In vitro bile acid binding activity and non-extractable polyphenols of dried persimmon and quince fruits

To elucidate functional aspect of regional horticultural products, in vitro bile acid binding activity and non-extractable polyphenol (NEPP) content of dried persimmon 'Ichidagaki' and quince 'Smyrna' fruits were determined. Seventy percent acetone insoluble solids (AIS) of dried persimmon showed a strong bile acid binding activity that was equivalent to around 30% of the activity of cholestyramine. The bile acid binding activity of quince AIS was moderate but lyophilized fruit showed higher activity than that of apple and fresh persimmon. NEPP content was determined using Folin-Ciocalteu reagent after acid hydrolysis or by direct reaction to AIS. The appropriate condition of hydrolysis or pre-treatment differed with dried persimmon and quince. Dried persimmon contained a high amount of NEPP as the main form of polyphenols, whereas quince fruit contained extractable polyphenols more than NEPP. The results suggest that these fruit products, especially dried persimmons, may have a certain potential to contribute to lowering cholesterol because of the strong bile acid binding capacity.