Loquat leaf extract and alginate based green composite edible coating for preserving the postharvest quality of Nanfeng tangerines

The present study was designed to investigate the preventive effect of loquat leaf (LL) based green extract combined with alginate-based composite against fungal infection in Nanfeng tangerine fruit. The sensory quality, physiological, and biochemical characteristics of postharvest citrus were estimated after the treatment. Results showed that LL extract's minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) to Penicillium digitatum were 0.625 mg/mL and 1.25 mg/mL, respectively. The scanning electron microscopy showed that LL extract could break, bend, and inhibit the average expected growth of P. digitatum hyphae. Concurrently, a composite coating of LL extract effectively reduces postharvest decay rate and weight loss, postpones fruit respiration, and delays the nutrient degradation of Nanfeng tangerines during cold storage. Also, a significant delay in MDA accumulation and an improved antioxidant defense system are shown by higher non-enzymatic antioxidants (ascorbic acid, phenols, and flavonoids) and higher ROS-scavenging enzymes (SOD, CAT, POD, and APX) were recorded. The green composite treatment could effectively delay the senescence and prolong the storage time of citrus. These results suggested that the green composite coating containing plant extract had great potential for citrus preservation.