Revised IFU Method No. 12 for Detection of Alicyclobacillus spp. in Fruit Juices

Alicyclobacillus spp. can be difficult to control in fruit juice products as their spores survive juice pasteurization temperatures and may subsequently germinate and grow after processing if conditions are suitable. The economic impact of such incidents can be very high.

The International Fruit and Vegetable Juice Association (IFU) Working Group on Microbiology has reviewed and modified the method to meet users’ demands for the detection of Alicyclobacillus spp. in fruit juices. The IFU method no. 12 is now more precise, more structured and therefore more reproducible. It includes improved culture media formulations and performance criteria which are in agreement with ISO procedures.

Enumeration and detection of Alicyclobacillus spp.

Depending on the type of sample and the purpose of the test, different enumeration / detection procedures can be used for spore forming thermo-acidophilic bacteria (Alicyclobacillus spp.):

• enumeration by poured-plate technique - to be used for quantitative results mainly for non-filterable samples;
• enumeration by filtration technique using membrane filtration technique -
• to be used for quantitative results for filterable samples;
• detection procedure C: Detection by enrichment - to be used for qualitative results (presence/absence test)

2018 changes to IFU method no. 12

An ISO-compliant validation within the IFU Microbiological Working Group was performed, ensuring a user-friendly laboratory implementation.

The main changes, compared to IFU method no. 12:2007, will be the following

• the title of the method has been changed to “Method on the Detection and Enumeration of Spore-forming Thermo-Acidophilic Spoilage bacteria (Alicyclobacillus spp.)",
• the optional usage of several media has been changed to the usage of one liquid (BAT broth) and one solid medium (BAT agar),
• a new pour plating method is introduced for enumeration in 1 g sample,
• performance testing for the quality assurance of the culture media has been added,
• the determined performance characteristics for this method have been added as a summery,
• optional pre-incubation of packed ready-to-drink products has been added to Annex E,
• matrix-dependent special processes have been added to Annex F.