Postharvest application of carrageenan oligosaccharides on quality attributes and activities of defense-related enzymes in strawberry (Fragaria×ananassa Duch)

The carrageenan oligosaccharides (COS) possessed versatile biological activities such as antibacterial, antioxidant, anti-inflammatory activities. Herein, we aimed to explore the effects of carrageenan oligosaccharides (COS) on the preservation of strawberries (Fragaria×ananassa Duch) and factors including decay percentage, hardness, soluble solids, titratable acids, vitamin C (VC) content, the activity of peroxidase (POD), polyphenol oxidase (PPO) were judged as criteria. Also, the expression of genes related to fruit-softening enzymes were detected by real-time qPCR. Soaking treatment of oligosaccharides could significantly (P < 0.05) improve the physical and chemical factors compared with the control group. As for the preservation mechanism of strawberries, the Real-time qPCR results showed that COS coating treatment significantly prolonged the shelf life of strawberries by suppressing the gene expression of cell wall degraded enzymes and ethylene biosynthesis enzymes, with the most obvious effects observed in the 10 mg/mL concentration group. This experiment explores the possibility of COS as a strawberry preservative, which lays a theoretical foundation for future practical application.