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Studies on the thermostability of lactase (Streptococcus thermophilus) in milk and sweet whey

Published online by Cambridge University Press:  01 June 2009

Norman A. Greenberg ,
Teresa Wilder  and
Raymond R. Mahoney
Norman A. Greenberg
Affiliation:
Department of Food Science and Nutrition, Massachusetts Agricultural Experiment Station, University of Massachusetts, Amherst, MA 01003, USA
Teresa Wilder
Affiliation:
Department of Food Science and Nutrition, Massachusetts Agricultural Experiment Station, University of Massachusetts, Amherst, MA 01003, USA
Raymond R. Mahoney
Affiliation:
Department of Food Science and Nutrition, Massachusetts Agricultural Experiment Station, University of Massachusetts, Amherst, MA 01003, USA
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Summary

The stability of lactase from Streptococcus thermophilus at 55 °C increased 7-fold, 2-fold and 1·5-fold in the presence of lactose, galactose and glucose respectively; maltose had no effect. Total stability over an 8 h period was more than 10-fold better in milk and sweet whey than in lactose solution, owing to the stabilizing influence of the milk proteins and the milk salts. Ovalbumin and reduced glutathione provided some extra stability but were not as effective as the milk components. In the absence of lactose the enzyme was less stable in milk and was not protected at all by sweet whey constituents. None of the milk protein fractions was as effective in the absence of lactose as when it was present. Enhanced thermostability of the enzyme in milk and sweet whey is due to contributions by all major milk components, but binding of lactose to the enzyme is the major factor controlling the extent of stabilization by other components.

Type
Original Articles
Information
Journal of Dairy Research , Volume 52 , Issue 3 , August 1985 , pp. 439 - 449
Copyright
Copyright © Proprietors of Journal of Dairy Research 1985

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References

REFERENCES

Barach, J. T., Adams, D. M. & Speck, M. L. 1976 Stabilization of a psychrotrophic Pseudomonas protease by calcium against thermal inactivation in milk at ultra high temperature. Applied and Environmental Microbiology 31 875–879CrossRefGoogle Scholar
Greenberg, N. A. 1982 Production, characterization and immobilization of Streptococcus β-galactosidase. Ph.D Thesis, University of Massachusetts, Amherst, MA, USAGoogle Scholar
Greenberg, N. A. & Mahoney, R. R. 1982 Production and characterization of β-galactosidase from Streptococcus thermophilus. Journal of Food Science 47 1824–1828, 1835CrossRefGoogle Scholar
Hemme, D., Nardi, M. & Jette, D. 1980 [β-Galactosidases and phospho-β-galactosidases of Streptococcus thermophilus.] Lait 60 595–618CrossRefGoogle Scholar
Larson, B. L. & Jenness, R. 1952 Characterization of the sulfydryl groups and the kinetics of the heat denaturation of crystalline β-lactoglobulin. Journal of the American Chemical Society 74 3090–3093CrossRefGoogle Scholar
Mahoney, R. R. 1984 Modification of lactose and lactase-containing dairy products with β-galactosidase. Developments in Dairy Chemistry-3 (Ed. Fox, P. F.). London: Applied Science.Google Scholar
Mahoney, R. R., Nickerson, T. A. & Whitaker, J. R. 1975 Selection of strain, growth conditions and extraction procedures for optimum production of lactase from Kluyveromyces fragilis. Journal of Dairy Science 58 1620–1629CrossRefGoogle ScholarPubMed
Ramana Rao, M. V. & Dutta, S. M. 1981 Purification and properties of β-galactosidase from Streptococcus thermophilus. Journal of Food Science 46 1419–1423Google Scholar
Whitaker, J. R. 1972 Principles of Enzymology for the Food Sciences New York: Dekker.Google Scholar