Physico-chemical properties of milk proteins modified by transglutaminase

Food consists of several components of a complex structure and different shapes to suit different tastes of consumers. Different food establishments are planning to develop new components of dairy products, whether in the microbiological, chemical characteristics or functional properties. A protein is considered the most important component of milk, in addition to its role in nutrition, it is a food component which works to improve the functional properties of the structure, stability and handling of dairy products. The functional characteristics of the protein in milk reflects the behavior of protein in the diet during the different manufacturing processes. Each property requires a special structure. Therefore we have to modify the protein structure in line with the required properties. Of the most important adjustment methods that can be used to modify the protein, the use of enzymes, and the transglutaminase is the most important enzymes used. The study focused on buffalo milk, the main type of milk consumed in Egypt, and, consequently, on the casein which considered the main component of the protein in milk. Transglutaminase was used at a concentration of 0.5 unit of enzyme per gram of protein in the sample through this study. This study was conducted in two parts. The summary of the results obtained are: Part I: Some functional properties of casein as a function of Transglutaminase. The electrophoresis of casein and TGase treated casein showed an increase in a molecular weight of the bands of casein fraction on the gel. The coagulation time of milk by using acid or rennet showed an increase as a result of transglutaminase. The acid clotting time rennet clotting time for TGase treated milk. The water holding capacity of casein treated by TGase was higher at a temperature of 5, 25, and 40 .ºC. The oil binding capacity of casein treated by TGase showed a higher value compared with untreated casein at 5, 25, and 40 ºC. Ethanol stability of casein treated samples was better than the control casein. Foaming capacity and stability was lower with casein treated samples than the control casein solution. The emulsifier capacity and stability properties were improved in the case of casein treated samples. The solubility of casein treated samples by TGase showed better values than the control casein solution. The buffering capacity of casein solution treated with enzyme showed better quality than the control casein samples. The rheological properties were improved as a result of treated casein by TGase. Part II: Manufacture of yoghurt Transglutaminase improves the viscosity of yoghurt which being Treatment 2 Treatment 1 Control. Synersis defect was reduced by using transglutaminase. The curd strength was increased by using TGase enzyme. The curd structure was improved and became compact with good distribution of protein and fat as seen with the electron microscope examination. Using transglutaminase is a good technique method for manufacture high quality yoghurt.