Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
-
This invention relates to the fortification of
proteinaceous foodstuffs which are deficient in both
threonine and sulfur-containing amino acids.
United States patent 3,878,305, R.A. Damico and
R. W. Boggs, issued April 15, 1975 describes a method of
fortifying certain proteinaceous foodstuffs which are char-
acterized by a nutritionally limiting content of sulfur-
containing amino acids with selected N-acyl derivatives of
the L stereoisomeric form of such sulfur-containing amino
acids, and products so fortified.
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As pointed out in great detail in U.S. 3,878,305,
there is considerable impetus to satisfy the protein re-
¢uirements in the diet of humans and commercially important
animals with proteins derived exclusively from vegetable
sources. Unfortunately, proteins derived from plant
species (including microbially-derived proteins) are not
of comparable nutritional quality to animal-derived
protein sources. This is evident, in part, by examina-
tion of the amino acid content of various plant proteins.
Nutritionists have applied the term "limiting~ to such
amino acids and have noticed that a protein characterized
by a particular limiting essential amino acid is effectively
leveled in nutritive value to the cont:ent of the first
limiting amino acid. For example, if a certain vegetable
lS protein is relied upon for the sole source of dietary
~tein, and ir that protein is chara~terized by an amino
acid profile revealing certain limiting amino acids, it
would be necessary to consume in the cliet an excessive
amount of that protein in order to insure the nutritionally-
required intake of those limiting essentia] amino acids.
In U.S. Patent 3,878,305 it is reported thatmethionine is an essential, but limiting, amino acid in
vegetable proteins such as soybean protein, microbially-
dèrived proteins, and like protein sources not of animal
origin. This methionine de~iciency cannot be alleviated
by simply adding methionine to such deficient proteins,
inasmuch as methionine can result in the formation of
bad tastes and foul odors in the food products fortified
therewith. Patentees found that certain N-ac~lated
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methionine derivatives do not suffer from this defect
and are nutritionally available and suitable for use
as a fortification means. Fortification of vegetable
proteins with N-acyl L-methionine results in a very
substantial increase in the nutritive value of vegetable
proteins such as soy protein and raises its nutritive
value to about 74% that of egg white proteins, which are
recognized as being an excellent source of essential
amino acids.
It has now been determined that threonine is a
second limiting amino acid in vegetable proteins and
that supplementation of such proteins with both N-acyl
L-methionine and threonine results in a protein having
a nutritional level of essential amino acids some 88%
lS that of egg white proteins.
The proteins prepared and foxtifi~d irl the m-nncr
of this invention are fully equivalent to meat and cheese
proteins derived ~rom animal sources.
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:~378G~;4
SI~M~ARY OF THE INVENTION
The present invention relates to proteinaceous
foodstuffs comprising:
i) an edible protein which is deficient in both
threonine and sulfur-containing amino acids;
ii) a nutritionally supplemental amount of
threonine; and
iii) a nutritionally supplemental amount of an - .. N-acyl L-methionine derivative, or ester or salt
10 - thereof, wherein the N-acyl substituent is
derived from fatty acids,
said ~oodstuffs being essentially free of ~-acyl D-methionine.
The present invention also encompasses compositions
for fortifying foodstuffs comprising N-acyl L-methionine
and threonine~ ,
- ~le present invention also encompasses a method
of fortifying protein foodstuffs w~lich. are deficient in
both methionine and threonine by adding thereto a nutri- i
tionally efective amount o~ N-acyl L-methionine and a
20 nutritionally effective amount of threonine. :~
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DESCRIPTION QF THE PREFER~ED EMBODIMENTS
As disclosed hereinabove, the present compositions
comprise proteins which are deficient in sulfur-containing
amino acidsO Such sulfur-containing amino acids include
methionine, cystine and cysteine. While the compositions
herein a~n be additionally supplemented with N-acyl-cystine
and -cysteine derivatives without substantially impairing
their desirable odor and flavor qualities (which the "free"
cystine and cysteine would do) this is not necessary in the
practice of this invention since it is well recognized that
methionine can supply the nutritional requirements for
cystine and/or cysteine, but that cystine and/or cysteine
cannot replace methionine in the diet. Accordingly, supple
mentation of the compositions with acylated cystine and/or
cysteine derivatives is not necessary to meet nutritional
requirements and is entirely optional ~erein.
The N-acyl L-methionine employed herein can be
used in its free acid form, in the form o an edible salt,
or as an N-acyl L-methionine ester which hydrolyzes and
de-acylates in the gut to provide L-methionine. The term
"N-acyl L-methionine derivative" as employed herein is in-
tended to encompass such edible, digestible salts and
este~s, as well as the free acid. A more complete descrip-
tion of the N~acyl L-methionine esters suitable for dietary
supplementation is contained in Boggs et al. U.S. Patent
3,952,115, issued April ~0, 1976. ~-
The method fox the identification and preparation
of the N-acyl derivatives of amino acids employed herein
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and an experimental procedure for evaluating the palat-
ability of foodstuffs fortified in accordance with this
invention are fully disclosed in U.S. Patent 3,878,305,
referred to hereinabove n . ' '
S The present compositions comprise proteins which
are also deficient in threonine. Threonine, its edible
salts and its esters which hydrolyze in the gut to provide
"free" threonine, can be used herein. At the present time,
L-threonine is believed to be the only form of this amino
acid which is metabolized by humans. Accordingly, current-
governmental regulations specify that only L-threonine can
be used to fortify foodstuffs intended for human consumption.
D,L-threonine (racemic mixtures) can be used in animal feeds.
The term "threonine" as employed herein encompasses the free
acid and the edible salts and esters; the free acid is preferred.
The classes of foodstufs cont~emplated by this
invention comprise any food source which, for reasons
of nutrition, require fortification with selected amino
acids. This invention finds it5 principal application
in foodstu~fs which contain protein derived substantially
from vegetable sources, e~g., the oil seeds and leguminous
seeds, principally the soybean, but other sources such as
.
microbially derived proteins are also fully contemplated
herein. Specific examples of such proteinaceous food- -
stuff products where the protein component is substantially
derived from the above sources include: textured vegetable
prote1n meat analogs, vegetable protein cheese analogs,
beverages, nut butters, breakfast cereal products,
proteinaceous snack products, pet foods and animal ~eeds.
.
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A detailed discussion of ~oodstuffs of the type employed
in this invention also appears in U.S. 3,878,305~
As noted hereinabove, the present compositions
supply a nutritionally supplemental ~or "effective")
amount of N-acylated methionine and threonine to the
foodstuffs. No absolute meaning can be attached to the
term "nutritionally supplemental or effective amount"
ln the abstract. However, a full discussion of this term,
as it relates to methionine, appears in U.S. Patent
3,878,305 and the same rationale applies to threonine
supplementation.
The threonine used in the human Eoodstuffs herein
is L-threonine (preferred) or its salts, e.g., sodium salt,
or esters, e~g., ethyl ester.
The N-acylated methionines herein include the N-acyl
L-methionine wherein the acyl group is derived from Cl,
and higher, especially Cl-C24, fatty acids, and the salts
and esters of such N-acylated L-methionines. Typical
examples of such compounds are set forth in U.S. Patent
3,878,305, and include N-formyl L-methionine, N-acetyl
L-methionine (highly preferred~, N-stearoyl L-methionine,
and the like.
Preerred compositions herein comprise mixtures of
N-acetyl L-methionine plus threonine, each in nutritionally
supplemental amounts, and proteinaceous foodstu~fs,
especially those derived from soybeans, fortified therewith.
The following animal tests demonstrate that threonine
is the second limiting amino acid in important vegetable-
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derived proteins. By supplementing such proteins with
threonine and N-acyl L-methionine, good tasting,
nutritious proteinaceous foodstuffs are secured.
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Animal Testinq
The usual tes~ for determining the nutritional
benefits of a protein foodstuff involves the protein
efficiency ratio (PER) test. In general terms, this
test involves feeding a diet comprising ca. 10% protein
to rats. The weight gain in the animals divided by
the protein consumed over a four-week period is the
PER. T~e results of a typical test involving composi-
tions of the present type are displayed in Table 1.
. . .
TABLE 1
_ _
ComPOsitiOn PER
Soybean protein isolate 1.6 1 0.2
Soybean protein isolate + NALM* 2.6 i 0.2
Casein (standard) 2.5 ~ 0.2
15 Meat 2.7 (defined)
Egg 3.3 * 0.2
Cheese ca. 2.8 ~ 0.2
Soybean protein isolate + 2.7 ~ 0.2
NALM + lysinè
20 Soybean protein isolate -~ 2.7 ~ 0.2
NALM ~ threonine
*N-acetyl L-methionine
Tests of the foregoing type indicated that PER
studies are not sensitive enough to determine the second
limiting amino acid in soybean protein. (However, it was
noted that soybean protein fortified with NALM and threonine,
in the presence or absence of lysine, resulted in
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increased food consumption and increased growth rate
in the rats.) On the basis of PER tests of the foregoing
type, it was determined that a more sensitive test of
the nutritive value of protein was required in order to
determine the second limiting amino acid.
A more sensitive test, the Slope Ratio Test (a
standard procedure), compares the weight gain in the
animals versus the percentage protein in the diet or ~ -
versus the percentage protein consumed. In the Slope
Ratio Test, the weight gain of the animals is measured
over a range of protein intake levels. In general terms,
the test involves the use o a reference protein, such
as egg, at three levels in the diet. The test protein is
aiso used at three levels. By selecting protein levels
in the range wherein weight gain and protein uptake are
roughly linear, it is possible to determine, graphicallys
the ratio of the slope of the test protein response line
to the slope o~ the reference protein response line. (The
reference protein line gives the greatest weight gain per
protein consumed, i~e., the greatest slope, and is defined
as "100%".~
The foregoing procedure was employed to test
compositions of the present type versus reference proteins
and other test proteins. The proteins were tested at the
?5 10%, 8% and 6% dietary levels. Under this situation,
which is quite stressful to the animals, diferences in
the nutritiva qualities of the protein due to their
differences in amino acid content are readily seen.
~ Results from the Slope Ratio Test appear in
Table 2.
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TABLE 2
Protein Relative Value
Egg 100 (Reference) -
Soy protein isolate 48
Soy protein isolate + NALM . 74
Soy protein isolate + NALM ~ 74
lysine
Soy protein isolate -~ NALM + 88
threonine
Soy protein isolate ~ NALM ~ 88
lysine + threonine
Reference Proteins
Meat 82 !.
Cheese 88
.
As can be seen fxom the foregoi.ng experiment,
threonine is the second limiting amino acid of soy
isolate protein and addition of this amino acid to soy
isolate-~AI~ compositions raises their nutritive value
to that o~ meat and cheese proteins.
20 ~ The important feature of this invention is that
~oodstuffs based on vegetable proteins,.and the like, can ~ ~ .
now be fortified to provide nutritional levels fully ;:
equivalent to meat, cheese, and the like, without undesir- :
able odors and flavors, even after storage or cooking.
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~7866'~
The following foodstuff compositions are prepared
in the same manner as that described in U.S. Patent
3,878,305, with the exception that threonine is added
to provide the additional nutritive benefits disclosed
hereinabove. The examples are typical of the composi-
tions which can be made according to the practices of
this invention but are not intended to be limiting
- thereof.
. . .
EXAMPLE I
A meat analog product is made according to the
ollowing formulation and procedure.
ComponentParts by Weiqht
~oyhe~n isolate 5~.0
Water ~ 40.0
N-acetyl-L-methionine1.8
Threonine (L form)2.5
Fat 10.0
Starch 10.0
Flavoring, color and salt 6.0
The components are blended to form a dough,
passed through a Brabender extruder at a temperature of
ca. 150C and at a pressure of 450 psi. This produces
a cylindrical product from the 4 mm. exit die. The
extruded product is dried and ground to particle sizes
having an average diameter of ca. 1/~ inch.
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3L~3786~
A product prepared in the manner of Example I
is hydrated and shaped into hamburger-like patties and
fried in an oiled pan. The composition has a nutritive
value (with respect to essential amino acids) comparable
S to that of cooked hamburger. No off-flavors attributable
to the degradation products of methionine are observed.
In Example I the N-acetyl L-methionine is replaced
by a nutritionally equivalent amount of N-formyl L-
methionine, ~-propionoyl L-methionine, N-stearoyl L-
methionine, N-palmitoleoyl L-methionine and N-linolenoyl
L-methionine, respectively, and an excellent, nutritive
food product is secured.
EXAMPLE II
A fortified peanut butter composition is prepared
h' adding 1.5 p~x~s b~ wcight L-thrconine ~extrac~ed from
drled egg white) and 0.5 parts ~y weight N-acetyl L- ;
methionine to a commercial peanut butter of the following
composition.
InqLredient Parts by Weiqht ;
Peanut paste gO,o
Salt 1.2
Sucrose 5.8
Molasses 0.5
Soybean monoglyceride - 0 7
~25 Soybean oil (iodine value 2) 0.84
Soyb-an oil (iodine value 107) 0.40
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The peanut butter composition prepared in the
foregoing manner provides nutritionally effective amounts
of methionine and threonine.
A sample of the fortified peanut butter composi-
tion of Example I~ is heated in a water bath at 95C ~-
for 2.5 hours to simulate shelf storage. No off-flavors
or odors attributable to the sulfur-containing amino
acids are noted.
EXAMPLE III
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A nutritionally complete cattle feed composition
encompassed by the present invention :is prepared by
grinding and mixing the following ingxedients. ~The
composition employs the relatively inexpensive D,L-threonine
mixture which is ~cceptahle for US9 in animal feeds.)
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Inqredient Parts_by Weiqht
Timothy hay 960
Dehydrated alfalfa 40
Yellow corn 600
Corn starch 300
Iodized salt 10
Bone meal 20
Soyhean meal 30
Biuret 28
N-acetyl-L-methionine 1.0
D,L-threonine 1.0
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The composition of Example III is fed to steers
at the rate of approximately 12 pounds per day. The
animals on this diet exhibit excellent growth rate and
the feed is characterized by the absence of potentially
S toxic degradation products of the methionine supplement.
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As can be seen from the foregoing, the present
invention encompasses compositions for fortifying food-
stuffs de~icient in sulfur-containing amino acids and
threonine comprising a nutritionally supplemental amount
of threonine and a nutritionally supplemental amount of
an N-acyl L-methionine derivative. Under current govern-
ment regulations, compositions for human use are those
wherein the threonine is L-threonine, whereas compositions
-for animal use can employ either L-threonine or D,L-threonine
mixtures. The compositions herein typically comprise
threonine and N-~cyl L-methionine derivatives at a weig~t
ratio in the range from about lO l to about 1:10.
As noted hereinabove, the N-acyl L-methionine
"derivatives" useful herein include the "free" acid form,
lS as well as esters and edible salts of the N-acyl
~-luethionine. L-methionine is acylated on the nitrogen
(N) atom to reduce objectiona~le odors and ~lavors. With
threonine, which is not a sulfur-containing amino acid,
N-acylation and/or esterification is not necessary since
odor and flavor problems, if any, are slight. However,
N-acylated and/or esterified threonines are useful
herein, inasmuch as such materials are edible (especially
when the N-acyl derivative is a Cl-C24 fatty acid moiety
and when the esterification is carried out using a Cl-C24
alcohol) and all such materials and edible salts are
encompassed by the term "threonine" as employed herein.
As can also be seen from the foregoing detailed descrip-
tion, the present invention also encompasses proteinaceous
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~7~36~L
foodstuffs selected from edible proteins and/or protein
sources which are deficient in both threonine and
sulfur-containing amino acids. Such foodstuffs are
fortified with nutritionally supplemental amounts of
S the N-acyl L-methionine derivatives and threonine, as
defined hereinabove. Under current governmental regula-
tions, foodstuffs for human use are fortified using the
I.-threonine, whereas foodstuffs for animal use can be
. for$ified with either L-threonine or D,L-threonine mix- ~.
tures.
In all of the foregoing compositions, N-acetyl
L-methionine is preferred .as the sulfur-containing amino
acid source.
The present invention also encompasses methods for
fortifying foodstufs which are deficient in sulfur- .
~ontaining amlno acids c~nd ~llreonine. ~uch fortification
methods comprise simply admixing with such foodstuf~s,
especially proteinaceous foodstufs such as soybeans, a
nutritionally supplemental amount of the compositions
herein which consist essentially of a nutritionally
supplemental amount of threonine and a nutritionally .
supplemental amount of an N-acyl L-methionine derivative, ..
all as described in detail hereinabove.
It will be appreciated by nutritionists and formu-
lators that the requisite amount of threonine and N-acyl
L-methionine derivatives employed in the compositions
and methods herein will depend on the amino acid content
of the nutritionally-deficient protein sources being
- fortified.... For most purposes, in order to bring ve~etable :
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1~37~3664
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(including microbially-derived) protein sources up to
meat, c~eese and/or egg values, from about 0.01% to
about 10%, more pre~erably from about 0.5% to about 5%,
b~ weight, of the N-acyl L-methionine derivative ~cal-
~ulated on the basis of the total protein content of theprotein source) is suf~icient to provide a nutritionally
supplemental amount of sulfur-containing amino acids.
Likewise, fortification of proteinaceous ~ood-
stuffs with nutritionally supplemental amounts of threonine
involves the use of from about 0~01% to about 10%, more
preferably from about 0.5% to about 5%, by weight, of
threonine, based on total protein present in said foodstuff.
What is claimed is:
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