Rheological Properties and Microstructure of Buffalo Yoghurt

The rheological properties and microstructure of buffalo yoghurt were investigated and compared to bovine yoghurt. Buffalo yoghurt exhibited a greater degree of thixotropy and a higher level of syneresis. These differences can be linked to the underlying microstructure of the yoghurt, which is more porous and contains bigger fat globules compared to bovine yoghurt. This study shows how milk properties other than the total solids content influence yoghurt quality. INTRODUCTION The rheological properties and structural arrangement of food components are critical parameters that determine the quality of semi-solid foods, such as yoghurt. The properties of the raw components also have a large effect on the product. Several milk types that are currently used to produce yoghurt differ in their composition and properties. These include bovine milk and small volumes from buffalo or other species. Buffalo milk is considered more nutritious than bovine milk due to its higher concentration of fat, protein, total solids and minerals i.e. calcium and phosphorous, it is consequently processed differently prior to yoghurt making with only pasteurisation and no homogenisation or fortification, due to the high solids content. In contrast, bovine milk is typically fortified and homogenised to produce a homogenous product with a desirable firmness and texture. To date few studies have examined the rheological properties of buffalo yoghurt, with no study of the microstructure of buffalo yoghurt. Comparisons to the wellstudied bovine system are also limited. Therefore, this study aimed to characterize the physiochemical and microstructural properties of buffalo yoghurt and to compare these properties with bovine yoghurt produced following standard industrial procedures. MATERIALS AND METHODS Production of yoghurt Yoghurt was produced from either raw unhomogenised buffalo milk (Shaw River, Victoria, Australia) or pasteurised homogenised bovine milk fortified with skim milk and whole milk powder (Pura Brand, Victoria, Australia). The chemical composition of the bovine milk after Rheological Properties and Microstructure of Buffalo Yoghurt Hanh Thi Hong Nguyen, Lydia Ong, Christophe Lefèvre, Sandra Elizabeth Kentish, and Sally Louise Gras 1 Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia. 2 The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia. 3 Institute for Technology Research and Innovation, Deakin University, Geelong, Victoria