Effects of fish sarcoplasmic proteins on the properties of myofibrillar protein gels mediated by microbial transglutaminase

Abstract

Fish sarcoplasmic protein (SP) was extracted and lyophilized to obtain the SP powder. Fish myofibrillar protein (MP) was mixed with SP powder (0, 0.1, 0.5, and 1.0 g/100 g) in 1.8 and 2.6 g/100 g NaCl in the presence of 0.5 g/100 g microbial transglutaminase (MTG) at 4 °C for 6 h. Shear stress of MP mixture decreased with increasing SP concentrations. High thermal stability of MP mixture, assessed by differential scanning calorimetry, at either 1.8 or 2.6 g/100 g NaCl, was observed when SP (1 g/100 g) was added. The myosin heavy chain partially disappeared, suggesting the formation of cross-linked proteins. The gel strength of MP was not affected by the addition of 0.1 g/100 g SP (P > 0.05) whereas it started to decrease when SP was added up to 0.5 g/100 g, regardless of the NaCl concentration. The cooking loss of the MP gel was reduced efficiently when SP was added, even at a low concentration (0.1 g/100 g). A further reduction of cooking loss was observed when SP concentration was increased. The smooth microstructure of the gel surface was observed in samples containing SP, showing the lower cooking loss of fish myofibrillar protein gel.