The effect of pre-harvest calcium chloride and chitosanapplications on the storage performance of blackberries

Blackberry fruit possesses desirable taste, aroma, and olfactory attributes, and its high content of vitamins and minerals, along with phytochemical compounds such as antioxidants, flavonoids, and phenolic substances, enhances its value in terms of human health. However, its short postharvest shelf life and susceptibility to decay and pathogenic organisms lead to significant quality losses. In this thesis study, calcium chloride (CaCl₂) and chitosan treatments were applied with the aim of preserving the quality attributes of blackberry fruit during storage. A 2% CaCl₂ treatment was applied to 'Jumbo' blackberry fruit during the early fruit set stage following flowering, and a chitosan treatment was administered 12 hours prior to harvest. The harvested fruits were stored for 15 days in a cold storage room at 2 ± 0.5 °C and 85 ± 5% relative humidity. Throughout the storage period, fruit quality parameters were evaluated under laboratory conditions. Weight loss, decay rate, red drupelet reversion (RDR), fruit color, flesh firmness, pH, titratable acidity, soluble solids content (SSC), vitamin C content, total phenolics, anthocyanins, and antioxidant activity were analyzed. The findings indicated that the combined use of both treatments was more effective in reducing weight loss. On the day of harvest, the highest SSC value was measured in the calcium + chitosan group, and by the end of the storage period, the highest values were observed in the chitosan and calcium + chitosan treatments. However, the CaCl₂ treatment was found to increase both the decay rate and RDR. In the phytochemical analyses, the treatments did not provide a significant improvement compared with the control on the day of harvest; nevertheless, calcium was observed to increase anthocyanin content by the end of the storage period. The inability of calcium to exhibit the expected effect suggests that its application during the early fruit stage may not have allowed sufficient accumulation in the tissues. Similarly, the effectiveness of chitosan is also considered to depend on proper dosage and timing.