RECENT ADVANCES IN ENZYMATIC MODIFICATIONS OF FOOD PROTEINS FOR IMPROVING THEIR FUNCTIONAL-PROPERTIES

The tailoring of food proteins by enzymes is a powerful tool to improv e their functional properties. Mainly proteinases from various on ins have been used for such purposes. Controlled proteolysis leads general ly to more soluble products with improved emulsifying properties but r elatively poor foaming properties. This latter was the case in our stu dies on proteolysis of wheat gluten. We also have demonstrated that po lypeptides characterized by a high functionality could be produced by proteolysis of wheat gluten. Depending on the: conditions of the prote olytic attack, the cleavage sites as well as the type of generated pep tides could be modified. In the case of milk proteins, peptic action o n the proteins in ethanolic medium or on moderately esterified protein s results in unique fragmentation. Besides fragmentation achieved by p roteases, the cross-linking of proteins to yield higher molecular size forms with transglutaminases was shown to improve the functional prop erties of proteins. These enzymes catalyse the binding of amines to pr oteins, cross-link the polypeptide chains and deamidate the glutaminyl residues. In the case of soybean isolates, gelification was obtained with lower protein concentrations. In the case of wheat gliadins, enzy matic deamination increased drastically the solubility in a wide range of pH. Additionally, enzymatically deaminated gliadins were shown to be very efficient in stabilizing emulsions. due to the formation of so luble polymers.