U.S. patent application number 10/849842 was filed with the patent office on 2004-10-28 for aqueous stable lysine solution.
This patent application is currently assigned to Ajinomoto Co., Inc.. Invention is credited to Hasegawa, Kazuhiro, Minami, Keita, Tanabe, Toshiya.
Application Number | 20040214895 10/849842 |
Document ID | / |
Family ID | 13263635 |
Filed Date | 2004-10-28 |
United States Patent
Application |
20040214895 |
Kind Code |
A1 |
Hasegawa, Kazuhiro ; et
al. |
October 28, 2004 |
Aqueous stable lysine solution
Abstract
Herein is disclosed an aqueous stable lysine solution containing
an acid radical in such amount that the solubility of lysine
therein has been increased than in the corresponding aqueous lysine
base solution, whereby during storage of lysine in the form of a
free-lysine solution (liquid composition), the precipitation of
lysine base crystals due to the drop in temperature is prevented
thereby improving the handling thereof during transportation
(transfer) etc.
Inventors: |
Hasegawa, Kazuhiro;
(Kawasaki-shi, JP) ; Tanabe, Toshiya;
(Kawasaki-shi, JP) ; Minami, Keita; (Kawasaki-shi,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Ajinomoto Co., Inc.
Tokyo
JP
|
Family ID: |
13263635 |
Appl. No.: |
10/849842 |
Filed: |
May 21, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10849842 |
May 21, 2004 |
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10083597 |
Feb 27, 2002 |
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10083597 |
Feb 27, 2002 |
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09882065 |
Jun 18, 2001 |
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09882065 |
Jun 18, 2001 |
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09518094 |
Mar 3, 2000 |
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6329548 |
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Current U.S.
Class: |
514/564 ;
562/562 |
Current CPC
Class: |
A23K 20/142 20160501;
C07C 229/26 20130101 |
Class at
Publication: |
514/564 ;
562/562 |
International
Class: |
A61K 031/198; C07C
229/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 1999 |
JP |
11-064625 |
Claims
What is claimed as new and desired to be secured by Letters Patent
is:
1. An aqueous stable lysine solution containing an acid radical in
such amount that the solubility of lysine therein has been
increased than in the corresponding aqueous lysine base
solution.
2. The aqueous stable lysine solution as set forth in claim 1,
wherein the content of the acid radical is 35% or less, in terms of
the ratio of the product of the molar number of the acid radical
multiplied by its valence to the molar number of the lysine.
3. The aqueous stable lysine solution as set forth in claim 1 or 2,
wherein said acid radical is the chloride radical (Cl.sup.-) and/or
the sulfate radical (SO.sub.4.sup.2-).
4. The aqueous stable lysine solution as set forth in claim 1,
wherein said acid radical is the chloride radical (Cl.sup.-) and is
contained within the range of 35% or less in terms of the molar
ratio thereof to the lysine.
5. The aqueous stable lysine solution as set forth in claim 1,
wherein said acid radical is the sulfate radical (SO.sub.4.sup.2-)
and is contained within the range of 17% or less in terms of the
molar ratio thereof to the lysine.
6. A lysine-enriched feed and an industrially produced mixed feed
wherein the aqueous stable lysine solution described in any one of
claims 1 to 5 has been used.
Description
BACKGROUND OF THE INVENTION
[0001] 1. [Technical Field to which the Invention Belongs]
[0002] The present invention relates to the stabilization of a
lysine solution, and in particular to the stabilization of a lysine
solution by incorporating a predetermined amount of an acid radical
therein.
[0003] Incidentally, the acid radical is the residue of an acid
molecule from which one or more hydrogen atoms capable of being
replaced by metal(s) have been removed, and it constitutes the
negative moiety of a salt. The acid radical often refers to an
atomic group such as the acid radical (SO.sub.4) of sulfuric acid,
but a single atom such as Cl in hydrogen chloride is also referred
to as an acid radical, this nomenclature being followed in this
specification.
[0004] Furthermore, the solubility of lysine refers to the
equilibrium maximum amount of lysine soluble in unit water amount
of a lysine solution.
[0005] Still furthermore, the product of the molar number of an
acid radical multiplied by its valence refers, e.g., to the molar
number of the acid radical when the acid radical consists of a
monovalent acid radical only, or to the product of the molar number
of the acid radical multiplied by 2 as its valence when the acid
radical consists of a divalent acid radical only, or to the sum of
the molar number of a monovalent acid radical and the product of
the molar number of a divalent acid radical multiplied by 2 as its
valence when the acid radical consists of both monovalent and
divalent acid radicals.
[0006] 2. [Prior Art]
[0007] As is well-known, lysine is used as one of the essential
amino acids in a large amount as a feed additive for producing a
feed for domestic animals such as cattle, pigs and chickens as well
as an industrially produced mixed feed. In so doing, however,
lysine is not used as crystals in the free and pure form but used
usually in the form of monohydrochloride, because lysine is readily
soluble in water, is hardly crystallized in the free form, exhibits
strong moisture absorption (i.e., is strongly hygroscopic), absorbs
carbon dioxide from the air, possesses a significantly unpleasant
odor and is liable to degradation. In the present specification,
lysine means lysine in the L-form (i.e. L-lysine) except quotations
from the prior art literature and is referred to as "lysine base"
when it is intended to emphasize that lysine is not in a salt form
but in the free form (free lysine)
[0008] The monohydrochloride is a compound which is stable, not
liable to degradation and readily crystallized, and does not
possesses properties such as moisture absorbing and unpleasantly
smelling. However, its production involves the problems of
additional raw material costs and process costs. Further, the use
of lysine monohydrochloride for enriching lysine in feeds and
industrially produced mixed feeds increases not only the content of
lysine but also the content of chlorides in the mixed feeds, but
this is generally undesired. Further, the ratio of lysine to
chlorides is also important. This is because, in feeding
experiments with crystalline amino acid feeds, it is often observed
that the positive effects of the amino acid added are completely
lost, when the amino acid is used as the hydrochloride, whereby the
chloride excess, in turn, occurs. For these reasons, lysine in the
chloride-free form has been strongly desired for the purpose of
nutritional enrichment for feeds and industrially produced mixed
feeds.
[0009] Under such technical background, the JP-B 3-5783 patent
document discloses an invention titled "A process for producing a
feed and an industrially produced mixed feed enriched with lysine
wherein an aqueous L-lysine solution containing 30 to 80 weight %
L-lysine is used".
[0010] With respect to the findings on which this prior art
invention is based, said document states, "It has been found that
when L-lysine is used in the form of an aqueous solution for
enrichment, L-lysine, which is unstable in the free form, can be
used for enrichment of feeds and mixed feeds. It has been
unexpected that the aqueous solution is stable even at high
temperatures in storage for a long time. A comparative experiment
has showed that an aqueous 70% L-lysine solution is not colored at
all after storage at 50.degree. C. for 6 weeks. An experiment on
by-products which may be formed depending on the condition has also
indicated minus. As compared with the product in solution,
crystalline L-lysine is evidently colored during this storage.
Formation of by-products has been confirmed in an analytical
experiment. Accordingly, the found behavior described above has
been absolutely unexpected, because general experience teaches that
products liable to degradation are more easily degraded in a
dissolved form than in a crystalline form". The patent document
makes comments on the advantages of the invention, "An aqueous
solution of lysine can be produced easily as compared with
crystalline L-lysine monohydrochloride, and the aqueous solution
has the advantage that the content of chlorides in mixed feeds is
not increased and the solution can be accurately metered even in a
small amount. When a mixed feed is to be enriched with L-lysine,
the L-lysine as a liquid composition does not usually require
inevitable production of a pre-mixture having L-lysine at a
correspondingly high concentration. The aqueous solution of lysine
can, directly at a desired concentration, be mixed uniformly with
other ingredients previously present at desired concentrations in a
mixed feed, for example by sprinkling the lysine solution in a
mixing cooker." Concerning the unexpectedness of the invention, the
document additionally states, "Although L-lysine is referred to as
one kind of amino acid which is destroyed first of all by heat
treatment not only in materials but also in feeds and mixed
feeds--this, free L-lysine is added in the form of an aqueous
L-lysine solution, and is unexpectedly stable even in feeds and
mixed feeds. Degradation and/or reaction does not occur due to
other feed ingredients. In a feeding experiment, an aqueous
L-lysine solution and L-lysine monohydrochloride exhibit the same
action insofar as these are used in the same molar amount".
[0011] The patent document describes, concerning the concentration
of the aqueous lysine solution of the invention disclosed therein,
"To achieve the desired improvement as to weight increase and
utilization of feed, various amounts of L-lysine should be added to
each mixed feed in order to compensate for the content of natural
L-lysine in feed protein. To use an aqueous L-lysine solution
according to the present invention, the amount thereof is generally
0.01 to 5%, relative to the weight of the finished mixed feed,
depending on the concentration of the L-lysine in the solution. In
this case, a solution with a L-lysine content of 30 to 80% by
weight, advantageously 50 to 70% by weight, is particularly
preferable.", and in respect of the process for producing the same,
the document states, "Such a solution is obtained by dissolving
L-lysine in a corresponding amount of water. In commercially
producing L-lysine, it is naturally easy and suitable to produce an
aqueous solution containing L-lysine at a desired concentration
during the commercial production of L-lysine. This evidently
facilitates production and does not so cost as in production of
particularly L-lysine monohydrochloride."
[0012] For nutritionally enriching feeds or industrially produced
mixed feeds with lysine, lysine in the form of a liquid composition
possesses such various advantages as described in JP-B 3-5783
supra, but the liquid composition of lysine described in the patent
document involves the problem that the lysine is easily
precipitated as free form lysine crystals as the temperature of the
atmosphere drops during storage. Precipitation of such crystals
will, in turn, cause clogging of pipes for transferring the liquid
composition of lysine in factories or during shipping and unloading
or make it difficult to transfer the liquid composition of lysine
at a predetermined concentration, thus worsening the handling of
the liquid composition of lysine.
[0013] To sum up, when lysine is used in the form of a liquid
composition, a lysine base solution has been used in many cases
because of higher solubility than in a lysine salt solution such as
lysine hydrochloride solution, lysine sulfate solution etc.
However, from the conventional lysine base solution with a
concentration of not less than 50% by weight, as described in JP-B
3-5783 supra, lysine base is crystalized when the temperature drops
during storage, to cause, e.g., clogging of piping, thus worsening
the handling in some cases.
SUMMARY OF THE INVENTION
[0014] [Problems to be Solved by the Invention]
[0015] Under the technical background described above, an object of
the present invention is to provide a method wherein during storage
of lysine in the form of a free-lysine solution (liquid
composition), the precipitation of lysine base crystals due to the
drop in temperature is prevented thereby improving the handling
thereof during transportation (transfer) etc. This object can be
achieved after all by raising the solubility of lysine in a lysine
base solution, and thus the object of the present invention is, in
other words, to provide a method of improving the solubility of
lysine in an aqueous lysine solution thus preventing precipitation
of lysine crystals during storage and transportation to improve its
handling.
[0016] The raised solubility of lysine in a lysine solution leads
to improvement of the handling of the lysine solution (liquid
composition) and the high-conc. lysine solution (high-conc. liquid
composition) thus provided, in turn, brings about the advantages
that it contributes to a reduction in the cost for transportation
of lysine solutions or that operational costs can be reduced in
spray-granulating by feeding a high-conc. solution.
[0017] [Means to Solve the Problems]
[0018] As a result of their eager study, the present inventors have
found that the acid radical of, e.g., hydrochloric acid (or
hydrochloride) or sulfuric acid (or sulfate) is added at a
predetermined ratio to the lysine, to an aqueous lysine base
solution, whereby the solubility of lysine can be raised than in
the original aqueous lysine base solution (as a matter of course,
the comparison having been conducted at a certain temperature), and
on the basis of these findings, the present invention has been
completed.
[0019] Accordingly, the present invention relates to an aqueous
stable lysine solution containing an acid radical in such amount
that the solubility of lysine therein has been increased than in
the corresponding an aqueous lysine base solution, said
corresponding aqueous lysine base solution meaning an aqueous
lysine base solution having the same composition as said aqueous
stable lysine solution of the present invention except with no acid
radical contained therein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows the solubility curve at 20.degree. C. of lysine
depending on the amount of hydrochloric acid relative to the lysine
(Example 1).
DETAILED DESCRIPTION OF THE INVENTION
[0021] Hereinafter, the present invention will be described in more
detail.
[0022] The aqueous stable lysine solution of the present invention
(liquid lysine composition) is an aqueous lysine solution
containing an acid radical at a predetermined ratio of the acid
radical to the lysine. Incidentally, such a liquid lysine
composition containing an acid radical at a predetermined ratio of
the acid radical to the lysine is a novel material (novel
composition). This is because the Japanese patent document supra
refers to an aqueous lysine base solution only, with respect to the
process for producing the liquid lysine composition, as in: "Such a
solution is obtained by dissolving L-lysine in a corresponding
amount of water" as quoted above, and an aqueous lysine solution
containing an acid radical at the ratio specified according to the
present invention has not been known in any other prior art
literatures.
[0023] Further, it is not easy from the prior art to find an
aqueous lysine base solution containing an acid radical at such
ratio that the solubility of lysine is higher at a certain
temperature than in its corresponding aqueous lysine base solution
containing no such acid radical at the same temperature. As has
been described above, lysine base is readily soluble in water,
while lysine monohydrochloride is readily crystallized. It is
reasonable therefrom to estimate that when hydrochloric acid is
gradually added to an aqueous lysine base solution, the solubility
of lysine is gradually decreased as the concentration of
hydrochloric acid is increased, thus bringing about crystallization
of lysine monohydrochloride, and it is difficult to estimate that
the solubility of lysine base is increased transiently during the
course in which the ratio of hydrochloric acid is raised until
lysine monohydrochloride is crystallized, as found by the present
inventors.
[0024] The aqueous stable lysine solution of the present invention
can be prepared very easily by those who are skilled in the art.
This is because lysine base crystals or lysine salt crystals are
dissolved at a certain temperature in a lysine base solution or in
its corresponding lysine base solution containing an acid radical,
and then the amount of the acid radical relative to the lysine in
the solutions and the solubility of lysine therein are measured,
thereby plotting the solubility curve of lysine depending on the
amount of the acid radical relative to the lysine so that the
desired amount (range) of the acid radical relative to the lysine
can be easily determined.
[0025] Of course, the aqueous stable lysine solution of the present
invention can be easily prepared by adding an acid radical to a
lysine base solution at a suitable ratio of the acid radical to the
lysine, and there are no limits thereto. Alternatively, the aqueous
stable solution can be prepared by any of the following
methods:
[0026] (1) A lysine-containing solution such as a lysine salt
solution or a mother liquor remaining after the lysine has been
precipitated as a salt thereof from a lysine fermentation broth or
a reaction mixture resulting from lysine fermentation, lysine
synthesis or protein hydrolysis, is passed through a
cation-exchange resin, whereby the lysine is adsorbed onto it.
Thereafter, the adsorbed lysine is eluted with, e.g., ammonia water
or the like, and the eluate is concentrated while the ammonia is
removed, to prepare a lysine base solution. A suitable amount of an
acid radical is added to this lysine base solution, whereby the
desired aqueous stable lysine solution can be prepared.
[0027] Here, the phrase "an acid radical is added" concretely means
addition of a free acid such as hydrochloric acid or sulfuric acid,
or its salt (sodium chloride, ammonium sulfate etc.). This is
because the free acid and its salt both contain an acid
radical.
[0028] (2) Calcium hydroxide, barium hydroxide etc. are added to
such lysine-containing solution described above, whereby an excess
sulfate radical contained therein is removed by precipitating it as
sparingly soluble salts such as barium sulfate until the acid
radical has been reduced to a predetermined level. Thus, the
aqueous stable lysine base solution can be obtained.
[0029] (3) The lysine-containing solution described above is passed
through an OH-form anion-exchange resin so that the acid radical is
removed by adsorbing it onto the resin, whereby the aqueous stable
lysine solution with a predetermined amount of the acid radical can
be obtained. In this case, the acid radical may be removed until it
is reduced to a predetermined level, and it is naturally not
necessary to remove all the acid radical moiety.
[0030] (4) A lysine base solution obtained from the above
lysine-containing solution by the method described in (1) above is
mixed with a lysine salt solution such as a lysine hydrochloride
solution, or with an acid radical-containing solution resulting
from fermentation or synthesis, or with a mother liquor remaining
after lysine hydrochloride crystals has been crystallized, whereby
the aqueous stable lysine solution with a predetermined amount of
the acid radical can be obtained.
[0031] The lysine stable solution of the present invention may
contain cations, proteins, organic acids etc. derived from a lysine
fermentation broth or a lysine synthetic mixture unless the effects
of the present invention are deteriorated.
[0032] The thus obtained lysine base solution containing an acid
radical from an acid such as hydrochloric acid, sulfuric acid, or
the like is a novel composition as described above and possesses
the effects of preventing the precipitation of lysine base crystals
at lower temperatures during storage while providing a higher conc.
solution.
[0033] Hereinafter, the foregoing will be described in more
detail.
[0034] FIG. 1 shows the solubility curve of lysine at, e.g.,
20.degree. C. depending on the amount of the hydrochloric acid
relative to the lysine, as measured by the present inventors
(Example 1 infra). The solubility (g) of lysine per 100 g water is
shown on the ordinate, while the molar ratio (%), relative to the
lysine, of the hydrochloric acid in the solution is shown on the
abscissa.
[0035] According to the findings of the present inventors, also at
other temperatures such as 30.degree. C. or -20.degree. C. and also
with respect to other acids such as sulfuric acid etc., the
solubility of lysine is increased in all the temperature range
until a certain point in the molar ratio, while the molar ratio of
an acid radical to the lysine is increased from 0.
[0036] As can be seen from FIG. 1, an aqueous lysine base solution
containing lysine in an amount of the solubility at 20.degree. C.
but no hydrochloric acid (which is an aqueous saturated lysine
solution) becomes supersaturated when the temperature is lowered to
less than 20.degree. C., to precipitate lysine base crystals. On
the contrary, however, if hydrochloric acid is contained in a
predetermined range, even an aqueous lysine solution containing the
same amount of lysine per unit water amount of the solution at the
same temperature hardly becomes supersaturated even if the
temperature is lowered to some degree, thus preventing
precipitation of lysine crystals.
[0037] The aqueous stable lysine solution according to the present
invention means an aqueous lysine solution from which, owing to
incorporation of an acid radical at a predetermined ratio of the
acid radical to the lysine, lysine crystals are hardly precipitated
upon a drop in temperature as compared with a lysine base solution
containing no acid radical (in order words, the solution is
stabilized with respect to precipitation of lysine crystals upon a
drop in temperature).
[0038] As can be seen also from FIG. 1, the lysine solution
containing hydrochloric acid can contain, e.g., at 20.degree. C.
lysine at higher concentrations per unit amount of water (e.g.,
weight) than in the corresponding lysine base solution containing
no hydrochloric acid.
[0039] In the aqueous stable lysine solution containing an acid
radical, from which lysine base crystals are hardly precipitated
upon temperature change (-30 to 80.degree. C.) in a practical
atmosphere, the content of the acid radical is preferably 35% or
less, more preferably in the range of 1 to 27%, and still more
preferably in the range of 5 to 25%, in terms of the ratio of the
product of the molar number of the acid radical multiplied by the
valence of the acid radical to the molar number of lysine.
[0040] The acid radical is preferably the chloride radical, the
sulfate radical or a mixture thereof. As described above, the
chloride radical includes the one derived from hydrochloric acid or
salts such as sodium chloride, potassium chloride and ammonium
chloride, and the sulfate radical includes the one derived from
salts such as sodium sulfate, sodium hydrogen sulfate, potassium
sulfate and ammonium sulfate. If the acid radical is the chloride
radical, the content thereof is preferably 35% or less, more
preferably in the range of 1 to 27%, and still more preferably in
the range of 5 to 25%, in terms of the ratio of the molar number of
the chloride radical to the molar number of the lysine. If the acid
radical is the sulfate radical, the content thereof is preferably
17% or less, more preferably in the range of 2 to 13%, and still
more preferably in the range of 6 to 13%, in terms of the ratio of
the molar number of the sulfate radical to the molar number of the
lysine. If the acid radical is a mixture of the chloride radical
and the sulfate radical, the content of the mixture is preferably
35% or less, more preferably in the range of 1 to 27%, and still
more preferably in the range of 5 to 25%, in terms of the ratio of
the sum of the molar number of the chloride radical and the product
of the molar number of the sulfate radical multiplied by 2 as its
valence to the molar number of the lysine.
[0041] There are no particular difficulting in a process per se for
producing a lysine-enriched feed or an industrially produced mixed
feed by the use of the aqueous stable lysine solution of the
present invention, and conventional known techniques using lysine
in the form of a liquid composition, for example, the techniques
described in JP-B 3-5783 supra can be used. That is, the desired
feed can be produced in the same manner as described in the patent
document supra except that the aqueous stable lysine solution of
the present invention is used in place of the "aqueous L-lysine
solution" referred to therein.
EXAMPLES
[0042] The present invention will be described in more detail by
reference to the Examples.
Example 1
[0043] (1) 1,015 g of medical grade lysine hydrochloride anhydride
crystals were dissolved in 5,000 g of deionized water and the
mixture was adjusted to pH 3.0 with reagent grade 35% hydrochloric
acid. The solution was passed at a flow rate of 19 L/hr through a
column packed with 19 L of NH.sup.+-form cation-exchange resin
("Diaion SK-1B", ex Mitsubishi Chemical Industries Ltd.), whereby
the lysine was adsorbed onto the cation-exchange resin. After
adsorption, the column was washed by passing 38 L of deionized
water therethrough at the same flow rate of 19 L/hr, and after 38 L
of 2 N ammonia water was passed through the column at the same flow
rate of 19 L/hr, 38 L of deionized water was passed therethrough at
the same rate of 19 L/hr, whereby the lysine was eluted. 76 L of
this eluted lysine solution was concentrated under reduced pressure
(50 mmHg) until the lysine concentration reached 70%, whereby a
lysine base solution was obtained. These procedures were repeated 5
times, whereby 4,600 g of aqueous 70% lysine solution was
obtained.
[0044] (2) A 1,800 g portion of the lysine base solution with a
lysine concentration of 70% obtained under (1) above was stirred
under cooling at a rate of -10.degree. C./hr from 50.degree. C. to
10.degree. C. so that lysine base crystals were precipitated. The
crystals were separated and air-dried, whereby 500 g of lysine base
crystals were obtained.
[0045] (3) 390 g of medical grade lysine hydrochloride anhydride
crystals were introduced into 300 g of deionized water and
dissolved by raising the temperature to 60.degree. C. in a water
bath. The solution was stirred under cooling to 15.degree. C. at a
rate of -10.degree. C./hr, whereby lysine hydrochloride. 2H.sub.2O
crystals were precipitated. The crystals were separated and
air-dried to give 280 g of lysine hydrochloride.2H.sub.2O
crystals.
[0046] 70% lysine base solution obtained under (1) above, 35%
hydrochloric acid and deionized water were used in the amounts
shown in Table 1 below, respectively, to prepare 7 kinds of
solutions. In these solutions, the lysine base crystals obtained
under (2) above and the lysine hydrochloride.2H.sub.2O crystals
obtained under (3) above were suspended respectively in the amounts
shown in the same table, and then stirred for 1 week during which
the temperature was kept at 20.degree. C.
[0047] The crystals were removed from these suspensions, and the
concentration of the chloride ions in each of the remaining
solutions was analyzed by an ion chromatographic analyzer "Yokokawa
IC7000 model", and the concentration of lysine therein was analyzed
by an amino acid analyzer "Hitachi L-8500 model". The results are
also shown in FIG. 1 below.
1 TABLE 1 Experimental Conditions 35% lysine Operation 70% lysine
hydrochloric deionized water lysine base hydrochloride No. solution
(g) acid (g) (g) crystals (g) crystals (g) 1 350 0 58 40 2 377 22
46 106 3 378 38 32 155 4 365 52 42 147 4.2 5 326 28 41 49 54 6 401
52 42 1.6 19 7 397 68 38 1.8 22
[0048] As can be seen from FIG. 1, the solubility of lysine is
increased when the chloride ions (the chloride radical) are
contained at a molar ratio of 27% or less to the lysine, as
compared with the case where the chloride ions are not
contained.
Example 2
[0049] Lysine base crystals obtained in the same manner as in
Example 1(2), lysine hydrochloride.2H.sub.2O crystals obtained in
the same manner as in Example 1(3) and deoinized water were used
respectively in the amounts in Table 2 below to prepare 5 kinds of
suspensions, and each suspension was stirred for 1 week during
which the temperature was kept at 30.degree. C. or -20.degree.
C.
[0050] The crystals were removed from these suspensions, and the
concentration of the chloride ions in each of the resulting
solutions. (supernatants) was analyzed by the ion chromatographic
analyzer "Yokokawa IC7000 model", and the concentration of the
lysine therein was analyzed by the amino acid analyzer "Hitachi
L-8500 model". The results are also shown in the same table.
2 TABLE 2 Experimental Conditions Results of Analysis of
Supernatant Components Operation deionized lysine hydrochloride
lysine base temperature Chloride ion solubility of lysine HCl/Lys
No. water (g) crystals (g) crystals (g) (.degree. C.) concentration
(wt %) (g/100 g-H.sub.2O) (molar ratio) 1 40 0 95 30 0 160 0% 2 37
30 80 30 3.4 175 22.8% 3 36 35 80 30 3.9 179 26.0% 4 37 45 58 30
5.0 160 35.0% 5 44 0 60 -20 0 102 0% 6 43 8 55 -20 1.4 106
11.5%
[0051] As can be seen from the table, the solubility of lysine is
increased too at varied temperatures by incorporating chloride ions
(i.e., chloride radical).
Example 3
[0052] 300 g of 60% lysine base solution obtained in the same
manner as in Example 1(1) was placed in a water bath and 63.5 g of
reagent grade 95% sulfuric acid was gradually added thereto. After
addition of sulfuric acid was finished, the mixture was kept at a
temperature of 50.degree. C. and then stirred under cooling from
that temperature to 10.degree. C. at a rate of -10.degree. C./hr,
to precipitate lysine sulfate crystals. The crystals were separated
and air-dried to give 90 g of lysine sulfate crystals. The lysine
sulfate crystals, lysine base crystals obtained in the same manner
as in Example 1(2) and deionized water were used respectively in
the amounts shown in Table 3 below to prepare suspensions, and each
suspension was stirred for 1 week during which the temperature was
kept at 20.degree. C. The crystals were removed from these
suspensions, and the concentration of the sulfate ions in each of
the resulting solutions (supernatants) was analyzed by the ion
chromatographic analyzer "Yokokawa IC7000 model", and the
concentration of the lysine therein was analyzed by the amino acid
analyzer "Hitachi L-8500 model". The results are also shown in the
same table.
3 TABLE 3 Results of Analysis of Experimental Conditions
Supernatant Components Operation deionized lysine sulfate lysine
base sulfate ion solubility of lysine No. water (g) crystals (g)
crystals (g) concentration (wt %) (g/100 g-H.sub.2O) 1 41 0 90 0
147 2 41 10 85 1.9 158 3 42 20 75 2.8 157
[0053] From the table, the effect of increasing the solubility of
lysine by incorporating sulfate ions (SO.sub.4.sup.2-, sulfate
radical) is recognized similarly to the case where chloride ions
(Cl.sup.-, chloride radical) are incorporated.
Example 4
[0054] A lysine base solution with a lysine concentration adjusted
to 62% was prepared by adding 26.8 g of 35% hydrochloric acid to
241 g lysine base solution with a lysine concentration of 74.3%
obtained in the similar manner as in Example 1(1) and then adding
22 g of deionized water thereto, and another lysine base solution
with a lysine concentration adjusted to 62% was prepared by adding
48 g of deionized water to 239 g lysine base solution with a lysine
concentration of 74.3%. The resulting solutions, that is, the
lysine base solution containing hydrochloric acid and the lysine
base solution containing no hydrochloric acid were stirred,
respectively, in sealed vessels in a thermostatic bath at
20.degree. C.
[0055] After 8 days, comparison of both solutions revealed that
lysine base crystals had been precipitated in the system where
hydrochloric acid was not added, whereas precipitation of crystals
was not observed in the system where hydrochloric acid was added.
Accordingly, the stability of the lysine base solution with respect
to precipitation of crystals can be improved by incorporating
hydrochloric acid (chloride ions).
Example 5
[0056] A lysine base solution with a lysine concentration of 75.6%
obtained in the similar manner as in Example 1(1), aqueous 25%
sodium chloride solution, aqueous 25% ammonium chloride solution
and deionized water were used respectively in the amounts shown in
Table 4 below, to prepare 2 kinds of solutions. Lysine base
crystals obtained in the same manner as in Example 1(2) were
suspended in these solutions in the amounts shown in the same
table, and stirred for 1 week during which the temperature was kept
at 20.degree. C.
[0057] The crystals were removed from these suspensions, and the
concentration of the chloride ions in each of the resulting
solutions (supernatants) was analyzed by the ion chromatographic
analyzer "Yokokawa IC7000 model", and the concentration of the
lysine therein was analyzed by the amino acid analyzer "Hitachi
L-8500 model". The results are also shown in the same table.
4 TABLE 4 Result of Analysis of Experimental Conditions Supernatant
Components 75.6% lysine 25% NaCl 25% NH.sub.4Cl deionized lysine
base Chloride ion Solubility of Operation solution solution
solution water crystals concentration lysine No. (g) (g) (g) (g)
(g) (wt %) (g/100 g-H.sub.2O) 1 151 36 10 16 3.1 164 2 122 27 11
3.3 178
[0058] [Effects of the Invention]
[0059] According to the present invention, a free acid such as
hydrochloric acid or sulfuric acid, or a lysine salt such as lysine
hydrochloride or lysine sulfate is added to a lysine base solution
at a predetermined ratio of the acid radical to the lysine in the
solution, whereby the concentration of lysine can be made higher
than in a solution of lysine base alone. That is, addition of an
acid radical in these forms can make the lysine base solution
stable at higher concentration, whereby even the lysine base
solution can be stored without undergoing the precipitation of
lysine base crystals due to, e.g., a drop in temperature, the cost
for transportation of lysine solutions can be reduced, and in the
case where the lysine solution is subjected to spray-granulation,
the high-conc. solution can be sprayed.
[0060] Briefly, the solubility of lysine in water can be improved
(i.e., increased) according to the present invention thereby
preventing the precipitation of crystals upon a drop in
temperature, and the stable lysine solution can be easily prepared
at a higher concentration, thus improving the handling of the
lysine solution during transportation etc.
* * * * *