Endospores of Thermophilic Bacteria in Ingredient Milk Powders and Their Significance to the Manufacture of Sterilized Milk Products: An Industrial Perspective

Milk powder is one of the most widely traded dairy products globally—with a large amount being used to manufacture commercially sterilized products. Milk powder invariably contains endospores of thermophilic bacteria—the dominant strains grow and produce spores in manufacturing steps operating in their temperature growth range. Although they produce proteolytic and lipolytic enzymes in vitro, and the spores have the potential to survive sterilizations, their presence in ingredient powders does not mean that spoilage of sterilized products is inevitable—treatment severity, low spore numbers in ingredient powders, variability in spore resistance, and in-market temperatures usually ensure commercial sterility.