International Journal of Horticulture, 2025, Vol.15, No.1, 8-20 http://hortherbpublisher.com/index.php/ijh 8 Research Insight Open Access Impact of Sugar and Organic Acid Metabolism on Pitaya Flavor and Nutritional Quality JunguiXu2*, Tianhui Shi 1,3*, Zizhong Wang2,YuxinHe1,3, ZhenLiu1 1 Hainan Institute of Zhejiang University, Sanya, 572024, Hainan, China 2 Hainan Huitian Agriculture Co., Ltd., Sanya, 572024, Hainan, China 3 College of Agricultural & Biotechnology, Zhejiang University, Hangzhou, 310058, Zhejiang, China * These authors contributed equally to this work Corresponding author: zhenliu2012@zju.edu.cn International Journal of Horticulture, 2025, Vol.15, No.1 doi: 10.5376/ijh.2025.15.0002 Received: 03 Nov., 2024 Accepted: 05 Jan., 2025 Published: 26 Jan., 2025 Copyright © 2025 Xu et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Xu J.G., Shi T.H., Wang Z.Z., He Y.X., and Liu Z., 2025, Impact of sugar and organic acid metabolism on pitaya flavor and nutritional quality, International Journal of Horticulture, 15(1): 8-20 (doi: 10.5376/ijh.2025.15.0002) Abstract This study conducts an in-depth analysis of the role of sugar and organic acid metabolism in the formation of dragon fruit flavor and the enhancement of its nutritional quality. The findings reveal that glucose, fructose, and sucrose are the primary sugars in pitaya, while malic acid and citric acid are the predominant organic acids. The balance between sugars and organic acids significantly influences the sweetness and overall flavor profile of pitaya, with secondary metabolites such as betalains further enriching its sensory attributes. Key genes and transcription factors (e.g., HpDof1.7, HpDof5.4) play critical roles in regulating sugar and acid metabolism, with a notable contribution to sugar accumulation during the fruit maturation stage. The study also examines the regulatory mechanisms of sugar-acid metabolism in relation to genetic background, cultivation practices, and post-harvest handling, emphasizing the importance of interdisciplinary approaches. This study provides scientific guidance for optimizing pitaya breeding and cultivation management, supporting the sustainable development of the pitaya industry, and meeting diverse consumer demands. Keywords Pitaya (Hylocereus spp.); Sugar metabolism; Organic acids; Flavor; Nutritional quality; Quality optimizatio 1 Introduction Pitaya, commonly known as dragon fruit, belongs to the genus Hylocereus and is native to Central America, such as Mexico, El Salvador, Guatemala, and Honduras. The primary species include Hylocereus costaricensis, H. undatus, and H. megalanthus, which are cultivated extensively in tropical and subtropical regions worldwide, including Brazil and Turkey (Constantino et al., 2021; Attar et al., 2022). The fruit is celebrated for its vibrant appearance, sweet taste, and high nutritional value, making it a popular choice for fresh consumption and industrial processing into beverages and desserts (Constantino et al., 2021; Lin et al., 2021). The economic value of pitaya has surged in recent years due to its increasing popularity and demand in both local and international markets (Chapai et al., 2024). The flavor and nutritional quality of pitaya are critical factors that influence its market competitiveness and consumer acceptance. The sweetness and overall taste of the fruit are primary determinants of consumer preference, which directly impacts market demand (Jiang et al., 2023). Additionally, the nutritional profile, including antioxidant capacity and phenolic content, enhances the fruit's appeal as a health-promoting food. High levels of antioxidants and phenolic compounds, particularly in red-fleshed varieties, contribute to the fruit's health benefits and market value (Attar et al., 2022). Therefore, understanding and improving these attributes are essential for maintaining and expanding pitaya's market presence. Sugars and organic acids play pivotal roles in determining the flavor, texture, and nutritional value of pitaya. The primary sugars found in pitaya include glucose, fructose, and sucrose, which contribute to the fruit's sweetness and overall taste profile (Constantino et al., 2021; Xie et al., 2022). Organic acids, such as malic and citric acids, influence the fruit's acidity and flavor balance. The metabolic processes governing the accumulation of these compounds are complex and involve various genes and biochemical pathways (Xie et al., 2022; Jiang et al., 2023).
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