## 3 Results and Discussion  
### Changes of Active Components of R. roxburghii Fruit at Different Stages of Maturity  
Figure 1A presented images of _R. roxburghii_ fruit at different stages of maturity, denoted by I, II, III, IV, and V corresponding to 45, 65, 75, 90, and 105 days after antibess, respectively. Figure 1B depicted the variations in active compounds of _R. roxburghii_ fruit across different maturity stages. During maturation, there was a significant increase (\(p<0.05\)) in TA, Vc, and SS levels, while TF, SOD, and ST concentrations significantly decreased (\(p<0.05\)). The levels of TP showed fluctuations with the progress of maturity. The acidity and palatability of _R. roxburghii_ fruit during the ripening process could be understood by analyzing the variation in total acidity (TA), which was the main index for evaluating the sourness of _R. roxburghii_[11]. As illustrated in Figure 1B, the TA content of _R. roxburghii_ fruit significantly increased (\(p<0.05\)) from stage I (214.19 mg/100 g) to stage V (850.05 mg/100 g) as it matured. Notably, there were rapid enhancements at stages III and V, with TA levels almost doubling compared to the preceding stages II and IV, respectively. Vitamin C (Vc), the main active substance in _R. roxburghii_ fruit, played a crucial role in generating antioxidant properties of _R. roxburghii_[26]. The concentration of Vc in _R. roxburghii_ fruit significantly increased (\(p<0.05\)) from stage I (535.42 mg/100 g) to stage V (3144.72 mg/100 g) as it matured (Figure 1B), consistent with findings from [PERSON] et al. [26]. During the maturation process of _R. roxburghii_ fruit, as the cells of the fruit expanded, L-ascorbic acid (AsA), also known as Vc, was rapidly accumulated in the cytoplasm primarily through the ascorbate-glutathione cycle. Furthermore, dehydroosaccharide reductase (DHAR) played a crucial role in the regeneration of AsA in the fruit and in the regulation of AsA levels within the ascorbate-glutathione cycle [27]. Vc content showed a slow increase in the initial two stages I (535.42 mg/100 g) and II (828.84 mg/100 g) due to the presence of ascorbate peroxidase (APX) and ascorbic acid oxidase (AAO), both known to be negatively correlated with Vc accumulation in plant cells [28; 29]. Additionally, [PERSON] [30] noted that these two enzymes were only detectable in the early stages of fruit ripening (around 65 days after antibess), becoming almost undetectable after around 70 days. This explained the rapid increase in Vc content from stage III (1459.94 mg/100 g) onwards, which was also demonstrated by [PERSON], [PERSON], and [PERSON] [27]. Soluble sugars (SSs) are the primary compounds responsible for the sweetness in fruits and are key quality indicators in assessing fruits and vegetables [31]. The SS content in _R. roxburgh_ fruituits significantly increased (_p_ < 0.05) from stage I (819.67 mg/100 g) to stage V (4648.45 mg/100 g) as they matured. During the ripening process of _R. roxburgh_ fruitus, complex macromolecular carbohydrates are broken down into smaller soluble carbohydrates, leading to a gradual rise in SS content. Notably, there was a rapid increase in SS content at stage II (2658.29 mg/100 g), where it was more than three times that of stage I (819.67 mg/100 g). Subsequently, the SS content continued to steadily increase from stage II onwards, eventually reaching the highest value of 4648.45 mg/100 g at stage V.  
SOD, which is a common endogenous and antioxidant enzyme in fruits, has a great impact on the texture, flavor and color of fruits [32; 33]. In contrast to the accumulation of TA, Vc, and SS, the content of SOD showed a slowly significant decrease (_p_ < 0.05) from stage I (1918.30 U/g) to stage V (1080.86 U/g) during the ripening process of _R. roxburgh_ fruit. The ripening process of _R. roxburgh_ fruit involves an oxidative phenomenon that leads to the accumulation of reactive oxygen species (ROS) such as superoxide radical, hydrogen peroxide, and hydroxyl radical [34].