# Enhancing the Content of Hesperidin and Nobiletin in Citrus Wines through Multi-Strain Fermentation
## 3 Results
### Physicochemical Properties and Antioxidant Activity of Nanfeng Tangerine Wine
The expression of these enzymes varies among different multi-strain combinations, leading to varying levels of hesperidin and hesperidin in the final product. Fermentation of alcohol has the potential to enhance the levels of beneficial active substances in citrus-based wine. Further PCA analysis of flavonoid compounds revealed that different fermentation processes produce unique concentrations of flavonoid compounds, presenting different functional characteristics in citrus wine (Figure 2C). The change in phenolic profile is the result of using different fermentation methods. This confirms that citrus wine's flavonoid content can be increased through different microbes or fermentation methods, contributing to improved wine quality. The overall amount of polyphenols in wines made using multi-strain combination fermentation techniques was notably less than in wines produced through Hg-10-Sc sequential fermentation. Among these methods, the Sc:(Ce.Hg)-1:100 fermentation resulted in the lowest total polyphenol content in Nandfeng tangerine wine (Figure 2A, Table 4). Seven phenolic acids were identified, including protocatechuic acid, p-hydroxybenzoic acid, chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid, and sinapic acid, with chlorogenic and caffeic acids being the most prevalent. Chlorogenic acid content significantly increased in multi-strain fermentation combinations, excluding pure culture fermentation with Sc. Studies have shown that chlorogenic acid (CGA) exhibits beneficial protective effects on liver diseases related to human signaling pathways [26; 27; 28]. The multi-strain combination of fermented wines (Figure 2D) contained eight different organic acids: oxalic acid, malic acid, vitamin C, lactic acid, acetic acid, citric acid, succinic acid, and fumaric acid. Table 5 demonstrates that the overall amount of organic acid in Sc(Ce.Hg)-1:100 was notably less compared to the other fermentation groups, primarily because of its reduced lactic acid output. The citric acid content in wines from the 1:1 and 1:100 multi-strain combination fermentation methods was up to 3000 mg/L lower compared to the juice, and the reduction of citric acid can decrease the tartness of the wine. There was no production of acetic acid in the multi-strain combination fermentation methods. Notably, except for Sc:(Ce.Hg)-1:100, the lactic acid content in the 1:1 and 1:100 multi-strain combination fermentation methods was significantly higher than in all other fermentation groups in this study, with no significant change in malic acid content. This may be due to a more favorable environment for malolactic fermentation, suggesting that the 1:1 and 1:100 multi-strain combination fermentation methods promote malolactic fermentation, thereby improving the smoothness of Nanfeng tangerine wine. The succinic acid content significantly increased in the multi-strain combination fermented wines, which is beneficial for antibacterial and detoxification effects and enhancing human immune function. The multi-strain combination fermentation methods can exploit the advantages of non-_Saccharomyces_ yeast in producing secondary metabolites, which are beneficial for increasing the content of beneficial components in the wine and improving wine quality by reducing undesirable substances. Figure 2: The content of polyphenols (phenolic acid and flavonoids) and organic acids in Nanfeng tangerine juice and Nanfeng tangerine wines. (**A**) is the content of total polyphenols; (**B**) is the content of phenolic acid. (**C**) is the content of flavonoids, and (**D**) is the content of organic acids detected by HPLC. Data shown are the mean \(\pm\) SD of triplicate, values with different Roman letters in the same row indicating significant differences at \(p<0.05\) (Duncan’s test).