Analysis of the Relationship Between Organic Acid, Total Soluble Solids, Total Phenolic, and Total Flavonoids in Ficus carica

This study systematically investigated the chemical characteristics and regulatory roles of organic acids on functional components in six introduced Ficus carica cultivars in Shandong Province. Results demonstrated that figs exhibited high water content (757.171-850.707 mg/g), organic acids (707.456-1518.634 mg/g) and total phenolic content (0.920-2.490 mg/g), with 'Banane' showing preferable comprehensive performance (total organic acids: 1518.634 mg/g; total phenols: 2.490 mg/g; citric acid: 29,173.767 mu g/g). A total of 24 organic acids were identified, with citric acid (16,363.575 mu g/g, 66.1%), malic acid (3937.604 mu g/g, 15.9%), and gluconic acid (2861.940 mu g/g, 11.6%) as dominant components, while 12 minor acids including maleic acid were first reported in figs. Partial least squares modeling revealed that citric acid, quinic acid, and trans-aconitic acid significantly promoted total phenolics/flavonoids (TP/TF) accumulation (regression coefficients: 0.256-0.367) through tricarboxylic acid (TCA) cycle-mediated carbon skeleton supply and activation of phenylpropanoid metabolism enzymes. Conversely, malic acid, maleic acid, and phosphoenolpyruvate (PEP) inhibited TP/TF synthesis (coefficients: < -0.200). Pyruvic and quinic acids enhanced total soluble solids (TSS) via glycolytic regulation, whereas malic and fumaric acids suppressed TSS. Principal component analysis classified cultivars into two groups: Group I ('Banane', 'Stella', '108B') with high citric acid, phenolics, and antioxidant capacity, suitable for functional food development; Group II ('Orphan', 'Ameiniya', 'Borji Red') dominated by malic acid and lower TSS, ideal for fresh consumption. Comprehensive evaluation (D-value) identified '108B' (D = 1.996) and 'Banane' (D = 1.979) as top-quality cultivars. This work elucidates the dual regulatory mechanisms of organic acids on fig nutrition and flavor, providing theoretical foundations for cultivar breeding and functional utilization. Future studies should integrate multi-omics approaches and industrial validation to optimize quality regulation strategies.