Effects of Hydrocooling on the Quality of Fresh Longan Fruits cv. Daw

抄録

One-day-old fresh longan fruits (Dimocarpus longan Lour. cv. Daw) were selected. The fruits were placed in 3-kg perforated plastic crates of commercial scale for each treatment. The treatments were: no pre-cooling, tap water immersion, pre-cooling with cold water 50, 100 and 200 ppm chlorine and also without chlorine. The cooling was for 10 min, and the final temperature of longan fruits reached 5°C. The effects of the hydrocooling treatments on the quality and decay of the fruits during storage at 5°C and 93 % relative humidity (RH) for three weeks were determined. By pre-treatment with cold water plus 50 ppm chlorine, the longan fruits showed significantly decreased peel browning and fruit decay in comparison to no pre-cooling and tap water immersion treatments. With this treatment, the fruits maintained the highest L* value both of the inner and outer peel, soluble solids content (SSC) in flesh, high sensory evaluation and peel desiccation was prevented. Therefore, the treatment could extend the storage life of longan fruits. Pre-cooling with no chlorine did not prevent fruit decay caused by fungi. Higher chlorine concentrations, 100 and 200 ppm, increased peel browning and fruit decay. Weight loss was not affected significantly by any treatments.