CaCl2-cold storage combination: An efficient preservation approach for prolonging the shelf life of passion fruit (Passiflora edulis)

Passion fruit (Passiflora edulis) is a highly perishable climacteric fruit that is susceptible to rapid postharvest deterioration including pericarp shrinkage and pulp separation. In this study, six preservation treatments were assessed for maintaining the quality of 'Qinguo No. 9' passion fruit: control (20 °C), water + 20 °C, 4 °C alone, water + 4 °C, CaCl2 + 20 °C, and their combination (CaCl2 + 4 °C). The lowtemperature treatments markedly decreased significantly reduced cumulative weight loss and maintained higher edible rates, with 4 °C alone showing the strongest effect in reducing weight loss. In terms of nutritional attributes, the CaCl2 + 4 °C treatment produced the highest soluble sugar content during the middle stage of storage. In addition, both CaCl2 + 4 °C and CaCl2 + 20 °C treatments significantly delayed flavonoid degradation and maintained elevated total phenolic levels during late storage, suggesting a synergistic interaction between calcium and low temperature in regulating secondary metabolism. Rather than simply optimising individual quality indicators, the combined treatment effectively balanced water retention, sugar accumulation, and antioxidant preservation throughout storage. These results indicate that CaCl₂ + 4 °C treatment represents a feasible strategy for extending the commercial shelf life of passion fruit while preserving both sensory and nutritional properties, particularly through improved mid-term sugar retention and enhanced latestage phenolic maintenance.