Effects of pretreatment methods on the flavor profile and sensory characteristics of Kiwi wine based on 1H NMR, GC-IMS and E-tongue

The pretreatment method of fruit before fermentation is a crucial step in fruit wine production, exerting a considerable influence on its overall quality, particularly on sensory characteristics and flavor profile. In this study, Pujiang kiwifruits as raw material, four pretreatment methods were employed in kiwi wine (KW) production, namely kiwi fruit crushing with peel (KCP), crushing without peel (KCW), kiwi fruit squeezing juice with peel (KJP), and squeezing juice without peel (KJW). The sensory characteristics and flavor profile of KW were evaluated using sensory evaluation, E-tongue, GC-IMS, and 1H NMR. KW produced through KCP method achieved the highest sensory evaluation score, compared to the others. E-tongue could effectively differentiate the taste features among KW produced by different pretreatment methods. A total of 137 compounds were characterized by the combination of GC-IMS and 1H NMR. Moreover, among the molecules quantified by GC-IMS and 1H NMR, the concentrations of 52 and 58 compounds, respectively, exhibited significant differences among the four groups, primarily comprising esters, organic acids and alcohols. Furthermore, enrichment analysis indicated that several metabolic pathways could be altered by different pretreatment methods. This study serves as a theoretical reference and application basis for the quality improvement of KW and offers insights on the reduction and utilization of winemaking by-products.