A multi-analytical approach for flavor deterioration assessment of coconut water using quantitative descriptive analysis, E-nose, GC-IMS, and GC × GC-TOF-MS

Quality deterioration of coconut water often leads to a significant change in flavor. This study intends to reveal the mechanism of flavor deterioration of coconut water under different storage temperatures in depth by combining various analytical methods including quantitative descriptive analysis (QDA), E-nose, GC-IMS and GC × GC-TOF-MS. The results showed that sweetness, sourness and umami of coconut water changed most significantly during the storage. The analysis of volatile compounds showed that the combination of GC × GC-TOF-MS and GC-IMS can provide a more comprehensive result of flavor changes during the storage of coconut water, and the results revealed that esters, aldehydes, and ketones changed significantly during the storage of coconut water. (E, E)-2,4-Heptadienal was screened as a differential volatile compound in coconut water during the storage, which is a degradation product of linoleic acid and linolenic acid. The results of relative odor activity value (ROAV) analysis indicated that the flavor changes in coconut water were mainly related to aldehydes and ketones. 2-Undecanone and (E)-2-nonenal were the volatile compounds that contributed significantly to the flavor deterioration of coconut water at both storage temperatures, and (E)-2-nonenal is a secondary degradation substance produced by the oxidation of linoleic acid. In summary, it can be found that the flavor deterioration of coconut water is mainly related to lipid oxidation, which clarifies the critical role of lipid oxidation in flavor changes and provides a new direction for the subsequent study of flavor changes in plant-based beverages.