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. ()-2,4-Decadienal derived from fatty acid oxidation dominated the fatty note in fried red jujube. 2-Ethyl-3,5-dimethylpyrazine formed the Maillard reaction dominated the roasty notes of baked red jujube.