Abstract: To compare the quality of goat milk by different concentrated methods, this paper explored the effect of vacuum combined heating or frozen concentrated methods on the physicochemical quality of goat milk (pH value, turbidity, color value, particle size, and secondary structure of casein and fat globule). The results showed that when the total solids were 25%, the pH value, turbidity, color value, particle size and casein secondary structure of three concentrated goat milk changed significantly (P<0.05). The fat globules of heated and vacuum heated concentrated goat milk became larger, while the fat globules of vacuum frozen concentrated goat milk did not change significantly. Particle size, fat globules, casein secondary structure and turbidity of vacuum frozen concentrated goat milk changed significantly compared with heating and vacuum heating concentrated goat milk(P<0.05), and vacuum frozen concentrated method had the least effect on goat milk color difference. When the total solids were 35%, the turbidity, color difference and pH value of the three concentrated goat milk changed significantly (P<0.05). The particle size of heated concentrated goat milk increased by 33.90% compared to fresh goat milk (P<0.05), but there was no significant change in the other two concentrated goat milk (P>0.05). There was no significant changed in casein secondary structure of vacuum heated concentrated goat milk(P>0.05). The turbidity, color difference, particle size and casein secondary structure of vacuum frozen concentrated goat milk were changed significantly compared with the other two types of goat milk(P<0.05), and fat globules less than the other two goat milk. Therefore, the quality of with goat milk of 25% total solids was better than that of 35% total solids, and the vacuum frozen condensed goat milk with 25% total solids concentrated level was better than other concentrated goat milk.
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