Physico-chemical characterisation of milks from individual goats

Abstract

In the last few decades, goat milk and its dairy products have acted as an important role in food industry in many places of the world. Information on composition and physico-chemical properties of goat milk is significant for economic development of the goat milk industry and commercial use of the products. However, those vital constituents and physical characteristics of goat milk, such as proteins, mineral contents, citrate, vitamins, and particle size to a large extent, are influenced by several factors including stage of lactation, goat breeds, genotype, individuality, season, and feeding condition. In addition, casein micelle size, as an important parameter in milk system, significantly impact the quality and property of goat milk and its dairy products. The main objective of this study was to determine the factors that influence casein micelle size in goat milk. Also, current work explored the variations of main nutritional compounds including protein, citrate and mineral (Na, K, Ca, P and Mg) contents in the milk of two goat breeds (Saanen and Toggenburg) during lactations. Results showed that casein micelle sizes were highly correlated with the proportion of κ-casein, β-casein and αs1-casein, statistically significant variations were found between casein micelle size and the levels of κ-casein, β-casein and αs1-casein proteins. Milk samples with a small casein micelle size were relatively abundant in κ-casein and αs1-casein compared with that of the large micelle, while the percentage of β-casein showed to be in direct proportion to micelle size. Other compounds such as whey protein, citrate, and mineral contents were observed no correlation with casein micelle size. These observations were found in the both goat breeds. On the other hand, factors such as casein micelle size, citrate and mineral contents (Ca, P and Mg) were showed significant differences during lactation, while protein content did not.