August, 1943
INDUSTRIAL AND ENGINEERING CHEMISTRY ACKNOWLEDGMENT
The experimental work upon which t was carried out by K. W. Gardiner, W. McBain, and R. D. Vold. LITERATURE CITED
(1) McBain, J. W.,and Burnett, A. J., J . (1922). (2) McBain, J. W.,Elford, W. J., and Vold, R. D., J . SOC.C h m . Ind., 59,243 (1940). (3) McBain, J. W.,and Lee, W. W., IND.ENQ. CEEM.,35, 784 (1943). (4) McBain, J. W.,and Lee, W. W., Oil & Soap, 20, 17 (1943).
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McBain, J. W., Vold, R. D., and Frick, M., J . Phys. Chem., 44, 1013 (1940). McBain, J. W., Vold, R. D., and Jameson, W. T., J . Am. Chsm. SOC.,81, 30 (1039). McBain, J. W . ,Vold, M. J., and Porter, J. L., IND. ENQ.CHEM.. 33, 104% McBain, Brit. Assoc. Advancement Sci Vold, R. I 1). Vold, R. D., J . Phys. Chem., 43, 1213 (1939). Vold, M. J., Macomber, M., and Vold, R. D.,J. Am Chem. Soo., 63,168 (1941). _. __ Vold, R. D ., Rosevear, F. B., and Ferguson, R. H., Oil & Soap, 16,48 ( l onQn\ ou,.
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Lipoid Oxidase in Soybean Meals R. J. SUMNERI AND D. K. TRESSLER New York State Agricultural Experiment Station, Geneva, N. Y The lipoxidase content of several samples of the three types of commercial soybean meal is investigated. In most cases the high temperatures reached in processing are sufficient to inactivate the peroxidizing factor completely. Considerable lipoxidase activity is found in a sample of solvent process meal extracted at 150°F, and in a special enzyme preparation used in the brewing industry. The results indicate that soybean meals made by conventional processing methods should not produce enzymic destruction of vitamin A or carotenoids.
suspension of linoleic acid (23) for 15 minutes. In the case of the more active materials, the length of the reaction period was adjusted to meet the requirements of the method. A blank determination was carried out with each sample, using an inactivated extract of the material under investigation. This was done in order to eliminate any error produced by oxidative rancidity in the samples. The activity of these extracts was expressed in units based upon the amount of oxygen consumed per minute by the peroxidation; one unit represents that activity which catalyzes the reaction of one microgram of oxygen in one minute under a specified set of conditions (3). The results are listed in Table I.
TABLEI. LIPOXIDASE CONTENT OF COMMERCIAL SOYBEAN PRODUCTS
S
UMNER and Sumner (2) demonstrated that the apparent oxidation of carotene by the enzyme formerly known as carotene oxidase is in reality an indirect result of the action of an unsaturated fat-peroxidizing enzyme. This observation was later confirmed by the independent investigations of Tauber (4). Since this enzyme is capable of destroying both vitamin A (1) and provitamin A pigments by an oxidation coupled with the peroxidation of unsaturated fats, an investigation of the enzymic activity of the various types of commercial soybean meals was undertaken. These meals are used extensively in livestock feeds as a source of protein, so that any possible vitamin A destruction assumes immediate importance. The soybean meals available commercially are products of the expeller process, the solvent process, or the hydraulic process. Samples of each of these types were procured from manufacturers. They were examined for lipoxidase activity by observation of their effect upon an aqueous suspension of linoleic acid (3). Also tested were raw soybeans and a soybean enzyme preparation used in the brewing industry. The samples of soybean meal were finely ground in a glass mortar and pestle, 0.5 gram of each was extracted with water, and the extracts were made up t o 25 cc. volume. One cc. of each extract was allowed to act on a standard 1
Present address, Mellon Institute, Pittsburgh, Penna.
Product Raw soybeans Soybean brew flakes Solvent extraction meal Hydraulic soybean meal Expeller soybean meal Expeller meal A Expeller meal B Expeller meal C Expeller meal D Expeller meal E Solvent extn. soybean meal Solvent meal A Solvent meal B Solvent meal C Solvent meal D
Max. Processing Temp., O F.
...
...
150 230 300
Units/ Gram 12,650 9,400 6,800 Inactive Inactive Inactive Inactive Inactive Inactive
220 Inactive Inactive Inactive Inactive
LITERATURE CITED
(1) Frey, C. N.,Schultz, A. S., and Light, R. F., IND.ENG.CHEM.. 28, 1254 (1936). ( 2 ) Sumner, J. B., and Sumner, R. J., J . Biol. Chem., 134,531 (1940). (3) Sumner, R. J., IND. ENQ.CHEW,ANAL.ED., 15, 14 (1943). (4) pauber, Henry, J . A%. Chem. Soc., 62,2251 (1940). A P P R O V ~by D the Station Director.
Paper 511.
