Abstract

Modification of Cheese Structure by Transglutaminase: With Specific Reference to Cheese Rheology and Yield

Barbaros Ozer, Professor, Ankara University

Transglutaminase (TGase; EC. 2.3.2.13) catalyses an acyl transfer reaction between the ?-carboxyamide group of peptide or protein-bound glutamine (an acyl donor) and primary amines (an acyl acceptor), including the e-amino group of lysine residues. This specific reaction yields new intra- and intermolecular crosslinks, leading eventually to the modification of the structure of proteins. The role of TGase in the improvement of the textural quality of low-fat or non-fat yogurt has been well demonstrated. The application of TGase in cheese technology seems promising, since similar results in terms of increased gel-strength and reduced syneresis not unlike those found in applications in yoghurt can be expected. Generally, TGase-induced crosslinks can lead to potential positive effects on rennet-gel strength. On the other hand it can lead to the deterioration of CMP release during the enzymatic phase of renneting. The release of CMP by means of rennet and the cross-linking of this fraction by TGase correlate with the subsequent gel development and strength. Therefore, it is essential to understand the role of cheese-making parameters on the combined action of TGase and rennet on milk proteins based on the physical properties and yield of brined type cheeses.