Properties of yoghurt treated with microbial transglutaminase and exopolysaccharides

Abstract

The focus of our study was to observe the simultaneous effects of microbial transglutaminase (MTG) treatment and exopolysaccharides (EPS) on the rheological and microstructural properties of a yoghurt. Transglutaminase was applied to milk before fermentation and simultaneously with a yoghurt culture. Yoghurts were fermented in short-term (42 °C, 6–8 h) and long-term (30 °C, 16–18 h) fermentations with a EPS-producing culture that produces EPS and a non-EPS-producing that does not. Treatment with transglutaminase caused an increase in gel strength and viscosity, especially in the case of simultaneous application of MTG and culture. Furthermore, the presence of EPS enhanced these properties. New three-dimensional structures of proteins decreased the size of pores between protein chains, which led to improved water binding properties. Syneresis was further reduced by the presence of EPS. Treatment of yoghurts with MTG decreased the extensive ropiness of EPS yoghurts and contributed to a higher acceptability of the texture.