Chitosan–putrescine nanoparticle coating attenuates postharvest decay and maintains ROS scavenging system activity of strawberry cv. ‘Camarosa’ during cold storage

The application of some natural compounds and cold storage can reduce postharvest loss and improve fruit quality and storability, which increase the fruit marketing period and exportation to distant markets. This study investigated the effectiveness of using coatings based on natural polymers to prolong the shelf life of fruits and protect their tissues from damage. Specifically, the researchers examined the impact of putrescine (PUT), chitosan (CTS) and chitosan–putrescine nano-composites (CTS-PUT NPs) on preserving the quality and reducing decay in strawberry. Strawberries were treated with either 1 mM or 2 mM of PUT, 0.1% CTS, 0.1% CTS-PUT NPs or distilled water at a temperature of 20°C for 5 min and then stored at 4°C for 12 days. At the end of the storage period, the lowest decay percentage was related to the treatments of CTS-PUT NPs and CTS, and the highest was observed in the control. The results showed that all coating treatments effectively prevented the excessive loss of ascorbic acid, fruit firmness, total soluble solids (TSS), and acidity (TA) compared to control at the end of the storage period. Additionally, strawberries treated with CTS-PUT NPs and CTS demonstrated the highest levels of total anthocyanin and total flavonoid. Antioxidant enzyme activities containing CAT and SOD were preserved at higher levels in treated strawberries than in the control during cold storage. These results confirm that the application of CTS and CTS-PUT NPs can effectively preserve fruit quality and prolong the longevity of strawberries during cold storage by enhancing their antioxidant capacity and scavenging free radicals.