## 3 Results and Discussion
### VOC Analysis of Strawberry Juice and Wines
#### 3.5.3 Hierarchical Cluster Analysis of Differential VOCs in Strawberry Juice and Wines  
As shown in Figure 6, the cluster heatmap analysis based on differential VOCs in strawberry juice and wine samples implied that the differences between the strawberry juice of cultivar BX and the strawberry wine of ZJ and other samples are relatively obvious.  
Figure 5: Coordinate analysis and variable importance in the projection (VIP) analysis of VOCs in strawberry juice and wines of different cultivars. (**A**) PCA; (**B**) OPLS-DA; (**C**) VIP value. BX: Snow White; TCL: Sweet Charlie; TZ: Tongzhougongzhu; ZJ: Akihime. Juice (m) samples, BXm: Snow White; TCLm: Sweet Charlie; TZm: Tongzhougongzhu; ZJm: Akhimine.  
In the strawberry juice of cultivar BX, the contents of \(\alpha\)-terpineol, linalool, \(\alpha\)-bisabolol, 2-methyl-butanoic acid, and hexanoic acid were relatively higher; these VOCs endow the strawberry juice of cultivar BX with fruity, sweet, floral, and other aromas. On the other hand, the contents of phenylethyl alcohol, octanoic acid, 3-methyl-1-butanol acetate, and geranyl vinyl ether in the strawberry wine of cultivar ZJ, which give the wine cheesy, floral, flowery, and other aromas, were relatively higher.  
Unlike wine, studies on the correlation between cultivar, origin, and fruit wine quality are still limited, especially research on the fermentation characteristics of different strawberry cultivars [13; 39]. Current research mainly focuses on the influence of environmental factors and maturity stages on the composition and antioxidant activity of strawberry fruits of different cultivars [40; 41; 42], and the identification of cultivars and their impact on fruit quality [43]. According to the above research, it was found that among the four popular strawberry cultivars, the strawberry juice of cultivar BX was rich in terpen and more suitable for fresh consumption. And the strawberry wine of cultivar ZJ had a relatively high content of VOCs, indicating that ZJ may be a suitable cultivar for strawberry wine brewing. Considering the large scale of strawberry cultivation in China, this study not only provides processing solutions for surplus strawberry fruits, but also helps to select strawberry varieties for planting, and there is no doubt that strawberry fruit wine has the strength to win a place in the booming fruit wine market [44]. In addition, only 42 volatile compounds were found in strawberry juice and wine samples in this study, and diverse research methods could be used to explore the aroma of strawberry wine. The comprehensive evaluation system combining GC-MS, electronic nose, electronic tongue, and sensory evaluation is a valid program to evaluate the flavor quality of strawberry wine, and the sensory evaluation based on consumer preferences is an indispensable support for strawberry wine to enter the market [45]. Considering the diversity of factors affecting the quality of fruit wine,  
Figure 6: Cluster heatmap analysis based on differential VOCs in strawberry juice and wine samples. Wine samples, BX: Snow White; TCL: Sweet Charlie; TZ: Tongzhougongzhu; ZJ: Akihime. Juice (m) samples, BXm: Snow White; TCLm: Sweet Charlie; TZm: Tongzhougongzhu; ZJm: Akihime.  
especially the reciprocal selection between the physicochemical properties of raw materials and fermentation strains [46], further studies will be conducted to reveal the effects of more cultivars, origin, vintage, yeast strains, and fermentation protocol on the quality of strawberry wine to provide more detailed data support for the production of strawberry fruit wine.