Effects of Dropping and Waxing Practices in the Packing-house Line on the Quality of Satsuma Mandarin (Citrus unshiu Marc.)

Abstract

In order to investigate the effects of handling practices such as dropping and waxing in a packing-house line on the quality of satsuma mandarin, simulated handling tests were conducted. To evaluate the handling practices, the change of quality during storage for a week was evaluated with respect to respiration rate, ethanol accumulation, sugar content (Brix) and citric acidity. Results were obtained asfollows.
1. An increase in the respiration rate was caused by the dropping practice and that increase was proportional to the number of drops. Immediatey after dropping from a height of 30cm onto the board with repetitions of 10, 20 and 30 times, the increment in the respiration rate was 198%, 265% and 315% respectively. The state of increased respiration rate continued and did not recover to an initial state until 40 hours or so of elapsed time from dropping practice.
2. When satsuma mandarin was waxed after the dropping practice, respiration rate seemed to decrease for a short time after the waxing treatment and to increase until 4 hours of elapsed time. The author thought that it was due to the decrease in gas permeability through the peel by waxing treatment.
3. The relationship between dropping height and maximum acceleration was as follows.
G=0.58H^0.89
where G: maximum acceleration (multiple of gravity)
H: dropping height (cm)
4. Ethanol accumulation appeared to be due to low oxygen concentration inside the fruit that occured as a result of increase in the respiration rate due to dropping the fruit. The ethanol buildup was accelerated by the lowering of gas permeability caused by waxing treatment. An ethanol content of more than 170mg/100ml caused an abnormal flavour in juice.
5. While sugar content of dropped fruit did not change, citric acidity decreased noticeably during storage for a week. The rate of decrement in case of early ripening fruit and late ripening one was 0.3g/100ml and 0.1g/100ml respectively.
6. As for the dropping practice, late ripening satsuma mandarins were affected more vigorously than the early ripening ones. The limit for the number of drops from 30cm was 20 times in case of early ripening fruit and 10 times in case of stored late ripening fruit. The waxing practice must be avoided in stored late ripening fruit.