Abstract:【Objective】Sweet cherry is a large fruit, colorful, delicious, nutritious and popular among consumers, and the cultivation of sweet cherry in Qinghai Province started in 1994, and began to plant on a large scale after 2000, with a cultivated area of about 32,600 mu, which is a characteristic fruit industry developed in Qinghai Province in recent years. And sweet cherry flavor plays a very important role in the consumer's preference, with the maturity of the fruit, the fruit body will occur extremely complex physiological and biochemical metabolic processes, and the volatile aroma compounds in the fruit also change. Therefore, the developmental period is a key factor affecting the production and accumulation of fruit aroma. To identify the aroma compounds in different varieties of sweet cherry fruits from the Qinghai province in China and to investigate the changes of these compounds during the fruit developmental stages.【Methods】Fruits from six sweet cherry varieties, Moreau, Qingying No.1, Celeste, 2018-20, Sweetheart, and Rainier, were used as experimental materials. Aroma compounds were analyzed with headspace solid-phase microextraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS) at four developmental stages, hardening stage (HS), veraison stage (VE), commercial maturity period (CMP), and full ripening period (RP, respectively). The variations in aroma compounds among these six varieties were compared using Venn diagrams, heatmap clustering analysis, and principal component analysis (PCA). Partial least squares discriminant analysis (PLS-DA) was applied to screen for differential aroma compounds and to analyze changes in their concentrations during different developmental stages.【Results】A total of 108 aroma compounds were identified across the four developmental stages in the six sweet cherry varieties, with 14 common aroma compounds. Specifically, 69, 46, 45, and 32 aroma compounds were detected in the HS, VE, CMP, and RP stage, respectively. During cherry fruit development, the Moreau variety showed a trend where aroma compound concentrations first increased and then decreased. The Qingying No.1 and Sweetheart varietes displayed an increase, followed by a decrease and then another increase. The 2018-20 variety exhibited a gradual decrease, reaching the lowest concentration in the RP stage. In contrast, the Celeste and Rainier varieties showed fluctuations, peaking at the RP stage.PLS-DA identified differential compounds with (Variable Importance in Projection）(VIP) values greater than 1, including 2-Hexenal (E), 2-Hexenal, Hexanal, and 2-Hexen-1-ol (E),Across different developmental stages of six cherry varieties, 2-Hexenal showed a trend of increasing concentrations from low to high, while 2-Hexenal (E) and 2-Hexen-1-ol (E) displayed a "W-shaped" trend. The concentration of Hexanal generally increased, then decreased, and increased again.The results showed that the six sweet cherry varieties were dominated by aldehydes from the HS phase to the PR phase; the contents of Moreau aroma substances showed a general tendency of increasing and then decreasing with the development of sweet cherries, among which aldehydes and olefins were the highest in the HS phase, which was obviously higher than that of other varieties, and then showed a decreasing tendency, and the lowest contents were found in the RP phase. The content of alcohols showed a trend of increasing and then decreasing. Alkane content was the highest in the HS period, slightly decreased in the VE period, increased in the CMP period, and decreased to the lowest in the RP period; 2018-13 varieties roughly showed a trend of first increasing and then decreasing 2018-20 varieties of RP content showed a gradual decline to the lowest trend, in which aldehydes showed a first increase and then a decline to the lowest RP content, alkanes showed a first increase and then a decline to the lowest RP content, alkanes showed a first increase and then a decline to the lowest RP content, and enols showed a first increase and then a decline to the lowest RP content. The RP content of Sweetheart varieties showed a general trend of increasing and then decreasing to the lowest, with aldehydes and alcohols showing the highest content in the VE period, then decreasing and increasing in the RP period; olefins showing the highest content in the HS period, then decreasing; and alkanes showing an increasing, then decreasing, then increasing RP content. Aldehydes content was highest during the HS period and then decreased slightly; alcohols content decreased and then increased to the peak in the RP period; olefins content was highest during the HS period; alkanes content increased and then decreased and then increased to the peak in the RP period. By partial least squares discriminant analysis, the substances with VIP values greater than 1 were screened out, and 2-hexenal (E)-(trans-2-hexenal), 2-hexenal (2-hexenal), hexanal (hexanal) and 2-hexen-1-ol (E)-(trans-2-hexen-1-ol) were identified as the main differential aroma substances, with 2-hexenal (E)-content being higher, accounting for 63.32% of the total aroma content. 63.32% of the total aroma content. The contents of the aroma substances varied in different developmental periods of the six varieties.【Conclusion】The six sweet cherry varieties exhibited distinct patterns in aroma compound changes during fruit development. The most important key aroma compounds identified were 2-Hexenal (E), 2-Hexenal, Hexanal, and 2-Hexen-1-ol (E). These findings provide a theoretical foundation for the genetics and breeding of aroma in sweet cherry, as well as for research on aroma synthesis metabolism and molecular biology.
PDF （）