A review of innovative techniques for rapid detection and enrichment of Alicyclobacillus during industrial processing of fruit juices and concentrates

Alicyclobacillus genus includes thermo-acidophilic, endospore-forming bacteria that cause spoilage of pasteurized fruit juice through formation of phenolic off-flavours. Effective quality control during fruit juice processing is a prerequisite and early detection of Alicyclobacillus in raw materials and finished products can guarantee product quality and longer shelf life. Highly sensitive, cost-effective traditional microbiological methods for Alicyclobacillus detection are often too slow in achieving results, therefore alternative culture-independent approaches have been proposed for rapid detection of Alicyclobacillus contamination in industrial production line. In this review, the various innovative techniques which have been exploited for rapid detection of Alicyclobacillus in contaminated juices and concentrates were appraised. The techniques were discussed under three analytical approaches, including (i) cells/spores-based detection (spectroscopy and immunoassays), (ii) nucleic acid-based detection (amplification and non-amplification methods), and (iii) metabolites-based detection (detection of specific phenolic off-flavours, assessment of total volatile profile of sample or detection of non-volatile metabolites). The sensitivity and rapidity of individual technique were highlighted as well as their drawbacks and recommendations for optimization. The combination of these innovative detection techniques with immunomagnetic separation and DNA-aptamer binding, as to achieve better assay sensitivity and rapidity are also discussed.