Hypocholesterolemic effect of compounded freshwater clam protein hydrolysate and Gracilaria

The muscles of freshwater clam and whole Gracilaria powder (WG) were separately extracted using hot water. The residual meat was first freeze-dried, then hydrolysed at 50 °C by Protamex to obtain freshwater clam hydrolysate (PX5). The WG was separated into two fractions, designated as soluble (SDF) and insoluble dietary fibre (IDF). The in vitro bile acid-binding capacities and inhibition of micellar solubility of cholesterol were then investigated using the compounded PX5 and dietary fibre of WG or IDF. Assuming that bile acid binds to cholestyramine at 100%, the relative bile acid-bindings of PX5 and WG were 35.9% and 41.1%, respectively. Bile acid-binding of compounded PX5 and WG showed the best synergistic effect at a ratio of 1:3 (w/w) and relative bile acid-binding of 45.7%, significantly higher than PX5 and WG alone. After peptic digestion, the resulting inhibitions against cholesterol micelle formation in cholestyramine, PX5, WG and IDF were 97.6%, 18.5%, 30.8% and 49.3%, respectively.