Postharvest abscisic acid application: impacts on red ripe tomato fruit quality

Abscisic acid (ABA) is a plant hormone involved in fruit development, ripening, and senescence in climacteric species such as tomato. Since carotenoids are precursors in ABA biosynthesis, their metabolism may be closely associated with ripening progression and postharvest quality changes. This study investigated the effects of postharvest ABA application on tomato fruit quality, carotenoid metabolism, and volatile organic compounds (VOCs) during shelf life. Tomato plants (cv. “Leader F1”) were grown in pots under controlled irrigation and nutritional conditions. Fruit were harvested at the red-ripe commercial stage and soaked for 30 min either in a 100 µM ABA solution or distilled water (control). Fruit were then stored at 20 °C for 13 d and analysed immediately after treatment (T0) and after 5 (T1), 8 (T2), and 13 d (T3) of shelf life. ABA treatment did not significantly affect colour parameters, titratable acidity, pH, total soluble solids, or fruit weight loss, indicating that commercial quality traits were substantially preserved during storage. However, ABA significantly affected carotenoid metabolism immediately after treatment. At T0, ABA-treated fruit showed lower concentrations of phytoene (− 42%), lycopene (− 43%), and β-carotene (− 49%) compared with controls. During shelf life, lycopene concentration in control fruit progressively declined from 163 to 68 µg g⁻¹ FW (− 58.5%), whereas ABA-treated fruit showed a more stable trend with intermediate recovery phases. Similarly, β-carotene levels remained stable in control fruit (average 7.7 µg g⁻¹ FW), while treated fruit showed a significant increase between T0 and T2. Approximately 150 VOCs were identified, mainly belonging to the group of esters (18.6%), carboxylic acids (14.4%), and aldehydes/ketones (14.4%). The total number of VOCs varied markedly during storage, averaging about 25 compounds at T0, 11 at T1, 13 at T2, and 34 at T3. ABA treatment altered the volatile profile by inducing specific esters immediately after treatment and modifying the accumulation of ripening-related compounds during shelf life. Nerylacetone reached a maximum concentration of 858 µg g⁻¹ FW in control fruit at T2, whereas ABA-treated fruit maintained more stable levels throughout storage. Overall, postharvest ABA application modulated carotenoid turnover and VOC composition without negatively affecting the main physicochemical quality parameters of tomato fruit.