The presence and metabolic activity of psychrotrophic microorganisms in milk and dairy products are reviewed. Problems involved in adequately defining the microorganisms and temperatures of growth are discussed. The sources and incidences of psychrotrophs in milk and dairy products and methods to control these microorganisms are presented. Methods ranging from simple plate counting techniques to detection of metabolites produced by the psychrotrophs are reviewed. Alterations of protein, lipid and carbohydrate fractions of milk and their effects on the keeping quality of milk and dairy products are discussed. Finally, additional research areas are suggested.
1Journal paper No. 8489 of the Purdue University Agricultural Experiment Station.