U.S. patent application number 12/094682 was filed with the patent office on 2008-12-18 for easily dispersible lipidic phase.
This patent application is currently assigned to NESTEC S.A.. Invention is credited to Corinne Appolonia-Nouzille, Philippe Frossard, Martin Leser, Martin Michel, Laurent Sagalowicz.
Application Number | 20080311211 12/094682 |
Document ID | / |
Family ID | 36499352 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080311211 |
Kind Code |
A1 |
Leser; Martin ; et
al. |
December 18, 2008 |
Easily Dispersible Lipidic Phase
Abstract
The present invention relates to the use of a lipidic phase
comprising an oil and a lipophilic additive (LPA), which is
suitable to make an oil-in-water emulsion by application of low
energy or a manual operation. The lipidic phase contains a
Lipophilic Additive (LPA) which forms self-assembly structures
inside the emulsion oil droplets. The aqueous phase contains a
hydrophilic emulsifier and the lipidic and aqueous phases are mixed
without using classical high shearing devices or homogenisers.
Inventors: |
Leser; Martin; (Bretigny,
CH) ; Sagalowicz; Laurent; (Cully, CH) ;
Michel; Martin; (Lausanne, CH) ; Frossard;
Philippe; (Moudon, CH) ; Appolonia-Nouzille;
Corinne; (Lausanne, CH) |
Correspondence
Address: |
BELL, BOYD & LLOYD LLP
P.O. Box 1135
CHICAGO
IL
60690
US
|
Assignee: |
NESTEC S.A.
Vevey
CH
|
Family ID: |
36499352 |
Appl. No.: |
12/094682 |
Filed: |
November 22, 2006 |
PCT Filed: |
November 22, 2006 |
PCT NO: |
PCT/EP06/68739 |
371 Date: |
May 22, 2008 |
Current U.S.
Class: |
424/489 ;
426/417; 426/602; 514/785; 977/773 |
Current CPC
Class: |
B01F 17/00 20130101;
A23D 7/011 20130101; A23D 7/0053 20130101 |
Class at
Publication: |
424/489 ;
514/785; 426/602; 426/417; 977/773 |
International
Class: |
A61K 9/14 20060101
A61K009/14; A61K 47/44 20060101 A61K047/44; A23D 7/00 20060101
A23D007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 22, 2005 |
EP |
05025405.1 |
Claims
1. A method for preparing an oil-in-water emulsion comprising using
a lipidic phase comprising an oil and a lipophilic additive (LPA),
wherein the LPA content in the lipidic phase comprises between
0.25-wt-% and 84 wt-%, and a mixing of the lipidic phase and an
aqueous phase containing an emulsifier is performed by using a
manual operation or a low energy device.
2. The method according to claim 1, wherein the LPA content in the
lipidic phase is between 2.5 wt-% and 80 wt.
3. The method according to claim 1, wherein the LPA content in the
lipidic phase is between 5 wt-% and 80 wt %.
4. The method according to claim 1, wherein the LPA content in the
lipidic phase is between 10 wt-% and 80 wt %.
5. Assembly comprising a pre-mix of a lipidic and an aqueous phase
in a container comprising means for preparing an oil-in-water
emulsion comprising an oil and a lipophilic additive (LPA), wherein
the LPA content in the lipidic phase comprises between 0.25-wt-%
and 84 wt-%, and mixing the lipidic phase and the aqueous phase
containing an emulsifier using a manual operation or a low energy
device.
6. Assembly comprising a lipidic phase separated from an aqueous
phase containing an emulsifier in a container, having an exit
comprising means for mixing both phases and preparing an
oil-in-water emulsion comprising an oil and a lipophilic additive
(LPA), wherein the LPA content in the lipidic phase comprises
between 0.25-wt-% and 84 wt-%, and mixing of the lipidic phase and
the aqueous phase containing an emulsifier is performed using a
manual operation or a low energy device.
7. Assembly comprising a lipidic and an aqueous phase comprising an
oil and a lipophilic additive (LPA), wherein the LPA content in the
lipidic phase comprises between 0.25-wt-% and 84 wt-%, and mixing
of the lipidic phase and the aqueous phase containing an emulsifier
is performed using a manual operation or a low energy device, both
phases being in a flexible pouch.
8. Method according to claim 1, wherein the manual operations or
low energy devices are selected from the group consisting of manual
squeezing, magnetic stirring, hand shaking, spoon or whisk
stirring, vortex mixing, membrane emulsification, static mixer,
kitchen mixer, nano-and microfluidics devices, pouch mixing, any
mixer which creates a turbulent flow, and combinations thereof.
9. Oil-in-water emulsion comprising a lipidic and aqueous phase
comprising an oil and a lipophilic additive (LPA), wherein the LPA
content in the lipidic phase comprises between 0.25-wt-% and 84
wt-%, wherein the oil droplets are of a diameter of 5 nm to
hundreds of micrometers and the droplets exhibit a nano-sized
self-assembled structurization with hydrophilic domains having a
diameter size of 0.5 to 200 nm due to the presence of the
lipophilic additive in the lipidic phase and mixing of the lipidic
phase and the aqueous phase containing an emulsifier is performed
using a manual operation or a low energy device.
10. Oil-in-water emulsion comprising an oil and a lipophilic
additive (LPA), wherein the LPA content in the lipidic phase
comprises between 0.25-wt-% and 84 wt-%, and mixing of the lipidic
phase and an aqueous phase containing an emulsifier is performed by
using a manual operation or a low energy device comprising the
dispersed oil droplets having a nano-sized self-assembled
structured interior comprising (i) an oil selected from the group
of consisting of mineral oils, hydrocarbons, vegetable oils, waxes,
alcohols, fatty acids, mono-, di-, tri-acylglycerols, essential
oils, flavouring oils, lipophilic vitamins, esters, nutraceuticals,
terrapins, terpenes and mixtures thereof, (ii) a lipophilic
additive (LPA) or mixtures of lipophilic and hydrophilic additives,
having a resulting HLB value (Hydrophilic-Lipophilic Balance) lower
than about 10, (iii) hydrophilic domains and an aqueous continuous
phase.
11. Method according to claim 1, wherein the oil droplets have an
internal structure selected from the group consisting of L2
structure, a combination of L2 and oil structure in the temperature
range of 0.degree. C. to 100.degree. C.
12. Method according to claim 1, wherein the oil droplets have a L2
internal structure in the temperature range of 0.degree. C. to
100.degree. C.
13. Method according to claim 1, wherein the oil droplets have an
internal structure selected from the group consisting of L2
structure, reversed micellar cubic, or reversed bicontiunous L3
structure, and a combination thereof in the temperature range of
0.degree. C. to 100.degree. C.
14. Method according to claim 1, wherein the oil droplets have a
reversed micellar cubic internal structure in the temperature range
of 0.degree. C. to 100.degree. C.
15. Method according to claim 1, wherein the oil droplets have a
reversed hexagonal internal structure in the temperature range of
0.degree. C. to 100.degree. C.
16. Method according to claim 1, wherein the oil droplets comprise
a material selected from the group consisting of flavours, flavour
precursors, drugs, lutein, lutein esters, .beta.-carotene,
tocopherol, tocopherol acetate, tocotrienol, lycopene, Co-Q.sub.10,
flax seed oil, lipoic acid, vitamin B.sub.12, vitamin D,
.alpha.-and .gamma.-polyunsaturated fatty acids or phytosterols,
food supplements, food additives, plant extracts, medicaments,
cosmoceuticals, peptides, proteins, carbohydrates, nutrients,
aromas, and aroma precursors.
17. Method according to claim 1, wherein the LPA is selected from
the group consisting of long-chain alcohols, fatty acids, pegylated
fatty acids, glycerol fatty acid esters, monoglycerides,
diglycerides, derivatives of mono-diglycerides, pegylated vegetable
oils, sorbitan esters, polyoxyethylene sorbitan esters, propylene
glycol mono- or diesters, phospholipids, phosphatides,
cerebrosides, gangliosides, cephalins, lipids, glycolipids,
sulfatides, sugar esters, sugar ethers, sucrose esters, sterols,
and polyglycerol esters.
18. Method according to claim 17, wherein the LPA is selected from
the group consisting of myristic acid, oleic acid, lauric acid,
stearic acid, palmitic acid, PEG 1-4 stearate, PEG 2-4 oleate,
PEG-4 dilaurate, PEG-4 dioleate, PEG-4 distearate, PEG-6 dioleate,
PEG-6 distearate, PEG-8-dioleate, PEG-3-16 castor oil, PEG 5-10
hydrogenated castor oil, PEG 6-20 corn oil, PEG 6-20 almond oil,
PEG-6 olive oil, PEG-6 peanut oil, PEG-6 palm kernel oil, PEG-6
hydrogenated palm kernel oil, PEG-4 capric/caprylic triglyceride,
mono, di, tri, tetraesters of vegetable oil and sorbitol,
pentaerythrityl di, tetra stearate, isostearate, oleate, caprylate
or caprate, polyglyceryl-3 dioleate, stearate, or isostearate,
polyglyceryl 4-10 pentaoleate, polyglyceryl 2-4 oleate, stearate,
or isostearate, polyglyceryl 4-10 pentaoleate, polyglyceryl-3
dioleate, polyglyceryl-6 dioleate, polyglyceryl-10 trioleate,
polyglyceryl-3 distearate propylene glycol mono- or diesters of
C.sub.6 to C.sub.20 fatty acid, monoglycerides of C.sub.6 to
C.sub.20 fatty acid, lactic acid derivatives of monoglycerides,
lactic acid derivatives of diglycerides, diacetyl tartaric ester of
monoglycerides, triglyceryl monostearate cholesterol, phytosterol,
PEG 5-20 soya sterol, PEG-6 sorbitan tetra, hexasterarate, PEG-6
sorbitan tetraoleate, sorbitan monolaurate, sorbitan monopalmitate,
sorbitan mono trioleate, sorbitan mono and tristearate, sorbitan
monoisostearate, sorbitan sesquioleate, sorbitan sesquistearate,
PEG-2-5 oleyl ether, POE 2-4 lauryl ether, PEG-2 cetyl ether, PEG-2
stearyl ether, sucrose distearate, sucrose dipalmitate, ethyl
oleate, isopropyl myristate, isopropyl palmitate, ethyl linoleate,
isopropyl linoleate, poloxamers, phospholipids, lecithins,
cephalins, oat lipids and lipophilic amphiphilic lipids from other
plants and mixtures thereof.
19. Method according to claim 1, wherein the emulsifier is selected
from the group consisting of low molecular weight surfactants
having a HLB>8, proteins from milk or soya, peptides, protein
hydrolysates, block co-polymers, surface active hydrocolloids such
as arabic gum, xanthan gum, surfactant-protein nanoparticles,
surfactant stabilized nano-or micro silica particle and mixtures
thereof.
20. A lipidic phase in powder form, which is easily reconstituted
into an aqueous phase at room or cold temperatures comprising using
a lipidic phase comprising an oil and a lipophilic additive (LPA),
wherein the LPA content in the lipidic phase comprises between
0.25-wt-% and 84 wt-%, and mixing of the lipidic phase and an
aqueous phase containing an emulsifier is performed by using a
manual operation or a low energy device.
21. The lipidic phase according to claim 20, wherein it is a final
product.
22. The lipidic phase according to claim 20, wherein it is selected
from the group consisting of a starting material, an intermediate
product and an additive to a final product.
23. Oil-in-water emulsion comprising dispersed oil droplets having
a nano-sized self-assembled structured interior comprising (i) an
oil selected from the group of consisting of mineral oils,
hydrocarbons, vegetable oils, waxes, alcohols, fatty acids, mono-,
di-, tri-acylglycerols, essential oils, flavouring oils, lipophilic
vitamins, esters, nutraceuticals, terrapins, terpenes and mixtures
thereof, (ii) a lipophilic additive (LPA) or mixtures of lipophilic
and hydrophilic additives, having a resulting HLB value
(Hydrophilic-Lipophilic Balance) lower than about 10, (iii)
hydrophilic domains comprising of water or a non-aqueous polar
liquid, comprising an aqueous continuous phase; and the LPA contact
of the lipidic phase prior to mixing is 0.25-wt-%-84 wt-% and
mixing is through use of an operation selected from the group
consisting of manual mixing and use of a low energy device.
Description
FIELD OF INVENTION
[0001] The invention relates to a lipidic phase comprising an oil
and a lipophilic additive (LPA), which is suitable to make an
oil-in-water emulsion by application of low energy or a manual
operation.
BACKGROUND OF THE INVENTION
Emulsions in Industry
[0002] Lipid phases, such as oils or fats are common ingredients
used in many different products. In order to give the lipid phase
containing products an acceptable physical homogeneity and
`shelf-life` (oil and water do not mix with each other) the bulk
lipid phase has to be broken up into small droplets, i.e. the lipid
phase has to be dispersed into an aqueous continuous phase. The
obtained product is an oil-in-water emulsion. The dispersed oil
droplets are stabilised by surface active molecules which form a
stabilization layer around the oil droplets. Both oil-in-water and
water-in-oil emulsions can be formulated depending on the
solubility of the used surface active molecules (also denoted as
emulsifiers) which stabilize the dispersed phase droplets.
Oil-in-water emulsions are stabilized by hydrophilic surface active
molecules, whereas water-in-oil emulsions are stabilized by
lipophilic emulsifiers.
[0003] In order to make stable and/or homogeneous oil-in-water
emulsions, the oil phase has to be dispersed as small oil droplets
having a radius from ca 100 nm up to several hundreds of
micrometers, into the continuous aqueous phase. For this,
homogenisers, i.e. machines which are able to add high energy to
the oil-water mixture are necessary to use. The formation of the
stabilization layer around the oil droplets during the
homogenisation step renders the oil droplets kinetically stable
against coalescence, flocculation, coagulation, Ostwald ripening or
creaming. The surface active material used in oil-in-water based
emulsion products can either be low molecular weight hydrophilic
surfactants, such as polysorbates, lysolecithins, etc., or
polymers, such as proteins, e.g. gelatin or from milk, soya, or
polysaccharides, such as gum arabic or xanthan, or (nano or
micro)-particles, such as silica particles, or mixtures
thereof.
[0004] Oil-in-water emulsion based products are ubiquitous
in--Food, Cosmetics, Pharmaceuticals or Agro-chemicals. Prominent
oil-in-water emulsion-based food products are for instance milk,
mayonnaise, salad dressings, sauces or clinical products. Prominent
oil-in-water emulsion-based products used in the cosmetical or
pharmaceutical Industry are lotions, creams, milks, pills, tablets,
dragees etc. The oil droplets in such products are usually made of
lipids, for instance, triglycerides, diglycerides, waxes, fatty
acid esters, fatty acids, alcohols, mineral oils, or
hydrocarbons.
Use of Emulsions
[0005] Emulsions are used either as a starting material,
intermediate or final product or as an additive to a final
product.
[0006] One of the uses of emulsions in Industry is to deliver
active compounds or functional molecules, such as, flavours,
vitamins, antioxidants, nutraceuticals, phytochemicals, drugs,
chemicals, etc. Administration of the active components requires
the use of an appropriate vehicle for bringing an effective amount
of the active component into the product and/or desired place of
action. Oil-in-water emulsions are commonly used delivery systems
since they take advantage of the increased solubility of lipophilic
active compounds in the oil with respect to water. In EP 1116515,
as an example of using emulsions for controlling flavour
performance, a hydrophobic active ingredient, such as a flavour
component, is mixed into a matrix via an extruder in form of an
oil-in-water emulsion in order to increase the stability of the
introduced active ingredient during further processing of the
product. In WO 00/59475, as an example for a pharmaceutical
oil-in-water emulsion, a composition and method for improved
delivery of ionizable hydrophobic therapeutic agents is described,
which are mixed together with an ionizing agent, a surfactant and a
triglyceride to form an oil-in-water emulsion. WO 99/63841, as an
example for the use of emulsions in the food area, describes
compositions comprising phytosterol having enhanced solubility and
dispersibility in an aqueous phase due to the formation of an
emulsion or a microemulsion.
[0007] Another reason to disperse a lipid into an aqueous phase in
form of an emulsion is to create a homogeneous and kinetically
stabilized oil and water containing product. This is a need in the
manufacture of a great variety of different products: For instance,
in ice cream production during the preparation of the ice cream mix
before freezing, in the production of mayonnaise, sauces,
dressings, creams, lotions, sprays and in lots of more oil
containing products in which a lipid phase has to be incorporated
into an aqueous continuous phase to obtain a kinetically stable and
homogeneous intermediate or end product. One drawback in all these
applications is that the oil-water mixture has to be treated with
high energy in order to get a sufficient dispersibility of the oil
phase, i.e., it is necessary to use specific and sometimes
expensive and sophisticated `high energy input` machines e.g.
homogenisers, high shearing mixers, ultrasound, jet mixers etc. to
obtain the stable emulsion.
[0008] The situation gets critical if no homogeniser or other high
energy input machine is available or can be used for the kinetical
stabilization of the water-oil mixture. One class of products which
suffers from this fact are the Instant or Kitchen products, which
usually can be prepared with only manual operation, e.g. shaking or
stirring. Instant products are well-known to the consumer. They are
well-accepted products since their preparation is easy and does not
require the use of sophisticated high energy mixers. Examples are
instant soups, spices, pastes, seasonings, butter substitutes, etc.
They are based on the principle of adding a concentrated stock
composition (paste, powder, liquid) to a product of choice during
food preparation at home or in a restaurant. The so prepared
products have the disadvantage that they have only a limited
storage stability, since the lipid phase is distributed in the
product in a inhomogeneous way leading quickly to extensive phase
separation after preparation. This sort of instability or
inhomogeneity in the prepared product is mainly observed when the
Instant products contain oil or other lipidic components.
Therefore, the word `inhomogeneity` describes the fact that the oil
phase is not distributed in a homogeneous, i.e., uniform, way
throughout the product. This situation can be easily visualized by
light microscopy, which allows to localize the oil/fat due to
specific oil coloration technology. If the oil inhomogeneity is
quite significant, non-dispersed macroscopic oil patches can be
observed also by eye.
[0009] In general, oil-based ingredients show insufficient
dispersion properties when added to water or water based products
without applying a high energy process. Manual operation generally
is not sufficient to get a stable product, therefore, leading to
the formation of very heterogeneous emulsions that quickly phase
separate and physically destabilize. The inhomogeneity of the oil
containing product is due to the fact that the created emulsion
droplets are very large (hundreds of microns) and polydisperse when
using low energy mixing.
[0010] U.S. Pat. No. 4,160,850 describes a mix suitable for the
consumer preparation of a spreadable butter-substitute product.
[0011] The final product in this case is a water-in-oil emulsion.
The mix consists of a mixture of a hard fat, an oil and a
water-in-oil emulsifier, which is added to the oil/fat phase to
stabilize the water phase which is added by the consumer during in
home preparation of the butter-substitute using a conventional home
mixer to form a water-in-oil emulsion. These products are quite
unstable when stored at room temperature and have to be
refrigerated to improve the product stability.
[0012] WO 03/053149 A1 discloses a method for the preparation of a
spreadable oil and water emulsion comprising mixing a base
composition with oil and/or water by a simple manual operation. The
base composition comprises a cold hydrating viscosifying agent,
such as the cold hydrating starch or a polysaccharide, a
hydrophilic emulsifier, such as hydrolysed lecithin, or caseinate
or a caseinate replacer, and optionally an acidifying agent. The
presence of the viscosifying agent, especially the polysaccharide
in the base composition leads to products with smaller average oil
droplet size in a final oil-in-water emulsion.
[0013] If the oil droplets in the oil-in-water emulsions are ultra
small, e.g. in the order of several manometers to about 200 nm
diameter, and spontaneously formed (without the use of a high
energy intake device) the emulsion is called an `oil-in-water
microemulsion` (Evans, D. F.; Wennerstrom, H. (Eds.); `The
Colloidal Domain`, Wiley-VCH, New York, (1999)). These emulsions
are clear and thermodynamically stable and, therefore, are for the
man skilled in the art different from ordinary emulsions the latter
being thermodynamically unstable and generally turbid.
[0014] JP 2004 008837 discloses an oil in water emulsion which
contains water-soluble solid particles present in the oil droplets.
The particles are in the size range of 20 nm to 10 .mu.m. The
particles are prepared in a water-in-oil (w/o) emulsion by means of
dehydration (i.e., not a spontaneous process) before the whole
particle/oil (S/O) suspension is dispersed in an aqueous phase
using the porous membrane emulsification process.
[0015] WO 02/076441 discloses the use of an alcohol-in-fluorocarbon
microemulsion as a precursor for the preparation of solid
nanoparticles. The nanoparticles have a diameter below 200-300
manometers. Nanoparticle formation is not spontaneous and triggered
by cooling the precursor microemulsion below about 35.degree. C.,
or by evaporating the alcohol in the precursor microemulsion or by
diluting the microemulsion with a suitable polar solvent.
[0016] US 2004/022861 discloses a w/o/w double emulsion, in which
the oil droplets containing an aqueous microscopic water phase
containing protein or another hydrophilic agent. The whole double
emulsion is sprayed into, for instance, liquid nitrogen via a
capillary nozzle for production of protein-loaded
microparticles.
[0017] All these examples describe the non-spontaneous formation of
solid hydrophilic (nano)particles using w/o microemulsions or w/o
or w/o/w double emulsions and needing an external trigger for the
solidification of the hydrophilic domains inside the oil droplets.
After preparation of the (nano)particles they are largely
unaffected by environmental factors such as temperature, pH, or
external fluid properties. It has to be mentioned that ordinary w/o
microemulsions in which the water droplets are not solidified, i.e.
fluid, are largely affected by such environmental factors.
[0018] It is the objective of the invention to provide a new
solution which allows to disperse a lipidic phase into an aqueous
phase to form an oil-in-water emulsion without using a high energy
intake mixing machine, but only a manual operation, such as hand
shaking or hand stirring with a spoon or an equivalent low energy
device which is used in the kitchen, restaurants or in Food Service
devices. A low energy device can be also selected from methods
allowing to form oil droplets using membrane emulsification,
nano-and microfluidics devices or static mixers. The lipidic phase
used for making the emulsion of this invention is easy to prepare
and does not need sophisticated mixing equipment.
DESCRIPTION OF THE INVENTION
[0019] The present invention is based on the finding of novel
nano-sized self-assembled structures in the interior of ordinary
oil droplets when the oil phase contains a lipophilic additive
(LPA). The structures inside the droplets are thermodynamically
stable and stabilized by the lipophilic additive (LPA). So, for the
purpose of this invention, a lipidic phase which consists of an oil
or fat and a lipidic additive, is defined from which an
oil-in-water emulsion, comprising oil droplets having a nano-sized
self-assembled internal structures, is made. The presence of the
nano-sized self-assembled structures inside the oil phase is
responsible for the significant reduction of the interfacial
tension established between the aqueous and the lipidic phase
measured with a common drop shape analysis tensiometer. Typically
the measured interfacial tension between the aqueous phase
(containing no additional emulsifier) or normal tap water and the
lipidic phase of this invention (oil, such as a triglyceride, plus
the LPA, such as unsaturated monoglycerides (DIMODAN U/J), is
between 1-5 mN/m when measured after an adsorption time which is
not longer than 10 to 100 seconds. The respective interfacial
tension between water and oil in the absence of an added LPA in a
triglyceride oil phase has been measured to be between 6 and 30
mN/m at room temperature, depending on the degree of purity of the
used oil and the salt content in the aqueous phase (no emulsifier
or surfactant added). If the water (containing no extra
emulsifier)-oil interfacial tension is lower than ca. 5 mN/m after
an adsorption time of less than 100 seconds (this time is called
also the `life time` of the oil droplet immersed in the water
phase), the break-up of the oil into small and homogeneous droplets
is significantly facilitated without using a high energy intake
device. Under such conditions, it is possible to form emulsions
which contain small and homogeneously distributed oil droplets
throughout the product. In order to make the created oil droplets
also stable against coalescence after they were formed, a
hydrophilic emulsifier is added to the system. In this way stable
and homogeneous emulsions can be produced just using low energy or
performing a manual operation. High shear homogenisers are
superfluous in this case. This means, that homogeneous and stable
oil-in-water emulsions can be prepared when a lipophilic additive,
such as the monoglyceride, is added to the oil phase prior to the
mixing in concentrations above 2-3 wt % on the total lipid phase
using only low energy procedures, such as manual operations, hand
shaking or stirring with a spoon, or similar low energy operation
processes. This lower lipophilic additive concentration limit,
however, depends on the chemical structure of both the LPA and oil
an can be as low as 0.1% LPA on the oil phase.
[0020] The characteristic low interfacial tension measured between
the lipidic phase of the present invention and an aqueous phase can
only be quantified in the absence of extra hydrophilic amphiphilic
molecules, surfactants or emulsifiers in the water phase. In this
case it can easily be measured and monitored by means of standard
tensiometers, such as a Pendant Drop tensiometer (example the
TRACKER tensiometer from Teclis-ITConcept from France, of the PAT
tensiometer from SINTERFACE Technologies from Berlin, Germany) or a
drop volume tensiometer (example the TVT 2 from Lauda, Germany).
The measurements are done in the absence of any additional
hydrophilic emulsifier, since adding an additional hydrophilic
emulsifier into the aqueous phase, would disturb the measurements.
The extra emulsifier would also adsorb to the interface and
decrease the measured interfacial tension. Of course, when making
the emulsion of the invention, the hydrophilic emulsifier is needed
in order to make the produced emulsion droplets stable against
coalescence.
[0021] The homogeneity of the obtained emulsions of this invention
is also reflected in the relatively low measured mean oil droplet
size. For instance, preparing an emulsion of this invention
containing 40% soybean oil and 1-10% DIMODAN U/J (the LPA)
calculated on the total lipidic phase, and 60% of an aqueous 5 wt-%
Na caseinate solution by using a propeller mixer produced oil
droplets which are 2-4 times smaller than the emulsion droplets
which do not contain DIMODAN U/J, respectively.
[0022] In an alternative embodiment of this invention the
oil-in-water emulsion is made by using a 2-chamber assembly. This
2-chamber assembly allows to store separately the lipidic and
aqueous phase of the invention before mixing. The assembly contains
at its exit means which allow to mix the lipidic and hydrophilic
phase to produce the oil-in-water emulsion of the invention. The
low energy mixing device can be a static mixer which is fixed at
the end of the assembly. When pressing the lipidic and aqueous
phases downwards the phases pass through the low energy mixing
device and the emulsion is formed. Experiments have shown that
using an oil phase, such as triglycerides, which contains no LPA or
a LPA concentration which is lower than 0.25 wt-% (calculated on
the total lipidic phase), no stable and homogeneous emulsion can be
prepared with the 2-chamber device.
[0023] In still another embodiment of this invention the
oil-in-water emulsion is made by pressing a pre-emulsion of the
lipophilic and aqueous phase through a static mixer in order to
produce the homogeneous and stable oil-in-water emulsion of this
invention. The homogeneous emulsion of this invention can also be
formed by simply shaking or compressing a pouch which contains the
lipidic phase of this invention and an aqueous phase. Such emulsion
products are used, for instance, in clinical or enteral nutrition
for tube feeding applications, where the mechanical forces for
mixing the instable oil-water mixture are usually very low.
[0024] In still another embodiment of this invention, the
oil-in-water emulsion is made by dissolving the respective emulsion
in form of a powder into cold water. In this case the oil,
containing the lipophilic additive, is easily dispersed and powder
material easily reconstituted by, for instance, stirring with a
spoon at room temperature or temperatures below 25.degree. C.
leading to a homogeneous, and stable oil-in-water emulsion.
[0025] In still another embodiment of this invention, the formed
oil droplets exhibit a nano-sized self-assembled structure in their
interior. This internal oil droplet structure is formed by the
presence of the lipophilic additive (LPA) and mainly consists of
nano-sized and thermodynamically stable hydrophilic domains, i.e.,
water droplets, rods or channels. The nano-sized domains, which are
formed spontaneously (thermodynamically driven) inside the emulsion
oil droplets, are stabilized by the LPA. The lipophilic additive
(LPA) has a slight amphiphilic character, i.e., it contains a
hydrophilic head group and a lipohilic chain. The hydrophilic part
of the LPA molecule is part of the hydrophilic domain structure.
The hydrophilic domains can be of the size of 0.5 to 200 nm of
diameter, preferably in the range of 0.5 to 150 nm of diameter,
even more preferably in the range of 0.5 to 100 nm of diameter, and
most preferably in the range of 0.5 to 50 nm. The size of the
hydrophilic domains critically depends on the amount of LPA added
to the oil droplets and on the type (chemical structure) of the
used oil. The spontaneous formation of the nano-sized
self-assembled structure inside the oil droplets is independent on
the energy intake, used to make the emulsion.
[0026] As used herein, the `hydrophilic domain` consists of the
water domains and the hydrophilic headgroup area of the LPA
molecules. Due to their ultra-small size, they also exhibit a large
surface area which is a suitable location for the solubilization of
a variety of different compounds.
[0027] The emulsions related to this invention are clearly
distinguished from emulsions commonly known as water-oil-water
double emulsions. w/o/w (water/oil/water) double emulsions are
oil-in-water emulsions, in which the oil droplets contain
micron-sized water droplets (Garti, N.; Bisperink, C.; Curr.
Opinion in Colloid & Interface Science (1998), 3, 657-667). The
water droplets inside the dispersed double emulsion oil droplets
are prepared (dispersed) by mechanical energy input, e.g.,
homogenisation, and, as a consequence, are thermodynamically
unstable and not self-assembled. The diameter of the inner water
droplets in a w/o/w double emulsion are larger than 300 nm
diameter. The emulsions of this invention can easily be
distinguished from ordinary w/o/w double emulsions since the
formation of the nano-sized self-assembled structure inside the oil
droplets of the emulsion of this invention is spontaneous and
thermodynamically driven, and the mean diameter of the water
droplets or channels is below 200 nm.
[0028] Thus the invention is directed towards oil droplets which
contain a nano-sized self-assembled structure with hydrophilic
domains. The oil droplets are formed by applying low energy or a
manual operation. The notion `self-assembly` or `self-organization`
refers to the spontaneous formation of aggregates (associates) or
nano-structures by separate molecules. Molecules in self-assembled
structures find their appropriate location based solely on their
structural and chemical properties due to given intermolecular
forces, such as hydrophobic, hydration or electrostatic forces
(Evans, D. F.; Wennerstrom, H. (Eds.); `The Colloidal Domain`,
Wiley-VCH, New York, (1999)). The result of self-assembly does not
depend on the process itself and corresponds to a state of minimum
energy (stable equilibrium) of the system.
Emulsion Formulation
[0029] The present invention concerns the use of a lipidic phase
comprising an oil and a lipophilic additive (LPA) for preparing an
oil-in-water emulsion wherein the LPA content in the lipidic phase
is comprised between 0.25-wt-% and 84 wt-%. Preferably the LPA
content is comprised between 2.5 wt-% and 80 wt-%. Even more
preferably said LPA content is comprised between 5 wt-% and 80
wt-%. Even most preferably the LPA content is between 10 wt-% and
80 wt-%, and wherein the aqueous phase contains a hydrophilic
emulsifier and wherein both phases are mixed. The interfacial
tension between the lipidic phase of the invention and an aqueous
phase which contains no hydrophilic emulsifiers, is below 5 mN/m
when measured upto 100 seconds or shorter.
[0030] Furthermore, the present invention concerns the use of a
lipidic phase wherein the mixing of lipidic and aqueous phases is
made by using a manual operation or a low energy device.
[0031] Another object of the invention is to provide an assembly,
comprising a pre-mix of the lipidic phase of the invention and an
aqueous phase containing a hydrophilic emulsifier in a container
and comprising further means for preparing the oil-in-water
emulsion of the invention.
[0032] Another object is to provide an assembly, comprising a
lipidic phase which is separated from an aqueous phase containing a
hydrophilic emulsifier in a container, with an exit comprising
means for mixing both phases and preparing the oil-in-water
emulsion of the invention.
[0033] Another object is to provide an assembly comprising a
lipidic and an aqueous phase containing a hydrophilic emulsifier,
where both phases are in a flexible pouch.
[0034] Another object is to provide an oil-in-water emulsion
comprising a lipidic and an aqueous phase containing a hydrophilic
emulsifier, wherein the means are selected from the group
consisting of manual squeezing, magnetic stirring, hand shaking,
spoon or whisk stirring, vortex mixing, membrane emulsification,
static mixer, kitchen mixer, nano-and microfluidics devices, pouch
mixing or any mixer which creates a turbulent flow, or combinations
thereof.
[0035] The present invention concerns also a lipidic phase which
after low energy mixing with an aqueous phase gives an oil-in-water
emulsion, wherein the oil droplets exhibit a nano-sized
structurisation with hydrophilic domains being formed by a
lipophilic additive (LPA). The LPA can be added as such or made in
situ by chemical, biochemical, enzymatic or biological means.
[0036] The amount of oil droplets (oil droplet volume fraction)
present in the emulsion of this invention is the amount generally
used in ordinary oil-in-water emulsion products. The volume
fraction of the lipidic phase can vary from a fraction of a percent
(<0.001% on the total product), as is used in therapeutic
oil-in-water emulsions, in which the lipidic phase is an expensive
drug, nutrient, chemical or another functional lipophilic
component, up to 80% (on the total product), as observed in HIPE's
(High Internal Phase Emulsions), such as, for instance, full-fat
mayonnaise.
[0037] More precisely, the present invention is directed to a
lipidic phase and its corresponding oil-in-water emulsion
comprising dispersed oil droplets having a nano-sized
self-assembled structured interior comprising [0038] (i) an oil
selected from the group consisting of mineral oils, hydrocarbons,
vegetable oils, fats, waxes, alcohols, fatty acids, mono-, di- or
tri-acylglycerols, essential oils, flavouring oils, lipophilic
vitamins, esters, nutraceuticals, terrapins, terpenes and mixtures
thereof, [0039] (ii) a lipophilic additive (LPA) or mixtures of
lipophilic and hydrophilic additives, having a resulting HLB
value(Hydrophilic-Lipophilic Balance) lower than about 10,
preferably lower than 8. [0040] (iii) hydrophilic domains in form
of droplets, rods or channels comprising of water or a non-aqueous
polar liquid, such as a polyol, and an aqueous continuous phase,
which contains emulsion stabilizers or emulsifiers.
[0041] As used herein, a `lipidic phase` refers to an oil phase
containing a certain amount of a `lipophilic additive`. The oil
phase can be also partially crystallized fat, such as hardened palm
oil, hardened palm kernel oil, butter fat at the temperature of
use. The temperature of emulsion formation can be between 4.degree.
C. and 100.degree. C.
[0042] As used herein, a `lipophilic additive` (abbreviated also as
`LPA`) refers to a lipophilic amphiphilic agent which spontaneously
forms stable nano-sized self-assembled structures in the bulk and
dispersed oil phase. In order to form self-assembly structures in
the oil phase, the LPA concentration in the oil phase must be
larger than the CMC (critical micellar concentration). Below this
concentration, no self-assembly structures are formed. For
instance, the CMC of unsaturated monoglycerides in triglyceride
oils is around 2 wt % and 0.1 wt % in squalene or kerosene. (J. Bus
et al. Progr Colloids Polymer Sci (1990) 82, 122-130). As shown in
this publication, the CMC critically depends on the molecular
structure of the oil and emulsifier, i.e. LPA.
[0043] The lipophilic additive (mixture) is selected from the group
consisting of fatty acids, sorbitan esters, propylene glycol mono-
or diesters, pegylated fatty acids, monoglycerides, derivatives of
monoglycerides, diglycerides, pegylated vegetable oils,
polyoxyethylene sorbitan esters, phospholipids, cephalins, lipids,
sugar esters, sugar ethers, sucrose esters, polyglycerol esters and
mixtures thereof.
[0044] According to the first embodiment of the invention the
oil-in-water emulsion exhibits oil droplets having an internal
structure taken from the group consisting of the L.sub.2 structure
or a combination of a L2 and oil structure (microemulsion or
isotropic liquid droplets) in the temperature range of 0.degree. C.
to 100.degree. C.
[0045] According to the second embodiment of the invention, the
oil-in-water emulsion exhibits oil droplets having a L2 structure
(microemulsion or isotropic liquid droplets) in the temperature
range of 0.degree. C. to 100.degree. C.
[0046] According to a third embodiment of the invention, the
oil-in-water emulsion exhibits oil droplets having an internal
structure taken from the group consisting of the L2 structure
(microemulsion or isotropic liquid droplets) or reversed micellar
cubic structure or reversed bicontinuous L3, and a combination
thereof in the temperature range of 0.degree. C. to 100.degree.
C.
[0047] According to a fourth embodiment of the invention, the
oil-in-water emulsion exhibits oil droplets having an internal
reversed micellar cubic structure in the temperature range of
0.degree. C. to 100.degree. C.
[0048] According to a fifth embodiment of the invention, the
oil-in-water emulsion exhibits oil droplets having an internal
reversed hexagonal structure in the temperature range of 0.degree.
C. to 100.degree. C.
[0049] According to a sixth embodiment of the invention, the
oil-in-water emulsion exhibits oil droplets having an internal
structure which is a combination of the previously described
structures in the temperature range of 0.degree. C. to 100.degree.
C.
[0050] All above mentioned internal structures can be without doubt
determined by SAXS analysis and by cryo-TEM (Qiu et al.
Biomaterials (2000) 21, 223-234, Seddon. Biochimica et Biophysica
Acta (1990) 1031, 1-69, Delacroix et al. J. Mol. Biol. (1996) 258,
88-103, Gustafsson et al. Langmuir (1997) 13, 6964-6971, Portes. J.
Phys: Condens Matter (1992) 4, 8649-8670) and fast Fourier
Transform (FFT) of cryo-TEM images.
[0051] For certain applications, the use of temperatures higher
than 100.degree. C. (for example retorting temperature) is also
possible and is covered by the present invention.
[0052] The lipophilic additive (LPA) can also be mixed with a
hydrophilic additive (having a HLB larger than 10) up to the amount
that the mixture is not exceeding the overall HLB of the mixture of
10 or preferably 8. The additive (mixture) can also be made in-situ
by chemical, biochemical, enzymatic or biological means.
[0053] The amount of added lipophilic additive is defined as
.alpha.. .alpha. is defined as the ratio LPA/(LPA+oil).times.100.
.alpha. is preferably higher than 0.25, more preferably higher than
0.5, even more preferably higher than 1 and even more preferable
higher than 2. The ratio .alpha.=LPA/(LPA+oil)*100 is preferably
lower than 84, more preferably lower than 70. Any combination of
the lower and upper range is comprised in the scope of the present
invention. .alpha. can be given either in wt-% or mol-%. The lower
and higher limit of .alpha. depends on the properties of the taken
oil and LPA, such as the polarity, the molecular weight, dielectric
constant, etc., or physical characteristics such as the critical
aggregation concentration or critical micellar concentration (CMC)
of the LPA in the oil droplet phase. The lower .alpha. limit is
generally comparable to or higher than the measured CMC exerted by
the used LPA/oil mixture. `Comparable to` means here that .alpha.
is >0.2.times.CMC.
[0054] The emulsion is stabilized by a hydrophilic emulsifier
suitable to stabilize ordinary oil-in-water emulsion droplets. The
emulsion can be aggregated (flocculated) or not depending on the
used emulsifier. The hydrophilic emulsifier is selected from the
group consisting of low molecular weight surfactants having a
HLB>8, gelatin, proteins from e.g. milk or soya, peptides,
protein hydrolysates, block co-polymers, surface active
hydrocolloids such as gum arabic, xanthan gum, diblockcopolymer- or
apoprotein-like biopolymers, such as protein-polysaccaride
conjugates or coacervates, or protein-polysaccharide,
protein-protein, or polysaccharide-polysaccharide hybrids,
conjugates or coacervates or mixtures of polymers and biopolymers,
or protein nanoparticles, surfactant-protein nanoparticles or other
nano- or micro-particles suitable to stabilize oil-in-water
emulsions.
[0055] The hydrophilic emulsifier can also be mixed with the LPA,
or with the oil, or with the LPA and the oil. This means, that the
hydrophilic emulsifier can partly also be present in the interior
of the oil droplet and affecting the internal nano-sized
self-assembled structure and the mixing behaviour during the
preparation of the emulsion.
[0056] The ratio .beta.=hydrophilic
emulsifier/(LPA+oil+emulsifier).times.100 describes the amount of
emulsifier used to stabilize the oil droplets with respect to the
oil plus LPA content. .beta. is preferably higher than 0.1, more
preferably higher than 0.5, more preferably higher than 1, and more
preferably higher than 2, and even more preferably higher than
5.
[0057] The ratio .beta.=emulsifier/(LPA+oil+emulsifier).times.100
is preferably lower than 90, more preferably lower than 75 and even
more preferably lower than 50. Any combination of the lower and
upper range is comprised in the scope of the present invention.
.beta. can be given either in wt-% or mol-%. The lower and higher
limit of .beta. depends on the properties of the taken emulsifier,
oil and LPA.
[0058] Various active components can be solubilized in the
nano-sized self-assembled structured interior of the oil droplets.
They can be oil-soluble, oil non-soluble, crystallinic or water
soluble components selected from the group consisting of
nutraceuticals, such as lutein, lutein esters, .beta.-carotene,
tocopherol, tocopherol acetate, tocotrienol, lycopene, Co-Q.sub.10,
flax seed oil, lipoic acid, vitamin B.sub.12, vitamin D, .alpha.-
and .gamma.-polyunsaturated fatty acids, phytosterols, flavonoids,
vitamin A, vitamin C or its derivatives, sugars, food supplements,
functional ingredients, food additives, plant extracts,
medicaments, drugs, pharmacologically active components,
cosmetically active components, peptides, proteins or
carbohydrates, aroma, salts and flavours.
[0059] In the oil-in-water emulsion according to the invention, the
lipophilic additive is selected from the group consisting of
myristic acid, oleic acid, lauric acid, stearic acid, palmitic
acid, PEG 1-4 stearate, PEG 2-4 oleate, PEG-4 dilaurate, PEG-4
dioleate, PEG-4 distearate, PEG-6 dioleate, PEG-6 distearate,
PEG-8-dioleate, PEG-3-16 castor oil, PEG 5-10 hydrogenated castor
oil, PEG 6-20 corn oil, PEG 6-20 almond oil, PEG-6 olive oil, PEG-6
peanut oil, PEG-6 palm kernel oil, PEG-6 hydrogenated palm kernel
oil, PEG-4 capric/caprylic triglyceride, mono, di, tri, tetraesters
of vegetable oil and sorbitol, pentaerythrityl di, tetra stearate,
isostearate, oleate, caprylate or caprate, polyglyceryl-3 dioleate,
stearate, or isostearate, polyglyceryl 4-10 pentaoleate,
polyglyceryl 2-4 oleate, stearate, or isostearate, polyglyceryl
4-10 pentaoleate, polyglyceryl-3 dioleate, polyglyceryl-6 dioleate,
polyglyceryl-10 trioleate, polyglyceryl-3 distearate propylene
glycol mono- or diesters of C.sub.6 to C.sub.20 fatty acid,
monoglycerides of C.sub.6 to C.sub.20 fatty acid, lactic acid
derivatives of monoglycerides, lactic acid derivatives of
diglycerides, diacetyl tartaric ester of monoglycerides,
triglyceryl monostearate cholesterol, phytosterol, PEG 5-20 soya
sterol, PEG-6 sorbitan tetra, hexasterarate, PEG-6 sorbitan
tetraoleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan
mono trioleate, sorbitan mono and tristearate, sorbitan
monoisostearate, sorbitan sesquioleate, sorbitan sesquistearate,
PEG-2-5 oleyl ether, POE 2-4 lauryl ether, PEG-2 cetyl ether, PEG-2
stearyl ether, sucrose distearate, sucrose dipalmitate, ethyl
oleate, isopropyl myristate, isopropyl palmitate, ethyl linoleate,
isopropyl linoleate, poloxamers, phospholipids, lecithins,
cephalins, oat lipids and lipophilic amphiphilic lipids from other
plants; and mixtures thereof.
[0060] The lipidic phase according to the invention is normally in
liquid or paste form. According to another embodiment of the
invention, the lipidic phase is dried and is available in powder
form. The powder can be easily reconstituted when added into an
aqueous or pure water phase. According to another embodiment of the
invention, the lipidic phase can contain other ingredients, such as
spices, herbs, or aromas.
[0061] The lipidic phase according to the invention is either a
final product or an additive or intermediate product. The amount of
the additive in the final product is not critical and can be
varied.
[0062] The oil-in-water emulsion obtained from the low energy
mixing of the lipidic phase of the invention with an aqueous phase
according to the invention is either a final product or an
additive. The amount of the additive in the final product is not
critical and can be varied.
[0063] The emulsion described in this invention is a novel type of
emulsion which we name `ISAMULSION` to describe the specific nature
of the oil droplets containing a structure being Internally
Self-Assembled, and to exclude the emulsion of this invention from
ordinary oil-in-water or w/o/w double emulsions, including nano-
and microemulsions, in which the oil droplets do not have a
nano-sized self-assembled structure with hydrophilic domains. The
ISAMULSION droplets basically consist of oil droplets which have a
nano-sized self-assembled structure with hydrophilic domains. This
nano-structure is of a reversed nature comprising the L2, the
microemulsion, the isotropic liquid phase, the micellar cubic, the
hexagonal H2, or the bicontinous L3 or phase. The structures in the
oil phase can appear as a single nano-structure or as a mixture of
different nano-structures.
[0064] It is, therefore, an object of this invention to provide a
lipidic phase or a mix containing this lipidic phase which allows
to easily prepare an oil-in-water emulsion formulation just by
adding low energy to the water-oil mixture. The lipidic phase can
be used as such or can be part of a ready-to-use product, which can
be used to freshly prepare the emulsion product during cooking or
food preparation in the kitchen, restaurants, cantines, during
camping or at other comparable occasions where no high shearing
device is at one's disposal. The ready-to-use product can be used
to freshly prepare a BBQ sauce or other sauces, marinade,
mayonnaise, ketchup, salad dressings, seasonings, spices, and
similar type of products.
[0065] Another field of application of the lipidic phase or the
ready-to-use product containing the lipidic phase of the invention
is for the fortification of home-made products with lipidic
(non-easy-dispersible) functional molecules, such as nutrients,
aromas, taste enhancers etc.
[0066] Another field of application is in Industrial or
semi-Industrial production where one is interested to add a
water-insoluble phase (lipidic phase) at a certain point without
the use of homogenisers.
[0067] The above described behaviour of the lipidic phase and its
adjacent oil-in-water emulsion can be easily used to design also
new ready-to-use oil containing products for Food, Pet Food,
Neutraceuticals, Functional Food, Detergents, Nutri-cosmeticals,
Cosmetics, Pharmaceuticals, Drug Delivery, Paints, Medical or
Agro-chemical Industry, Explosives, Textiles, Mining, Oil well
drilling, Paper Industry, Polymer Industry.
BRIEF DESCRIPTION OF THE DRAWINGS
[0068] FIG. 1 shows the structure found in the interior of the
ISAMULSION oil droplets as a function of (=100*LPA/(LPA+oil),
[0069] FIG. 2 shows a Cryo-TEM micrograph of a typical ISAMULSION,
showing the nano-sized hydrophilic domains inside single oil
droplets.
[0070] FIG. 3 shows the small angle X-ray scattering (SAXS) pattern
of an ISAMULSION, of the bulk oil phase (nano-structured by LPA),
which was used for making the ISAMULSION and of the corresponding
ordinary emulsion (without LPA, without nano-structure). The
scattering curve of an ordinary emulsion is clearly different from
the curve of the ISAMULSION.
[0071] FIG. 4 shows the small angle X-ray scattering (SAXS) pattern
of ISAMULSIONS containing various amounts of LPA, i.e., .alpha.
values(.alpha.=100*LPA/(LPA+OIL)). Oil=Tetradecane,
LPA=Monolinolein. The content of the LPA determines the
concentration and size of the self-assembled hydrophilic domains
inside the oil droplets.
[0072] FIG. 5 shows a schematic of an Isamulsion oil droplet, which
contains hydrophilic domains. Note that the hydrophilic domains can
be spherical or non-spherical, i.e. rods, disks or channels. The
hydrophilic domain consists of the polar head group of the LPA and
the solubilized water.
[0073] FIG. 6 (upper curve) shows the small angle X-ray scattering
(SAXS) curve of an ISAMULSION containing oil droplets that have a
reversed micellar cubic Fd3m structure.
[0074] FIG. 7 shows the interfacial tension measured between the
lipidic phase of the invention (in this case soybean oil+Dimodan
U/J as LPA) against pure water as a function of the DIMODAN U/J
content, using the Pendant Drop technique.
[0075] FIG. 8 shows the interfacial tension measured between the
lipidic phase of the invention (in this case soybean oil+Dimodan
U/J as LPA) against pure water as a function of the DIMODAN U/J
content, using the Drop volume tensiometer.
[0076] FIG. 9 shows the oil droplet size D32 (Sauter droplet
diameter, given in microns) of ISAMULSIONS as a function of the
DIMODAN U/J content in the oil phase, given as wt-% of Dimodan U/J
in soybean oil. The ISAMULSION oil phase (soybean+DIMODAN U/J) is
constant 40 vol % in all emulsions. Emulsions are stabilized by 5
wt-% Na-Caseinate (on aqueous phase); Emulsions are prepared by
using a low energy stirrer. Malvern Mastersizer data FIG. 1
represents the typical sequence of structures found in the interior
of the dispersed oil droplets of the ISAMULSION as a function of
the content of the lipophilic additive in % (%
LPA=.alpha.=100*LPA/(LPA+OIL)) and temperature. Changing .alpha.,
i.e., the LPA content in the oil droplets, allows to change and
modulate the nano-structure inside the droplets. L2 denotes a
reversed microemulsion-like structure; LC denotes the existence of
a liquid crystalline phase or a mixture of different liquid
crystalline phases, such as the reversed micellar or reversed
hexagonal, or reversed bicontinuous cubic. As FIG. 1 shows, a
defined nano-sized self-assembled structure is formed at a given
temperature and a specific amount of added lipophilic additive
(.alpha. value) inside the oil droplets (for a closer description
of the mentioned structures, see Evans, D. F.; Wennerstrom, H.
(Eds.); `The Colloidal Domain`, Wiley-VCH, New York, (1999)). The
amount of added LPA allows to precisely control the type of
self-assembly structure, amount of water present in the hydrophilic
domains, the amount of internal interface and the size, dimension,
of the self-assembly nano-structure formed inside the ISAMULSION
droplets.
[0077] Depending on the used oil-type and type of lipophilic
additive, the minimum amount of LPA (.alpha.) needed to initiate
the spontaneous formation of the self-assembled internal droplet
structure (also denoted as critical micellar concentration CMC or
critical aggregate concentration) is between 0.1 and 15 wt-% (on
the oil phase). Moreover, the .alpha. value at which a phase change
in the oil droplets is observed depends also on the used type of
oil and/or lipophilic additive.
[0078] The internal nano-sized self-assembled structure of the oil
droplets in the emulsion can be detected by means of
Cryo-Transmission Electron Microscopy or SAXS.
[0079] The cryo TEM image of FIG. 2 was obtained using the standard
technique of Adrian et al (Adrian et al. Nature, (1984) 308,
32-36). A home made guillotine was used for sample freezing. A
droplet of 3 .mu.l sample dispersion was deposited onto a copper
grid covered with a holy carbon film containing holes of about 2
.mu.m in diameter. A filter paper was pressed on the liquid side of
the grid (blotting) for removing excess sample solution.
[0080] Immediately after liquid removal, the grid, held by
tweezers, was propelled into liquid ethane. Frozen grids were
stored in liquid nitrogen and transferred into a cryo-holder kept
at -180.degree. C. Sample analysis was performed in a Philips CM12
TEM at a voltage of 80 kV. Low dose procedures were applied to
minimise beam damage. In some cases a home build environmental
chamber similar to the one described by Egelhaaf et al (Egelhaaf et
al, J. Microsc. (2000) 200, 128-139) was used. The temperature
before thinning and vitrifying was set at 25.degree. C. and 100%
humidity was used. The ISAMULSION can be identified by the presence
of small bright features inside the oil droplets. FIG. 2 is a
Cryo-TEM micrograph of a typical ISAMULSION showing characteristic
distances between the bright features of about 7-8 nm. It should be
noted that such bright features are not observed for standard
non-structured emulsions and there is no contrast inside
non-structured emulsion droplets.
[0081] The SAXS curves of FIG. 3 were obtained by a standard
equipment (Bergmann et al. J. Appl. Cryst. (2000) 33, 869-875),
using a X-ray generator (Philips, PW 1730/10) operating at 40 kV
and 50 mA with a sealed-tube Cu anode. A Gobel mirror is used to
convert the divergent polychromatic X-ray beam into a focused
line-shaped beam of Cu K.sub..alpha. radiation (.lamda.=0.154 nm).
The 2D scattering pattern is recorded by an imaging-plate detector
and integrated to the one-dimensional scattering function I(q)
using SAXSQuant software (Anton Paar, Graz, Austria), where q is
the length of the scattering vector, defined by
q=(4.pi./.lamda.)sin 74/2, .lamda. being the wavelength and .theta.
the scattering angle. The broad peaks of scattering profiles were
desmeared by fitting these data with the Generalized Indirect
Fourier Transformation method (Bergmann et al. (2000), 33,
1212-1216). The characteristic distances are given by d=2.pi./q.
FIG. 3 shows the small angle X-ray scattering patterns of an
ISAMULSION (same as investigated in FIG. 2) together with the
corresponding non-dispersed bulk oil phase (nano-structured by LPA)
that it is made from, and the corresponding ordinary
emulsion(without LPA, without nano-structure). It can be seen that
the ISAMULSION shows the same peak position as the non-dispersed
bulk oil phase that it is made from. The characteristic distance
for both is about 7.5 nm. This characteristic distance is higher
than the diameter of the hydrophilic domain. Therefore the
hydrophilic domains have a size smaller than 7 nm. For the man
skilled in the art, this small size of the hydrophilic domains
demonstrates that the internal structure of the oil droplet is
thermodynamically stable. Moreover, for the corresponding ordinary
emulsion, in which no LPA is added (no nano-structure), no peak is
observed. This is an additional prove of the presence of a
nano-sized self-assembled structure inside the oil droplets of an
ISAMULSION. It does not change upon dispersion in water, indicating
that the internal ISAMULSION droplet structure is in a
thermodynamic equilibrium state.
[0082] FIG. 5 shows a schematic of an oil droplet which has been
nano-structured by addition of a LPA. The structural definition of
a hydrophilic domain is specified. Hydrophilic domains include the
polar part (head group) of the LPA (and not the hydrocarbon tail
region and the water part). The minimum diameter of a hydrophilic
domain can be about 0.5 nm which is more or less the cross section
of 2 head groups containing no water molecules. The minimum size of
the polar part of a lipophilic additive or emulsifier is about 0.2
nm. The diameter of a water molecule is about 0.3 nm.
[0083] FIGS. 6 and 7 are showing oil-water tension measurements as
a function of the LPA (DIMODAN U) content in the oil (soybean
oil).
[0084] FIG. 8 shows the Sauter diameter D32 of emulsions made with
low energy intake as a function of the DIMODAN U content in the
soybean oil phase.
EXAMPLES
[0085] The various embodiments of this invention provide an
oil-in-water emulsion in which the dispersed oil droplets exhibit a
nano-sized, self-assembled structure of hydrophilic domains due to
the presence of a lipophilic additive (LPA). The presence of the
LPA in the oil phase allows to prepare oil-in-water emulsions using
only low energy intake mixing. The following examples are
illustrative in nature and are not to be construed as limiting the
invention, the scope of which is defined by the appended
claims.
Example 1
Generic Examples of an ISAMULSION
Showing How to Detect the Specific Isamulsion Droplet Structure in
a Reference Model System
[0086] Typically 1-5 wt % of a mineral oil, such as tetradecane,
was added to 95 wt % water containing already 0.375 wt % of the
emulsifier (Tween 80 or Pluronic F127). 0.5-4 wt % LPA (glycerol
monolinoleate) was then added to the mixture. The total amount of
lipophilic molecules (mineral oil+LPA) was 4.625 wt % (.alpha. is
between 9 and 80). Ultrasonication was then carried out for 20
minutes. The ISAMULSION character of the emulsions was confirmed by
cryo-TEM images and SAXS curves such as the ones of FIG. 2 and FIG.
3-4. FIG. 2, FIG. 3, were obtained from those generic examples with
a composition of 2.4 wt % mineral oil(tetradecan)-2.2 wt % LPA
(.alpha.=48)-0.375 wt % primary emulsifier(pluronic F127)-95 wt %
water. In addition, corresponding bulk samples (non dispersed
samples containing the oil and the LPA but no emulsion stabilizer)
were prepared and analysed. The weight ratio
oil(tetradecan)/LPA(glycerol monolinoleate) was 1.1/1.0. The
mixture oil-LPA-water was heated and mixed with a Vortex until the
sample was homogeneous. After addition of 0, 5, or 10 wt % water to
the oil/LPA mix, the sample was clear indicating that the water was
totally solubilized into the oil/LPA mixture and a w/o
microemulsion was formed. After addition of higher amounts of
water, the sample shows phase separation. It was noted that the
samples containing 15 and 20 wt % water show the same SAXS curves
as the corresponding ISAMULSION sample (2.4 wt % mineral oil-2.2 wt
% LPA-0.375 wt % emulsifier). This demonstrates that ISAMULSION
droplets show the same characteristic distance of 7.5 nm as
observed in the corresponding bulk phases(see FIGS. 2 and 3). FIG.
4 shows that ISAMULSIONS are formed (e.g. a peak in the SAXS curve
is observed) already with relatively low LPA and high oil contents
(e.g. 3.9 wt % mineral oil (tetradecan)-0.725 wt % LPA (glycerol
monolinoleate, .alpha.=16), 0.375 wt % emulsifier(pluronic
F127)-95% water). However an ISAMULSION is not formed when no LPA
is present as shown in FIG. 3 (composition 4.625 wt % oil
(tetradecan), 0.375 wt % pluronic F127, 95 wt % water). Also with
higher amounts of LPA (.alpha. values) (Example of a composition:
1.32 wt % tetradecan-3.3 wt % LPA (.alpha.=71)-0.375 wt % Pluronic
F127) an ISAMULSION is formed. The structure is more ordered than
observed with a lower .alpha. value (LPA content) and shows a
reversed micellar cubic arrangement of the hydrophilic domains, as
shown by the SAXS curves (FIG. 6; upper curve).
Example 2
ISAMULSION Obtained by the Hydrotrope Route and Vortexing
[0087] 1 wt % emulsifier (Pluronic F127) was dissolved in 89 wt %
water forming the aqueous solution. 2.5 wt % mineral oil
(tetradecan) and 2.5 wt % LPA (glycerol monolinoleate, .alpha.=50)
were dissolved in 5 wt % ethanol forming the lipidic solution. The
aqueous solution was slowly added to the lipidic solution while
vortexing. At the end of the process, the ISAMULSION, i.e.,
droplets having an interior nano-sized self-assembled structure has
formed.
Example 3
ISAMULSIONS Obtained by Hand-Shaking of the Lipidic and Aqueous
Phase
[0088] 0.5-4.5 wt % of soybean oil (on the total emulsion product)
was mixed first with 0.5-2.0 wt % LPA (Dimodan U/J, Danisco,
Dannmark; on the total emulsion product,
10.ltoreq..alpha..ltoreq.80) to prepare the lipidic phase. This
mixture was added to 95% water containing 0.375% of the emulsifier
(Pluronic F127). The total amount of lipidic phase (oil+LPA; given
on the total emulsion product) was 4.625 wt %. The mixture was hand
shaken. A homogeneous milky and relatively stable emulsion was
formed. The ISAMULSION character of the emulsions was confirmed by
cryo-TEM images and SAXS.
Example 4
ISAMULSIONS Obtained by Stirring the Lipidic Phase and Skimmed Milk
with a Propeller Stirrer
[0089] 1.2 wt % of soybean oil (on the total emulsion product) was
mixed first with 1.8 wt % LPA (Dimodan U/J, Danisco, Dannmark; on
the total emulsion product, .alpha.=60) to prepare the lipidic
phase. 3 wt % of this lipidic phase was added to 97% skimmed milk.
The mixture was stirred with a propeller stirrer. A homogeneous
milky and stable emulsion was formed. 50% of the emulsified oil
droplets where smaller than 44 .mu.m, as measured with the Malvern
Mastersizer. The measured D32 was 10 .mu.m. The milk and the oil
droplets in the milk were still stable after one week storage at
refrigerated temperatures. However, when compared with the
respective milk products made out of soybean oil only (no LPA added
to the oil phase) using the same preparation method, the oil
droplets were significantly larger than the droplets in the
emulsion of this invention (oil droplets contain a LPA) and the
milk was significantly creamed after one week of storage at
refrigerated temperatures. Only 50% of the oil droplets in the milk
after preparation were smaller than 150 .mu.m (D32 was 35 .mu.m).
This means that they are more than 3 times larger than the oil
droplets in the emulsion of this invention in which the oil
contained 60% (on the lipidic phase) of LPA.
Example 5
ISAMULSIONS Obtained by Stirring the Lipidic Phase and an Aqueous
Na Caseinate Phase with a Propeller Stirrer
[0090] 39 wt % of soybean oil (on the total emulsion product) was
mixed first with 1.0 wt % LPA (Dimodan U/J, Danisco, Dannmark; on
the total emulsion product, .alpha.=2.5) to prepare the lipidic
phase. 40 wt % of this lipidic phase was added to 60% of a 5 wt %
Na Caseinate solution. The mixture was stirred with a propeller
stirrer. A homogeneous milky and stable oil-in-water emulsion was
formed. 50% of the emulsified oil droplets were smaller than 73
.mu.m, as measured with the Malvern Mastersizer. The measured D32
was 13 .mu.m (see FIG. 9). The emulsion and the oil droplets in the
emulsion were still stable after one week storage at refrigerated
temperatures. However, when compared with the respective emulsion
made out of soybean oil only (no LPA added to the oil phase) using
the same preparation method, the oil droplets were significantly
larger than the droplets in the emulsion of this invention (oil
droplets contain the LPA, see FIG. 9) and the emulsion was
significantly creamed and some free oil was detected at the surface
of the solution after one week of storage at refrigerated
temperatures. Concerning the oil droplet size in this emulsion, 50%
of the oil droplets were smaller than 150 .mu.m after preparation
and the D32 was 35 .mu.m (see FIG. 9) i.e., still significantly
larger than the respective emulsion of this invention, in which the
oil contained 2.5 wt % of LPA (calculated on the oil phase).
[0091] The smaller mean droplet sizes generated with the ISAMULSION
formulation is connected with the lower interfacial tension .gamma.
exerted between the lipidic phase (soybean oil plus DIMODAN U/J)
and pure water (.gamma..ltoreq.5 mN/m) compared to the interfacial
tension measured between the oil (no added DIMODAN U/J) and pure
water (.gamma..gtoreq.5 mN/m) (see FIGS. 7 and 8).
[0092] The ISAMULSIONS prepared according to the above mentioned
examples can be used as such or as an additive.
[0093] Having now fully described the invention, it will be
understood by those of ordinary skill in the art that the same can
be performed within a wide and equivalent range of mixing
conditions and formulations without affecting the scope of the
invention or any embodiment thereof.
* * * * *