Overview of endospore-forming bacteria in food: The road towards a harmonised method for the enumeration of their spores

Endospore-forming bacteria are an important challenge for the food industry due to their ubiquitous nature, widespread presence in the food chain and sophisticated survival mechanisms. An accurate method is needed that can provide insight into the quality of raw materials, predict spoilage potential and ensure food safety. A plethora of methods exist for the enumeration of spore-forming bacteria which vary among countries, industries and food producers. These methods describe a wide range of values in the key method parameters, such as heat treatment, growth medium, incubation time, and temperature. Consequently the results obtained can vary leading to misalignment and confusion. In addition, many of these methods are empirical and have not been validated. A harmonised international approach for the enumeration of spores is needed to provide consistent and reliable results on which to base food safety and quality decisions. A group of experts associated with the Internal Standardisation Organisation working group undertaking this task has identified the main endospore-forming bacterial species occurring in foods based on a wide selection of publications. Endospores are typically formed by bacteria belonging to twelve families originating from the Negativicutes, Bacilli and Clostridia classes, with the latter two being the most important for the food industry. This review will be used as a first step in method standardisation.