Best Estimated Aroma and Taste Detection Threshold for Guaiacol in Water and Apple Juice

ABSTRACT: Alicyclobacillus acidoterrestris can produce sufficient guaiacol (methoxyphenol), a metabolic by-product of the bacterium, in apple juice to cause a detectable taint characterized by an antiseptic off-odor or distinct medicinal flavor and lingering aftertaste. Bacterial spoilage may not be visibly detectable. The objective of this study was to determine the best estimate threshold (BET) for detection of guaiacol in water and commercial pasteurized apple juice from concentrate using the forced-choice ascending concentration method of limits with an experienced 17-member sensory panel. The mean BET for aroma detection of guaiacol in water and apple juice was 0.48 ppb and 0.91 ppb, respectively. The mean BET for taste detection of guaiacol in water and apple juice was 0.17 ppb and 0.24 ppb, respectively. Individual aroma BET values ranged from 0.06 ppb to 4.71 ppb guaiacol in water and 0.17 ppb to 4.71 ppb for guaiacol in apple juice. Individual taste BET values ranged from 0.01 ppb to 4.71 ppb for guaiacol in water and apple juice. The taste BET was equal to or lower than the aroma BET for guaiacol in both water and apple juice for all panelists. There was about a 500-fold range in guaiacol taste detection between panelists, with some individuals exhibiting a BET value as low as 10 ppt (trillion). The information should be useful for developing quality assurance sensory methodology to evaluate potential apple juice flavor spoilage by Alicyclobacillus spp.