International Journal of Horticulture, 2025, Vol.15, No.1, 8-20 http://hortherbpublisher.com/index.php/ijh 18 8.3 Post-ripening and storage techniques Post-ripening and storage techniques significantly influence the sugar and organic acid content of pitaya, affecting its flavor and nutritional quality. Proper postharvest treatment and storage conditions can help maintain or even enhance these attributes. For instance, the use of controlled atmosphere storage and temperature management can prevent the degradation of sugars and organic acids, thereby preserving the fruit's taste and nutritional value (Li et al., 2018). The application of plant oil-based coatings (Sta-Fresh®) and carnauba wax coatings (Endura-Fresh™) has been shown to effectively reduce water loss and skin wrinkling in pitaya, extending its shelf life to 15 days. These treatments help maintain the appearance, texture, and nutritional attributes of pitaya, such as soluble solids and acidity, under low-temperature conditions (7 °C, 85% relative humidity) (Razali et al., 2021). Additionally, treatments with compounds like p-Anisaldehyde significantly reduce fruit senescence and preserve higher antioxidant enzyme activity (Xu et al., 2021). Blue light treatment can markedly slow the reduction in respiration rate and acidity in pitaya, while increasing the levels of certain organic acids and soluble sugars. Gaining deeper insights into these postharvest technologies is crucial for optimizing the flavor and nutritional quality of pitaya during storage and transportation. 9 Concluding Remarks Studies have shown that sugar and organic acid metabolism play a crucial role in determining the flavor and nutritional quality of pitaya fruit. Glucose, fructose, and sucrose are the primary sugars, while malic acid and citric acid are the predominant organic acids. The interactions among these compounds significantly affect the sweetness, sourness, and overall flavor balance of dragon fruit, which is crucial for consumer acceptance and market competitiveness. Key transcription factors such as HpDof1.7, HpDof5.4, and HpWRKY3 regulate sugar accumulation by activating sugar metabolic genes like HpSuSy1 and HpINV2. Additionally, the application of methyl jasmonate (MeJA) has been shown to enhance phenolic accumulation and maintain fruit quality under stress conditions. Nutritional analysis further indicates that red-fleshed pitaya varieties exhibit higher antioxidant capacities compared to white-fleshed ones. The findings have several implications for pitaya cultivation and quality improvement. Understanding the genetic and biochemical pathways regulating sugar and organic acid metabolism can facilitate the development of new cultivars with enhanced flavor and nutritional quality. For instance, key transcription factors and sugar transporters (such as HuSWEET12a and HuSWEET13d) provide targets for genetic engineering to increase sugar content. Additionally, exploring the application of MeJA treatments can improve post-harvest quality and extend shelf life by maintaining higher levels of phenolic compounds and sugars. Optimizing cultivation techniques based on the nutritional characteristics of different pitaya varieties can also meet specific market demands, such as high-antioxidant varieties for health-conscious consumers or high-sugar varieties for the dessert industry. Future research should continue to delve into the molecular mechanisms of sugar and organic acid metabolism, particularly the interactions between key transcription factors and metabolic genes, to uncover more precise regulatory networks. Simultaneously, the integration of multi-omics approaches (such as transcriptomics, metabolomics, and epigenomics) should be employed to explore the metabolic characteristics of different pitaya cultivars, enabling the development of specialty varieties tailored to diverse market demands. Additionally, innovative post-harvest treatments and storage technologies, such as bioactive coatings or light-quality treatments, are recommended to extend the shelf life of pitaya fruits and enhance storage quality. These studies have the potential to further improve the quality and market competitiveness of pitaya, providing new impetus for the high-quality development of the industry. Acknowledgments The author extends special thanks to Dr. X. Fang, Professor and Director of the Hainan Institute of Tropical Agricultural Resources, for reviewing the manuscript and providing valuable suggestions for revision. The author also sincerely appreciates the two anonymous peer reviewers for their comprehensive evaluation of the manuscript and constructive feedback.
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