Cracking and quality attributes of jujube fruits as affected by covering and pre-harvest Parka and GA(3) treatments

Abstract

This study was carried out to investigate the effects of rain protective covering (RPC) together with Parka and gibberellic acid (GA(3)) treatments on cracking rates and quality attributes of jujube fruits. RPC was mounted 5 weeks before the commercial harvest date. 1% Parka (containing 7.5% stearic acid, 5% cellulose and 1% calcium) and GA(3) (15 mg L-1) were sprayed to experimental trees 3 and 2 weeks before the commercial harvest date. As compared to the control, all treatments (Parka, GA(3) and GA(3) + Parka) yielded lower cracking rates. Cracking rates were also significantly lower in covered trees than in uncovered trees. However, GA(3) + Parka treated fruit had significantly lower cracking rates than both the control and the other treatments. GA(3) treated fruits had significantly higher weight, width, hue angle and firmness values, but significantly lower L* values than the control fruits. As compared to the control, all treatments yielded a significantly lower respiration rate and soluble solids content, but higher titratable acidity, vitamin C and total phenolics. The covered fruits had significantly higher hue angle, respiration rate, vitamin C, total phenolics, total flavonoids and antioxidant activity (free radical scavenging activity on DPPH and FRAP) than the uncovered ones. It was concluded based on the present findings that rain-protective covering could be used as an efficient tool to reduce cracking rates in jujube fruits without any negative effects on the other quality attributes. It was also concluded that Parka and GA(3) treatments reduced cracking rates significantly and such a reduction was more remarkable with combined GA(3) + Parka treatments.