Effect of chitosan-based melatonin composite coating on the quality of minimally processed pomegranate aril-sacs during cold storage

The current study evaluated the potential of chitosan-based melatonin (CH-MT) composite coating to maintain quality and delay senescence of minimally processed pomegranate aril-sacs during refrigerated storage. Mature pomegranate fruit (cv. Wonderful) without physical defects were processed into aril-sacs. Subsequently, the following treatments were applied; distilled water (control), CH 0.5% (w/v), CH+0.1 mM MT, CH+0.4 mM MT, CH+0.8 mM MT, and CH+1 mM MT. Each treatment was applied by immersing the aril-sacs in the coating solution for 3 min and allowed to dry at room temperature. Aril-sacs were then packed in polyethene terephthalate punnets (three to four aril-sacs/punnet) and stored at 5 degrees C and 85% RH for 21 days. Aril color, weight loss, respiration rate, ascorbic acid content, total anthocyanins, browning index, and antioxidant capacity were monitored during storage at 3 days intervals. The study results showed that the CH-MT coating treatments significantly (p < 0.05) delayed the increase in aril-sacs weight loss and respiration rate. These treatments also retained higher aril chroma, ascorbic acid, anthocyanin content, DPPH-radical scavenging activity, and aril-sacs antioxidant power (FRAP). In addition, surface browning development was significantly suppressed in the coated aril-sacs compared with control sacs. However, the effectiveness of CH-MT treatments in maintaining the quality of aril-sacs was concentration-dependent, with CH+0.8-1 mM MT treatments showing the best results. Therefore, CH+0.8-1 mM MT treatments are recommended to suppress the development of physiological disorders and maintain the quality of minimally processed pomegranate aril-sacs. Novelty Impact Statement This study focuses on the development and application of chitosan-melatonin composite coating (CH-MT) as an active and functional formulation to maintain quality and extend the storage life of minimally processed pomegranate aril-sacs. The results showed that incorporating melatonin with chitosan improved the effectiveness of chitosan base coating. This was demonstrated by the CH-MT coating's enhanced retention of ascorbic acid, anthocyanins, radical scavenging activity, and antioxidant power. Further, delaying the increase in aril-sacs surface browning, weight loss, and respiration rate. The study findings are valuable in the commercial adoption of safe preservation technologies to maintain the quality and maximize the storability of minimally processed products.

Automated summary

This study evaluated the potential of a chitosan-based melatonin composite coating to maintain the quality and delay senescence of minimally processed pomegranate aril-sacs during refrigerated storage. The results showed that the coating treatments significantly delayed weight loss and respiration rate, retained desirable properties such as color, ascorbic acid content, anthocyanin content, and antioxidant capacity, and suppressed surface browning development. The recommended treatment concentration for optimal results was 0.8-1 mM melatonin. The findings of this study have important implications for preserving the quality and extending the storage life of minimally processed pomegranate aril-sacs.