Effect of aeration on extracellular enzyme synthesis by psychrotrophs growing in milk during refrigerated storage

• Published in: Journal of food protection Vol. 47; no. 9; pp. 697 - 702
• Main Authors: Griffiths, Mansel W., Phillips, John D.
• Format: Journal Article
• Language: English
• Published: Des Moines, IA International Association of Milk, Food and Environmental Sanitarians 01.09.1984
• Subjects: aeracion; aeration; Biological and medical sciences; cold storage; Food industries; Fundamental and applied biological sciences. Psychology; lait; leche; milk; Milk and cheese industries. Ice creams; proteasas; protease; proteases; proteinases; psychrotrophic bacteria; triacylglycerol lipase; Aeration; Shelf life; Cold storage; Microbiological testing; Lipolysis; Milk
• ISSN: 0362-028X; 1944-9097; 1944-9097
• DOI: 10.4315/0362-028X-47.9.697

Aerating milk markedly reduced proteolysis but increased lipolysis during storage at 6°C. The increase in lipolysis was due to native milk lipoprotein lipase, and aeration conditions could be modified to overcome this deleterious effect. The decrease in proteolysis was due primarily to a decrease in the amount of protease synthesized rather than a change in the bacterial flora of the milk. It was shown that protease and lipase production by psychrotrophs growing in milk was subject to catabolite repression by glucose. Differences in levels of certain metabolites produced by bacteria growing in aerated and non-aerated milks may be a factor contributing to the decrease in protease activity.