Testing for Alicyclobacillus
The genus Alicyclobacillus consists of gram-positive, acidophilic and thermophilic, spore-forming bacteria typically found in soil. Alicyclobacillus spores, often brought into food manufacturing facilities on contaminated fruit, are able to survive typical pasteurization procedures. The non-pathogenic bacteria can cause disinfectant-like off-flavors in the final product, especially affecting fruit juices, concentrates, and preparations as well as tomato products. Most spoilage-related studies concerning Alicyclobacillus focus on the species A. acidoterrestris.
Spoilage of shelf stable fruit juice products by Alicyclobacillus bacteria can be very costly to the fruit juice industry. The spores, often present in fruit concentrates, are heat resistant and can survive many heat processes used by juice manufacturers. It is therefore important that concentrates and other raw materials are screened for spores of these taint producers to reduce the risk of spoilage of processed products.
Merck provides unique dehydrated culture media for cultivating Alicyclobacillus. The media’s granules, which cause far less dust than powdered media, dissolve rapidly in water and minimize component separation and clumping, even in warm or humid conditions. Its greater solubility and homogeneity makes it easier to use and more efficient. All of Merck’s dehydrated culture media meet the highest performance standards as laid out in ISO 11133.
|Method||IFU Method 12 – post-processing samples and packaged products||IFU Method 12 – post-processing samples and packaged products|
|Dilution||YSG broth or BAT broth /
sterile demineralized water (concentrates only)
|Heat shock (unheated products)||80°C, 10 minutes|
|Filtration (for filterable samples)||0.45 µm filter or enrichment|
|Incubation (for non-filterable samples)||2-5 days, 45 ±1°C||7 days, 45 ±1°C|
BAT agar (catalogue number 1.07994) or YSG agar, 45°C 2-5 days
BAT agar or YSG agar, 45°C 2-5 days