Detection of medicinal off-flavor in apple juice with artificial sensing system and comparison with test panel evaluation and GC–MS

Guaiacol, a potent volatile compound, has proven to be responsible for the distinct medicinal off-flavor in spoiled apple juice produced by Alicyclobacillus acidoterrestris. In this study, the artificial sensing system electronic nose (e-nose) was employed to detect this off-flavor compound in apple juice, using GC–MS and test panel evaluation as reference, as well as water as a comparative medium. Principle component analysis and linear discriminant analysis were employed to evaluate the capacity of e-nose for guaiacol detection in both media. A loadings analysis was used to examine the sensorsʹ chemometric discrimination. Multiple regression analysis was applied to investigate the potential relationship between the concentration of guaiacol and the e-nose response. The detection limit based on e-nose for guaiacol in apple juice was 0.25–0.5 mg/L. For comparison, a 12-member test panel evaluation found an aroma detection threshold of 1.50 mg/L in apple juice, and the GC–MS detection limit for guaiacol in apple juice was determined to be 0.4 μg/L. In summary, the e-nose was capable of detecting guaiacol in apple juice, with significantly higher sensitivity than the test panel evaluation. This information should be useful for developing instrumental sensory detection techniques for rapid scanning of potential medicinal off-flavor in Alicyclobacillus-spoiled apple juice prior to consumer perception.