THE EFFECT OF CHITOSAN AND SALICYLIC ACID IN IMPROVING CERTAIN QUALITY CHARACTERISTICS AND REDUCING THE DETERIORATION OF STRAWBERRIES DURING COLD STORAGE

Аннотация

The strawberry (Fragaria × Ananassa Duch.) is among the most susceptible fruit crops to rapid post-harvest deterioration. This is due to high respiration and transpiration rates, the tenderness of the fruit tissues, and its susceptibility to microbial infection. This results in weight loss, reduced firmness, and deterioration in their physical and chemical properties, therefore shortening their shelf life and reducing their market value. Gradually, recent research has focused on the use of natural and environmentally safe treatments, including chitosan and salicylic acid, due to their role in preserving fruit quality, slowing down ageing processes and reducing post-harvest losses.

The objective of this study was to assessment of effect of chitosan and salicylic acid, and their interaction, on the preservation of certain quality attributes of strawberries during cold storage. The experiment was conducted using a factorial design to investigate three concentrations of chitosan (0, 0.5 and 1 per cent) and three levels of salicylic acid (0, 0.138 and 0.276 g L⁻¹), however assessing the effect of the treatments on weight loss rate, fruit firmness, total soluble solids (TSS), total acidity, vitamin C content, anthocyanins and total sugars.

The finding showed that chitosan, salicylic acid and their interaction had significant effects on all the characteristics studied. The use of chitosan reduced the rate of weight loss and maintained fruit firmness compared with the control treatment; it also contributed to improving the chemical characteristics by increasing total soluble solids, total acidity, vitamin C content, anthocyanins and total sugars. Similarly, the use of salicylic acid slowed down the maturing and ageing processes and reduced oxidative stress, which had a positive effect on preserving fruit quality during cold storage.

The results of the interaction analysis indicated that treatment with 1% chitosan combined with 0.276 g L⁻¹ salicylic acid was the most effective, as it achieved the lowest rate of weight loss (14.18%) and the highest fruit firmness (6.84 N), as well as the highest total soluble solids content (9.28 per cent), the highest total acidity (0.71 per cent), the highest vitamin C content (52.30 mg/100 g fresh weight), the highest anthocyanin content (56.57 mg/100 g fresh weight) and the highest total sugar content (7.34%) compared with the control treatment, which recorded the lowest values for most of the traits studied.

This development is attributed to the synergistic effect between chitosan and salicylic acid, as chitosan formed a semipermeable membrane that reduced the rates of respiration, transpiration and water loss, whilst salicylic acid helped to regulate physiological processes, reduce ethylene production, enhance the antioxidant system and maintain the integrity of cell membranes, thereby slowing down deterioration processes and preserving fruit quality during storage.

The study concludes that the use of chitosan at a concentration of 1 per cent combined with salicylic acid at a concentration of 0.276 g L⁻¹ represents a promising and environmentally friendly treatment for preserving the quality characteristics of strawberries and extending their shelf life, and can be incorporated into post-harvest treatment programs to reduce wastage and improve the marketable and nutritional quality of the fruit.