A review on spore-forming bacteria and moulds implicated in the quality and safety of thermally processed acid foods: Focusing on their heat resistance

Abstract

Spore forming microorganisms pose significant challenges in the food industry, contributing to spoilage and foodborne illnesses. Despite the unfavourable pH conditions of acid foods, certain acid-resistant spore forming bacteria and moulds have shown their capacity to grow, and thereby posing quality and safety concerns. This review discusses our current knowledge of different spore forming bacteria, including Alicyclobacillus spp., Bacillus spp., and Clostridium spp., as well as ascospore producing moulds such as Byssochlamys spp., Neosartorya spp., and Talaromyces spp., involved in the spoilage of various acid food products. The main concerning attribute increasing the spoilage risk of these microorganisms, together with their acid resistance, is their resistance to heat, a primary preservation method employed in shelf stable acid foods. Therefore, particular emphasis has been given to the heat resistance of those spore formers. This review consolidates diverse research findings on the heat resistance of spores/ascospores derived from these spoilage microorganisms. It highlights the complexity of inactivation kinetics influenced by spore associated and heating-medium associated factors. Moreover, how certain spoilage spore formers might raise food safety concerns by creating conductive environments for pathogens in acid foods is being discussed. The lack of knowledge on the spoilage potential and heat resistance of certain spore formers in acid foods, as well as the need for future research to identify the potential spoilage risk of spore formers in novel acid foods, are also highlighted. Overall, this review highlights the challenges posed by spore forming bacteria and moulds in acid foods, shedding light on their heat resistance, spoilage potential, and implications for food quality and safety.