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Epimerization of lactose to free lactulose in heated model milk solutions

Published online by Cambridge University Press:  01 June 2009

Barry D. Greig  and
Gerald A. Payne
Barry D. Greig
Affiliation:
*National Institute for Research in Dairying (University of Reading), Shinfield, Reading, RG2 9AT, UK
Gerald A. Payne
Affiliation:
*National Institute for Research in Dairying (University of Reading), Shinfield, Reading, RG2 9AT, UK
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Summary

The kinetics of the epimerization of lactose to lactulose were determined for two ‘model milk’ solutions, one containing lactose and the other lactose and lysine. The lysine was added to lactose to determine whether amino groups of proteins act as base catalysts promoting the production of free lactulose. The presence of lysine actually reduced the rate of production of free lactulose, presumably by the formation of amino-sugar complexes. The rate of production of free lactulose over the range of processing conditions was shown to be first order for both systems. Thermal effects on lactose were shown to be complex. The epimerization of lactose to lactulose was reversible and both sugars were thermally decomposed to their monosaccharides. The difference in the rate of production of free lactulose between the lactose, and the lactose and lysine solutions was also observed in processed milk and its ultrafiltrate (protein free).

Type
Original Articles
Information
Journal of Dairy Research , Volume 52 , Issue 3 , August 1985 , pp. 409 - 417
Copyright
Copyright © Proprietors of Journal of Dairy Research 1985

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References

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