Abstract: The characteristic aroma-active compounds of seven samples of red jujube slices during hot air drying were detected and characterized by headspace solid phase microextraction-gas chromatography-olfactometry-mass spectrometry (HS-SPME-GC-O-MS) combined with sensory analysis and partial least squares regression (PLSR) analysis. The results revealed that the major volatile components in dried jujube slices were esters (19), ketones (15), acids (15), aldehydes (12), alcohols (9), hydrocarbons (6) and furan compounds (2). A total of 18 aroma compounds (with odor activity value, OAV > 1) were identified, including esters (3), alcohols (1), acids (2), aldehydes (4), ketones (7) and furan compound (1). Sensory evaluation revealed that the major aroma characteristics of dried jujube slices were caramel-like, roasted, sweet, bitter and burnt. A positive correlation between sensory attributes and aroma-active compounds were clearly elaborated by PLSR. The PLSR results indicated that 2,3-butanedione and 3-hydroxy-2-oxobutane were significantly and positively correlated with the roasted sweet attribute, while γ-butyrolactone, 4-cyclopentene-1,3-dione and 2,5-dimethyl-4-hydroxy-3(2H)-furanone had a significantly positive impact on the caramel-like attribute. 5-Methyl furfural and 5-methyl-2(5H)-furanone were positively correlated with the bitter attribute. 5-Hydroxymethylfurfural was the most powerful odor-active compound that contributed to the burnt flavor. 3-Hydroxy-2-methyl-4H-pyran-4-one, 4H-pyran-4-one and 2,3-dihydro-3,5-dihydroxy-6-methyl were the major sources of the burnt and bitter flavor. These results were verified by the flavor obtained from sensory evaluation with gas chromatography olfactometry.

Key words: dried jujube slices; odor activity value; headspace solid phase microextraction-gas chromatography-olfactometry-mass spectrometry; partial least squares regression