Bioscience Evidence 2026, Vol.16, No.4, 291-303 http://bioscipublisher.com/index.php/be 293 antioxidant capacity was not controlled by a single compound but resulted from coordinated changes among anthocyanins, flavonols, flavonoids, and flavanols. 2.3 Flavonoids, vitamin C and nutritional quality In addition to anthocyanins, blueberry fruit contains abundant flavonols, flavanols, and other non-anthocyanin phenolic compounds, which together form an important nutritional foundation of blueberry fruit. The accumulation patterns of different flavonoid compounds are not completely consistent during fruit development. Flavonols and flavanols are generally higher at the immature stage, followed by continuous transformation and redistribution as fruit ripens. Günther et al. (2020) analyzed metabolic changes during different developmental stages of northern highbush and rabbiteye blueberries and found that flavonoid metabolites were mainly accumulated in the skin tissue and showed clear spatial and temporal variation during ripening. The fruit skin maintained high levels of flavonoids and anthocyanins throughout maturation, whereas the corresponding metabolites in the pulp were much lower, which partly explains the stronger antioxidant capacity of blueberry skin. Flavonoids contribute not only to antioxidant capacity but also to fruit flavor formation and quality differences among cultivars. Even when different cultivars have similar total flavonoid contents, their specific flavonoid compositions may vary considerably, resulting in differences in antioxidant activity and sensory characteristics. Li et al. (2023) used combined metabolomic and transcriptomic analyses to investigate flavonoid metabolism during fruit ripening among different blueberry cultivars. The results showed significant differences in flavonoid metabolic pathways among cultivars, and some flavonol compounds were closely associated with fruit coloration and ripening regulation. Therefore, blueberry nutritional quality should not be evaluated only based on total flavonoid or total anthocyanin content, but should also consider the combined effects of different flavonoid components. Although vitamin C content in blueberry is generally lower than that of anthocyanins and other phenolic compounds, it remains an important indicator of fruit nutritional quality. Vitamin C contributes to antioxidant activity and works together with phenolic compounds to maintain the stability of the fruit antioxidant system. Significant differences in vitamin C content exist among cultivars and developmental stages, and its accumulation pattern is jointly regulated by genetic background and environmental conditions. Therefore, vitamin C, together with flavonoids and phenolic compounds, should be considered as an important component of comprehensive blueberry quality evaluation. 3 Environmental Factors Affecting Bioactive Compound Accumulation in Blueberry Fruit 3.1 Variety and genetic background Genetic background is one of the most stable and important factors determining bioactive compound accumulation in blueberry fruit and provides the basis for fruit quality formation. Compared with environmental factors such as light, temperature, and water availability, genotype determines the potential accumulation capacity of anthocyanins, phenolics, flavonoids, and vitamin C, while environmental conditions and cultivation practices mainly regulate the expression of this genetic potential. Even under the same ecological conditions and management practices, significant differences in nutritional quality can still be observed among blueberry cultivars. Therefore, appropriate cultivar selection has become the first step in high-quality blueberry production. Liu et al. (2025) evaluated 26 highbush blueberry cultivars (Vaccinium corymbosum L.) grown in the same orchard in Shandong Province under uniform management conditions and compared their fruit quality and bioactive compound profiles. The results showed significant differences among cultivars in soluble solids content, titratable acidity, vitamin C content, anthocyanin composition, and antioxidant capacity. Among them, ‘Sunrise’, ‘Bluegold’, ‘Elliott’, ‘Amblue’, and ‘Briteblue’ showed better overall performance, with higher sugar accumulation, stronger antioxidant activity, and richer anthocyanin profiles. In contrast, some cultivars with relatively high yield did not necessarily have higher functional compound levels. These findings indicate that fruit quality is not determined only by cultivation management but is also strongly controlled by cultivar genetic characteristics, and different cultivars have different potentials for quality formation (Liu et al., 2025).
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