Sugars and organic acid profiles are associated with textural diversity in jujube fruit

Fruit texture is a critical quality trait affecting the consumer acceptance and processing suitability of jujube (Ziziphus jujuba Mill.). Soluble sugars and organic acids are not only fundamental to flavor but also serve as key metabolic indicators associated with textural diversity. However, how the accumulation of soluble sugars and organic acids relates to textural variation remains largely unexplored. This study systematically evaluated 109 jujube germplasm accessions for soluble sugars, titratable acidity, and fruit hardness at full-red maturity. Hierarchical clustering based on these traits classified the germplasm into three distinct groups: Group I (high acidity and low hardness, 29.36%), Group II (balanced traits, 55.96%), and Group III (high sugar and high hardness, 14.68%). Textural profile analysis revealed that Group III exhibited significantly superior texture, with hardness, gumminess, and chewiness exceeding those of Group I by 97.99%, 99.91%, and 210.22%, respectively. High-performance liquid chromatography (HPLC)-based quantification of the primary metabolites showed that the favourable texture of Group III was associated with a markedly higher accumulation of sucrose, fructose, and glucose. In contrast, Group I possessed significantly high concentrations of citric acid and malic acid, which were higher than those of Group III by 401.75% and 141.27%, respectively, and which correlated with its softer texture. Correlation and principal component analyses further highlighted a strong antagonistic relationship between sugar and organic acid accumulation, with sugars positively and organic acids negatively associated with key textural parameters. This germplasm-based classification, coupled with the identified sugar–organic acid signatures, provides a clear phenotypic and biochemical framework for breeding, and suggests that sugar and organic acid metabolism may indirectly influence fruit texture through osmotic regulation and modulation of the cell wall microenvironment.