Differential Nitrogen Retention from Casein, Lactalbumin, and Soy Protein, and Hydrolysates Therefrom

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Abstract
Progressively increasing levels of the test materials provided in the diets of protein impoverished mature white rats revealed the following: A positive N balance was established at a lower N intake level with unhydrolized lactalbumin than with any of the other products; if a relative value of 100 was assigned to the lactalbumin, the value for the casein would be about 80 and that of the soy protein between 50 and 60. The evidence indicates that in each instance the natural protein is slightly superior to its hydrolysate in maintaining a positive N balance. Loss of N during the 48 hrs. following hemorrhagic shock induced in white rats by withdrawing blood from the heart was increased 185% when the animals were injd. with an unhydrolyzed colloidal casein suspension; 110% when injd. with soy protein hydrolysate; 49% when injd. with casein hydrolysate; and only 39% when injd. with lactalbumin hydrolysate.