Abstract
Fibroin foam powder prepared from fibroin solution, which can be used as an ingredient in food to produce foam in sponge cake, was studied to examine its effects on serum cholesterol concentration in rats fed diets with or without cholesterol. The digestibility of fibroin foam powder in vitro was 11-25%. Addition of fibroin foam powder to a cholesterol-enriched diet lowered the serum total cholesterol level significantly. The total liver cholesterol in rats fed the cholesterol-enriched diet with fibroin foam powder tended to decrease in comparison with that in rats fed the cholesterol-enriched diet alone. The amounts of excreted bile acids were higher in the rats fed the cholesterol-free and -enriched diets with fibroin foam powder than in the rats fed the same diets without fibroin foam powder. Increases in the amounts of feces and fecal bile acids in the rats fed the fibroin foam powder suggest that the cholesterol-lowering effect of fibroin foam powder is due partly to promotion of bile acid excretion by its indigestible fraction.
