Characterization of Ester Odorants of Apple Juice by Gas Chromatography-olfactometry, Quantitative Measurements, Odour Threshold, Aroma Intensity and Electronic Nose

In this study, twenty ester compounds of juiced apples from three different varieties were identified and quantified by gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS) analysis. Six esters were selected as the key odour-active compounds by omission Tests. Perceptual interaction among esters was investigated through odour thresholds and intensity of six esters and fifteen binary mixtures. Most of these mixtures followed an addition behavior. Ethyl butanoate and butyl acetate had a synergistic effect. Sensory analysis revealed that fruity, sour and green notes were enhanced significantly by adding the binary mixture of ethyl butanoate and butyl acetate (E&B). Electronic nose (e-nose) data showed that, compared with the individual ester, the response values of E&B were increased on four sensors. Moreover, with regard to partial least squares regression (PLSR), fruity, sour and green notes attribute covaried well with five sensors of e-nose. The present study would provide a theoretical basis for understanding the aroma characteristic of apple juice, hoping to be helpful for the improvement of apple juice aroma and flavour.