Influence of alginate and microbial transglutaminase as binding ingredients on restructured fish muscle processed at low temperature

BACKGROUND: In view of the increasing demand for fresh products in Western countries recently, there is considerable interest in commercialising restructured fish products having the appearance of fresh fish. A number of methods have been studied for the purpose of inducing cold gelification. Two of the most common methods, namely addition of alginates and addition of transglutaminases, have been studied mainly in connection with meat products. The present study deals with the use of alginate and transglutaminase as additives in cold gelification of minced hake (Merluccius capensis) muscle. The experiments were targeted on the effects of concentration and combined effects of additional additives on physicochemical characteristics and mechanical properties. RESULTS: As regards mechanical properties, the effectiveness of sodium alginate was improved by addition of a low concentration (1 g kg(-1)) of calcium chloride (CaCl2), whereas a higher concentration (10 g kg(-)1) reduced the binding ability of the alginate. The presence of sodium caseinate (15 g kg(-1)) in combination with microbial transglutaminase (MTGase) was important in helping to increase the work of penetration in fish gels induced at low temperature. Examination of the chemical properties of the muscle gels showed that sodium alginate did not establish covalent protein-protein bonds, while MTGase dramatically increased the number of covalent bonds formed between adjacent muscle proteins. CONCLUSION: With both ingredients, thermostable fish gels of good quality were produced at temperatures below 10 degrees C. Gels induced by sodium alginate were considerably improved by addition of 1g kg(-1) CaCl2. However, gels induced by MTGase were better suited for the preparation of restructured products. (c) 2008 Society of Chemical Industry.