Effects of heat treatment and stabilizing salts supplementation on the physicochemical properties, protein structure and salts balance of goat milk

Abstract

This study investigated the effects of heat treatment and stabilizing salts on the physicochemical properties, protein structure and salt balance of goat milk. Heat treatment altered the quantity of sediment (peak width) and particle concentration (delta backscattering) of goat milk observed in Turbiscan spectrograms. A higher Turbiscan Stability Index, and greater sediment thickness and velocity were observed in UHT goat milk than in UHT cow milk, indicating poorer heat stability of goat milk than cow milk. The poor heat stability of goat milk might be caused by the heat-induced conversion from stretching structure (β-sheet and β-turn) to globurizing structure (random coil and α-helix) of protein, and changes in distributions of proteins (β-CN, αs1-CN, αs2-CN, κ-CN, β-LG and α-LA), calcium and phosphorus between supernatant and sediment. Compared with UHT goat milk without stabilizing salts, the addition of stabilizing salts increased the amounts of calcium and phosphorus in the supernatant and decreased the amounts of sediment, protein particle size, and globular protein structure in UHT goat milk. This demonstrates that stabilizing salts can be used to improve the heat stability of goat milk.