Comparison of fresh watermelon juice aroma characteristics of five varieties based on gas chromatography-olfactometry-mass spectrometry

Qualitative and quantitative analysis and odor active value (OAV) calculation were applied to identify the aroma-active compounds of fresh watermelon juice in five varieties: Seedless, Jingxin, Lianfa, Qilin, and Texiaofeng. Principal component analysis and cluster analysis were selected to compare the similarity and difference among watermelons juices. Fifty-five volatiles were identified in watermelon juice in five varieties, among which 6 volatiles were identified for the first time in watermelon. (Z)-6-nonenal, (E, Z)-2,6-nonadienal, (E)-2-nonenal, and (E, E)-2,4-nonadienal contributed greater to aroma profiles than alcohols due to lower threshold through odor active values. It was indicated by principal component analysis and cluster analysis that watermelon juices were separated into three groups, Jingxin, Lianfa-Texiaofeng, and Seedless-Qilin, whose characteristic volatiles were aldehydes, alcohols, and ketones respectively. The average distance between JX and the other varieties was higher than that of others through cluster analysis, indicating that the aroma of Jingxin differed from that of the other four varieties greatly.