Identification and formation of key aroma-active compounds in red jujube as affected by different processing methods

Processing methods significantly affect the aroma characteristics of red jujube; however, few studies have explored how. Gas chromatography-tandem mass spectrometric detection, gas chromatography-olfactometry, relative odor activity value and quantitative descriptive analysis were used to investigate the aroma changes of red jujube during typical processing (freeze drying, baking, frying and steaming); furthermore, the formation of aroma-active compounds in processed red jujube was predicted based on untargeted metabolomics. After freeze drying, the total aroma content increased by 0.90 %, while it decreased by 51.59 %, 74.11 % and 78.74 % after baking, frying and steaming, respectively. In addition, ethyl esters dominated the sweet and fruity notes in freeze-dried red jujube, which were formed via combination of fatty acids metabolism, pyruvate metabolism and amino acid catabolism. (E,E)-2,4-Decadienal derived from fatty acid oxidation dominated the fatty note in fried red jujube. 2-Ethyl-3,5-dimethylpyrazine formed via the Maillard reaction dominated the roasty notes of baked red jujube.