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Selection of Sterilization Conditions for Xinjiang Bactrian Camel Milk and Its Thermal Stability

YANG Jie,DOU Zhi-hua,LI Guan*   

  1. College of Life Science and Technology, Xinjiang University, Ürümqi 830046, China
  • Online:2013-11-15 Published:2013-10-28
  • Contact: LI Guan

Abstract:

The relative density, titratable acidity, pH, viscosity, alcohol stability, lactose content and total protein content
of mixed milk samples from 10 bactrian camels in Ürümqi suburb, Xinjiang autonomous region were determined as a
function of sterilization temperature and time. The sterilization efficiency was evaluated based on decimal logarithm of
survival fraction (lg (N/N0)). Protein denaturation in milk samples at each thermal treatment was assayed by SDS-PAGE.
The results showed that after 5, 10 min and 15 min at 75 ℃, the total number of colonies was reduced by 60.2%, 61.9% and
81.9%, respectively, without a significant effect on physiochemical parameters (P > 0.05); however, the alcohol stability
was significantly influenced (P < 0.05). Heating time at 60—75 ℃ did not significantly protein content (P > 0.05). Heating
temperatures of 65—100 ℃ exhibited a significant effect on lactose content (P < 0.05). The thermal stability of various
protein components followed the order: lactate dehydrogenase > α-lactalbumin > albumin > lactoferrin. No significant
effect on milk proteins was observed after heat treatment at 60 ℃ (P > 0.05). The effect of heat treatment at 65—100 ℃ on
milk proteins was significant (P < 0.05). From these results, it can be concluded that heat treatment at 75 ℃ for 5—15 min
can kill 81.9% of the microbes in bactrian camel milk, resulting in lower degree of protein denaturation

Key words: bactrian camel milk, sterilization conditions, heat stability, physical and chemical properties

CLC Number: