Peanut Protein Isolation, Composition, and Properties

Peanut Protein Isolation, Composition, and Properties

BY JETT C. ARTHUR, JR. Southern Regional Research Laboratory, N e w Orleans, Louisiana'

CONTENTS I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11. Production and Processing.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111. Composition of Peanuts.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV. Solubility and Isolation of the Proteins., . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. Composition of Peanut Protein.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VI. Physical Chemical Properties of the Proteins.. . . . . . . . . . . . . . . . . . . . . . . . . 1. Dissociation System of the Globulin.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Electrophoretic Analyses ................................... 3. Light Scattering Investig 4. Ultraviolet Absorption in Solut ...........................

Page 393 394 397 397 399 399 399 401 403

. . . . . . . 404

. . . . . . . . 405

X. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References.,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

408 408

I. INTRODUCTION Plant storage proteins are a major agricultural commodity. More than 50 millions of tons of seeds, containing from 20 to 30% of storage proteins, are harvested annually. These seeds usually contain oil in an amount equal to or greater than the content of protein. About 15 millions of tons of the seeds are harvested in the United States, about 10 millions in China, and about 5 millions in India. 1 One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture. 393

394

JETT C. ARTHUR, JR.

The principal seeds are peanuts (10,400,000 tons), cottonseed (13,200,000 tons), and soybeans (18,900,000 tons). In the United States, the cottonseed and soybeans are sources of edible vegetable oil for production of cooking oils, shortenings, and oleomargarine. The oil-free residue of the vegetable oil industry is used as a livestock feed, and a small quantity of soybean meal is used in the manufacture of adhesives. Peanuts are used primarily as foods in the United States. Traditionally in areas of major production, except the United States, the oilseeds have been used as livestock feeds and exported t o Europe. However, in recent years vegetable oil industries, similar to those in the United States and Europe, have been developed in other countries, particularly in India and South America. The nutritional values of the proteins contained in these oilseeds are affected by associated components. For example, the chemical pigments, gossypols, contained in cottonseed make the oil-free meals toxic for most animals unless fed in limited quantities or unless the meals are prepared by special processes. Raw, oil-free soybean meals are usually toasted to increase their nutritive values. Oil-free peanut meals apparently do not contain a toxic component. The food value of the proteins are comparable; however, when compared with animal proteins, the oilseed proteins are found t o be deficient in lysine and methionine and probably tryptophan. The future utilization of oilseed proteins for foods, feeds, or industrial products offers great promise. The need for research to assist in the development and expansion of uses for these valuable protein materials is evident. Extensive literature reviews on the information available on cottonseed proteins (237) and soybean proteins (238-240) have been published. The object of this review is to report the extent of the basic information available on peanut proteins. It is hoped that this report will be of value t o organizations in planning their future research on peanut proteins. This oilseed protein has the greatest use in foods and probably the most promising future for industrial uses. At present, the United States is the only nation having a complete peanut industry, including product,ion, processing, food and feed utilization. The most significant reports on the physical properties of peanut proteins have originated in Great Britain.

11. PRODUCTION AND PROCESSING The peanut (also known as ground-nut, earth-nut, pistache de terre, goober, monkey nut, manilla nut, ground beans, and pindars) is grown widely in tropical and subtropical regions. The cultivated species of the peanut, Arachis hypogaea, is a member of the family Leguminosae. The peanut is a native of South America, and about fifteen species of wild

PEANUT PROTEIN ISOLATION, COMPOSITION, AND PROPERTIES

395

forms have been found growing in the southern parts of Paraguay and Brazil, in the northeastern part of Argentina, and throughout Uruguay (22,153). Shortly after the discovery of South America, the peanut was introduced into Africa and Europe, and, during the period of the African slave trade, was introduced into the American colonies. The cultivation of peanuts was largely confined to Virginia until after the War between the States. Seeds were carried home by the soldiers, and the cultivation of peanuts spread throughout the South (19,153). During the 1920’s, George Washington Carver of Tuskegee Institute was instrumental in bringing to the attention of the Congress of the United States, the Tariff Commission, and the people of the South the high food value of peanuts and the almost unlimited possibilities for their commercial cultivation (19,153). Three principal varieties of peanuts are grown commercially in the United States, namely, Virginia, Spanish, and Runner. The peanut plant forms a bush or vine above ground which may grow to a length of 1 to 3 feet. The dried vines may be used for hay and are about equal to soybean or cowpea hay in feeding value. The fruit of the peanut is matured beneath the surface of the soil. The pod or shell which forms is cellulosic in nature and contains from 1 to 3 seeds at maturity (19). During harvesting in the southeastern area of the United States the whole peanut plant is usually “plowed out.” After a few hours, the soil is shaken off by hand, and the plants are stacked or shocked by hand around poles about 6 t o 7 feet high with crosspieces nailed to the poles about 6 to 10 inches above the ground. The peanuts will cure in 2 to 4 weeks in warm weather. In attempted mechanization of these operations, the use of heated dryers to speed up the curing has been investigated (25). The seed, remaining after shelling, is made up of three parts, (1) the testa or skins, (2) the heart or germ, and (3) the kernels separated into two parts. In the shelled whole nut uses, the testa are usually removed during processing. In peanut butter uses, both the testa and germs may be removed. In the peanut oil industry the whole seed is usually crushed or extracted to remove the oil (19,99). In removing the oil from the seeds, four methods have been used on a plant scale, namely, hydraulic press.ing, screw pressing, solvent extraction, and prepressing followed by solvent extraction (19). Most newly constructed plants use prepressing followed by solvent extraction methods to remove the oil (173). Usually the initial oil content of the seeds is reduced from 45-50% to 1 5 2 0 % by mechanical pressing; then the content of oil is further reduced to about 1% by solvent extraction. In the United States the production of peanuts increased gradually

396

JETT C. ARTHUR, JR.

from 1919 to 1934 with a small fraction of the crop being crushed for oil. In 1934 the United States government instituted programs to encourage the crushing of peanuts for oil. This led t o a record crushing of 280,000tons of peanuts in 1940. Subsequently, minimum price support programs and acreage controls were introduced which caused an increase in production to about 1,000,000tons per year and a decrease in the crushing of peanuts TABLE I Peanuts: U . S. Acreage, Production, Value, and Disposition 1941-60a Total acreage Acreage Producplanted, harvested, tion, Year 1,000 acres 1,000 acres 1,000 tons 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 a

2,945 4,701 5,150 4,113 4,100 4,173 4,366 4,146 3,091 2,927

1,900 3,355 3,528 3,068 3,160 3,142 3,380 3,311 2,332 2,277

738 1,096 1,088 1,040 1,021 1,019 1,091 1,169 938 1,010

Total used for Food uses, seed, Crushed, 1,000 tons 1,000 tons 1,000 tons

Value, $1,000 68,746 133,248 155,025 167,352 168,878 185,399 220,360 246,495 194,696 220,138

124 215 227 168 146 225 210 193 222

133 144 120 120 116 123 114 90 89 84

455 679 686 787 800 694 757 945 784

-

-

U. S. Dept. Agr., Agricultural Statistics 1951 (230).

TABLE I1 Peanuts: Production in Specified Countries, Average 1936-59, Annual 19@-60a Production, 1,000 tons Country

Average 1935-39 1949

India China United States Georgia Texas Alabama North Carolina Virginia French West Africa Nigeria and Cameron Brazil World total U. 8. Dept. Agr.. Agricultural Statistics 1951 (230).

3,296 2,913 614

-

-

876 355 15 9,550

3,817 3,244 938 306 167 145 122 98 723 500 154 11,050

1950 3,200

-

1,019 340 162 163 123 112 612 400 110 10,410

PEANUT PROTEIN ISOLATION, COMPOSITION, AND PROPERTIES

397

for oil. I n 1952, the wholesale and retail prices of peanuts are maintained a t such high levels that they are principally grown for whole nut, confection, and butter uses. Only peanuts of low quality or peanuts under subsidized programs are crushed for oil (19,230). The United States acreage, production, value, and disposition of peanuts are given in Table I. The portion of the crop which is not harvested is “ hogged off” (230). On a worldwide basis peanuts are one of the largest oilseed crops. In recent years there have been significant increases in the production of peanuts in Brazil. Comparisons of the cultivation of peanuts in different countries are given in Table I1 (230). 111. COMPOSITION O F PEANUTS The cellulosic shell comprises about 20-30% of the weight of the mature peanut. The proximate composition of peanut shells has been reported on a moisture-free basis, as follows: protein, 5-7.3”; ether extract, 1.2-2.1 %; crude fiber, 66-80%; nitrogen-free extract, 10.6-21.2%; ash, 3-4.6%. The presence of reducing sugars, 0.6%, disaccharide sugars, 1.7%, starch, 0.7%, and pentosans, 18%, has also been reported (26-27, 84,92,100,187). The seeds contain a n average of 45-5001, of oil, 25-30% of protein, 5-12% of carbohydrates, about 3 % of crude fiber, and 2.5% of ash (24,45,60,92,96,100,105,169-171,187,219). Ten t o twelve per cent of the nitrogen content of peanuts is usually reported a s nonprotein nitrogen (92). The composition of peanut oil expressed as glycerides on a molar basis is approximately : monosaturated-oleo-linoleins, 45 % ; linoleodioleins, 24 %; triolein, 19 %; monosaturated-dioleins, 11 % ; and oleodisaturated, about 1 %. The oil also contains small quantities of phosphatides, lecithin, cephalin, phytosterols, antioxidant, and mineral constituents (60,92,100,187).

IV. SOLUBILITY AND ISOLATION OF THE PROTEINS I n 1880 Ritthausen (172) reported the isolation of a protein product

from oil-free peanut meal, using aqueous sodium chloride solution as the solvent for extraction of the protein. Lichnikov (131) in 1913 proposed the classification of peanut protein into three fractions, albumin, globulin, and gluten components, based on their relative solubilities in water, salt solutions, and aqueous potassium hydroxide, respectively. I n 1916 Johns and Jones (109-113,119,121) gave the two major fractions of peanut protein the names arachin and conarachin, based on sohbility data, which are commonly referred t o today. They suspended

398

JETT C. ARTHUR, JR.

500 grams of oil-free peanut meal in 2.5 liters of 10% sodium chloride solution. The suspension was clarified by filtering. The protein fraction which was precipitated from the clarified solution on addition of ammonium sulfate to 0.2 saturation was designated arachin. The precipitated globulin was isolated by filtering, resuspended in 10 % sodium chloride, and reprecipitated by dialysis. The precipitate of arachin was washed with ethanol and ether and dried in vacuo. Ammonium sulfate was added t o 0.8 eaturation to the initial filtrate resulting from the isolation of arachin. The fraction of protein precipitated was designated as conarachin. Subsequently, Jones and Horn (122) reported that arachin was not completely precipitated from sodium chloride solution by ammonium sulfate until the solution contained 0.4 saturation with ammonium sulfate. Macheboeuf and Tayeau (134-137,191) isolated arachin and conarachin and reported that their isoelectric points were 5.1-5.2 and 3.9-4.0, respectively. Fontaine and others (20,23,34,35,39,78-80,82,83,97,152,160,164,165, 184) have investigated the effects of type of salt, salt concentration, and pH of aqueous solutions on the solubility on peanut proteins. The most effective salts for dispersing the proteins at pH values between 5 and 6 are calcium, barium, and magnesium chlorides in concentrations of 0.25 to 1.0 N . Sodium and potassium salts (except fluorides and acetates) are good dispersing reagents at 1.0 N concentration. More than 90% of the protein contained in solvent-extracted meals is dispersed in aqueous sodium hydroxide at pH 7.5. The minimum solubility of the proteins in aqueous solutions occurs at pH 4.5. Hoffpauir and Guthrie (102) have proposed a unique method for the isolation of proteins low in ash and phosphorus contents and for the purification of protein preparations. They used anion exchange materials to increase the pH of aqueous suspensions of peanut meal and cation exchange materials to reduce the pH of the protein dispersion t o the isoelectric range. The use of specially prepared aminized and phosphorylated cotton fabrics as ion exchange materials has made the method practical. Since peanut proteins are very soluble in water in their native state, Sugarman (188) has proposed the simultaneous extraction of oil and proteins from macerated kernels by vigorously mixing the kernels with water and then separating the oil, proteins, and insoluble constituents by centrifugation. The isolation of protein, free of the pigments contained in the testa of red-skinned varieties of peanuts, has been reported (62,101,186). Irving and others (107) proposed the precipitation of the protein from an alkaline extract of peanut meal by successively lowering the pH. They claimed that the protein which precipitated at about pH 6 was free of

PEANUT PROTEIN ISOLATION, COMPOSITION, AND PROPERTIES

399

red color. Bonotto (31) reported that washing of the oil-free meal with a dilute solution of sulfur dioxide prior t o extraction and isolation of the protein diminished the red coloring in the protein. McLean (142,144) claimed that protein extracted from meal in an alkaline solution at pH 8.0-8.5 was low in red color. Probably the most successful method for removing the red coloring matter of the testa has been washing of the seeds with dilute alkali prior t o extraction of the oil (38). The two schemes usually followed in the isolation of peanut proteins from oil-free meals are (1) the “salting-in” and “salting-out” method of Jones and Horn (122) for the preparation of arachin and conarachin and (2) extraction of the proteins with dilute aqueous sodium hydroxide a t pH 7.5 and precipitation of the proteins with gaseous sulfur dioxide a t p H 4.5 (7,10,36,47-50,54,127,139-141,163,166). The method of Jones and Horn (122) previously outlined is used in preparing purified fractions of peanut protein for physical chemical investigations. The second method is commonly used in preparing a fraction of whole peanut protein whose chemical analysis is reproducible. This method consists of (1) suspending 1 kg. of oil-free peanut meal in 10 liters of water, (2) adding of concentrated solution of sodium hydroxide t o adjust the p H of the suspension from 6.2-6.6 to 7.5, (3) clarifying of the suspension by centrifugation, (4) adding gaseous sulfur dioxide t o reduce the p H of the solution to 4.5, and (5) isolating the precipitated protein from the solution b y filtering or centrifuging. Yields of 65-750/, of the initial content of nitrogen of the meal can be obtained in the isolated protein.

V. COMPOSITION OF PEANUT PROTEIN Protein, prepared by the second method, specifically that of Arthur and others (7,10), has an elementary composition on a moisture-free basis as follows: lG.23% of nitrogen (Kjeldahl), 0.74% of ash, and 0.06% of fat. The amino acid contents of different preparations of peanut protein (calculated t o 16% of nitrogen) are given in Table 111. The analyses of the protein isolated by the method of Arthur and others (7,lO) were reported by Murphy and Dunn (154). They obtained the values by microbiological assay methods. The analyses of the other preparations were compiled from various literature sources by Guthrie and others (92,100). VI. PHYSICAL CHEMICAL PROPERTIES OF THE PROTEINS 1. Dissociation System of the Globulin The usual methods for isolating the globulin from a saline solution of peanut protein are by dilution with water and acidification t o p H 5.0

400

JETT C. ARTHUR, JR.

TABLEI11 Amino Acid Content of Peanut Proteina Protein Preparation, Amino acid

%b

Protein (154) Total protein (92) Arachin (92) Conarachin (92) ~

Glycine Alanine Valine Leucine Cystine Aspartic acid Glutamic acid Tyrosine Phenylalanine Proline Tryptophan Arginine Lysine Histidine Methionine Threonine Serine Hydroxylysine Isoleucine

4.1

-

4.7 6.7 12.0 20.0

-

5.4

14.0 3.1 2.0 1.1 3.4 4.0

5.6 4.2 8.0 7.0 1.9 5.8 19.2 4.4 5.4 2.0 10.6 3.4 2.1 1.2 2.9 4.3

1.8 4.1 1.1 3.9 1.1 5.3 16.7 5.5 2.6 1.4 0.9 13.5 5.0 1.9 0.5 2.6 5.2 0.01

2.1 14.6 6.0 1.8 2.1 2.0 5.0

-

Calculated to 16 % nitrogen. Numbers in parenthesis are reference8 which indicate method of preparation of protein and literature source of analyses. b

or by 40 % saturation with ammonium sulfate. The proteins isolated from peanut meal by either of the methods had been reported by Johns and Jones (110) t o be identical in their properties as evaluated by elementary or amino acid composition. However, Johnson and others (52,114,116,117) have shown that the globulin, arachin, salted out of the saline solution with ammonium sulfate consists of one sedimenting species having a constant of Stoo 14.6 and that the globulin precipitated by dilution and acidification to pH 5.0 from the saline solution consists of two sedimenting species having constants of Szo0 14.6 and 9.5. If this dissociated globulin is redissolved in aqueous sodium chloride and then salted out, a globulin consisting of one sedimenting species with S20° 14.6 is obtained. Also the ultracentrifugal analysis of a 6 % sodium chloride extract of oil-free peanut meal yields a single globulin component with SzOo14.4 and a small quantity of very low molecular weight protein. From these results they concluded that the globulin, arachin, was a dissociation system composed of a parent molecule which divided into two molecules under certain experimental conditions.

PEANUT PROTEIN ISOLATION, COMPOSITION, AND PROPERTIES

401

The factors necessary for the dissociation of arachin were investigated by sedimentation analysis of different preparations in phosphate buffers, p = 0.1, initial p H 7.98 and final pH 7.6. A 1 % solution of undissociated arachin, S2oo 14.6, in 6% sodium chloride solution a t p H 6.0 was prepared. The globulin which precipitated on dilution of the solution of arachin by a tenfold addition of water, resulting in a decrease in concentration of protein and salt, consists of one species with Szoo 14.9. The globulin which precipitated on addition of a ninefold volume of 6% sodium chloride solution and acidification t o p H 5.0, resulting in a decrease in protein concentration and in pH, consists of one species with SZOO 14.6. The globulin which precipitated on dialyzing the solution of arachin against water adjusted to pII 5.0, resulting in a decrease in salt concentration and pH, consists of two species with S2,0 8.3 and 13.4. Johnson and Shooter (117) concluded that a low salt concentration and a p H about equal to 5.0 are essential to dissociate arachin, Szoo 14.6. Danielsson (64) determined the sedimentation constants of the globulin components of thirty-four species in the family Leguminosae. The constants for globulins isolated from Arachis hypogaea were SzOo 1.93, 8.40, and 13.05. The latter two constants are in agreement with those determined by Johnson and others (52,114,116,117). For four of the species Danielsson (64) reported the presence of another globulin component with Szoo18-20. Subsequently, Goring and Johnson (89) reported that associated arachin had one principal component with S2O0 13.3; however, they also found that 6.3% of the protein had a constant of S*oO 21.1. From these data if the molecules are assumed t o be spherical in shape, the following association-dissociation system is probable: kii

2As $4Aa

kiii 3

16A

This would indicate that the native, associated globulin contained in the peanut has a molecular weight of at least 600,000. The native globulin readily and irreversibly dissociates into arachin which has a molecular weight of about 300,000. It has been shown that arachin is reversibly dissociated by dilution and acidification into two molecules having molecular weights of about 150,000. These molecules dissociate into smaller molecules having molecular weights of about 40,000. Sedimentation and diffusion constants for peanut protein components reported by Eirich and Rideal (72) showed that unfractionated protein contains globulins with approximately these molecular weights. 2. Electrophoretic Analyses Electrophoretic examination of arachin, both Szoo14.6 and 9.0 species, has shown that the two species have similar mobilities a t 20" C. in

402

JETT C. ARTHUR, JR.

phosphate buffer, p = 0.10, at p H 6.88, 7.08, and 7.94. No complete separation of the two components having molecular weights of about 330,000 and 180,000 was effected at any pH. Examination of arachin, S 2 0 ° 14.6 species, indicated the slow dissociation of the parent molecule. Although incomplete separation of the associated and dissociated species was obtained in electrophoresis, qualitative estimation of the rate of dissociation at pH 7 yields a half-life of about 50 hours and a t pH 8, a half-life of greater than 100 hours (118). I n barbiturate buffer, p = 0.04, a t p H 7 the half-life of dissociation of arachin is much less than 50 hours, and a t p H 8 the half-life ranges from 100 to 200 hours (118). The examination of peanut meal extract, arachin, and conarachiti in ammonia buffer, p = 0.1, p H 9.26, has been reported (81,106). The meal extract which contains about 98% of the protein is composed of one major component and two minor components. Arachin which represents about 63% of the protein is composed of two components in a ratio of about 3 t o 1. Conarachin which represents about 33% of the protein is composed of two components in a ratio of about 4 t o 1. These data are summarized in Table IV. TABLEIV Mobilities and Estimates of the Relative Amounts of the Protein Components in the Peanut Meal Extract, Arachin, and Conarachino A Component Fraction Buffer extract of peanut meal Arachin, twice reprecipitated Conarachin, once reprecipitat,ed Conarachin, twice reprecipitated

33 Component

C Component

Mobilityb Per centc Mobility Per cent Mobility Per cent 6.3

76

5.1

11

3.7

13

6.0

76

5.3

24

-

-

6.0

80

-

-

3.5

20

6.0

78

-

-

3.4

22

a From Irving, Fontaine, and Warner (81,106). Ammonia. buffer, p tration 0.8 %. b Cm.2 volt-' sec.-L X 106 reduced to Oo C. Calculated from the descending pattern.

= 0.1, pH 9.26,

protein concen-

The calculation of the probable limits of the net charge of the protein molecules of the arachin system from their electrophoretic mobility was made assuming two extreme models, a solvated sphere and a n unsolvated cylinder. I n phosphate buffer, p = 0.1, p H 6.8-8.0, the SzO0 9.0 fraction has probable net charges of 30.6-35.3, assuming a sphere, and of 33.4-38.3,

PEANUT PROTEIN ISOLATION, COMPOSITION, AND PROPERTIES

403

assuming a rod. For the Szoo14.6 species, the values are 36.1-42.25 for spheres and 39.3-46.0 for rods. The increased net charge of the S20° 14.6 species is probably due to adsorbed sulfate ions (115). In determining the effects of type of buffer and pH on the analysis of peanut meal extracts, the same electrophoretic pattern was obtained over a pH range from 8.3 to 10.2 with borate, veronal, ammonia, and glycine buffers, 1.1 = 0.10 (124). The patterns determined in glycine buffers had sharper boundaries. The effects of increasing the pH of glycine buffers from 10.2 to 11.4 on the patterns were to decrease the amount of the faster moving components, to increase the amount of the slower moving components, and finally to yield a single diffuse component. This effect of hydroxyl ion on the pattern was shown to be reversible.

3. Light Scattering Investigations Arachin, 93.7% Szoo13.3 and 6.3% Szoo 21.1, was examined in phosphate buffer, p = 0.5, pH 7.4, protein concentration 0.38 g./100 ml., by means of light scattering apparatus. In a filtered solution arachin had an apparent molecular weight of 17,000,000 with IsO/Ilzo of 1.8. On further clarification by ultrafiltration, the molecular weight was 333,000 with 160/1120 of 1.074. This value is in agreement with the accepted value for the molecular weight of arachin of 330,000 calculated from sedimentation and diffusion constants (89).

4. Ultraviolet Absorption in Solution The ultraviolet absorption spectra of arachin, associated species (S2,o 14.6) and dissociated species (Szoo14.6 and 9.5) in phosphate buffer at pH 7.3 and 11.0, are identical (65). This agrees with ultracentrifugal data that the two species are equilibrium states of the same molecule. The ultraviolet absorption spectra of arachin and conarachin a t pH 7.3 are similar; however, at pH 11.0 the spectra are very different. The data indicate that if conarachin, the slower sedimenting species, results from the dissociation of arachin, the dissociation takes place in such a manner that conarachin has a lower percentage of tyrosine than arachin. Reversible changes in the spectra of total peanut protein, both arachin and conarachin, in phosphate buffers over a pH range of 7.3-11.0 can be explained as due to the ionization of the tyrosine groups in the molecule (65). 5. Viscosity of Aqueous Solutions Rurnett and others (43) reported that the viscosity of peanut protein solutions was very sensitive t o changes in concentration of protein. ’ protein, become thixotropic at Solutions, containing more than 26%

404

JETT C . ARTHUR. JR.

pH 8.5. At protein concentrations above 28% and at p H values below 10.0, these workers reported that the solutions either gelled or developed a very high viscosity. Thomson and others (67,68,147,195,203-205,228) studied the reactions of peanut protein with aqueous sodium hydroxide, urea, and ammonium hydroxide. They reported the correlation of the viscosities of the solutions with concentrations of protein and sodium hydroxide, time, and temperature. The gelation of the solutions decreased by raising the temperature of the solutions to 70" C. Arthur and Many (3,12) have shown that alkaline solutions of peanut protein may be classed as viscoelastic solutions. The viscosities of the solutions are relatively large values when measured a t low rates of shear and decrease with increasing rate of shear to an approximately constant value. The viscosities of peanut protein solutions, containing urea or sodium hydroxide, increase with maturation t o a maximum value. This phenomenon could be explained by Astbury's hypothesis that peanut protein in its native state is a globular molecule which unfolds in alkaline or urea solution (15-17). The unfolding of the molecule would increase its axial ratio and the interaction between molecules resulting in an increase in viscosity. Mann (138) has found that the intrinsic viscosity of peanut protein in 10 M urea is increased by the reaction of the protein with terephthalyl dichloride. VII. CHEMICAL REACTIONS OF THE PROTEINS The chemical reactions of peanut protein have been principally investigated with respect to the stabilizing of derived products. Mechanisms of reactions have not been investigated (29,75,87,88,91,158,162,193). The use of formaldehyde, acetic anhydride, ketene, benzoquinone, acid chlorides, and aqueous solutions of sodium nitrite, sodium sulfite, and sodium cyanate t o increase the water-resistance of peanut protein fibers and bristles has been reported in the patent literature (58,76,77,87, 88,115,138,151,161,162,193,194,206). The use of polyvalent metals, such as aluminum, chromium, zinc, cadmium, and mercury, t o decrease the absorption of water by fibers and bristles has also been claimed (29,201,202,211-215). VIII.

PEANUT PROTEIN IN FOODS AND FEEDS 1. Nutritional Value of the Proteins

The utilization of peanut protein in foods or feeds has usually been as whole nuts and as relatively oil-free cake or meal. The results of a

PEANUT PROTEIN ISOLATION, COMPOSITION, AND PROPERTIES

405

great number of investigations on the nutritive value of the proteins have been reported. The use of different techniques and of meals defatted by various methods has caused considerable variability in results (18,21,28, 32,44,51,53,63,71,74,94,108,149,150,155,174,189,190,233,234,236) . In 1950 Murphy and Dunn (154) reported an evaluation of the nutritive value of isolated peanut protein relative t o that of beef, rabbit, tuna fish, and casein. The amino acid composition of the peanut protein which they used is given in Table 111. They determined the growth and reproductive response of female mice fed a t a 19% dietary protein level. The growth-promoting qualities of peanut protein were not significantly different from those of animal proteins, evaluated as gain per day, gain per gram of food, or gain per gram of protein. There was not a significant difference in the reproductive and lactational response of female mice on lysine diets containing beef, rabbit, tuna fish, or peanut protein methionine as sources of protein. The response of the mice on peanut lysine or peanut protein was significantly lower than on animal protein proteins. In comparative feeding trials with peanut meal supplying protein equivalent to 5.5% of the diet, Altschul and others (1) reported that solvent-extracted and hydraulic-pressed meals supported chick growth as well as screw-pressed soybean-oil meal and nearly as well as hydraulicpressed cottonseed meal. Grau (90) has found that to obtain optimum growth of chicks on commercial peanut cake lysine and methionine must be added to the diet. Jones and Divine (120) reported that to support maximum chick growth the protein must be supplemented by addition of methionine and tryptophan. As a source of dietary protein in mixed feeds for beef and dairy cattle, swine, poultry, dogs, and rats, peanut cake has been found by numerous investigators to compare favorably with other vegetable proteins (30,120, 148,207,231).

+

+

+

2. Food Uses

Most of the harvested peanut production in the United States is used for food. About 75% of the harvested crop is cleaned and shelled, and about 25% of the crop enters the trade as whole, unshelled nuts. The U. S. No. 1 shelled nuts are used in peanut butter, salted nuts, confections, and bakery products (57). The commercial production of peanut butter has consumed as much as 35-50 percent of the U. S. No. 1 shelled nuts. Peanut butter is usually marketed in glass containers; however, the butter is also used as filler in candy and sandwiches. The caloric value and protein, thiamine, riboflavin,

406

JETT C . ARTHUR, JR.

and niacin contents of peanut butter compare favorably with other food products such as pork, beef, and dry beans (57). Salted peanuts consume about 25 to 35% of the shelled nuts. The nuts may be roasted and salted without removing the skins. About 15 to 25% of the shelled nuts is used in candies, such as, chocolate and plain peanut bars, peanut brittle, and sugar-coated peanuts. A small quantity of peanuts is used by bakeries in making peanut cookies (57). 3. Feed Uses The use of whole peanuts in hog production in the southeastern area of the IJnited States is an established industry. The hogs are carried during the spring and summer on maintenance rations. After the harvesting of the peanuts in the fall the hogs are turned into the fields for grazing until they reach a finished weight. About 25% of the acreage, equivalent to about 200,000 tons of peanuts, is “hogged off” (230). Peanut cake, remaining after the removal of the oil from the kernels, is ground t o meal and mixed with ground shells to adjust the protein content to 45%, the trading rule value. I n the United States this modified meal, amounting t o about 100,000 tons annually, is available on a limited and local scale as a livestock feed (230).

IX. NONFOOD USES FOR PEANUT PROTEINS 1. Fibers

The concept of the preparation of a fiber from peanut protein was a result of the x-ray interpretation of the denaturation of the protein in solution (15-17,178,179). The native protein, occurring in a coiled, nonfibrous configuration, is denatured in alkaline or ores solutions to form fibrous molecules. The orientation of these fibrous molecules and the restraining of them in a fixed position have resulted in the preparation of a wool-like fiber. The details of the preparation of this fiber have been extensively reviewed elsewhere (2,66). The properties of the fiber have been reported under two names Ardil in Great Britain and Sarelon in the United States. The fiber is lightcream colored in its natural state and has a soft hand luster and warmth similar to that of wool. The fiber has an affinity for dyes normally used on natural protein fibers. Solid shades of unions composed of wool and peanut protein fiber can be obtained. Fibers with tensile strengths of 0.8-1.0 gram per denier (dry) and of 0.3-0.5 gram per denier (wet) with elongation-at-break characteristics similar to wool have been made (4-6,8,11,13,33,46,55-56,58,61,69-70,73,76,77,85,86,93,95,98,123,125,126, 132,133,143,145,146,151,159,161,167,175-177,180,183,185,194,196-202, 206,208-218,220-227,229,232,235).

PEANUT PROTEIN ISOLATION, COMPOSITION, AND PROPERTIES

407

The construction of a plant in Scotland to extrude the fibers commercially has been reported (181). 2. Glues

Burnett and others (37,41,42) have prepared water-soluble glues from peanut protein isolated from defatted peanut meal. The glues are rewettable, flexible, and nonwarping and are suitable for making gummed tape and paper. The use of defatted peanut meal in plywood glues has been reported in the United States and India (40,103,104,129,156,157). Peanut meal, which has a minimum of 50% protein content and a nitrogen solubility of at least 70% in 1 M sodium chloride, is satisfactory for making waterresistant glues.

3. Paper Coatings and Sizes Coatings containing peanut protein compare favorably in adhesive strength with coatings containing casein or soybean protein (9,14,128,192). Reflectance data indicate that coatings containing peanut protein are slightly darker, i.e., the “yellowness” of all three coatings was about the same, and the “whiteness” of the coatings containing casein and soybean protein was about 5 % greater than coatings containing peanut protein. Corwin and Dunham (59) prepared a product suitable for sizing paper by extracting defatted peanut meal by aqueous ammonium hydroxide or borax. The solution of protein was clarified and concentrated by evaporation; then it was used as a sizing solution. Singh and Singh (182) reported that peanut protein was used alone and in combination with rosin in aqueous solution to prepare paper sizes. 4. Fire Extinguishing Compound

Levin (130) patented a process for preparing a fire extinguishing liquid utilizing peanut cake. The cake is suspended in aqueous calcium hydroxide, and the solution is heated at 95” C. for 2 hours, filtered, and neutralized. The clarified solution is concentrated to 35-400/, of solids. The foam produced on agitation of this solution is dense and relatively permanent. 5. Molding Powder

A water-resistant molding powder can be prepared by mixing finely ground defatted peanut meal with synthetic resins, such as condensation products of phenols and formaldehyde (168).

408

JETT C. ARTHUR, JR.

X. SUMMARY The worldwide production of peanuts exceeds 10,000,000 tons annually, with about 10% of the crop being grown in the United States. The protein content of the nuts is about 25% which makes the peanut a significant source of vegetable protein for foods, feeds, and industrial products. Peanut protein consists of two principal fractions, arachin and conarachin. Arachin is a dissociation system, and its apparent physical chemical properties are dependent on the state of equilibrium existing between the associated and dissociated species. Although chemical treatments have been devised for stabilizing derived products, very little information is available on the chemical reactions of the proteins. The nutritional value of peanut protein compares favorably with other vegetable proteins; however, when compared with animal proteins, peanut protein is found to be deficient in lysine and methionine. Fibers, glues, sizings, and other industrial products have been made experimentally from peanut protein. The production of a wool-like &ber from peanut protein is being expanded t o an industrial scale.

REFERENCES 1. Altschul, A. M., Irving, G. W., Jr., Guilbeau, W. F., and Schaefer, H. C. (1948). Poultry Sci. 27, 402. 2. Arthur, J. C., Jr. “ Peanut Protein Fibers,” Colloid Chemistry-Theoretical and Applied, Vol. V l l I . Jerome Alexander, Editor. (In preparation.) 3 . Arthur, J. C., Jr. (1949). J . Am. Oil Chemists’ SOC.28,688. 4. Arthur, J. C., Jr. (1949). J . Southern Res. 1, 6. 5. Arthur, J. C., Jr. (1949). Mfrs.’ Record 118,40. 6. Arthur, J. C., Jr. (1951). Peanut J . and Nut World 30, 21. 7. Arthur, J. C., Jr. U. S. Patent 2,529,477, Nov. 14, 1950. 8. Arthur, J. C., Jr. (1951). 1960-61 Yearbook of Agriculture, U. S. Dept. Agr., pp. 611-14. 9. Arthur, J. C., Jr., and Cheng, F. W. (1949). Am. Dyestuff Reptr. 38,535. 10. Arthur, J. C., Jr., Crovetto, A. J., Molaison, L. J., Guilbeau, W. F., and-Altschul, A. M. (1948). J . Am. Oil Chemists’ SOC.26, 398. 11. Arthur, J. C., Jr., and Many, H. G. (1950). Am. Dyestuff Reptr. 39, 719. 12. Arthur, J. C., Jr., and Many, H. G. (1952). Am. Dyestuff Reptr. 41,385. 13. Arthur, J. C., Jr., and Many, H. G. (1949). Teztile Res. J . 19, 605. (19,50). Oil MilE Gazetteer 64, 55. 14. Arthur, J. C., Jr., Mason, T. W., Jr., and Adams, Mabelle E. (1948).; J . Am. Oil Chemists’ SOC.26, 338. 15. Astbury, W. T., “Proteins,” ColEoid Chemistry-Theoreticat and Applied, Val. V. Jerome Alexander, Editor. (1944). pp. 529-44. 16. Astbury, W. T. (1945). Nature 166, 501. 17. Astbury, W. T., Dickinson, S., and Bailey, K. (1935). Biochem. J . 29, 2351.

PEANUT PROTEIN ISOLATION, COMPOSITION, AND PROPERTIES

409

18. Avera, F. L. U. S. Patent 2,552,925, May 15, 1951. 19. Bachman, K. L., Crowe, G. B., and Goodman, K. V. (1947). “Peanuts in Southern Agriculture.” U. S. Dept. Agr., Bur. Agr. Eeon. 112 pp., 1947. 20. Badami, V. R. K. (1932). J. Mysore Agr. Exptl. Union 13, 115. 21. Baernstein, H. D. (1937). J. Biol. Chem. 122, 781. 22. Bailey, L. H. (1939). The Standard Cyclopedia of Horticulture, Vol. 111, p. 2505. The Macmillan Company, New York. 23. Basu, U. P., and Sen-Gupta, S. K. (1944). J. Zndian Chem. SOC.21, 389. 24. Baudoin, N. (1950). Oleagineux 0, 241. 25. Beattie, W. R., and Beattie, J. H. (1943). U. S. Dept. Agr., Farmers Bull. 1666, 31 PP. 26. deBelsunce, G. (1926). Bull. Matieres Grasses 1926, 1. 27. Berthelot, A., and Amoreux, G. (1943). Bull. SOC.Chem. B i d . 16, 1561. 28. Fournicr, S. A., Beuk, J. F., Chornock, F. W., Brown, L. C., and Rice, E. E. (1949). Food Research 14, 413. 29. Bjorksten, J. (1951). Advances in Protein Chem. 6, 343. 30. Blaylock, L. G., and Richardson, L. R. (1950). Poultry Sci. 29, 656. 31. Bonotto, M. U. S. Patent 2,101,805, Dec. 7, 1937. 32. Borchers, R., and Ackerson, C. W. (1950). J. Nutrition 41, 339. 33. Bouvet, R. (1946). Fibre and Fabric 99, 6. 34. Brown, W. L. (1944). J. B i d . Chem. 164, 57. 35. Brown, W. L. (1942). J. B i d . Chem. 142, 299. 36. Burnett, R. S. (1946). Chem. Eng. News 24, 478. 37. Burnett, R. S. (1945). Ind. Eng. Chem. 37, 861. 38. Burnett, R. S. U. S. Patent 2,463,740, Mar. 8, 1949. 39. Burnett, R. S., and Fontaine, T. D. (1944). Ind. Eng. Chem. 36, 284. 40. Burnett, R. S., and Parker, E. D. (1946). Trans. Am. SOC.Mech. Engrs. 68, 751. 41. Burnett, R. S., Parker, E. D., and Roberts, E. J. (1945). Znd. Eng. Chem. 37,980. 42. Burnett, R. S., and Roberts, E. J. U. S. Patent 2,421,113, May 27, 1947. 43. Burnett, R. S., Roberts, E. J., and Parker, E. D. (1945). Ind. Eng. Chem. 37,276. 44. Buss, L. W., and Goddard, V. R. (1948). Food Research 13, 506. 45. Caines, C. M. (1947). Chemist and Druggist 147, 506. 46. Caldwell, W. A., and Jack, J. U. S. Patent 2,495,566, Jan. 24, 1950. 47. Calvert, F. E. U. S. Patent 2,451,659, Oct. 19, 1948. 48. Calvert, F. E. U. S. Patent 2,534,226, Dec. 19, 1950. 49. Calvert, F. E. U. S. Patent 2,534,227, Dec. 19, 1950. 50. Calvert, F. E. U. S. Patent 2,534,228, Dec. 19, 1950. 51. Cama, H. R., and Morton, R. A. (1949). Abstr. Commun. 1st Intern. Congr. Biochem. 1949, 36. 52. Campbell, H., and Johnson, P. (1944). Trans. Faraday SOC.40, 221. 53. Cecil, S. R., and Woodroof, J. G. (1951). Georgia Agr. Expt. Sta., Bull. N O .266, 3. 54. Chang, KeChung, and Yung-Sheng, Chao. (1935). J. Chinese Chem. Soc. 3, 177. 55. Chibnall, A. C., and Bailey, K. U. S. Patent 2,358,383, Sept. 19, 1944. 56. Chibnall, A. C., Bailey, K., and Astbury, W. T. Brit. Patent 467,704, June 22, 7. 193 57. Clay, H. J. (1941). U.S. Dept. Agr., Misc. Pub. 416, 124 pp. 58. Clegg, 0. (1951). Textile Mercury and Argus 124, 185. 59. Corwin, J. F., and Dunham, H. V. U. S. Patent 2,174,438, Sept. 26, 1939. 60. Cross, W. E. (1932). Rev. ind. y agr. Tucuman 22, 307. 61. Croston, C. B., Evans, C. D., and Smith, A. K. (1945). Ind. Eng. Chem. 37,1194.

410

JETT C. ARTHUR, JR.

62. Dangoumau, A., Debruyne, H., and Cluzan, R. (1951). BUZZ.mens. ZTERG 6, 297. 63. Daniels, A. L., Loughlin, R. (1918). J. Biol. Chem. 33, 295. 64. Danielsson, C. E. (1949). Biochem. J. 44, 387. 46, 487. 65. Dean, A. C. R. (1949). Trans. Faraday SOC. 66. Diamond, C. (1949). Elastomers and Plastomers 2, 287. 67. Dickson, J. P., and Sever, W. Brit. Patent 537,740, July 4, 1940. 68. Dickson, J. P., and Sever, W. U. S. Patent 2,358,219, Sept. 12, 1944. 69. Dimsdale, W. H., and Smith, R. C. M. Brit. Patent 610,647, Oct. 19, 1948. 70. Dreyfus, H. U. S. Patent 2,291,701, Aug. 4,1942. 71. Dunn, K. R., and Goddard, V. R. (1948). Food Research 13, 512. 72. Eirich, F. R., and Rideal, E. K. (1940). Nature 146, 541, 542, 551, 552. 73. Elliot, S. (1951). Reyon, Synthetica, Zellwolle 29, 313. 74. Eselgroth, T. W. (1950). Canner 110, 16, 17, 22, 24. 75. Ferry, J. D. (1948). Advances in Protein Chem. 4, 1. 76. Fieldsend, E. C., and Boyes, W. H. D. Brit. Patent 513,910, Oct. 25, 1939. 77. Fieldsend, E. C., and Boyes, W. H. D. U. S. Patent 2,347,677, May 2, 1944. 78. Fontaine, T. D., and Burnett, R. S. (1944). Ind. Eng. Chem. 36, 164. 79. Fontaine, T. D., Detwiler, S. B., Jr., and Irving, G. W., Jr. (1945). Znd. Eng. Chem. 37, 1232. 80. Fontaine, T. D., Irving, G. W., Jr., and Markley, K. S. (1946). Ind. Eng. Chem. 38, 658. 81. Fontaine, T. D., Irving, G. W., Jr., and Warner, R. C. (1945). Arch. Biochem. 8, 239. 82. Fontaine, T. D., Pons, W. A., Jr., and Irving, G. W., Jr. (1946). J. Biol. Chem. 164, 487. 83. Fontaine, T. D., Samuels, C., and Irving, G. W., Jr. (1944). Znd. Eng. Chem. 36, 625. 84. Fraps, G. S. (1917). Tezas Agr. Ezpt. Sta. Bull. 222, 38 pp. 85. Gapp, K. (1949). Kunstseide u. Zellwolle 27, 91. 86. Goldsmith, M. T. (1950). Tertile Research J. 20, 613. 87. Gordon, W. G., Brown, A. E., and Jackson, R. W. (1946). Ind. Eng. Chem. 38, 1239. 88. Gordon, W. G., Jackson, R. W., and Brown, A. E. U. S. Patent 2,525,792, Oct. 17, 1950. 89. Goring, D. A. I., and Johnson, P. (1952). J. Chem. SOC.33. 90. Grau, C. R. (1946). J. Nutrition 32, 303. 91. Gustavson, K. H. (1949). Advances in Protein Chem. 6, 353. 92. Guthrie, J. D., Hoffpauir, C. L., Stansbury, M. F., and Reeves, W. A. (1949). U . S. Dept. Agr., Bur. Agr. Ind. Chem., AIC-61 (Revised). 93. Happey, F. (1949). Nature 164, 184. 94. Harris, B. R., and Joffe, M. H. U. S. Patent 2,560,509, July 10, 1951. 95. Harris, M., and Brown, A. E. (1947). Teztile Research J. 17, 323. 96. Haworth, R. D., MacGillivray, R., and Peacock, D. H. (1951). Nature 167, 1068. 97. Hellot, R., and Macheboeuf, M. (1947). Bull. SOC.chim. biol. 29, 817. 98. Henderson, J. (1951). Dyer 106, 557. 99. Hennefrund, H. E., and Lacy, M. G. (1939). U.S. Dept. Agr., Bur. Agr. Econ., Bibliography No. 80, 244 pp. 100. Hoffpauir, C. L., and Guthrie, J. D. (1945). Peanut J . and Nut World 24, No. 6, 26.

PEANUT PROTEIN ISOLATION,

COMPOSITION,

AND PROPERTIES

411

Hoffpauir, C. L., and Guthrie, J. D. (1947). J. Am. Oil Chemists’ SOC.24,393. Hoffpauir, C. L., and Guthrie, J. D. (1949). J. Biol. Chem. 178, 207. Hogan, J. T., and Arthur, J. C., Jr. (1951). J . Am. Oil Chemists’ SOC.28, 272. Hogan, J. T., and Arthur, J. C., Jr. (1952). J. Am. Oil Chemists’ SOC.29, 16. Hutt, H., Malkin, T., Poole, A. G., and Watt, P. R. (1950). Nature 166, 314. Irving, G. W., Jr., Fontaine, T. D., and Warner, R. C. (1945). Arch. Biochem. 7, 475. 107. Irving, G. W., Jr., Merrifield, A. L., Burnett, R. S., and Parker, E. D. U. S. Patent 2,405,830, Aug. 13, 1946. 108. Jacquot, R. (1951). Bul. mens. ITERG6, 40. 109. Johns, C. 0. (1919). Cotton Oil Press 2, 41. 110. Johns, C. O., and Jones, D. B. (1916). J. Biol. Chem. 28, 77. 111. Johns, C. O., and Jones, D. B. (1917). J. Biol. Chem. 30, 33. 112. Johns, C. O., and Jones, D. B. (1918). J . Biol. Chem. 36, 491. 113. Johns, C. O., and Jones, D. B. (1917). J . Franklin Inst. 184, 120. 114. Johnson, P. (1946). Trans. Faraday SOC.42, 28. 115. Johnson, P., and Joubert, F. J. (1951). J. Polymer Sci. 7, 605. 116. Johnson, P., Joubert, F. J., and Shooter, E. M. (1950). Nature 166, 595. 117. Johnson, P., and Shooter, E. M. (1950). Biochem. et Biophys. Acta 6, 361. 118. Johnson, P., Shooter, E. M., and Rideal, E. K. (1950). Biochem. et Biophys. Acta 6, 376. 119. Jones, D. B. (1941). Proc. of 1st Annual Meeting of the National Peanut Council 1, 31. 120. Jones, D. B., and Divine, J. P. (1944). J . Nutrition 28, 41. 121. Jones, D. B., Gersdorff, C. E. F., and Moeller, 0. (1924). J. Biol. Chem. 62, 183. 122. Jones, D. B., and Horn, M. J. (1930). J. Agr. Research 40, 673. 123. Joubert, F. J. (1952). Nature 169, 498. 124. Karon, M. L., Adams, M. E., and Altschul, A. M. (1950). J. Phys. & Colloid Chem. 64, 56. 125. Keggin, J. F. U. S. Patent 2,504,844, Apr. 18, 1950. 126. Knight, C. I,. Brit. Patent 549,642, Dec. 1, 1942. 127. Kodangekar, P. R., Mandlekar, M. R., and Mehta, T. N. (1946). J. Indian Chem. Soc. Ind. News Ed. 9, 34. 128. Konen, J. C., and Schroeder, B. W. U. S. Patent 2,462,811, Feb. 22, 1949. 129. Lauchs, I. F. U. S. Patent 1,942,109, Jan. 2, 1934. 130. Levin, D., U. S. Patent 2,405,438, Aug. 6, 1946. 131. Lichnikov, I. S. (1913). Iz Rezul’t Veget Opytov Lab. Rabot (Rec. Trav. Lab. Argon.) 9, 378. 132. Low, A. M. (1945). Indian Textile J . 66, 63. 133. Lundgren, H. P. (1949). Advances in Protein Chem. 6, 305. 134. Macheboeuf, M. A., and Tayeau, F. (1942). Bull. soc. chim. biol. 24, 260. 135. Macheboeuf, M. A., and Tayeau, F. (1943). Corps. gras, savons 1, 132. 136. Macheboeuf, M. A., and Tayeau, F. (1944). Corps. gras, savons 2, 8. 137. Macheboeuf, M. A., Tayeau, F., and Bouville, J. (1942). Compt. rend. SOC. biol. 136, 557. 138. Mann, G. E. (1953). J. Am. Chem. SOC.76, 3526-29. 139. McGeoch, S. N. Brit. Patent 570,908, July 27, 1945. 140. McGeoch, S. N. Brit. Patent 574,984, Jan. 29, 1946. 141. McGeoch, S. N. U. S. Patent 2,424,408, July 22, 1947. 142. McLean, A. Brit. Patent 513,896, Oct. 25, 1939. 101. 102. 103. 104. 105. 106.

412

JETT C. ARTHUR, JR.

143. McLean, A. Brit. Patent 515,454, Dec. 5, 1939. 144. McLean, A. U. S. Patent 2,230,624, Feb. 4, 1941. 145. McMeekin, T. L., Reid, T. S., Warner, R. C., and Jackson, R. W. (1945). Znd. Ens. Chem. 37, 685. 146. Merrifield, A. L., and Pomes, A. F. (1946). Textile Research J. 16, 369. 147. Millidge, A. F., and Knight, C. L. U. S. Patent 2,459,952, Jan. 25, 1949. 148. Mitchell, H. H., and Beadles, J. R. (1950). J. Nutrition 40, 25. 149. Monceaux, R. H. (1950). Bull. acad. natl. med. 134, 802. 150. Monceaux, R. H. (1951). Oleagineux 6, 147. 151. Moncrieff, R. W. (1951). Skinner’s Silk and Rayon Rec. 26, 538. 152. Mori, S. (1944). J . Agr. Chem. SOC.Japan 20, 265. 153. Morris, Nelle J., and Dollear, F. G. (1949). U . S. Dept. Agr., Bur. Agr. Ind. Chem., Southern Regional Research Lab., AIC 151, 231 pp. 154. Murphy, E. A., and Dunn, M. S. (1950). Food Research 16, 498. 155. Murthy, H. B. N., Swaminathan, M., and Subrahmanyan, V. (1950). J. Sci. Znd. Research (India)9B, 173. 156. Narayanamurti, D., Ranganathan, V., and Ikram, M. (1943). Forest Research Znst., Dehra Dun, Indian Forest Bull. 116, 21 pp. 157. Narayanamurti, D., and Singh, K. (1942). Forest Research Znst., Dehra Dun, Indian Forest LeaJEet 16, 9 pp. 158. Neurath, H., Greenstein, J. P., Putnam, F. W., and Erickson, J. 0. (1944). Chem. Revs. 34, 157. 159. Newton, H. P., Rollins, M. L., Smith, H. O., Fynn, P. J., Altschul, A. M., Arthur, J. C., Jr., and Vix, H. L. E. (1948). Proc. Louisiana Eng. SOC.34, 82. 160. O’Hara, L. P., and Saunders, F. (1937). J. Am. Chem. SOC.69, 352. 161. Oku, Masami, and Hosokawa, Yutaka. (1942). J. Agr. Chem. SOC. Japan 18,217. 162. Olcott, H. S., and Fraenkel-Conrat, H. (1946). Znd. Eng. Chem. 38, 104. 163. Opper, A. V. L., and ter Horst, W. P. U. S. Patent 2,450,810, Oct. 5, 1948. 164. Perov, S. S. (1948). Doklady Vsesoyuz. Akad. Sel’sko-Khoz. Nauk. im. V . 1. Lenina 3. 165. Pickett, T. A. (1948). J. Am. Chem. Soc. 70, 3516. 166. Pominski, J., Gordon, W. O., McCourtney, E. J., Vix, H. L. E., and Gastrock, E. A. (1952). Znd. Eng. Chem. 44, 925. 167. Punnoose, T. V. (1945). Indian Textile J. 66, 929. 168. Quintin-Toronelli, J. French Patent 846,314, Sept. 14, 1939. 169. Ramakrishnan, C. V., and Banerjee, B. N. (1950). J. Indian Chem. SOC.27,655. 170. Rao, R. R., and Venkataraman, P. R. (1949). J. Am. Pharm. Assoc. 38, 184. 171. Reeves, W. A., and Guthrie, J. D. (1950). Arch. Biochem. 26, 316. 172. Ritthausen, H. (1880). PjZugers Arch. ges. Physiol. 21, 81. 173. Rose, Downs, and Thompson, Ltd. (1952). Oil Mill Gazetteer 66, 13. 174. Ruegamer, W. R., Poling, C. E., and Lockhart, H. B. (1950). J . Nutrition 40, 231. 175. Scott, W. M. (1947). Chemurgic Digest 6, 192. 176. Scott, W. M. (1947). U . S. Dept. Agr., Bur. Agr. Znd. Chem., AIC-165, 8 pp. 177. Scott, W. M. (1947). Peanut J. and Nut World 27, 47, 48, 90-92. 178. Senti, F. R., Copley, M. J., and Nutting, G. C. (1945). J. Phys. Chem. 49, 192. 179. Senti, F. R., Eddy, C. R., and Nutting, G. C. (1943). J. Am. Chem. SOC.66,2473. 180. Sherman, J. V., and Sherman, S. L. (1946). The New Fibers, pp. 191-208. D. Van Nostrand Co., New York. 181. Silk and Rayon (June 1951). 750.

PEANUT PROTEIN IBOLATION, COMPOSITION, AND P RO P ERTI ES

413

182. Singh, C., and Singh, K. (1945). Indian Forest Bull. 126, 13 pp. 183. Sisley, J. P. (1950). Teintex 16, 225. 184. Smirnova-Ikonnikova, M. I., and Veselova, E. P. (1951). Doklady Akad. Nauk. S.S.S.R. 77, 1071. 185. Societa generale italiana della viscosa. French Patent 850,498, Dec. 18, 1939. 186. Stansbury, M. F., Field, E. T., and Guthrie, J. D. (1950). J . Am. Oil Chemists’ SOC.27, 317. 187. Stansbury, M. F., Guthrie, J. D., and Hopper, T. H. (1944). Oil & Soap 21,239. 188. Sugarman, Nathan. Private communication. 189. Sure, B. (1950). Arkansas Agr. Expt. Sta. Bull. 493, 3. 190. Takeda, Y., Shimada, Shiro, and Kinoshita, S. (1943). J . Agr. Chem. SOC.Japan 19, 91. 191. Tayeau, F. (1941). Compt. rend. SOC. biol. 136, 591-96 (1941). 192. Teale, R. P. U. S. Patent 2,228,158, Jan. 7, 1941. 193. Tetlow, W. E. (1950). J . Sci. Food Agr. 1, 193. 194. Tetlow, W. E., and Thomson, R. H. K. Brit. Patent 654,513. June 20, 1951. 195. Thomas, J. E. L., and Traill, D. U. S. Patent 2,463,827, March 8, 1949. 196. Thomson, R. H. K. Brit. Patent 551,923, March 16, 1943. 197. Thornson, R. H. K. Brit. Patent 570,631, July 16, 1945. 198. Thomson, R. H. K. (1948). Chem. Age (London) 68, 687. 199. Thomson, R. H. K. (1946). J. SOC.Dyers Colourists Symposium Fibrous Proteins, 173. 200. Thomson, R. H. K. U. S. Patent 2,460,372, Feb. 1, 1949. 201. Thomson, R. H. K. U. S. Patent 2,533,297, Dec. 12, 1950. 202. Thomson, R. H. K., and Caldwell, W. A. U. S. Patent 2,532,350, Dec. 5, 1950. 203. Thomson, R. H. K., and Johnston, A. (1947). J . SOC.Chem. Znd. 66, 373. 204. Thomson, R. H. K., and Swift, S. R. U. S. Patent 2,417,576, March 18, 1947. 205. Thomson, R. H. K., and Traill, D. (1945). J. SOC.Chem. Ind. 64,229. 206. Thomson, R. H. K., and Traill, D. U. S. Patent 2,506,252, May 2, 1950. 207. Thuriaux, L., and Lenaerts, L. A. Comitd spec. Katanga 19/tY, 25 pp. 208. Traill, D. (1945). Am. Dyestuff Reptr. 34, 228. 209. Traill, D. (1945). Ann. Repts., SOC.Chem. Ind. Progress Applied Chem. 30, 212. 210. Traill, D. (1948). Ann. Repts., SOC.Chem. Znd. Progress Applied Chem. 33, 295. 211. Traill, D. Brit. Patent 492,677, Sept. 26, 1938. 212. Traill, D. Brit. Patent 492,895, Sept. 26, 1938. 213. Traill, D. Brit. Patent 495,332, Nov. 10, 1938. 214. Traill, D. Brit. Patent 543,586, March 4, 1942. 215. Traill, D. (1945). Chemistry & Industry 58. 216. Traill, D. (1950). Chemistry & Industry 23. 217. Traill, D. (1945). Znd. Chemist 21, 71-74, 95. 218. Traill, D. (1945). J. SOC.Dyers Colourists 61, 150. 219. Traill, D. (1951). J. SOC.Dyers Colourists 67, 257. 220. Traill, D. (1946). J. Textile Znst. 37, P295. 221. Traill, D. (1945). Teztile Mfr. 71, 71. 222. Traill, D. (1946). “The Times” Trade and Eng. 68, 6. 223. Traill, D. U. S. Patent 2,189,481, Feb. 6, 1940. 224. TrcLill, D. U. S. Patent 2,358,427, Sept. 19, 1944. 225. Traill, D., and McLean, A. (1945). J. SOC.Chem. Znd. 64, 221. 226. Traill, D., Seddon, R. V., and Sever, W. Brit. Patent 524,090, July 30, 1940. 227. Traill, D., Seddon, R. V., and Sever, W. U. S. Patent 2,340,909, Feb. 8, 1944.

414

JETT C. ARTHUR, JR.

228. Traiil, D., and Simpson, G. K. Brit. Patent 639,342, June 28, 1950. 229. Traill, D., and Simpson, G. K. U. S. Patent 2,535,103, Dec. 26, 1950. 230. U. S. Dept. Agr., Agricultural Statistics (1951). U. S. Government Printing Office, Washington, D. C. 231. Waldo, M. M., and Goddard, V. R. (1950). J . Home Econ. 42, 112. 232. Whewell, C. S. (1945). Ann. Repls., Soc. Chem. i n d . Progress Applied Chem. SO, 96. 233. Wolff, Hans. U. S. Patent 2,554,479, May 22, 1951. 234. Woodroof, J. G., Thompson, H. H., and Cecil, S. R. (1949). Food Znds. 21, 186. 235. Wormell, R. L. (1948). J . Textile Znst. 39, T219-24. 236. Zucker, T. F., and Zucker, L. (1943). Znd. Eng. Chem. 36, 868.

Other Oilseed Protein References 237. Fontaine, T. D. (1948). “Cottonseed Proteins,” Zn Cottonseed and Cottonseed Products, Ed. A. E. Bailey, pp. 409-465. Interscience Publishers, New York. 238. Burnett, R. S. (1951). “Soybean Protein Food Products,” In Soybeans and Soybean Products, Ed. K. S. Markley, pp. 949-1002. Interscience Publishers, New York. 239. Burnett, R. S. (1951). “Soybean Protein Industrial Products,” ibid., pp. 10031053. 240. Circle, Sidney J. (1951 ) “Proteins and Other Nitrogenous Constituents,” ibid., pp. 275-370.