Synergistic Treatment with Ozone Water and Morpholine Fatty Acid Salts Improves Postharvest Quality in Mandarin Oranges

Citrus rot seriously reduces the quality of citrus, causes economic losses, and is an urgent problem for the citrus industry. Effective preservation and pretreatment methods have an important impact on the maintenance of mandarin orange quality. In this study, mandarin orange was pretreated through single and synergistic treatments with ozone water and morpholine fatty acid salts in order to assess their effects on the fruit's physicochemical properties. First, the parameters of the ozone water treatment, including time and ozone water concentration, were optimized to determine the optimal pretreatment conditions for the subsequent mandarin orange preservation. Subsequently, the mandarin oranges subjected to different pretreatments (ozone water, morpholine fatty acid salts, ozone water + morpholine fatty acid salts, water, and blank control) were stored at 25 ± 2 °C and 75% relative humidity for 20 d to simulate retail conditions (shelf-life). Finally, the surface microbial content, firmness, weight loss, total soluble solids content, respiration rate, decay rate, and surface morphology of mandarin orange peel were assessed during the storage period. The results showed that the synergistic treatment with ozone water and morpholine fatty acid salts significantly reduced the surface microbial content (Lg CFU/g = 3.91), weight loss (2.79%), decay rate (2.5%), and firmness losses on day 20 compared to other single treatments (<i>p</i> < 0.05). Hence, synergistic treatment with ozone water and morpholine fatty acid salts is a new green mandarin orange preservation technology with promising applications in controlling postharvest diseases and extending the storage period.