EMULSIFYING ACTIVITY OF HEAT-TREATED SARCOPLASMIC PROTEIN FROM SARDINE

The emulsifying activity of sarcoplasmic protein (Sp-P) from sardines was evaluated in connection with heat-treatment. The solubility of sar dine Sp-P decreased with a rise in heating temperature over 40 degrees C when heated at various temperatures from 20 to 100 degrees C for 15 min at pH 7.0. After the heat treatment at a temperature above 60 deg rees C, the Sp-P was insolubilized up to 95%, and the soluble fraction s were composed mainly of a component of ca. 12 kDa, parvalbumin. The soluble proteins from the higher temperature abuse showed excellent em ulsifying activity. The emulsifying activity of the parvalbumin fracti ons prepared from Sp-P by Sephadex G-75 chromatography was greater tha n that of the other protein fraction of Sp-P at equal concentration (1 mg/ml) and did not decrease on heating at 80 degrees C for 15 min. Th e parvalbumin fraction is considered to play an important role in the emulsification process with water-soluble proteins from sardines.