Spore-forming bacteria in the dairy chain

Abstract

Spore-forming bacteria form the most diverse and most complex group of bacteria in terms of their elimination from the dairy chain, due to their ability to form highly resistant spores. As ubiquitous microorganisms, spore-formers can enter the product along the milk-processing continuum from different sources, and subsequently cause spoilage in various types of dairy products. The most important classes of spore-forming bacteria relevant to the dairy industry are Bacilli and Clostridia. Bacilli are responsible mainly for the spoilage and decreased shelf-life of fluid milk, while Clostridia cause late gas blowing in cheese. Spore-forming microorganisms contaminate raw milk primarily at the farm level, with potential for recontamination to occur at various points along the dairy production continuum. The most effective measure in reducing spore load at the farm level is adequate pre-milking teat preparation, while at the dairy plant level, bactofugation and microfiltration are applied. Understanding the ecology of spore-formers can improve application of systematic approaches for controlling the spoilage bacteria in dairy processing systems. Also, novel technologies, such as high-pressure processing, ultrasound treatment, irradiation etc., could provide the dairy industry with the powerful tools to eliminate these bacteria from the dairy chain.