Identification of medicinal off-flavours generated by Alicyclobacillus species in orange juice using GC-olfactometry and GC-MS

AIMS: The objective of this study was to identify compounds responsible for medicinal off-flavours produced by different species and strains of Alicyclobacillus in orange juice using a combination of chromatographic-coupled olfactometric techniques and gas chromatography-mass spectrometry (GC-MS). METHODS AND RESULTS: Each of five Alicyclobacillus strains was inoculated into separate juice samples and incubated up to 28 days at 45 degrees C. Aroma compounds in the juice were analysed by GC-olfactometry (GC-O) and confirmed using GC-MS. GC-O identified three components that were described as medicinal/antiseptic. Microbial populations were enumerated at timed intervals by spiral plating onto Alicyclobacillus agar. Within 28 days incubation, all five strains produced medicinal off-aromas from guaiacol and at least one halogenated phenol. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to evaluate individual juice aroma components produced by Alicyclobacillus species using olfactometry and to demonstrate that at least three medicinal off-flavour compounds are associated with the growth of alicyclobacilli in orange juice.