Abstract:

2-Methylvaleric acid, 3-methylvaleric acid and 4-methylvaleric acid are three isomers of methylvaleric acids and all of them can be used in food. Their aroma intensities are different. In this work, the aroma thresholds of the three methylvaleric acids were evaluated by 3-AFC test to be 63.49, 0.886 mg/kg and 0.713 mg/kg, respectively. Meanwhile, their aroma intensities were also compared with the determined values by electronic nose. Results showed that the aroma intensities of the three flavor compounds from strong to weak were 4-methylvaleric acid, 3-methylvaleric acid and 2-methylvaleric acid at identical concentrations of 10, 100 mg/kg and 1000 mg/kg. The determined results by both methods were consistent. Therefore, the position of the methyl group exhibited an obvious effect on aroma intensity of methylvaleric acids and the aroma intensity was increased with the increase of distance between the methyl group and the carboxyl group.

Key words: methylvaleric acid, aroma intensity, threshold, three alternative forced-choice test (3-AFC test), best estimated threshold