Physicochemical and Functional Characterization of Cocosin, the Coconut 11S Globulin

Abstract

The physicochemical and functional characteristics of the major coconut storage protein, 11S globulin or cocosin, were investigated.Cocosin was purified by a combination of salt extraction, selective precipitation, and gel filtration chromatography. The solubility of cocosin at different pH was higher at µ=0.5 than at µ=0.08. The 24 and 21 kDa basic polypeptides of cocosin were more resistant to chymotrypsin digestion than the 35 and 32 kDa acidic polypeptides. Cocosin emulsions were most stable at 0 M NaCl, followed by emulsions in 0.1 M and 0.4 M NaCl. The available SH groups were found to be 21.6 mole SH/mole cocosin. Cocosin was observed to be stable under various pasteurization conditions from 63°C, 30 min to 100°C, 10 sec. However, heating at 100°C for 10 min and longer degraded cocosin up to 60%. The thermal denaturation midpoint temperature, T_m, of the trimeric cocosin was 77.6°C while that of the hexameric form was 100.5°C.