## 2 Results and Discussion  
### Sensory and Chemical Profiles of Monovarietal Wines  
The blending experiment design was based on different aroma characteristics of four monovarietal wines. According to sensory results in Figure 1a, CF wines (Cabernet Franc) exhibited high intensity of 'green pepper' and 'herbaceous'. CS wines (Cabernet Sauvignon) also had relatively high intensity of 'green pepper', while having the lowest intensity of 'herbaceous'. In MA wines (Marselan), the note of 'baked sweet potato' was identified as a combined description of 'caramel', 'fragrance','sweet', and 'light toasted flavor' by panelists, which might be accordant to 'honey' and 'caramel' descriptions obtained in MA wines in a previous study [17]. As for PV wines (Petit Verdot), the intensity of 'green pepper' was much lower than the other three monovarietal wines and the note of 'tropical fruity' had higher intensity, especially when compared to CF wines. The difference of intensities in 'berry' and 'floral' between four monovarietal wines was slight. Aroma characteristic is regarded to be determined by volatile composition in wines. A total of 91 volatile compounds were detected in wines in this study, which were specifically divided into 7 C6/C9 alcohols, 17 other alcohols, 6 acetates, 18 ethyl esters, 17 other esters, 6 aliphatic acids, 8 isoprenoids, 9 other compounds, and 3 MPs. Detailed information and compound numbers are shown in Table S1. A radar map of the total concentration of compounds in each category of wine aroma was conducted (Figure 1b). CF wines exhibited lower concentration level of C6/C9 alcohols and acetates, especially comparing to PV wines. In addition to C6/C9 alcohols and acetates, the concentration of other alcohols was highest in PV wines, while the level of ethyl esters and MPs was lowest. Isoamyl acetate (banana and sweet notes) and phenethyl acetate (rose, honey, and fruity notes) are regarded as important acetates in wines [6; 18], which could contribute to high intensity of 'tropical fruity' in PV wines. On the contrary, MA wines had the lowest concentration of acetates and higher level of isoprenoids and ethyl esters. As for CS wines, the main trait was that C6/C9 alcohols, MPs, ethyl esters and acetates all remained at relatively high levels, representing a more abundant volatile profile. The distinction in the sensory score of 'green pepper' in monovarietal wines (Figure 1a) was consistent with the difference of MPs (Figure 1b). The high levels of MPs could be the reason for the highest score in 'green pepper' and 'herbaceous' in CF wines. Among three MPs detected in this work, IBMP concentration was higher, compared to IPMP and SBMP (Table S1), and it is regarded as the most important compound contributing to the notes of 'green bell pepper', 'leafy', and 'herbaceous' [19]. As a result of the sensory characteristics and high concentration of MPs, CF wines were regarded as base wines, and the other three monovarietal wines were treated as counterpart wines to participate in binary blending. Since a difference in volatiles such as C6/C9 alcohols, acetates, and ethyl esters existed among CS, MA, and PV wines, the influence of these volatiles on modifying the sensory expression of MPs was further investigated through the experiments of blending. Impact of Blending Types and Proportions on Chemical and Sensory Profiles of Blending Wines Volatile chemical and sensory profiles in monovarietal CF wines and three binary blending wines (CS, MA, and PV wines) with two proportions were analyzed at three-month intervals during six-month bottle aging. The binary blending samples are denominated as CFC, CFM, and CFP. The abbreviation of '82' refers to CF base wines blended in proportion of 80% with the other wines blended in a proportion of 20%, while '64' refers to CF base wines blended in proportion of 60% with the other wines blended in proportion of 40%.