Milk-clotting potential of fruit extracts from Solanum esculentum, Solanum macrocarpon L. and Solanum melongena

Abstract

Fruit extracts from Solanum esculentum, Solanum macrocarpon L. and Solanum melongena were tested for their milk-clotting potential. The release of substances associated with milk-clotting was highly dependent upon quantity of berries, extraction duration and sodium chloride concentration. The highest milk-clotting activity was obtained after 8 h (for S. esculentum and S. melongena), and 12 h (for S. macrocarpon) of soaking 20 g of fruit in 6% NaCl 4°C. In these conditions, there was a non linear relationship between the milk-clotting time and the amount of fruit extracts from each species. The loss of milk-clotting activity was dramatic after wet-heating of extracts from S. esculentum and S. macrocarpon at 80°C for 10 min and after dry-heating of fruits at 100°C for 24 h. Heat treatment did not significantly affect the clotting activity of extract from S. melongena. Fruit extracts from S. esculentum had the greatest milk-clotting activity followed by extracts from S. macrocarpon and S. melongena. Extracts from S. esculentum and S. macrocarpon exhibited a proteolytic activity on the casein.