Thermal characteristics of freeze-dried camel milk and its major components

Abstract

Thermal characteristics of freeze-dried whole and skimmed camel milk, and its major components were measured by differential scanning calorimetry (DSC). The thermogram of whole milk showed three endothermic peaks (two for fat-melting and the other for non-fat solids-melting) and three shifts. Two shifts at low temperature were related to the glass transitions. The shift at higher temperature after melting of non-fat solids could be related to the structure ordering in milk after solids-melting. It was difficult to identify which components in the milk were providing these transitions and to trace the glass transitions of each component in the milk due to the complex interactions of the components’ phases. For this reason, different major components of the camel milk (fat, cream, casein, whey protein, and lactose) were separated and then measured its thermal characteristics. The thermogram of camel milk fat showed two endothermic peaks, one wide and the other sharp. The shape of the endotherm for fat was related to the melting of different fractions of fatty acid. The glass transitions of the isolated casein, whey and lactose were also determined separately.