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Effects of long-term deep-freeze storage on the condition of the fat in raw sheep's milk

Published online by Cambridge University Press:  01 June 2009

Eric C. Needs
Eric C. Needs
Affiliation:
AFRC Institute of Food Research, Reading Laboratory, Shinfield, Reading RG2 9AT, UK
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Summary

Effects of long-term deep-freeze storage on the stability of fat in raw sheep's milk were assessed by measuring free fatty acid (FFA) concentrations, lipoprotein lipase activity and the amount of solvent-extractable fat. Portions of milk from three herds were frozen and stored at – 12, – 20 and – 27 °C. There was a gradual increase in FFA during 6 months storage, the rate of lipolysis being affected by storage temperature and differences between herds. After 6 months storage the residual lipase activity was only 2% (– 12 °C), 11% (– 20 °C) and 24% (– 27 °C) of the initial activity in fresh milk. The potential for lipolysis in the stored samples, after they were removed from storage and allowed to thaw to 4 °C, gradually fell as storage time was prolonged. This may be due to the loss of lipase activity.

Type
Original Articles
Information
Journal of Dairy Research , Volume 59 , Issue 1 , February 1992 , pp. 49 - 55
Copyright
Copyright © Proprietors of Journal of Dairy Research 1992

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References

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