Validation of the Method on the Detection of Alicyclobacillus spp. in fruit juices

Fruit juices play a significant role in promoting a nutritious diet for individuals. They are recognized as stable products due to their acidic nature, which inhibits the growth of most bacteria. However, a group of heat-resistant, thermo-acidophilic bacteria known as Alicyclobacillus, capable of forming spores, can potentially lead to spoilage of commercially processed fruit juices. This spoilage, known as "flat sour" type, is characterized by the absence of gas production but the presence of chemical compounds, such as the metabolite guaiacol, that indicate spoilage. The ability of Alicyclobacillus spores to survive pasteurization and germinate under favorable conditions raises serious concerns for the global fruit juice industry. For this reason, Alicyclobacillus spp. has been recognized as a significant microorganism for quality control purposes. Different microbiological techniques have been developed to identify Alicyclobacillus strains, and among them, the most efficient approach is the IFU Method No 12, which was developed by the Working Group on Microbiology of the International Fruit and Juice Association (IFU). Therefore, the purpose of this article is to validate IFU’s Alicyclobacillus detection method for the accredited microbiology laboratory at Merieux Nutrisciences in Vila Nova de Gaia, Portugal under the ISO 16140-2 standards.