International Journal of Horticulture, 2025, Vol.15, No.1, 8-20 http://hortherbpublisher.com/index.php/ijh 14 5.3 Post-harvest handling and its impact on metabolism Post-harvest handling, particularly storage conditions, plays a vital role in maintaining the metabolic stability of sugars and organic acids in pitaya. Storage temperature and humidity levels can affect the rate of metabolic reactions, leading to changes in the sugar and acid content of the fruit. Proper storage conditions are essential to preserve the flavor and nutritional quality of pitaya (Wu et al., 2019). During ripening and storage, significant changes occur in the sugar and acid content of pitaya fruits. The levels of glucose, fructose, and sucrose increase as the fruit matures, while the content of organic acids such as malic and citric acids may decrease. These changes are regulated by the expression of specific genes involved in sugar and acid metabolism. For instance, the expression of HpINV2 and HpSuSy1 increases during fruit maturation, correlating with the elevated accumulation of glucose and fructose (Wei et al., 2019). Understanding these changes is crucial for optimizing post-harvest handling practices to ensure the best possible flavor and nutritional quality of pitaya fruits. 6 Impact on Nutritional Quality 6.1 Contribution of sugars to nutritional value Sugars are a primary source of energy in pitaya, contributing significantly to its caloric content. The predominant sugars in pitaya are glucose and fructose, with sucrose also present in some species (Constantino et al., 2021; Mou et al., 2022; Xie et al., 2022). For instance, Hylocereus undatus contains approximately 9.83% total sugars, distributed as 4.75% glucose and 5.08% fructose, while Hylocereus megalanthus has 5.93% total sugars, including 0.99% glucose, 3.25% fructose, and 1.69% sucrose (Constantino et al., 2021). These natural sugars provide essential energy, making pitaya a valuable fruit for quick energy replenishment. The sugar composition significantly impacts the flavor and palatability of pitaya. The sweetness of the fruit, primarily due to glucose and fructose, is a crucial determinant of consumer preference (Wei et al., 2019; Jiang et al., 2023). The balance of these sugars enhances the overall taste, making pitaya a desirable fruit for fresh consumption and in processed forms such as beverages and desserts (Constantino et al., 2021). The presence of sucrose in Hylocereus megalanthus, for example, contributes to its perceived sweetness, despite its lower total sugar content, making it suitable for carbohydrate-restricted diets while still being sensorially appealing. 6.2 Nutritional significance of organic acids Organic acids in pitaya, such as malic and citric acids, play a vital role in digestion and overall health. These acids can enhance digestive processes by stimulating the production of digestive enzymes and improving nutrient absorption (Constantino et al., 2021; Xie et al., 2022). Additionally, organic acids can help maintain the pH balance in the stomach, promoting a healthy digestive tract. Organic acids also exhibit antioxidant properties, contributing to metabolic health. For instance, malic acid and citric acid found in pitaya have been shown to possess antioxidant activities, which can help neutralize free radicals and reduce oxidative stress (Li et al., 2018; Constantino et al., 2021). This antioxidant capacity is crucial for preventing chronic diseases and supporting overall metabolic functions. 6.3 Effect on consumer health and preferences The nutritional profile of pitaya, rich in natural sugars and organic acids, influences health-related consumer choices. Consumers seeking natural energy sources and digestive health benefits may prefer pitaya due to its balanced sugar content and the presence of beneficial organic acids. Moreover, the antioxidant properties of these components make pitaya an attractive option for health-conscious individuals (Li et al., 2018; Constantino et al., 2021). The balance of sugars and organic acids in pitaya significantly affects its taste and marketability. A higher sugar content enhances sweetness, while the presence of organic acids adds a refreshing tartness, creating a complex flavor profile that appeals to a wide range of consumers (Constantino et al., 2021; Xie et al., 2022; Jiang et al., 2023). This balance not only improves the sensory attributes of the fruit but also increases its market value,
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