu.m. In an exemplary embodiment, the microparticles absorb about
25% weight/weight of non-aqueous liquid while remaining as distinct
free flowing microparticles. Thus, in an exemplary embodiment, the
loaded microparticles find use as free-flowing powders.
[0041] The powder form facilitates handling and packaging of the
product on a commercial scale. Moreover, free-flowing powders are
easily mixed and blended with other powders that may be needed as
e.g., dietary supplements. Powders are less labor intensive to
handle than other forms because they are easy to scoop from a
container to apply and/or disperse e.g., in a honeybee colony.
[0042] In one aspect, the invention provides a free-flowing starch
powder comprising starch foam microparticles that have a porous,
mostly open cell structure. The starch foam microparticles absorb
non-aqueous solutions and/or solvents while remaining, on the
whole, as a free-flowing powder. In an exemplary embodiment, the
starch foam microparticles absorb essential oils.
[0043] Starch, in its native form, is a free flowing powder.
However, native starch powder is comprised of solid particles of
starch. Although a thin film of non-aqueous liquid can be formed
around each individual starch granule by mixing the native starch
powder with a non-aqueous liquid, only a small percentage of the
liquid can be loaded into the starch powder before the flow
properties begin to change. Typically, for example, loading more
than about 5% non-aqueous liquid (weight basis) onto native starch
powder markedly affects the flowability and dispersion of the
starch. Indeed, typically, loading more than about 5% non-aqueous
liquid onto the starch particles results in agglomeration of the
starch granules.
[0044] In an exemplary embodiment, the starch foam microparticles
disclosed herein are able to be loaded with a much higher
percentage of non-aqueous liquid (about 25% by weight) than are
native starch powders, while still remaining as a free flowing
powder. Without being bound by theory, it is believed that since
the starch foam microparticles are porous, they are able to draw
the non-aqueous liquid into the interior regions of the individual
starch microparticles by capillary action. Thus, the non-aqueous
liquid sequestered in the interior of the starch particle has
little effect on the flow properties.
[0045] Starch foam microparticles have numerous uses including, but
not limited to, providing an edible delivery system for feeding
bees. In an exemplary embodiment, starch foam microparticles are
used to feed bees nutritional oils. In another exemplary embodiment
the starch foam microparticles are used to feed bees essential
oils.
[0046] In still another exemplary embodiment, the starch foam
microparticles are used to feed bees essential oils that have
mitocidal properties. In another exemplary embodiment the essential
oils with mitocidal properties are fed to the bees to control
Varroa mites. Thus, the starch foam microparticles also provide a
method for controlling Varroa mites in bee colonies.
[0047] In another exemplary embodiment, starch foam microparticles
are loaded with a fragrance. In another exemplary embodiment,
starch foam microparticles are loaded with a pharmaceutical. In
another exemplary embodiment, starch foam microparticles are loaded
with a pheromone.
[0048] In one exemplary embodiment, starch foam microparticles are
used to produce composite plastics. In another exemplary
embodiment, composite plastics comprising starch foam
microparticles are biodegradable. In another exemplary embodiment,
the plastic composites are plastic films.
Starches
[0049] Starch is a complex plant carbohydrate used by plants to
store excess glucose. All plants make starch. Starch typically
occurs as a reserve polysaccharide in the leaf, stem, root (tuber),
seed, fruit, and/or pollen of the plant. In its purified form,
natural unmodified starch is a white tasteless and odorless
powder.
[0050] Starch is frequently used in cooking for thickening sauces.
In industry, starch typically is used e.g., in the manufacture of
adhesives, paper, and textiles. Other exemplary uses of native
starch is as a disintegrant in pharmaceutical tablets, and as a
carrier for various substances.
Unmodified Starch
[0051] Biochemically, starch comprises two polymeric carbohydrates
known in the art as amylose and amylopectin. Amylose is an
.alpha.(1,4)-linked glucose, polymer which is essentially a linear
chain without branching. Amylopectin on the other hand, is a
branched glucose polymer in which branch chains are linked to the
main chain of .alpha.(1,4)-linked polymer by
.alpha.(1,6)-linkages.
[0052] As is known in the art, starch, in its raw state, is
typically found in the form of solid, dense granules. The granules
typically occur in a size range that is between about 2 microns
(e.g., in wheat starch), to over about 100 microns (e.g., in potato
starch (see e.g., Cameron and Donald (1992) Polymer
33:2628-2635)).
[0053] Starch granules hydrate in aqueous solution, swelling as
much as about 10% in volume. Additional swelling occurs when an
aqueous suspension of granules is heated, until a temperature is
reached where there is a transition from organization to
disorganization. This is known as the gelatinization temperature
and typically occurs over a range of about 10.degree. C.
[0054] In plants, native starch is synthesized by a series of
enzymatic reactions (see e.g., Advances in Food and Nutrition
Research, Vol. 41 supra; Martin and Smith (1995) Plant Cell.
7:971-985; Myers et al., (2000) Plant Physiol. 122: 989-997). Genes
or cDNAs of most starch biosynthetic enzymes from corn, potato,
barley, and wheat have been cloned, and the cloned genes have been
used to over- or under-express starch biosynthetic enzymes (see
e.g., Stark, D. M., et al., (1992) Science 258:287; and Flipse, E.,
et al., (1994) Theor. Appl. Genet. 88:369). Thus, in an exemplary
embodiment, starch foam microparticles comprise starch from a
transgenic plant that expresses one or more cloned starch
biosynthetic genes.
[0055] The relative proportions of amylose and amylopectin differ
in starches derived from different species and different cultivars
within species. For example, amylose content of wheat starch is
about 0% for waxy wheat cultivars and about 22-30% (about 29% on
average) for normal (non-waxy) wheat cultivars, and high amylose
wheat cultivars are also known (see e.g., U.S. Pat. 7,001,939). In
some maize cultivars the com starch has an amylose content as high
as about 60-70%.
[0056] The amylose and amylopectin content of starch can be
measured by methods known in the art. In exemplary embodiments,
amylose content is measured by the colorimetric methods (see e.g.,
Kuroda et al. Jpn. J. Breed. 39 (Suppl. 2):142-143, (1989)) and/or
by amperometric titration (see e.g., Fukuba and Kainuma,
"Quantification of Amylose and Amylopectin" in: Starch Science
Handbook, Nakamura M. and Suzuki S., eds Tokyo: Asakura Shoten, pp
174-179, (1977)). Starch concentration of solutions are determined
by any method known in the art e.g., by the phenol-sulfuric acid
method (Dubois et al., (1956) Anal. Chem. 28:350-356) with glucose
as a standard.
[0057] Starch structures also differ in different species and in
different cultivars within species. For example, barley and wheat
amylopectins have larger portions of short branch chains (6 to 14
glucose units), and proportionally fewer branch chains of 11 to 22
glucose units when compared to e.g., maize amylopectin (see e.g.,
Jane et al., (1999) Cereal Chem. 76 (5): 629-637; and Song and
Jane, (2000) Carbohydrate Polymers. 41:365-377).
[0058] In accordance with the differences in starch structure and
composition, the size, shape, and gelatinization temperature of raw
starch granules also vary based on the botanical source of the
starch. For example, tapioca starch granules typically vary in
diameter from between about 5 microns to about 35 microns, potato
starch from between about 15 microns to about 100 microns, maize
from between about 5 microns to about 25 microns, and rice starch
granules vary from, between about 3 microns to about 8 microns in
diameter. Shapes typically include various, but are not limited to
near perfect spheres, flattened ovoids, elongated disks, and
polygons, and are characteristic of the source of the raw starch
granule. Thus, a person of skill in the art can identify the plant
source of a starch by observing the size and shape of the raw
starch granule e.g., with the aid of a microscope.
[0059] As noted above, starch is found in nearly every type of
plant tissue including, but not limited to the fruit, seeds, stems,
leaves, rhizomes and/or tubers. Isolation of starch from plants is
achieved by any of numerous methods well known in the art.
Exemplary methodology is disclosed in e.g. Advances in Food and
Nutrition Research, Vol. 41 supra; Starch Chemistry and Technology,
R. L. Whistler ed., Academic Press (1984); and Starch: Properties
and Potential, Galliard, T., ed., John Wiley and Sons (1987).
Modified Starch
[0060] Modified starch refers to starch that has been treated in
order to modify one or more of its physical or chemical properties.
Modification is brought about by any means known in the art e.g.,
including, but not limited to chemical modification, physical
modification, modification by biotechnological methods, and
traditional plant breeding methods (see e.g., Starch in Food:
Structure, Function and Applications, Ann-Charlotte Eliasson, Ed.
CRC Press, 2004).
[0061] Chemical modification typically alters the arrangement of
glucose chains in the starch granules, and/or introduces additional
chemical groups to the starch e.g., phosphate. Chemical
modification can be achieved by any method known in the art (see
e.g., Tomasik P, and Schilling C H. (2004) Adv. Carbohydr. Chem.
Biochem. 59:175-403). Physical processes, e.g., heat, are also used
to modify the characteristics of the starch. Starch is also
frequently modified enzymatically, e.g., to promote reorganization
of the glucose chains in the starch. Traditional plant breeding and
modern biotechnology methods are also used to modify starch. For
example in exemplary embodiments breeding methods are used to
manipulate the type of starch made by different plants e.g., by
modifying the enzymes responsible for making the "branches" in
amylopectin to influence the structure of the amylopectin made by
the plant.
[0062] Exemplary modified starches include, but are not limited to
pregelatinized starches, acid, modified starches, cationic
starches, starch esters, cross-linked starches,
hypochlorite-oxidized starches, hydroxyalkyl starches and/or starch
phosphate monoesters.
Starch Foam Microparticles
[0063] In an exemplary embodiment, the invention provides starch
foam microparticles. Starch foam microparticles comprise porous
solid starch foam comprised of a network of air-filled cells/pores.
In an exemplary embodiment, starch foam microparticles absorb
non-aqueous liquids and after doing so, the population of starch
foam microparticles remains as a free flowing powder.
[0064] Although starch, in its native form, is a free flowing
powder native starch powder is distinguished from powders
comprising starch foam microparticles by virtue of the fact that
native starch powder is comprised of solid particles of starch
whereas, in contrast, starch foam microparticles are a porous
foam.
[0065] In one exemplary embodiment, starch foam microparticles have
a diameter of less than or equal to about 50 microns (.mu.m) at
their widest point. In one exemplary embodiment, a population of
starch foam microparticles of a specified size e.g., a population
of starch foam microparticles that are at less than or equal to
about 50 .mu.m diameter at their widest point, is a population
wherein at least about 75% of the starch foam microparticles
comprising the population are of the specified size. In other
exemplary embodiments, at least about 80%, at least about 85%, at
least about 90%, at least about 91%, at least about 92%, at least
about 93%, at least about 94%, at least about 95%, at least about
96%, at least about 97%, at least about 98%, at least about 99%, at
least about 100%, of the starch foam microparticles comprising the
population are of the specified size. In other exemplary
embodiments, starch foam microparticles have a diameter of less
than or equal to about 45 .mu.m, less than or equal to about 40
.mu.m, Or less than or equal to about 35 .mu.m. In another
exemplary embodiment, starch foam microparticles have a diameter of
less than or equal to about 30 .mu.m. In another exemplary
embodiment, starch foam microparticles have a diameter of less than
or equal to about 25 .mu.m. In another exemplary embodiment, starch
foam microparticles have a diameter of less than or equal to about
20 .mu.m. In other exemplary embodiments, starch foam
microparticles have a diameter of less than or equal to about 15
.mu.m, about 10 .mu.m, or about 5 .mu.m. In still other exemplary
embodiments, starch foam microparticles have a diameter of less
than or equal to about 4 .mu.m, about 3 .mu.m, about 2 .mu.m, about
1 .mu.m, about 0.5 .mu.m, or about 0.1 .mu.m.
[0066] Starch foam microparticles are low density. Native starch
granules have a density that is typically about 1.4 g/cm.sup.3 or
more. Starch foam microparticles are porous, and thus typically
have a density that is less than about 1.4 g/cm.sup.3. Typically,
the density of starch foam microparticles, is in a range that is
less than about 1.3 g/cm.sup.3 and greater than or equal to about
0.10 g/cm.sup.3. In one exemplary embodiment, starch foam
microparticles have a density that is less than or equal to about
1.0 g/cm.sup.3. In another exemplary embodiment, starch foam
microparticles have a density that is less than or equal to about
0.75 g/cm.sup.3. In other exemplary embodiments, starch foam
microparticles have a density that is less than or equal to about
0.60 g/cm.sup.3, less than or equal to about 0.50 g/cm.sup.3, less
than or equal to about 0.40 g/cm.sup.3, or less than or equal to
about 0.35 g/cm.sup.3. In another exemplary embodiment, starch foam
microparticles have a density that is in a range that is between
about 0.14 g/cm.sup.3 to about 0.34 g/cm.sup.3. In another
exemplary embodiment, starch foam microparticles have a density
that is less than or equal to 0.32 g/cm.sup.3. In other exemplary
embodiments, starch foam microparticles have a density that is less
than or equal to about 0-30 g/cm.sup.3 , and/or less than or equal
to about 0.20 g/cm.sup.3.
[0067] In an exemplary embodiment, starch foam microparticles are
used as carriers for non-aqueous liquids. Native starch particles
can be loaded with a thin film of non-aqueous liquid. However, only
a small percentage of the non-aqueous liquid can be loaded into the
native starch powder before the flow properties of the powder begin
to change. Typically, for native starch powders, the amount of
non-aqueous liquid that can be loaded onto a native starch granule
is about 5% on a weight basis. In contrast, in an exemplary
embodiment, starch foam microparticles can be loaded with at least
about 25% non-aqueous liquid on a weight basis, and still remain a
free-flowing powder. Thus, in one exemplary embodiment, starch foam
microparticles are loaded with a non-aqueous liquid e.g., one of
more essential oils. In one exemplary embodiment, the non-aqueous
liquid is a food for honey bees. In another exemplary embodiment,
the non-aqueous liquid is a mitocide. In another exemplary
embodiment, the non-aqueous liquid is a pharmaceutical. In another
exemplary embodiment, the non-aqueous liquid is a fragrance.
[0068] In another exemplary embodiment, starch foam microparticles
are used as fillers in plastic composites.
Production of Starch Foam Microparticles
[0069] Starch foam microparticles are typically prepared from a
starch melt. Once formed, the starch melt is treated to exchange
the water in the melt with air. The exchange takes place under
conditions that minimize the effects of surface tension and thus
maintain the integrity of the network of cells in the foam
structure (see e.g., Glenn and Irving (1995) Cereal. Chem. 72,
155-161 and U.S. Pat. No. 5,958,58.9; Microcellular Starch Based
Foams. In Agricultural Materials as Renewable Resources; Fuller,
G., McKeon, T. A., Bills, D. D., Eds., ACS Symposium Series 647,
American Chemical Society, (1996) 88-106; and Glenn and Irving,
supra).
[0070] Although starch foam microparticles can be produced by any
method known in the art, in an exemplary embodiment, solvent
exchange is used to provide conditions that minimize the effects of
surface tension and maintain the integrity of the network of cells
in the foam structure. Any suitable solvent may be used for solvent
exchange. In an exemplary embodiment the solvent is a water
miscible solvent. In one exemplary embodiment, the water miscible
solvent is an alcohol e.g., methanol, ethanol, isopropanol. In
another exemplary embodiment the water miscible solvent is a ketone
e.g., acetone, ethyl acetate.
[0071] Typically, as noted above, starch foam microparticles are
prepared by first forming a starch melt. In an exemplary
embodiment, the initial concentration of starch to water for
forming a melt is in a range of concentration that is between about
1% to about 20% starch, weight by volume. In other exemplary
embodiments, the concentration range varies according to the type
of starch used. The exact amount for any given application is
readily determined by one of skill in the art e.g., by way of trial
runs, having the benefit of this disclosure.
[0072] In one exemplary embodiment, the starch is unmodified wheat
starch, and the concentration of starch to initial water in the
melt is between about 6% to about 10% weight by volume. In another
exemplary embodiment, the concentration of unmodified wheat starch
is about 8%. In another exemplary embodiment, the starch is
unmodified high amylose starch e.g., high amylose corn starch, high
amylose wheat starch etc. In one exemplary embodiment, the
concentration of unmodified high amylose starch to initial water
for preparation of a melt is in a range that is between about 5% to
about 8%. In another exemplary embodiment, the concentration of
unmodified high amylose starch is about 8%. In another exemplary
embodiment, the concentration of starch in the suspension is in a
range that is between about 2% to about 5% by weight.
[0073] Starch foam microparticle size is influenced by the
temperature at which the melt is processed. For example, in FIG.
1(C) the scanning electron micrograph illustrates that when starch
is heated in water to a temperature of about 95.degree. C., for
about 30 minutes, the starch gelatinizes but leaves a swollen
starch envelope or remnant that is larger than the size of the
original starch granule. Without being bound by theory, it is
believed that the starch granule remnant limits the particle size
that may be obtained. Typically, heating the starch melt to over
about 100.degree. C. e.g., 101.degree. C., 102.degree. C.,
103.degree. C., 104.degree. C., 105.degree. C., 106.degree. C.,
107.degree. C., 108.degree. C., 109.degree. C., or more, will
completely dissolve the envelope and allow the formation of smaller
microparticles (typically less than or equal to about 50 microns
(.mu.m)). Higher temperatures e.g., at least about 110.degree. C.,
111.degree. C., 112.degree. C., 113.degree. C., 114.degree. C.,
115.degree. C., 116.degree. C., 117.degree. C., 118.degree. C.,
119.degree. C., or 120.degree. C. cf. FIG. 1(F), or more, up to
about 150.degree. C., completely dissolve all starch granule
remnants. Thus, the particle size can be reduced to a still smaller
diameter e.g., typically less than or equal to about 40 .mu.m, less
than or equal to about 30 .mu.m, less than or equal to about 20
.mu.m, less than or equal to about 10 .mu.m, less than or equal to
about 5 .mu.m, less than or equal to about 1 .mu.m, and/or less
than or equal to about 0.5 .mu.m. In general, the higher the
temperature used to form the melt, the smaller and tighter the size
range of microparticles obtained. However, starch will begin to
degrade at temperatures above 200.degree. C. Therefore, to achieve
the smallest starch particles one of skill in the art would
appreciate that the temperature should be high enough to dissolve
the starch envelope, but low enough to prevent degradation of the
starch e.g., around 120.degree. C.
[0074] In an exemplary embodiment, starch microparticles, are made
by pumping the starch melt through an atomizing nozzle to form very
small droplets. In this embodiment, viscosity of the starch melt is
kept low to facilitate pumping of the melt through the atomizing
nozzle. In an exemplary embodiment, the concentration of starch is
in a range that is between about 2% to about 5%. In this
embodiment, the droplets fall froth the nozzle by gravity into a
container of water miscible solvent e.g., an alcohol, and are there
collected and further dehydrated in additional changes of solvent.
Typically, this method produces spherical, or approximately
spherical porous starch foam microparticles.
[0075] In another exemplary embodiment, the starch melt is formed
as disclosed above, and then the resulting melt is poured into a
container and allowed to cool and gel. In an exemplary embodiment
the starch concentration is in a range that is between about 8% to
about 12%. The gel is then placed in a container of water miscible
solvent and thoroughly sheared with a high-speed mixer. The
shear-formed particles are further dehydrated in additional changes
of water miscible solvent. Typically this method produces starch
foam microparticles that are angular in shape.
Loading Starch Foam Microparticles With Non-Aqueous Liquid
[0076] Starch foam microparticles are loaded with non-aqueous
liquids by any method known in the art. In an exemplary embodiment,
starch foam microparticles are mixed with non-aqueous liquid and
allowed to absorb the liquid. In one exemplary embodiment the
non-aqueous liquid comprises a mixture of non-aqueous liquids. In
another exemplary embodiment the non-aqueous liquid comprises a
carrier liquid that is evaporated off after loading of the starch
microparticles.
[0077] In one exemplary embodiment, starch foam microparticles are
loaded with 25% non-aqueous liquid by mixing a powder comprising
starch foam microparticles with non-aqueous liquid such that the
non-aqueous liquid comprises about 25% of the mixture. The mixture
is allowed to stand in order to allow the starch foam
microparticles to absorb the liquid. In another exemplary
embodiment, starch foam microparticles are loaded with about 24%
non-aqueous liquid, about 23% non-aqueous liquid, about 22%
non-aqueous liquid, about 21% non-aqueous liquid, 20% non-aqueous
liquid by mixing a powder comprising starch foam micro particles
with non-aqueous liquid such that the non-aqueous liquid comprises
20% of the mixture. In other exemplary embodiments, starch foam
microparticles are loaded with about 19% non-aqueous liquid, about
18% non-aqueous liquid, about 17% non-aqueous liquid, about 16%
non-aqueous liquid, about 15% non-aqueous liquid, about 14%
non-aqueous liquid, about 13%, non-aqueous liquid, about 12%
non-aqueous liquid, about 11% non-aqueous liquid, about 10%
non-aqueous liquid, or less than about 10% non-aqueous liquid.
Similarly, in other embodiments starch foam microparticles are
loaded with a non-aqueous liquid by mixing the desired amount of
non-aqueous liquid to be loaded with an appropriate amount of
powder comprising starch foam microparticles.
Powders
[0078] Particulate and powdered materials are useful in a wide
variety of situations. For example, free-flowing powders facilitate
the handling and packaging of product on a commercial scale.
Free-flowing powders are also easily mixed and blended with other
powders. Powders are easy to scoop from a container and are easy to
apply and disperse e.g., in a honeybee colony. Thus, from an
application perspective, powders are easier and less labor
intensive to handle than other solid forms e.g., solid blocks.
[0079] As is known in the art, powders have numerous measurable
physical properties including e.g., properties associated with the
particles e.g., particle size distribution, particle density; and
bulk powder properties e.g., flowability.
[0080] Flowability is an exemplary bulk property of powders.
Numerous factors affect the flowability e.g., humidity, moisture
absorption, and aeration. For example, with many powders, the
addition of excess air (aeration) reduces packing density as well
as the interparticulate forces, thereby improving flowability of
the powder. In contrast, exposure to moisture tends to reduce
flowability since the moisture displaces the air, and increases the
various cohesive forces between particles of the powder. In some
cases where the particle is capable of moisture absorption itself,
the particle weight may also increase. Thus, exposure to moisture
typically decreases flowability. Powder flowability is readily
measured by one of skill in the art using known methods (see e.g.,
U.S. Pat. No. 6,065,330, U.S. Patent Application Publication No.
20060070428, and A Laboratory Handbook of Rheology, Chapter III,
Van Wazer et al., Interscience (1966)).
[0081] In one exemplary embodiment, the invention provides a powder
comprising starch foam microparticles wherein the starch foam
microparticles absorb at least about 25% by weight of a non-aqueous
liquid and the powder remains free flowing.
[0082] In another exemplary embodiment, powders comprising starch
foam microparticles having a small particle size e.g.,
microparticles that are less than or equal to 20 microns in
diameter at their widest point, facilitate ingestion by honeybees.
In another exemplary embodiment powders comprising starch foam
microparticles are used in the production of composite films. In
another exemplary embodiment, powders comprising starch foam
microparticles are used as chemical delivery systems. In another
exemplary embodiment, powders comprising starch foam microparticles
are used in pharmaceutical compositions.
Chemical Delivery Systems
[0083] In exemplary embodiments the starch foam microparticles are
chemical delivery systems. The delivery system can be used with any
non-aqueous chemical e.g., an oil, 2-heptanone, hexane, alcohol
etc. . . . Thus, in an exemplary embodiment, the starch foam
microparticles provide a chemical delivery system for an oil. In
another exemplary embodiment, the starch foam microparticles are
chemical delivery system for an essential oil. In another exemplary
embodiment, the starch foam microparticles provide a chemical
delivery system for agrochemical e.g., 2-heptanone. In another
embodiment the starch foam microparticles are chemical delivery
system for at least one chemical effective for controlling Varroa
mites in bee colonies.
Oils
[0084] In exemplary embodiments the starch foam microparticles are
loaded with at least one oil. The oil is either a volatile or
non-volatile oil. In an exemplary embodiment the oil is a carrier
oil for a volatile chemical. In another exemplary embodiment, the
oil is a member selected from the group consisting of a vegetable
oil, a petroleum based oil, a synthetic oil, and a plant extracted
oil. In another exemplary embodiment, the oil is a volatile oil,
e.g., an essential oil.
Essential Oils
[0085] Essential oils, also known as ethereal plant oils, are
natural substances found in many aromatic plants-herbs, flowers,
and trees. Essential oils are present in various parts of the plant
e.g., leaves, seeds, flowers, and bark and give the plant its
particular signature scent. In Nature, plants produce essential
oils to e.g., attract bees for pollination, to repel insects, and
to help protect the plant from disease. As is known in the art,
extracted essential oils, are typically produced in the form of
concentrated, hydrophobic liquids that comprise the volatile
aromatic compounds from the plant. Extracted essential oils offer a
wide range of therapeutic and other possibilities for human use
(see e.g., E. Guenther, The Essential Oils, vol. 4, Van Nostrand,
N.Y., (1950) and E. Guenther, The Essential Oils, vol. III (Van
Nostrand, N.Y., 1949)). Essential oils can be obtained by any
method known in the art e.g., essential oils can be extracted or
manufactured.
[0086] In an exemplary embodiment, catnip oil is absorbed by/loaded
onto the starch foam microparticles. In one exemplary embodiment,
catnip oil is absorbed by/loaded onto the starch foam
microparticles and used to attract honeybees.
[0087] In one exemplary embodiment, cinnamon oil is absorbed
by/loaded onto the starch foam microparticles. In another exemplary
embodiment cinnamon oil is absorbed by/loaded onto the starch foam
microparticles and used an attractant for bees. In another
exemplary embodiment cinnamon oil is absorbed by/loaded onto the
starch foam microparticles as an attractant for bees and as a
miticidal agent. In another exemplary embodiment cinnamon oil is
absorbed by/loaded onto an insecticide. In another exemplary
embodiment cinnamon oil is absorbed by/loaded onto a
fragrance/perfume.
[0088] In one exemplary embodiment, clove oil, is absorbed
by/loaded onto the starch foam microparticles.
[0089] In another exemplary embodiment, camphor oil is absorbed
by/loaded onto the starch foam microparticles.
[0090] In another exemplary embodiment, Citronella Oil, which in an
exemplary embodiment, is obtained from fresh grass of Cymbopogon
species e.g., Cymbopogon nardus is absorbed by/loaded onto the
starch foam microparticles. In one exemplary embodiment, citronella
oil is a perfume/fragrance. In another exemplary embodiment,
citronella oil is an insect repellent.
[0091] In another exemplary embodiment, eucalypt oil, or dinkum
oil, which in an exemplary embodiment, is obtained from fresh
leaves of Eucalyptus species e.g., Eucalyptus globulus, is absorbed
by/loaded onto the starch foam microparticles. In an exemplary
embodiment eucalypt oil is an inhalation expectorant.
[0092] In another exemplary embodiment, patchouli oil, which in an
exemplary embodiment, is obtained from Pogostemon species e.g.,
Pogostemon cablin is absorbed by/loaded onto the starch foam
microparticles. In an exemplary embodiment, patchouli oil is a
perfume. In another exemplary embodiment, patchouli oil is an
insect repellent. In another exemplary embodiment patchouli oil is
a miticidal agent.
[0093] In another exemplary embodiment, peppermint oil, which in an
exemplary embodiment, is obtained from Mentha species e.g., Mentha
piperita, is absorbed by/loaded onto the starch foam
microparticles.
[0094] In another exemplary embodiment, rosemary oil, which in an
exemplary embodiment, is obtained from Rosmarinus species, is
absorbed by/loaded onto the starch foam microparticles.
[0095] In another exemplary embodiment, spearmint oil which in an
exemplary embodiment, is obtained from Mentha species e.g., Mentha
spicata, is absorbed by/loaded onto the starch foam
microparticles.
[0096] In another exemplary embodiment, tea tree oil, which in an
exemplary embodiment, is obtained from leaves of Melaleuca species
e.g., Melaleuca alternifolia is absorbed by/loaded onto the starch
foam microparticles. In one exemplary embodiment, tea tree oil is
dispensed by the starch foam microparticles as a miticidal agent.
In another exemplary embodiment tea tree oil is dispensed by the
starch foam microparticles as an attractant for bees and as a
miticidal agent. In still another exemplary embodiment, tea tree
oil is an insecticide.
[0097] In another exemplary embodiment, thyme oil, which in an
exemplary embodiment, is obtained from Thymus species e.g., Thymus
vulgaris, is absorbed by/loaded onto the starch foam
microparticles. In one exemplary embodiment thyme oil is absorbed
by/loaded onto the starch foam microparticles as a miticidal agent.
In another exemplary embodiment thyme oil is an attractant for bees
and a miticidal agent. In another exemplary embodiment thyme oil is
an insecticide.
[0098] In another exemplary embodiment, wintergreen oil, is
absorbed by/loaded onto the starch foam microparticles. In one
exemplary embodiment wintergreen oil is a miticidal agent. In
another exemplary embodiment wintergreen oil is an attractant for
bees and a miticidal agent. In another exemplary embodiment
wintergreen oil is an insecticide.
[0099] In some exemplary embodiments, more than one essential oil
is combined to make a mixture that is absorbed by/loaded onto the
starch foam microparticles. In one exemplary embodiment, the
mixture comprises clove oil. In another embodiment, the mixture
comprises thyme oil. In another embodiment, the mixture comprises
clove oil and thyme oil.
[0100] In other embodiments sweet almond oil, apricot kernel oil,
grapeseed oil, avocado oil, peanut oil, olive oil, pecan oil,
macadamia nut oil, sesame oil, evening primrose oil, walnut oil and
wheat germ oil are carrier oils absorbed and/or dispensed by the
starch foam microparticles.
Honey bees
[0101] An exemplary application for starch foam microparticles is
in the honeybee industry. Bees are insects of the order
Hymenoptera, Superfamily Apoidea, and comprise a group of about
20,000 species of bees that live throughout the world. Honeybees
are of the genus Apis and belong to the family Apidae. At least
four species of honeybee are commonly recognized: the dwarf, or
midget, bee Apis florae; the giant, or rock, bee Apis dorsata; the
oriental (Indian, Chinese, Japanese, etc.) bee Apis cerana; and the
common (European, African, etc.) honey bee Apis mellifera. The
existence of another giant bee, Apis laboriosa, has recently been
confirmed.
[0102] Honeybees, in particular Apis mellifera, are the primary
pollinators of most commercial crops in North America, and are the
most widely used and actively managed pollinators in the world.
Indeed, Apis mellifera produce more than $270 million of honey and
wax and pollinate over $14 billion of crops annually in the U.S.
alone. Thus, honeybees have a significant economic impact, and
therefore, maintaining healthy bee colonies is an essential aspect
of much agricultural practice.
[0103] Unfortunately, a serious threat to honeybees is the
parasitic mite, Varroa destructor. Varroa mites deform developing
bees, cause weight loss and premature death and transmit various
viral diseases. Varroa mite infestations can completely destroy
infected honeybee colonies in as little as a few weeks when
remedial measures are not taken. Indeed beekeepers and the
beekeeping industry worldwide have reported epidemic losses of
managed bee colonies ranging from 25 to 80% (see e.g., U.S. Pat.
No. 6,843,985; Oldroyd, B. P. (1999) Tree 14 (8):312-315; Contzen,
C. et al. (2004) Thermochimica Acta, 415:115-121; and De Jong, D.
et al. (1982) J. Apic. Res., 21: 165-167). Thus, Varroa destructor
has had a catastrophic effect on populations of managed and feral
honey bee colonies.
[0104] Naturally, beekeepers and the beekeeping industry have taken
steps to attempt to control infestations of Varroa. Current methods
include, but are not limited to biotechnical, genetic and chemical
means (see e.g., Kanga, L. H. B. et al. (2002) Journal of
Invertebrate Pathology 81, 75-184). Biotechnical methods include,
but are not limited to measures such as mite trapping devices.
While trapping devices are effective, they are also labor intensive
and not particularly efficient (Kanga supra). Chemical means of
control include, but are not limited to an EPA-registered plastic
strip impregnated with the contact pyrethroid pesticide,
fluvalinate (Apistan.RTM. strips). Unfortunately however, some
populations of Varroa have shown resistance to this pesticide (see
e.g., Elzen, P. J. and Westervelt, D. (2002) American Bee Journal
142 (4): 291-292; Elzen, et al. (1999) Apidologie 30 (1): 13-17;
and Macedo, P. A et al. (2002) American Bee Journal 142 (7):
523-526).
[0105] The organophosphate coumaphos (CheckMite+.RTM.) has been
used to control fluvalinate-resistant Varroa, but mites resistant
to coumaphos are already evident (Elzen & Westervelt 2002
supra), and there are a number of sites across the U.S. where
Varroa appears to be resistant to both coumaphos and fluvalinate
(see e.g., Elzen, G. W. (2001), In Biopesticides and Pest
Management, Campus Books International, New Delhi, pp. 258-261).
Furthermore, fluvalinate and coumaphos are lipophyllic and can
contaminate honey, beeswax and other hive products (see e.g.,
Wallner, K. (1999) Apidologie 30: 235-248).
[0106] Therefore, what is needed in the art are effective methods
for controlling Varroa that are nontoxic to humans and to which the
mites do not readily become resistant.
[0107] Ethereal plant oils, also known as essential oils, are known
in the art to be capable of controlling bee mites (see e.g.,
Calderone et al. (1997) J. Econ. Entomol. 90:1060-1086; Colin M. E.
(1990) J. Applied Entomol. 110:19-25; Imdorf et al. (1999) Apiacta
32 (3): 89-91; Sammataro et al. (1998) Amer. Bee J. 138: 681-685).
Indeed, essential oils e.g., clove, thyme, wintergreen, patchouli,
tea tree oil, or combinations thereof, can either kill, or
adversely affect Varroa mites thereby facilitating their control
and/or elimination from bee colonies.
[0108] Commercial products that incorporate essential oils have
been developed. One exemplary commercial essential oil product,
Apivar.RTM. (thymol and camphor based), is available in the United
States for Varroa control. Apivar.RTM. is designed to create a
plume of oil vapors that kill the Varroa on adult bees.
Unfortunately however, vapor-phase oil products tend to exhibit a
high variation in oil volatility under different environmental
conditions. Consequently, mite control with a vapor phase delivery
system is unpredictable. Thus, prior to the discovery and
development of the starch foam microparticles disclosed herein, a
predictable system for effective delivery of essential oils to bee
colonies did not exist.
[0109] Therefore, in an exemplary embodiment, the invention
provides starch foam microparticles that absorb a non-aqueous
solution comprising at least one essential oil that is effective
for controlling Varroa mites. In another exemplary embodiment,
essential oils are loaded on the starch foam microparticles at an
amount of about 25% weight/weight. In another exemplary embodiment
essential oils are loaded on the starch foam microparticles at an
amount of about 24% weight/weight. In other exemplary embodiments
essential oils are loaded on the starch foam microparticles at an
amount of about 23% weight/weight, about 22% weight/weight, about
21% weight/weight, about 20% weight/weight, about 19%
weight/weight, about. 18% weight/weight, about 17% weight/weight,
about 16% weight/weight, about 15% weight/weight, about 14%
weight/weight, about 13% weight/weight, about 12% weight/weight,
about 1.1% weight/weight, about 10% weight/weight, about 9%
weight/weight, about 8% weight/weight, about 7% weight/weight,
and/or about 6% weight/weight.
[0110] In other exemplary embodiments, essential oils are loaded on
the starch foam microparticles at an amount at an amount of about
5% weight/weight, about 4% weight/weight, about 3% weight/weight,
about 2% weight/weight, about 1% weight/weight, and or about 0.5%
weight/weight. In one exemplary embodiment, loading about 25%
essential oils by weight, the starch foam microparticles remain in
the form of a free flowing powder that exhibits no clumping.
[0111] Bees readily consume particles that are small enough to get
into and traverse the proboscis. Typically, for easy consumption by
bees, the particle is equal to or smaller than about 20 .mu.m.
Fortunately, in exemplary embodiments, the starch foam
microparticles are small enough for bees to eat. Thus, in one
exemplary embodiment, starch foam microparticles are equal to or
less that about 20 .mu.m in diameter at their widest point.
[0112] In an exemplary embodiment, the loaded, free flowing starch
foam microparticles are mixed with other bee attractants e.g.,
powdered sugar, and the resulting mixture is fed to the bees.
Without being bound by theory it is believed that bees utilize the
particles and the encapsulated oils as a source of food, and the
ingested oil provides systemic control of the parasitic mites.
[0113] In one exemplary embodiment, Varroa mites are killed by
direct contact with at least one essential oil that is fed to the
bees in the form of loaded starch foam microparticles. In this
embodiment, mites come in contact the starch encapsulated oils on
the exterior of the bee, much the same way mites pick up cuticular
hydrocarbons from the bees on a routine basis. Thus, in an
exemplary embodiment, when the bees are fed the starch foam
microparticle encapsulated oils, the mites pick up a low level of
the oils from contact with the bees, and are incapacitated.
[0114] In another exemplary embodiment, Varroa mites are controlled
by impaired reproduction. In this exemplary embodiment, the starch
foam microparticles comprising at least one essential oil are
ingested by nurse bees. When the nurse bees feed larvae, essential
oils in the bee milk and communal food are ingested by the larvae.
When female Varroa mites feed on treated larvae or larval food at
the bottom of the cell, they ingest the essential oils and this
adversely affects their reproduction. In one exemplary embodiment,
reproduction is adversely affected when the female mites are unable
to lay eggs. In another exemplary embodiment, reproduction is
adversely affected when the essential oils are present in lower
concentrations, which allows the females to lay eggs, but delays
development of immature mites and thus, ultimately results in death
of the mites while they are still immature. Thus, starch foam
microparticles provide means for systemically controlling of Varroa
mites in bees and in bee colonies using essential oils.
[0115] In another exemplary embodiment, starch foam microparticles
absorb a chemical that is not an essential oil, and that has
miticidal properties e.g., pyrethroids, organophosphates, and/or
2-heptanone. In an exemplary embodiment, 2-Heptanone is absorbed by
the starch foam microparticles. 2-Heptanone vapor acts as an
attractant for Varroa mites at low concentrations but has miticidal
properties at higher concentrations (see e.g., U.S. Pat. No.
6,843,985).
[0116] Thus, in exemplary embodiments, starch foam microparticles
microparticles provide a food source, both alone and empty and/or
in combination with an essential oil, and at the same time loaded
starch foam microparticles are used to control infestations of
Varroa mite in honeybees and honeybee colonies.
Pharmaceuticals
[0117] In an exemplary embodiment starch foam microparticles are a
carrier for a pharmaceutical. In one exemplary embodiment starch
foam microparticles provide a vehicle oral administration of
pharmaceutical compositions to persons in need thereof e.g., as
particles within a capsule. However, many drugs have to be
administered by injection, since they are either subjected to
degradation or are insufficiently absorbed when they are
administered orally, nasally or by the rectal route. A drug
preparation intended for parenteral administration should be
biocompatible and biodegradable and the degradation products should
be non-toxic. In addition particulate drugs intended for injection
should be small enough to pass through an injection needle.
Typically particulate drugs intended for injection are smaller than
200 .mu.m at their widest point. Therefore, in another exemplary
embodiment, starch foam microparticles provide a vehicle for
parenteral administration of pharmaceutical compositions to persons
in need thereof.
[0118] Starch foam microparticles can be used with any nonaqueous
formulation/preparation/emulsion of at least one pharmaceutical
e.g., Anti-asthmatics e.g., Terbutaline; Antibacterials e.g.,
penicillin; Antifungals e.g., Fluconazole; Anti-inflammatory agents
e.g., Benzidamine, Pyroxicam; Antivirals e.g., Acyclovir.
Fragrance Dispensers
[0119] People perceive objects and other people to a significant
degree in part through their sense of smell, and their behavior is
profoundly affected by this. Even small concentrations of aromas
can influence people's moods and, consequently, their behavior.
Therefore, in an exemplary embodiment the invention provides starch
foam microparticles that absorb a volatile chemical or substance,
wherein the chemical or substance is fragrant to humans e.g., an
essential oil or synthetic perfume e.g., "Pleasures" by Este
Lauder.
Plastic Products And Plastic Films
[0120] Fillers are routinely used in making plastic composite films
and injection molded articles. One recent technological
breakthrough in the plastics industry is the development of polymer
nanocomposites, i.e. plastics resins reinforced with nanosize
additives. The properties of nano-composite materials are
influenced by the properties of the individual starting materials
and their morphology and interfacial characteristics. Thus, in an
exemplary embodiment, starch foam microparticles are used as a
filler in composite plastic products e.g., thermoformed plastic
products, and/or extruded plastic products. Thermoformed plastic
products are known in the art (see e.g., co-pending U.S. patent
application Ser. No. 11/431,496 filed May 9,2006). Plastic
composite products comprising starch foam microparticles can be
formed into any shape or form e.g., squares, circles, triangles,
rectangles, cubes, pyramids, stars, chairs, loungers, beds, boxes,
spheres, boats, rods, beams, balls, cones, u-shape, horseshoe,
animal, car, plant, insect, etc, that is, any convenient and/or
desirable shape.
[0121] Particle size of the filler is an important parameter in
determining how much filler can be added to a plastic while still
retaining the functionality of the material. Particle size is
particularly important in plastic films because of the extremely
small sample thickness of a film. For example, a large filler
particle that spanned the thickness of the film would create a weak
point in the film. Thus large particles are not an ideal choice for
composite plastic films.
[0122] In contrast, very small particles can be added without
compromising the film properties since the small particles will not
span the thickness of the film. Furthermore, fillers with very
small particles can be added in greater amounts without
compromising the film properties because the small particles will
not span the thickness of the film. Additionally, small particles
that can form a very strong interaction with the polymer chains
produce a composite matrix with enhanced performance.
[0123] Therefore, in an exemplary embodiment, the invention
provides starch foam microparticles for the manufacture of
composite plastic films. In one exemplary embodiment, the invention
provides starch foam microparticles for the manufacture of
composite plastic films, wherein the starch foam microparticles are
less than or equal to about 50 microns in diameter at their widest
point. In another exemplary embodiment, the invention provides
starch foam microparticles for the manufacture of composite plastic
films wherein the starch foam microparticles have a diameter at
their widest point which is in the nanometer range e.g., about 100
nm, about 150 nm, about 200 nm, about 250 nm, about 300 nm, about
350 nm, about 400 nm, about 450 nm, about 500 nm, about 550 nm,
about 600 nm, about 650 nm, about 700 nm, about 750 nm, about 800
nm, about 850 nm, about 900 nm, about 950 nm, and/or about 999 nm.
In another exemplary embodiment, starch powders comprising starch
foam microparticles haying a diameter at their widest point which
is in the nanometer range, are added in an amount that is less than
or equal to about 50% on a weight basis to plastic for the purpose
of making composite plastic films. Thus, in exemplary embodiments,
starch foam microparticles having a diameter at their widest point
which is in the nanometer range, are added in an amount that is
about 50% on a weight basis, about 45% on a weight basis, about 40%
on a weight basis, about 35% on a weight basis, about 30% on a
weight basis, about 25% on a weight basis, about 20% on a weight
basis, about 15% on a weight basis, about 10% on a weight basis,
about 5% on a weight basis, about 1% on a weight, or less than
about 1% on a weight basis, to plastic for the purpose of making
composite plastic films. In another exemplary embodiment, the
invention provides starch foam microparticles for the manufacture
of composite plastic films wherein the starch foam microparticles
have a diameter at their widest point which is less than or equal
to about 25% the thickness of the film.
[0124] In another exemplary embodiment, the invention provides
starch foam microparticles that have improved interfacial
interactions with plastic materials. Improved interfacial
interactions can be achieved by any method known in the art (see
e.g., WO03/074604 and Vinidiktova, N. S., et al. (2006) Mechanics
of Composite Materials 42:273-282). In another exemplary
embodiment, the invention provides starch foam microparticles
comprising modified starch, wherein the modification improves the
interfacial interaction between the starch foam microparticles and
the plastic. Modifications to improve interfacial interactions are
known in the art (see e.g., Vinidiktova, N. S., et al. supra).
Starch foam microparticles can be added to any plastic known in the
art e.g., polyethylene, polyvinyl chloride, polyvinylidene;
chloride, polystyrene, polypropylene, plastarch material,
polylactic acid, polyhydroxybutyrate and/or combinations of these
or any known plastics.
[0125] The following examples are offered to illustrate, but not to
limit the invention.
EXAMPLES
Example 1
Preparation of Starch Foam Microparticles I
[0126] The following example illustrates one exemplary method by
which starch foam microparticles are produced.
[0127] Temperature treatments were performed using a 1 L pressure
reactor (Paar Instrument Co., Moline, Ill.) equipped with a mixer
and heat controller (Model 4843). Aqueous starch suspensions (8%,
w/w) were heated at 4.degree. C. min.sup.-1 and stirred
continuously (330 rpm) while heating. Scanning electron micrographs
confirm that when starch is heated in water to a temperature of
about 95.degree. C., the starch gelatinizes but leaves a starch
envelope or remnant that is roughly die size of the original starch
granule cf. FIG. 1(A). The starch granule remnant limits the
particle size that may be obtained. The particle size limitations
are overcome by heating the starch melt to at least about over
100.RTM. C. and or to at least about 120.degree. C. At 120.degree.
C., the starch granule remnants are completely dissolved and the
starch the particle size can be reduced to a much smaller diameter
cf. FIG. 1.
[0128] In this example, a temperature of 120.degree. C. was reached
and held for 10 minutes before the melt was cooled to 80.degree. C.
and poured into molds. The melt was allowed to gel at 5.degree. C.
overnight. The gel was placed into 10 volumes of ethanol (95%) and
sheared with a high shear mixer (e.g., an IKA.RTM. mixer) to
completely disintegrate the gel and disperse it in the ethanol. The
ethanol effectively dehydrated the gel and formed white, opaque
particles. The particles were filtered and resuspended in 100%
ethanol to completely dehydrate the starch particles. The particles
were again filtered and spread on trays and dried at 80.degree. C.
for two hours. The dried starch particles were placed in a mortar
and crushed with a pestle to form a free-flowing, white starch
powder.
Example 2
Preparation of Starch Foam Microparticles II
[0129] The following example illustrates another exemplary method
by which starch foam microparticles are produced.
[0130] Temperature treatments were performed as in Example 1. In
this example, a temperature of 120.degree. C. was reached and held
for 10 min before the melt was pumped through an atomizer. The
atomized starch mist was collected in a container of 100% ethanol.
The starch particles were filtered and resuspended in 100% ethanol
to remove moisture. The starch particles were filtered, dried and
ground in a mortar and pestle as in Example 1. The particles that
resulted were primarily spherical and formed a free-flowing
powder.
Example 3
Plastic Composite Films And Injection Molded Products
[0131] The following Example illustrates the use of starch
microparticles for the manufacture of plastic composite films
and/or injection molded products.
[0132] Powders formed as described in Examples 1 and 2 will be
gravimetrically fed (K tron Soder Model 9475-70057, Pitman, N.J.)
into a Leistritz co-rotating twin-screw (18 mm) extruder (Model MIC
18/GL 30D, Nurnberg, Germany). A second feeder will be used to
meter polyethylene pellets into the extruder. The extruder contains
six heating zones that will be adjusted to
75/95/115/125/125/100.degree. C. in order from the feed port to the
die. The screw speed will be maintained at 60 rpm and the screw
configuration will consist of two sections of kneading blocks
separated by conveying elements.
[0133] The blends will be extruded through a 2 strand (2 mm dia.)
rod die and cut into strands approximately 0.5 m in length. The
strands will be pelletized (.about.2.0 mm, micropelletizer, Model
1, Wayne Machine and Die Co., Totowa, N.J.) and used for blowing
films or injection molding. The shear within the extruder will
effectively disperse the starch microparticles throughout the resin
matrix. Starch powders with nanometer particle size ranges will be
added up to 50% on a weight basis.
Example 4
Controlling Parasitic Mites In Honeybee Colonies-I
[0134] The following Example illustrates the use of starch
microparticles for controlling parasitic mites in honeybee
colonies.
[0135] Powders formed as described in Examples 1 and 2 were
prepared. Thymol oil was blended with 100% ethanol (1:3). Eighty
grams of starch powder were added to sixty grams of the blend of
thymol and ethanol. The starch was air-dried to allow the ethanol
to evaporate and simply leave the residual thymol oil. The product
was a free-flowing powder with no clumping and containing 20%
thymol. This powder was added to other ingredients that were
attractive to honeybees. The honeybees readily consumed the starch
powder blend. The population of parasitic mites was reduced to 10%
of the control.
Example 5
Controlling Varroa Mites In Bee Colonies
[0136] The following example illustrates the use of starch foam
microparticle encapsulated essential oils for the control of Varroa
mites in honeybee colonies.
[0137] Varroa destructor, a parasitic mite of honeybees Apis
mellifera (L.), has had a catastrophic effect on populations of
managed and feral honey bee colonies. Since the economic impact of
bees as pollinators and honey producers is large, the health of bee
colonies is imperative. Therefore, the use of starch foam
microparticle encapsulated essential oils to affect mite control
improves bee health and has beneficial economic consequences.
[0138] The use of starch foam microparticle encapsulated essential
oils is effective for mite control in the contact phase and in the
systemic phase.
[0139] The "contact phase" is the phase where mites come in contact
with the ingested starch encapsulated oils that end up on the
exterior of the bee. This occurs much the same way that mites
typically pick up cuticular hydrocarbons from the bees on a routine
basis. In general, mites have no cuticular hydrocarbons of their
own. Thus, the mites pick up oils from the hair and cuticle of bees
which under the usual conditions thereby limits their detection in
the colony and protects their cuticle. However, without being bound
by theory, it is believed that when the bees are treated with the
encapsulated oils, the mites pick up a low level of the oils from
the bees and this incapacitates the mite.
[0140] The "systemic phase" gets oils into the colony through the
bees eating the encapsulations and subsequently passing them on to
their larvae. FIG. 3 shows the pathway the oils traverse to enter
the larval hemolymph (blood).
Experimental
[0141] A series of trials were conducted. The trials demonstrated
that starch encapsulations, prepared as in Example 4, above, at 25%
active ingredient (AI), fed to the bees mixed with powdered sugar
at 2.5% final AI effectively controlled mites. Over an eight week
period, the starch encapsulated oils significantly reduced mite
populations in the treated colonies and reduced mite infestation in
brood cells.
[0142] FIG. 4 shows the number of adult mites found on sticky
boards of colonies treated with starch encapsulated clove oil. Week
1 was a pretreatment time for the quantification of the average
number of mites present in the colony. Following week 1,
applications of the oils were made as needed in the five treatment
nucleus colonies over the experimental period. Fifteen gram
treatments were placed on the top bars of the colonies and sticky
boards were placed on the bottom boards to catch mites that dropped
from the bees. The sticky boards were changed each week.
[0143] Mite numbers decreased following the three week incubation
time of immature bees. The decrease at week five indicates that
there were fewer mites invading cells following the introduction of
the oils at week 2. In Week 10, a commercial acaracide
(Apistan.RTM.) was applied to determine the number of remaining
mites that were not affected by the oils. Results of the week 10
Apistan.RTM. treatments indicated that there was no difference
between previous five weeks and the final application, thereby
demonstrating that the treatments were highly effective in reducing
mite numbers in the colonies.
[0144] In another treatment, shown in FIG. 5, starch encapsulated
thymol was applied to five nucleus colonies as described for clove
oil treatment above. Results of the thymol treatment were even more
dramatic than seen in the clove treatment. Numbers of mites reduced
more quickly and were numerically lower in the final weeks of the
experiment.
DISCUSSION
[0145] Results show that the starch encapsulations are very
effective in reducing the number of mites entering cells and are
very effective at controlling the number of mites present in the
colonies treated with starch foam microparticle encapsulated
essential oils. Any effective essential oil can be encapsulated and
delivered to colonies using the starch foam microparticle
technology. The essential oil can be a single essential oil, or a
combination of one essential oil with a carrier oil, or one
essential oil combined with one or more other essential oils e.g.,
thymol; thymol and clove; clove, patchouli, and thymol; etc. . .
.
[0146] It is understood that the examples and embodiments described
herein are for illustrative purposes only and that various
modifications or changes in light thereof will be suggested to
persons skilled in the art and are to be included within the spirit
and purview of this application and scope of the appended
claims.
* * * * *