Effects of Different Chemically Modified Starches on the Rheological Properties of Stirred Non-fat Yoghurt

Abstract

The use of chemically modified starches to improve the physical properties of non-fat stirred yoghurt was investigated. Yoghurts were prepared from non-fat milk powder, sucrose, water and tapioca starch acetates (TSA-1, TSA-2, TSA-3), tapioca distarch phosphates (TDP-1, TDP-2, TDP-3) or native tapioca starch at 1% (w/w). Syneresis, particle size distribution and viscoelastic properties of the yoghurts were determined, and flow behaviour was described using the Herschel-Bulkley model. Furthermore, interactions between milk proteins and modified starches attributed to protein surface hydrophobicity were characterized. Results showed that yoghurts with starch acetates exhibited higher yield stress, consistency coefficient (K) values, hysteresis loop area, storage modulus (G′) and loss modulus (G″). Protein surface hydrophobicity was significantly influenced by the addition of starch acetates, and TSA-3 yoghurt exhibited the lowest values. This study concluded that the addition of TSA-3 starch showed better results in terms of the rheological properties of non-fat yoghurt.