Effects of hot water dip or heat conditioning of 'Star Ruby' grapefruit quality during quarantine treatment and simulated storage duration

Postharvest hot water dip and heat conditioning treatments were conducted to determine treatment effects to freshly harvested grapefruit 'Star Ruby' under quarantine conditions and after additional storage time. a) Control: standard application of exporters used as control with 53°C hot chemical bath with 500 ppm Imazalil that fruit passing in 60 s, b) 60°C hot chemical bath with 500 ppm Imazalil that fruit passing in 60 s (HW), c) 48 h conditioning fruits at 28-30°C with 70-80% RH followed by 60°C hot chemical bath with 500 ppm Imazalil that fruit passing in 60 s treatments were conducted. Fruits were sorted after treatments and packed inside 40×60×14 telescopic boxes with 14 kg weight and 45 fruits size. As soon as finishing the packaging fruits were put in precooling cold room facility until initial temperature decreased to 1°C and fruit initial temperature of each treatment were controlled by 3 thermocouples during the process. After precooling to 0.5°C fruits were waited for 16 days at the mentioned conditions that was written in protocol of grapefruit export to Japan from Turkey. This quarantine treatment continued with increasing the initial temperature to 6-8°C in 7 days and finishing the protocol about 25-30 days of shipment. Additional storage and shelf life evaluation were also evaluated in conducted experiment. Weight loss (%), total soluble solids (%), titratable acidity (%), amount of fruit juice (%), antioxidant activity (%), total phenols (mg gallic acid L^‑1), the fruit peel color (h°), chilling injury (%) analysis were done to evaluate effects of treatment on fruit overall quality parameters.