INDUSTRIAL AND EIL'GINEERING CHEMISTRY
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then assayed for vitamin D potency, and the results, expressed as Steenbock units per pound, are given in Table I. The relation of the physical properties, film thickness, average velocity, and travel time, to the vitamin D potency of the milk is shown in Figure 4. The direct proportionality shown between vitamin D potency and travel time is of interest since it suggests the importance of time in the irradiation of milk. An explanation for this importance of time can be deduced from the probable movement of the fluid in flowing films. Apparently the flow is of a turbulent nature (3) as indicated by the elongation produced in aggregates of finely divided pigments or drops of insoluble coloring when placed on the film (1). Turbulence in the flow would tend to cause an interchange of substances in the surface zone of the film. Since the antirachitic activation of milk, because of the absorption characteristics of the effective radiation ( 2 , 4 ) ,is limited essentially to surface reactions, effective interchange of materials between the surface zone and deeper layers of the films would result in uniform exposure and activation when flms of various capacities are exposed for equal periods. Thus a direct ratio as indicated by the data will exist between vitamin D potency and travel time of the film.
Acknowledgment metals. The thickness of a film when flowing over a polished 15-8 stainless steel surface was similar to that when flowing over machined steel. However, when a pickel-finish 18-8 stainless steel surface was used, the film was thicker, indicating that friction retarded the film velocity. When the machined steel surface was moved from a vertical position to one 45' with the vertical, the thickness of the film became significantly greater. Since the properties of the milk films show definite relations to their respective capacities, it was desirable t o ascertain whether similar relations might exist between these properties and the effectiveness of applied ultraviolet radiation expressed as vitamin D potency. Milk films 20 inches in length with capacities of 100, 300, 600, 1000, and 1500 pounds per linear foot per hour were established and irradiated under fixed conditions with a quartz mercury arc. The irradiated milk was
The authors are indebted to H. C. Jackson of the Department of Dairy Industry and L. R. Ingersoll of the Department of Physics, University of Wisconsin, and the Wisconsin Alumni Research Foundation, for their interest in supplying facilities and instruments required to carry out this work.
Literature Cited (1) Beck, H.H.,and Weckel, K. G., IND. ENQ.CHEM.,Anal. Ed.,8, 258 (1936). (2) Supplee, G.C., and Dorcas. M. J., J. Dairg Sci., 17,433 (1934). (3) Ibid., 17, 527 (1934). (4) Trebler, H.A,, Robinson, F. W., and Bird, L. A., unpublished studies.
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U. S. Pharmacopaia X, Interim Revision Announcement No. 2, 1934.
RECEIWDAugust 12, 1936. Submitted for publication with the approval of the Director, Wisconsin Agricultural Experiment Station.
The Effect of Active Soybean on Vitamin A CHARLES N. PREY, A. S. SCHULTZ, AND R. P. LIGHT The Fleischmann Laboratories, New York, N. Y.
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seeds, particularly soybeans, improve the crumb color of the loaf of bread when used in suitable proportions. The bleacking action is due to an oxidation of the carotene in the flour. The reaction may be observed by shaking a carotene solution in oil with a weak suspension of ground soybeans in the presence of oxygen; after a few minutes the highly colored carotene solution is decolorized. T h e acidity should not be greater than pH 5. Heating above 50" C. inactivates the soybean; if a solution ,of carotene in oil is shaken with an aqueous suspension of the #heated soybeans in the presence of oxygen, the carotene is not decolorized. The effect of the decolorization of carotene by ground .soybeans on its vitamin A potency was studied. A carotene solution containing 3000 U. S. P. units of vitamin A per cc. was used, and groups of standardized vitamin A assay animals were given the following daily supplements: 1. A 0.001-cc. portion carotene solution equivalent to 3 U. S. P. units. EGUME
2. A 0.001-cc. portion of carotene solution e uivalent to 3 U. S. P. units after it had been shaken wi& a suspension of 3 mg. of inactive soybean in 1cc. of water. 3. A 0.09-cc. portion of carotene solution equivalent t o 272 U. S. P. units after it had been shaken with a suspension of 10 mg. of active soybean in 1 cc. of water.
The control group and the second group receiving the inactivated soybean-carotene mixture were fed an amount of carotene equivalent to 3 U. S. P. units daily; they gave a normal growth response with this dosage. The third group was fed the active soybean-carotene mixture, which contained 272 U. s.P. units before decolorization. The response on this level as well as a t lower levels was negative. The results indicate that under these conditions the vitamin A activity of carotene is completely destroyed. Results obtained in this laboratory also indicate that treatment with active soybean destroys a t least 99 per cent of the vitamin A present in cod liver oil. RECEiYED
September 2, 1936.
