Using of Microbial Transglutaminase as a Substitute for Part of Skim Milk Powder in Spinach Yoghurt
Subject Areas : Microbiology
Vajiheh Fadaei Noghani
1
(استادیار گروه علوم و صنایع غذایی، واحد شهر قدس، دانشگاه آزاد اسلامی، تهران، ایران)
Azam Mofidi
2
(دانش آموخته کارشناسی ارشد گروه علوم و صنایع غذایی، واحد شهر قدس، دانشگاه آزاد اسلامی، تهران، ایران)
Mahdi Zarei
3
(دانشیار گروه بهداشت و کنترل کیفی مواد غذایی، دانشکده دامپزشکی، دانشگاه شهید چمران، اهواز، ایران)
Keywords:
Abstract :
Introduction: Microbial transglutaminase (MTGase) enzyme is one of transferase enzymes that can catalyze the formation of ε-(δ glutamyl-)-lysine cross links in proteins via an acyl transfer reaction. The enzymatic cross linking of proteins by means of microbial transglutaminase strengthens protein-based food structures at the molecular level and positively affects properties such as serum holding capacity and gel firmness. In this study, the effect of using this enzyme (0.1, 0.2 and 0.3 g L-1) ,as a substitute for part of the skim milk powder, was evaluated. Materials and Methods: The effect of enzyme on selected physicochemical (eg pH, titratable acidity, syneresis and viscosity) and organoleptic properties (texture, flavor, odor and overall acceptability) of spinach yoghurt was examined. Evaluations were performed at 0, 5, 10 and 15 days of storage at 4°C. Results: In general, addition of different concentrations of MTGase caused no significant changes in acidity and pH of yoghurt samples. However, it increased the viscosity and decreased the syneresis. It was indicated that the concentration of 0.1 g L-1 could be considered as the optimum concentration for MTGase. Although higher concentrations could produce better properties, but it was not economical, because fewer concentration of enzyme was able to create a sample similar to the control. Conclusion: The results showed that the MTGase is an acceptable substitute for skim milk powder in spinach stirred yoghurt.