Evaluation of pH-treated fish sarcoplasmic proteins on rheological properties of fish myofibrillar protein mediated by microbial transglutaminase

摘要

Fish sarcoplasmic protein (SP) could be exploited in the water-holding agent for fish protein gels, except that the gel strength is reduced. The adjustment of pH could modify protein interactions to overcome the inferior effect. Fish SP solutions were adjusted to pH 3 or 12, neutralised to pH 7 and lyophilised to be pH-treated SPs. These SPs along with lyophilised untreated SP (Normal SP) were incorporated into fish myofibrillar protein (MP) with microbial transglutaminase (MTG). The denaturation temperature (T_d) of MP mixed with normal SP was 66 ℃ with the lowest shear stress value. The denaturation of MP mixed with pH-treated SP reduced to be 57 ℃, resulting in increased shear stress. The cooking loss of MP gel was reduced by adding pH-treated SPs, while the breaking forces were similar to control. The result indicated that pH-treated SPs could be used to reduce cooking loss of MTG-mediated MP gels without affecting the gelling properties.