In the fruit and vegetable processing industry, it is common to hear about spoilage. This term refers to the deterioration of products caused by Alicyclobacillus. Its presence in packaged fruit products is known to cause alterations in their organoleptic properties, such as taste and smell, and even sediment formation, discoloration, or cloudiness.

Consumer complaints used to be the only reason companies became aware of the problem, as the absence of gas production makes it difficult to detect deterioration. The taste produced by Alicyclobacillus has been described as medicinal, disinfectant, or phenolic. These characteristics are due to the formation of chemical compounds such as guaiacol and halophenols, which are perceptible in extremely low concentrations and can ruin the sensory quality of products.

Alicyclobacillus acidoterrestris is the species primarily responsible for incidents of spoilage, although other species, such as A. acidiphilus, A. pomorum, A. hesperidum, A. herbarius, A. cycloheptanicus, and A. acidocaldarius, have also been implicated due to their ability to produce contaminating compounds or because they have been isolated from spoiled products.

Although Alicyclobacillus poses an economic threat to the fruit processing industry, the consumption of products containing Alicyclobacillus does not pose a health risk as it is not considered a pathogenic microorganism.

How is Alicyclobacillus detected in industry?

Due to the difficulty of controlling this microorganism in fruit processing and the economic impact of the incidents it causes, the International Fruit and Vegetable Juice Association (IFU) published Method No. 12 in 2019 for the detection and enumeration of thermoacidophilic spore-forming bacteria (Alicyclobacillus spp.) as well as the detection of other bacteria with similar characteristics that produce guaiacol.

This method is applicable to:

• Juices and related products and their ingredients intended for human consumption.
• Environmental samples, including process water in the area where juices and related products are produced and handled.

Specifically, the method describes the analysis for enumerating and detecting the bacteria. For enumeration, membrane filtration is used for filterable products or a product volume for non-filterable products. The detection method starts with the enriched sample to obtain qualitative results (absence/presence).

The sample or, where applicable, the initial dilution is subjected to heat treatment (80°C for 10 minutes) to select and germinate the spores. The recommended medium according to the IFU is BAT broth and agar, in which it must be incubated at 45°C for 3–5 days.

Control and prevention of Alicyclobacillus contamination

To prevent spoilage caused by Alicyclobacillus, the affected industry must implement effective control and prevention practices at critical processing points, such as:

• Raw material quality control: perform microbiological tests on fruit and other ingredients prior to processing to ensure they are free from contamination.
• Good hygiene practices: maintain strict hygiene in production facilities, including proper cleaning and disinfection of equipment and surfaces.
• Proper pasteurization processes: ensure that pasteurization processes are rigorous enough to eliminate any bacterial contamination.
• Proper packaging: ensure that containers are clean and properly sterilized before use.
• Proper storage: store products in optimal conditions, avoiding high temperatures that may promote the germination of Alicyclobacillus spores.

The presence of Alicyclobacillus can result in serious deterioration of organoleptic quality, which negatively affects consumer acceptance of the product. By maintaining good hygiene practices and proper quality control measures, the industry can minimize the risks associated with the presence of Alicyclobacillus and offer high-quality products.