Effect of Transglutaminase on Texture and Flow Properties of Stirred Probiotic Yoghurt during Storage

Abstract

The aim of this work was to study the effect of different concentrations of transglutaminase (TG), inactivated or not inactivated - 0.02, 0.06 and 0.12% (w/w) - on the textural characteristics and flow properties of stirred probiotic yoghurt prepared from pasteurized skim milk (0.1% [w/w] fat). The physicochemical characteristics and the textural and rheological properties of yoghurt samples were determined after production and during 10 days of storage. The gel structure of yoghurt samples produced with not inactivated TG was stronger than that of samples produced with inactivated TG and control sample. Yoghurt containing 0.12% (w/w) TG not inactivated showed the highest hysteresis loop area (3,580Pa·s) after 5 days of storage. Hysteresis loop area of samples with 0.12% (w/w) inactivated TG after incubation for 2h at 40C is 56% lower compared with samples manufactured with the same concentration of not inactivated TG after 10 days of storage. Practical Applications: To produce yoghurt with low energy value, improved gel characteristics, and good physical and chemical properties, enzyme transglutaminase (TG) can be used. Enzymes are potential tools to increase the formation of covalent cross-links in protein foods. The addition of TG can reduce proteins and milk fat to produce nonfat yoghurt with the same rheological characteristic as yoghurt from whole fat milk. There are two different ways for the application of TG: simultaneously or prior to the fermentation. In the first case, TG was simultaneously added with starter culture. Pretreatment of milk with TG addition prior to fermentation demands additional process time as well as thermal inactivation step and has the advantage of a constant pH during the cross-linking reaction. © 2013 Wiley Periodicals, Inc.