THE USE OF SOY BEAN AS FOOD.*t BY THOMAS B. OSBORXE AND LAFAYETTE B. AMENDEL. WITH THE COOPERATION OF EDNA 1,. FERRY AND ALFRED J. WAKEMAX. (From the Laboratory of the Connecticut Agricultural Experiment Station and the Shefield Laboratory of Physiological Chemistry in Yale Tiniversity, New Zlaven.) (Received for publication, October 12, 1917.) The demand w,hich the international shortage of food has created for cheaply produced and easily obtainable sources of all nutrients, and particularly of suitable proteins and fats, has directed attention anew to the possibilities of the soy bean. This leguminous seed which has long been employed in the dietary of many inhabitants of the Far East has hitherto found appli- cation in this country almost solely as a suitable food for diabetics. Its use in this special application is attributable to the fact that, in contrast with other leguminous seeds, the soy bean contains traces only of starch and comparatively small quantities of those carbohydrates which are available to the human organism. Be- sides its introduction into diabetic cookery, the soy bean has been recommended occasionally for use in infant feeding.1 The employment of the soy bean for silage and as a hay crop in agri- culture is better known. Owing to the richness of the bean in oil, the latter is extensively expressed for commercial uses, the press cake thereby becoming available as a fertilizer or latterly as a food product. The results of an extensive investigation2 of the range of proxi- mate composition of many varieties of soy beans grown in this country are given in the table; likewise analyses of seven commer- * The expenses of this investigation were shared by the Connecticut Agricultural Experiment Station and the Carnegie Institution of Wash- ington, D. C. i A preliminary account has been published in Proc. Sot. Exp. Biol. and Med., 1917, xiv, 174. 1 Ruhrlh, J., Arch. Pediat., 1909, xxvi, 496; J. Am. Med. Assn., 1910, liv, 1664; Arch. Pediat., 1911, xxviii, 841; Am. J. Med. SC., 1915, cl, 502. 2 Street, J. I’., and Bailey, E. M., J. Znd. and Eng. Chem., 1915, vii, 853. 369 by guest on January 12, 2020 http://www.jbc.org/ Downloaded from
Transcript
THE USE OF SOY BEAN AS FOOD.*t
BY THOMAS B. OSBORXE AND LAFAYETTE B. AMENDEL.
WITH THE COOPERATION OF EDNA 1,. FERRY AND ALFRED J. WAKEMAX.
(From the Laboratory of the Connecticut Agricultural Experiment Station and the Shefield Laboratory of Physiological Chemistry in
Yale Tiniversity, New Zlaven.)
(Received for publication, October 12, 1917.)
The demand w,hich the international shortage of food has created for cheaply produced and easily obtainable sources of all nutrients, and particularly of suitable proteins and fats, has directed attention anew to the possibilities of the soy bean. This leguminous seed which has long been employed in the dietary of many inhabitants of the Far East has hitherto found appli- cation in this country almost solely as a suitable food for diabetics. Its use in this special application is attributable to the fact that, in contrast with other leguminous seeds, the soy bean contains traces only of starch and comparatively small quantities of those carbohydrates which are available to the human organism. Be- sides its introduction into diabetic cookery, the soy bean has been recommended occasionally for use in infant feeding.1 The employment of the soy bean for silage and as a hay crop in agri- culture is better known. Owing to the richness of the bean in oil, the latter is extensively expressed for commercial uses, the press cake thereby becoming available as a fertilizer or latterly as a food product.
The results of an extensive investigation2 of the range of proxi- mate composition of many varieties of soy beans grown in this country are given in the table; likewise analyses of seven commer-
* The expenses of this investigation were shared by the Connecticut Agricultural Experiment Station and the Carnegie Institution of Wash- ington, D. C.
i A preliminary account has been published in Proc. Sot. Exp. Biol. and Med., 1917, xiv, 174.
cial soy bean “flours” prepared from the unpressed beans. These flours contain more protein and fat and less of all the other in- gredients, owing presumably to the bolting to which they are subjected.
Range of Composition of Soy Bean Products (Street and Baize@).
Soy bean meal
Calculated on water-free basis
per cent Protein (N X 6.25). . 36.8-45.5 Fat............................... 14.1-19.0 N-free extract.. . 26.2-32.9
Street and Bailey2 estimated the meal to contain on an average 4.5 per cent of total sugars, 0.5 per cent starch, 3.1 per cent dextrin, 4.9 per cent pentosan, 4.9 per cent gala&an, 3.3 per cent cellulose, 1.4 per cent organic acids, and 8.6 per cent waxes, color principles, etc.
Recent studies in nutrition have shown the importance of supplementing our knowledge of the chemical composition of naturally occurring foods by a “physiological” investigation of the availability and suitability of the groups of nutrients which they contain. This has already been emphasized, for example, in the case of corn, wheat, certain legumes, etc.3
8 For the leguminous proteins see Osborne, T. B., and Mendel, L. B., 2. physiol. Chem., 1912, lxxx, 21; J. Biol. Chem., 1914, xviii, 1; McCollum, E. V., Simmonds, N., and Pitz, W., J. Biol. Chem., 1917, xxix, 521.
For the maize kernel see Osborne and Mendel, Carnegie Institution of Washington, Publication No. 166, pt. ii, 1911; 2. physiol. Chem., 1912, lxxx, 21; J. Biol. Chem., 1912-13, xiii, 233; 1914, xvii, 325; xviii, 1, 95; 1916, xxv, 1; 1916, xxvi, 293; 1917, xxix, 69, 289. Hogan, A. G., ibid., 1916, xxvii, 193; 1917, xxix, 485. McCollum, Simmonds, and Pitz, ibid., 1916-17, xxviii, 153, 483.
For the cotton seed see Osborne and Mendel, J. Biol. Chem., 1917, xxix, 69, 289. Richardson, A. E., and Green, H. S., ibid., 1916, xxv, 307; 1917, xxx, 243; xxxi, 379,
Many other illustrations have been summarized by McCollum, J. Am. Med. Assn., 1917, Ixviii, 1379 (this discusses some of the underlying prin- ciples involved). See also Mendel, L. B., ibid., 1915, lxiv, 1539.
Our recently published experiments in the study of the use of cotton seed as food,4 as well as agricultural practice, show the danger of drawing conclusions as to the nutrient value of natural products on t’he basis of the customary chemical analysis alone; and t.hcy demonstrate the occasional possibility of converting an inappropriat,e food int.0 a desirable one by a simple expedienkby the application of heat’, in the case of the cotton seed.
In testing the nutrit’ive possibilities of various soy hem prod- ucts we have em$oyed white rat,s which were fed according to the plan followed for rnany yca+rs in our earlier investigations. Whew the question of the suitsbilit’y of the protein alone was involved the other ingredients of the diet wcrc furnished in the form of “protein-free milk,” starch, butter fat, and lard. That at Icast, one of the proteins--glycinin”-of the soy bC:tn can facilitate growvt h satisfactorily has already been indicated.6 Like- wise the suitability of t.hch proteins of the soy bean as supplement,s to the corn proteins has hcon derllorlstruted.7
Experiments in which raw soy bean mea18 was used as t,he source of protein in ihe diet indicated that in the preponderating number of c:jses the rats made comparatively littlc growth, despite the addit,ion of the known essent.ial ingredients other than protein. On the basis of our experience with the cotton seed, we attempted to find some method of trca&ing the beans which would render them as suitable for nutrition as the commercial soy bean “flour” which we had used. Extracting the rneal with ether failed to increase its acceptabilit,y (see Rat,s 4096, 4694, Chart I, first period). In t’his respect, the soy bean differs from the cotton seed. IIeat,ing the soy barn meal in an electric oven at 110°C. for 4 hours likewise failed to cause any considerable irnprovcment
4 Osborne and Mendel, J. Biol. Chem., 1917, xxix, 269. 6 For the preparation and properties of glycinin SW Osborne, 1’. B., and
Campbell, G. F., J. Am. Chem. Sot., 1898, xx, 419. Osborne, T. TL, Ergebn. Physiol., 1910, x, 47; and Abdcrhalden’s IIandb. biochem. Arbeitsmethoden, 1910, ii, 311.
6 Osborne and hlcndel, 2. physiol. Citon., 1912, lxxx, 324, Curve 20. ’ Osborne and LMcndel, J. Biol. Chem., 1917, xxix, 69. 8 The meal was prepared in the laboratory by grinding the entire bean
in a Hobart electric mill. After putbing t,hc beans through the mill twice, the men1 n-as sifted through a fine wire sieve and the bits of hull which would not pass through the mesh were thrown away.
in most cases (see Rats 4145, 4144, Chart I). Occasionally, when the animals would eat more freely of the dry-heated meal they grew fairly well (see Rats 4164,4135, 4142, Chart I). When, on the other hand, the meal was mixed with sufficient distilled water to make a thick mush, heated on the steam bath for 3 hours, and subsequently dried in a current of air at SO-90”, the result- ing product, fed as the sole source of protein in an otherwise suitable food, promoted growth at a normal rate (see all rats, Chart I; Rats 4148, 4160, 4162, 4149, Chart II; Rats 4156, 4137, 4147, 4151, 4338, 4343, 4340, 4339, 4341, 4342, Chart III; Rats 3925, 4181, 4184, 4199, Chart IV). Similar results were obtained when commercial soy cake mcalg was used as the source of protein (see R.ats 4196, 4104, 4118, 4152, 4110, 4200, 4031, 4141, 4035, 4039, 4335, 4336, 4333, 4337, Chart 11; Rats 4076, 4071, 4080, 4070, 4330, 4332, 4329, 4328, 4331, Chart III; Rats 4077, 4083, 4081, 4072, Chart IV). We assume that this soy cake meal was prepared from residues obtained in the extraction of oil; and presumably heat was employed to facilitate this process as it is in the case of other oil-rich seeds, e.g., the cotton seed. It is stated that soy oil is produced at times in the cotton seed oil mills.
The question then arose as to the cause of the variations in the apparent nutritive value of these different preparations. Evidently there is nothing toxic in the raw meal, for none of the rats which ate it died. The failure to grow was seemingly asso- ciated with a failure to eat the meal readily; for the few rats which ate liberal amounts of the food made satisfactory growth (see Rat 3925, Chart IV). It is probable, therefore, that cooking the meal made it somewhat more palatable than simply heating it, thereby inducing the rats to consume more of the food, with a resulting gain in weight. Cooking the meal changes its flavor very decidedly, giving it a taste similar to that of peanuts; whereas both the raw and the dry-heated meals have a disagreeable raw flavor.
Incidentally we have studied growth upon diets prepared with soy bean flour sold for human consumption. The results ob- tained with the four brands investigated differed. With two
g The soy cake meal used was obtained from the Cereo Company, Tappan, x. Y.
preparations good gr0wt.h was accomplished. LVith the other t\vo t,he an+& grew only slowly, as in our experiments with dry-heated soy bean meal foods; but when the commercial prod- ucts were cooked, good growt’h was obtained in accord with the experience with our own cooked soy bean meal. It seem* likely that, the different rc3ults obtained with the commercial say bean flours are due to unlike methods of heating in their preparation.
A study of t’he alimentary utilization of t,he different product.3 was also made to see if that factor would throw any light on the differences bct,necn them. L1lthough there is no marked varia- tion between t,he utiliz:tt,ion of the nitrogen of the raw meal and the cooked, such as was previously found to be the case with phaseolin, the prolein of the kidney bean, nev&heless the nitrogen of the commercial soy cake and the cooked meal was utilized somewhat better than was t,he case with the raw and dry-heat.ed meals. It is conceivable that, t,he process employed in rn:lrluf:~ct,uring the soy cake in the one cnsc, and the method of cooking used in the other, t,c:ndcd to get t.he meal into a more finely divided condition than could be done by merely grinding the beans, and t,hus ren- dered the prot,ein more accessible to the action of the digestive enzymes.
* These figures represent tho :~wra~c results for three or four rats take11 ovc’r a period of 3 wcclis.
These utilization figures correspond very well with those ob- tained by nlendel and ITimP for both men and dogs. With the cooked beans they found that men utilized about, 85 per cent of the nitrogen and dogs 75 to 88 per cent’. Oshimall states that the digestibility of the protein of various Japanese soy bean products is 79 to 93 per cent.
Having demonstrated that the proteins of the soy bean, unlike
those of the other leguminous seeds thus far investigated, are adequate for promoting normal growth, it was important to deter- mine to what extent the soy bean is capable of furnishing the essential vitamines and salts of the diet. On a ration consisting of soy cake meal or of cooked soy bean meal together with an artificial salt mixture,12 starch, butter fat, and lard, rats have completed their normal growth, showing that the soy bean con- tains an adequate amount of the (‘water-soluble vitamine.” When lard entirely replaced the butter fat rats have grown normally for over 200 days without showing any symptoms of a nutritive decline. This is decidedly longer than the majority of our rats have grown on a diet without the addition of fat-soluble vitamine derived from special sources like butter fat. It seems, therefore, that the soy bean contains some of the essential fat-soluble vitamine. In harmony with this we have never observed any symptoms of eye disease which commonly are manifested by rats kept for some time without a suitable supply of the “fat- soluble vitamine.“13 The only admixture besides lard to the soy bean meals in the diet of the animals represented on Chart IV was starch and inorganic salts. Other illustrations of rats which have grown on the soy bean meal-lard diets (with the addition of natural “protein-free milk”) are represented on Chart II, Rats 4152, 4110, 4141, 4039. It should be noted, however, that in general the growth of the animals on the soy bean-lard
l2 The composition of the salt mixture used is as follows.
The chemicals used were analyzed and allowance was made for moisture, etc. The acids were mixed and the carbonates and ferric citrate added to them. The traces of KI, MnSOd, NaF, and KzAlz(SOJ2 were added as solutions of known concentrations. The final resulting mixture was evaporated to dryness in a current of air at 99-100°C. and ground to a fine powder.
l3 Osborne and Mendel, J. Biol. Chem., 1913-14, xvi, 423; 1914, xvii, 401; 1915, xx, 379.
diets has not been as satisfactory as in those cases in which butter fat was furnished in the ration (Chart III). Furthermore it appears as if the animals receiving along with the lard only the soy cake meal (from which much oil has been expressed) as the source of “fat-soluble vitamine” grew less satisfactorily than the rats on the whole soy bean meal-lard diets. Whether this is merely a coincidence or whether some of the “fat-soluble vita- mine” has been expressed with the oil, we are not yet able to decide.
The majority of our rats kept on a diet consisting of cooked soy bean meal or of soy cake meal with the addition of starch, butter fat, and lard, but without added mineral ingredients, have failed to make any appreciable gain in weight. The addition to the food of 5 per cent of an artificial salt mixture, however, induced an immediate resumption of growth, thus proving that from the standpoint. of a perfect mixture of nutrients the soy bean is deficient in its mineral constituents (see Chart V). An analysis of the ash of the meal and the soy cake used in our experiments gave the following results:
Per cent of the air-dry material. I I
Soy cake meal. Soy bean meal.
Total ash. Calcium. Magnesium. Potassium. Sodium.. Chlorine.. Phosphorus.
These figures show that the soy bean is relatively ipoor in calcium and chlorine, and suggest these as limiting factors. The addition of a small amount of calcium carbonate to a food in which the soy bean was the sole source of mineral constituents tended to stimulate growth to some extent, though not so effi- ciently as the addition of the more complex salt mixture mentioned above. During these experiments distilled water only was supplied to the rats.
On diets containing either the soy bean meal or the commercial
soy cake meal, together with fats and “protein-free milk” or our “artificial” salt mixture, several broods of vigorous young have been produced, and these young have grown normally on diets the same as those on which their parents were raised. This is a further demonstration of the nutritive efficiency of this legume, in striking contrast with the adverse results obtained with kidney beans and garden peas.
So far as we are aware the soy bean is the only seed hitherto investigated, with the possible exception of flax and millet,‘4 which contains both the water-soluble and the fat-soluble uniden- tified dietary essentials or vitamines. This fact, taken with the high physiological value of the protein, lends a unique significance to the use of the soy bean as food.‘”
I4 McCollum, E. V., and Pitz, W., J. Biol. Chem., 1917, xxxi, 229. 1jSince this paper went to press an article by Daniels, A. L., and
Nichols, N. B., The nutritive value of the soy bean, appeared in J. BioZ. Chem., 1917, xxxii, 91.
CHART I. Showing the growth of rats on diets containing soy bean meal as the source of protein. The favprable effect of cooking the meal (period-) in contrast with dry-heated meal (period - . . -. . -) and particularly raw meal (period - - - - -) is shown. In the case of Rats 4096 and 4094 the raw meal was extracted with ether (in the first period - - - - -) without improving the acceptability of the ration, in contrast with what happens in the case of the cotton seed meal (see Osborne and Mendel, J. Biol. Chem., 1917, xxix, 289).
The composition of the diets is given below.
- -
._ Period Period------ P&Od-
Rats. Rats. --
% % 4096 3929 4097 3931
::z 4144 4164
3926 3929 3928 3931
4135 4139 4145
4094 4696
4135 4142 4145 4144
4164
-- - Percent.
-
53
22
18 7
-
53
22
18 7
-
53
25 25
- -
53
5 17 18
7
-
50
-
2: 18
7
- -
50
5 20 18
7
- -
50
5 20
25
Raw soy bean meal . “ “ ‘I “
extracted with ether. 38 Soy bean meal heated
dry at 110°C.. Cooked soy bean meal. “Natural protein-free
milk”. . 28 “Artificial protein-free
milk”* Salt mixture.. Starch.. 2 Butter fat., 18 Lard i 14
50
5 20
25
50
25
18 7
- * The “artificial protein-free milk” employed is described in J. Biol.
Chem., 1913, xv, 317. The one marked “IV” was used.
CHAIW II. ShoGng excellent growth of rats from an cnrly period on diets containing soy bean meal (cooked) or soy cake meal (which has been he&cd during the commercial removal of the oil) as the source of protein in the diet. Several of the females were mated and gave birth to litters of normal young which throve on the same diet. Curves of growth for some of these are reproduced at the right-hand side of the chart.
CHART III. Showing growth and reproduction on diets containing cooked soy bean meal or soy cake meal, which has been heated during the commercial removal of the oil, as the sole source of protein and “water- soluble” vitamine in the diet. Additional “fat-soluble” vitamine was given in the form of butter fat in contrast to the experiments shown in Chart IV which had no butter fat in the diet. Several of the females were mated and gave birth to litters of normal young which throve on the same diet, Curves of growth for some of these arc reproduced at the right-hand side of the chart.
CHART IV. Showing growth on diets containing soy bean meal or soy cake meal as the sole source of protein and “vitamines” in the diet. These experiments show that suitably prepared soy bean meals, supplemented by appropriate inorganic salts, furnish practically all of the essential nutri- ents. ‘The experience with Rat 3925, which grew to considerable size on a diet containing the soy bean meal in its raw form shows that in contrast with cotton seed meal the product is not toxic, and can be utilizedasa nutrient, provided that it is eaten in suitable amounts. The ultimate failure of this rat to grow further on this raw meal diet was reversed when the meal was cooked. None of these animals received fat in any other form than that contained in the soy bean and in lard. The bean must therefore contain some “fat-soluble vitamine.” One gains the impression that the animals receiving the whole bean meal (including all of its oil) grew somewhat more satisfactorily than those receiving the soy cake meal (with much oil expressed) as the source of “fat-soluble vitamine.” Whether the quantity of the “fat-soluble vitamine” thus furnished is sufficient to permit all animals to complete their growth without additions from other sources remains to be determined. At any rate when butter fat is added somewhat better growth is uniformly obtained over longer periods (see Chart III).
CIIART I’. Showing the prompt improvement in growth when a mixture of inorganic salts (XC page 375) was added to the rations consisting of soy bean or soy cake meal, starch, and fat. The beginning of the period during which the added salf,s were fed is indicat,ed by an arrow.
The periods during which butter fat was fed are indicated by B; other- wise lard was used as the fat. The contrast between the cooked and un- cooked meal is shown in several instnnres. It is sometimes missing and never so conspicuous as on the previous charts, owing to the fact that the le.ck of adequate inorganic salts forms a limiting factor in growth which no amount of cooking of the meal can rcrncdy.
The diets had esscnt,i:tlly t,he following composition:
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