Preharvest sorbitol–calcium treatment reduces chilling injury and postharvest losses in pomegranate cv. 'Mollar de Elche' stored at 2 °C and 7 °C

Pomegranate (Punica granatum L.) cv. 'Mollar de Elche' is a Protected Designation of Origin (PDO) variety cultivated in south-eastern Spain, with an annual production of approximately 40,000 tonnes. Chilling injury during cold storage is the main postharvest disorder affecting this cultivar, resulting in membrane damage, loss of firmness, and premature deterioration that collectively contribute to substantial food waste along the supply chain. Conversely, storage at higher temperatures may lead to dehydration, rind hardening, and a shortened shelf life. Calcium is an essential macronutrient involved in maintaining cell wall integrity and membrane stabilisation by phospholipid binding, whereas sorbitol acts as a carrier for metabolites with limited mobility and it’s been studied the osmoprotective effect and enhancing the synthesis and accumulation of bioactive compounds. In this study, trees received eight preharvest foliar applications, one every 15 days, of a sorbitol–calcium complex (2.5% sorbitol + 0.7% Ca(NO₃)₂) and a control with water, both supplemented with a non-ionic surfactant. After harvest, fruit were held at 2 °C or 7 °C and 95 % relative humidity for 41 days under commercial storage conditions. Firmness, respiration rate, ion leakage, and malondialdehyde (MDA) content were monitored at regular intervals, and chilling-injury symptoms were evaluated visually. Treated fruit showed lower ion leakage (26.166 ± 1.221 % vs 34.027 ± 1.220 % (p < 0.05)) and MDA accumulation (0.928 ± 0.261 µmol kg^-1 vs 3.280 ± 0.725 µmol kg^-1 (p < 0.05)), higher firmness retention, lower respiration rate, and a reduced incidence of chilling-injury symptoms compared with untreated controls, with the most pronounced differences observed at 2 °C. These results indicate that the combined preharvest application of sorbitol and calcium enhanced cell membrane stability, delaying the development of chilling injury symptoms and thereby extending the commercial shelf life of pomegranate and reducing postharvest food losses.