Cultivar-specific divergence in volatile aroma profiles of heat-stressed grapes uncovered via GC×GC-TOFMS

To investigate the differential responses of table grape cultivars with varying heat tolerance to heat stress, this study used the heat-tolerant cultivar 'Shenyue', the heat-sensitive cultivar 'Jumeigui', and the intermediate cultivar 'Kyoho' as experimental materials. HS-SPME/GC × GC-TOFMS was employed to analyze the effects of heat stress on basic physicochemical properties and volatile organic compounds (VOCs) in grape berries at different developmental stages. The results indicated that the impact of heat stress on the physicochemical characteristics and volatile profiles of grape berries was both cultivar-specific and developmental stage-dependent. At the VOC metabolism level, the three cultivars exhibited three distinct response patterns: 'Shenyue' showed a "delayed enhancement", 'Jumeigui' displayed "over-activation", and 'Kyoho' demonstrated "metabolic suppression". Furthermore, key heat-stress indicator VOCs were identified for each cultivar. Aroma fingerprint analysis further revealed that heat stress significantly reconfigured the sensory aroma profile of grape berries, with the extent of impact also being cultivar-specific and developmental stage-dependent.