In vitro binding of bile acids by lupin protein isolates and their hydrolysates

This study investigates the in vitro binding of bile acids by lupin, lupin protein isolates, and their hydrolysates compared to soybean products and cholestyramine. Sodium cholate, sodium deoxycholate, sodium chenodeoxycholate, sodium glycocholate and sodium taurocholate were individually tested and analyzed spectrophotometrically by enzymatic reaction. A degree of hydrolysis of up to 20% did not affect the bile-acid binding capacity. De-oiled lupin and its hydrolysate bound all the bile acids to a significantly greater extent than de-oiled soy and its hydrolysate. Acid-soluble protein isolate from lupin showed a greater bile-acid binding capacity than acid-insoluble protein isolate. The amount of bile acid bound by acid-soluble lupin protein isolate was sometimes greater than the amount of bile acid bound by cholestyramine, which is well known as a cholesterol-reducing agent. There was no selective binding of particular types of bile acids. It can be concluded from these results that acid-soluble protein isolate from lupin may have potential application as a cholesterol-reducing agent for hypercholesterolemic patients.