Note: Descriptions are shown in the official language in which they were submitted.
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B k~round of the Invention
A major concern of food scientists today is the ever
increasing need for an inexpensive source of nutritionally
suitable protein. Various by-products from food processing
have been studied and found to be relatively good,
nutritionally adequate protein sources. The whey from
milk, the bran from wheat, and the waste li~uor from
alfalfa preparation have all been found to be excellent
sources of protein. Such products as fish protein
concentrate have been developed ~ith a high protein
requirement in mind.
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For many years, the soybean has been used as a
protein supplement to animal feeds and also human
foods. More recently soybean prices have risen
dramatically and the total supply has been seriously
reduced. Dry edible beans are commonly used in human
diets. Though they are abundant in protein, they have
traditionally been only a secondary source of protein
to the homemaker. This limited usage is largely due
to taste preferences and flatulence factors, Beans
yield large amounts of protein per acre and constitute
a valuable potential source of world protein.
The extraction of protein from dried beans has
been studied by several investigators. W. D. Powrie
reports in the Journal of Agricultural Food Chemistry
1961, volume 9, page 67 on the Extraction of Nitro-
geneous Constituents from the Navy Bean; R. J. Evans
and M. H. Kerr report in the Journal of Agricultural
Food Chemistry 1963, volume 11, page 26 on the Protein
Isolation, Extraction and Precipitation of Nitrogeneous
Constituents of Dry Navy Beans and F. L. Murphy reports
on the Preparation of Bland, Colorless, Non-Flatulent
High Protein Concentrates from Dry Beans, page 63 of
the 7th Research Conference on Dry Beans at Ithaca
and Geneva, New York held by the Agricultural Re-
search Service, U. S. Department of Agriculture. Up
until now, however, dried beans have not been used
as a regular raw material for extraction of protein.
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Summary of the Invention
The present invention is directed to an efficient
and economical procedure for the extraction of commer-
cially viable amounts of protein from dried beans.
The extracted protein has essentially the same lysine
and methionine content as does the whole bean and in
general the biological value (BV) is slightly higher
than protein from soybeans.
The process of the present invention is specifi-
cally directed to extracting protein from dried beansbotanically named Phaseolus w lgaris and Phaseolus
aureus which include for example, kidney beans, navy
beans, California small white beans, Pink, Pinto and
Great Northern beans. The protein is extracted from
the natural bean without any pretreatment for removal
of oil and the protein is extracted in its native state
without being denatured as may occur in the extraction
of soybean protein. The dried bean protein is bland
without any appreciable bean flavor such as may be
experienced with soybean protein. It may be spray
dried to a white powder for increasing the protein
content and enhancing the flavor and baking quality
of cookies and other baked goods.
In accordance with the present invention, the
selected dried beans either Phaseolus w lgaris or
Phaseolus aureus in finely divided state are mixed
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into an aqueous solution of sodium chloride of con-
centration of not more than about 0.6% w/v NaCl at
ordinary room temperature. The sodium chloride solu-
tion quite readily dissolves or solubilizes the pro-
tein and in about thirty minutes the fibrous solids
are removed as by filtration or in a centrifuge. The
remaining liquid with the dissolved or solubilized
protein is acidified to cause the protein to precipi-
tate. The precipitated protein is separated as a con-
centrated paste which may be spray dried to a powder.
Any ordinary acid may be used to precipitate the bean
protein but hydrochloric acid is preferred.
This very efficient and inexpensive process isbased on the unexpected discovery that an extremely
dilute aqueous sodium chloride solution containing
not over about 0.6% w/v NaCl is extremely effective
for extracting protein from Phaseolus vulgaris and
Phaseolus aureus dried beans. Best results are
achieved with an aqueous sodium chloride solution
containing 0.2% w/v NaCl which appears to be the
optimum concentration for the extraction of dried
bean protein. The use of dilute aqueous sodium
chloride solutions containing 0.2% w/v NaCl increases
the extracted yield of protein from dried beans up
to about 50% over the amount extracted with ordinary
water. Significant advantage in yield is still ex-
perienced with sodium chloride solutions of 0.2 to
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0.05% w/v NaCl concentration and there is advantage
in merely adding some sodium chloride to the water
used for extraction. When the concentration of the
aqueous sodium chloride extraction solution exceeds
0.6% w/v NaCl to any extent there is a drast;c reduc-
tion in the yield of extracted bean protein. For
example, a 1.0% w/v NaCl solution will extract only
about one-half the amount of bean protein that is
ordinarily extracted with 0.5% w/v NaCl solution in
accordance with the present invention and the amount
of bean protein extracted with 1.0% w/v NaCl solution
is less than the amount extracted with ordinary water.
Example 1
Bean flour was formed by passing dried Pink beans
through a Hammermill. The bean flour contained about
20% by weight of protein. 2.0 Kg. of the bean flour
was mixed with 10.0 liters of sodium chloride solution
containing 0.5% w/v NaCl and the slurry mixture was
stirred for 40 minutes. The slurry was then centri-
fuged for 30 minutes at 8000 r.p.m. The supernatant
was separated from the residue and acidified with 6.0N
hydrochloric acid to a pH of about 3.5 to precipitate
the proteins. The supernatant was again centrifuged
for 30 minutes at 8000 r.p.m. to separate the bean
proteins from the whey. The resulting bean protein
concentrate was spray dried to a white bean protein
concentrated powder.
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Examples 2-4
The method of Example 1 was followed in separate
runs using ordinary water, a sodium chloride solution
of 1.0% w/v NaCl and a sodium chloride solution of
2.0% w/v NaCl.
Analyses were performed to determine the yield
of percent protein in the bean protein concentrate
(BPC) using the Official Methods of Analysis of the
American Organization of Analytical Chemists
(AOAC 1970) with the following results:
TABLE I
Protein Content
Example /O NaCl Solution BPC % Yield of BPC %
1 0.0 7.04 71.5
2 0.5 8.96 84.5
3 1.0 3.70 88.5
4 2.0 3.76 88.0
Examples 5 and 6
The procedure of Example 1 was followed in separate
runs using dried Great Northern beans extracted with a
sodium chloride solution of 0.5% w/v NaCl and 1.0% w/v
NaClO
Examples 7 and 8
The procedure of Examples 5 and 6 was followed
using dried Pinto beans with the fnllowing results:
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TABLE II
Protein Content
Example % NaCl Solution % Yield of BPC %
0.5 11.32 78.0
6 1.0 5.34 74.0
7 0.5 9.96 89.3
8 1.0 3062 90.0
Example 9
The procedure of ~xample 1 was followed using
dried Great ~orthern beans and analyses were made us-
ing AOAC 1970 procedures to determine the pr ~ imate
composition of the bean protein concentrate (BPC),
residue and whey. In the following Table the carbo-
hydrate content was determined by difference:
TABLE III
% Pro- % Mois-
Fraction tein % Fat % Ash ture % Carbohydrate
Milled
Bean20.76 3.12 4.3610.23 61.53
BPC 84.38 0.97 1.602.85 10.20
Dried
Whey27.48 1.13 9.4310.67 51.29
Residue7.41 2.37 3.413.48 83.33
The dried residue and whey produced in accordance
with the present invention have a potential use as
animal feed because of the high carbohydrate and
fiber content and relatively high protein content.
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Examples 10-13
The method of Example 1 was followed in a number
of separate runs to determine the yield of percent pro-
tein from different quality rejected dried beans. In
Example 10 whole dried Great Northern beans were used.
Example 11 were moldy 5reat Northern dried beans which
were infected with the white mold Scheratini sclera-
tiorum. Example 12 were split Great Northern dried
beans and in Example 13 the Great Northern dried beans
were wrinkled and off color. Protein extraction from
rejected beans was as follows:
TABLE IV
% Protein % Protein % Protein % Protein
Example Raw Flour in BPC Dry Whey in Residue
21.8 77.90 29.46 10.30
11 22.59 79.79 24.92 15.64
12 20.52 84.85 24.58 12.48
13 22.62 79.19 32.09 15.50
Protein extracted from the Great Northern, Pink
and Pinto dried beans in the preceding examples was
high in lysine content as compared to soy meal. Nutri-
tional and digestibility studies of these bean pro-
teins showed that gross digestibility is slightly
lower than soy while biological value (BV) is slightly
higher than soy. ~hese bean proteins were used to
advantage in bread and cookies to enhance the protein
value. In bread, the protein content was increased
by about 15% with acceptable crumb texture and with
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an expected drop in loaf volume. In sugar cookies,
the protein content was increased by about 30% with
enhanced width, height ratio or spread of the cookie
during baking. In both cases there was no off color,
objectionable aroma or flavor and the texture was normal.
The method of Example 1 was followed in a number
of separate runs using good grade Great Northern beans
and an increasing concentration of sodium chloride with
the following results:
TABLE V
Protein Content
Example % NaCl Solution BPC % Yield of BPC %
14 0.0 10.12 70.5
0.2 12.07 78.0
16 0.4 10.95 81.4
17 0.5 11.32 78.0
18 0.6 8.19 80.8
19 0.8 5.56 73.0
Referring to Table V, it will be seen that there
is a material reduction in the amount of extracted
protein when the sodium chloride solution exceeds 006%
w/v NaCl.
It will be understood that the claims are intended
to cover all changes and modifications of the preferred
embodiments of the invention, herein chosen for the
purpose of illustration, which do not constitute a de-
parture from the spirit and scope of the invention.
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S~PPLEMENTA~Y DISCLOSUR~
It has now been found that protein can be
extracted from at least one other family of beans, identified
botanically as Phaseolus lunatus which includes lima beans,
following the procedure described in the principal disclosure.
EXAMPLE 20
The procedure of Example 1 was followed using
dried lima beans with the following results:
TABLE VI
Example % NaCl Solution% Yield Protein
BPC%
. .
0.5 8.54 84.2
It has also been found, according to a pre-
ferred embodiment of the present invention that best results in
yield of protein are obtained by acid precipitation of hot
protein. Heat may be applied to the liquid before or during
acid precipitation to raise the temperature above about 80C
and preferably to about 90C. Acid precipitation of the hot
protein at about 90C gives a very significant and surprising
increase in yield. The extracted protein at the time of acid
precipitation may be heated above 90C but there is no appreciable
advantage in this and at temperatures above about 115C, the
protein starts to discolor, the yield begins to drop and a
slight caramel flavor develops.
Studies were conducted to determine the effect
of heat on acid precipitation of the dissolved or solubilized
protein remaining in the liquid after separation of the fibrous
Solias .
EXAMPLE 21
~0 A mixture of Phaseolus vulgaris and Phaseolus
lunatus in the proportion of 33.2% of Michigan Navy, 23.6% Pinto,
10.2% Great Northern, 7.1% Red Kidney and 6.0% lima beans were
extracted in accordance with the procedure of Example 1 except
that acid precipitation of the extracted protein was carried
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out at the following temperatures with the following results:
TABLE VII
BPC Yield Protein Yield
Acid Precipitation % Original /O Original
Temperature C Bean Weight Bean Protein Weight
11.84 39.74
10.31 39.77
9.07 33.97
10.86 37.83
17.72 52.10
100 17.20 53.80
110 16.20 50.06
It is believed that the significant increase in yield
of protein above about 80C is due to the fact that the
heat rapidly denatures the bean proteins which tend to be-
come insoluble and are recovered in the BPC fraction instead
of going off with the whey fraction. At above about 100C
the yield begins to drop and above about 115C the protein
discolors and a caramel flavor develops.
EXAMPLES 22-26
The procedure of Example 1 was followed in extracting
protein from the following beans at the specified acid
precipitation temperatures.
TABLE VIII
Acid BPC Yield Protein Yield
Example of Precipitation % Original % Original Bean
Bean Variety TemPerature C Bean Weight Protein Weight
22 - Navy 2512.65 41.95
9016.05 52.41
3023 - Pinto 2515.50 53.23
9016.70 57.18
24 - Great 2515.55 46.96
Northern 9017.90 55.14
25 - Kidney 2514.80 43.05
9010.99 46.80
26 - Lima 256.45 18.98
9012.84 50.99
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In all cases the yield of protein was
significantly better by carrying out acid precipitation at
about 90C.
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