Abstract:

Soy protein peptides have significant hypocholesterolemic activity. But at present most studies are focused on
small molecular peptides, and few explorations have been made on their hypolipidemic mechanism. In the present study, an
in vitro gastrointestinal digestion model was applied to simulate the gastrointestinal digestion of tofu protein. The digested
products were classified into three levels: > 10 000, 3 000-10 000, and < 1 000, according to their molecular weights (MR).
The effect of these digested products on disrupting the transportation of micellar cholesterol was explored based on dietary
mixed micelles (DMM) experiments with two experimental matrixes and two test methods. The results indicated that the
products with MR > 10 000 had the strongest suppressing effect on transportation of micellar cholesterol. The absorption rate
of micellar cholesterol in their presence was 62.40%, which was superior to the positive control, VAWWMY (Val-Ala-Trp-
Met-Tyr) with an absorption rate of micellar cholesterol of 68.41%. The effect of the products with MR > 10 000 was enhanced
first and then reduced with the increase in its concentration. In addition, the results of two cholesterol detection methods and the
transportation efficiencies of two cholesterol micelles were consistent. Peptides derived from in vitro digestion of tofu protein
exerted a significant inhibitory effect on the micellar solubility of cholesterol. The current work has provided the first approach to
exploring the potential effect of tofu protein hydrolysates (TPH) on reducing cholesterol absorption in the intestine.

Key words: tofu, digested peptides, dietary mixed micelles (DMM), cholesterol transport and absorption