抄録
Three typical packing houses of Citrus Unshiu, which contains different types of sizer, namely belt, drum and modified drum respectively, were investigated. The efficiencies of sizer, cleaner and adhered water remover of the fruit were studied together with the occurrence of abrasion injury.
The rise of respiration rate of the fruit was induced by handling practice at each process, and the rate at the point of weighing process was found to be 1.6 times as compared with that at receiving entrance.
The degree of abrasion injury of fruit was evaluated by means of tannic acid-ferric chloride dyeing method and Penicillium spore inoculation. Brushing process was revealed to cause a remarkable injury on fruit.
Among the three types of sizer, belt type showed the highest sizing efficiency over all size of fruit.
Unless the water is used for cleaning the fruit, removing the surface chemicals on fruit by brushing is quite difficult within the time of half a minute.
As mentioned above, the process of brushing was revealed to increase the abrasion injury of fruit, but could not remove so much of the adhered chemicals on fruit.
Due to the results obtained from investigation, some experiments were conducted according to the experimental planning method using an orthogonal table of L27 (313) to establish the standard of design for brushing process.
Cleaning rate of fruit by brushing method was limited to the lower level of 20 to 50 percent, in spited of long brushing time of 90 seconds.
Factors that influence the cleaning rate of fruit were searched by the method of analysis of variance:
(1) The effect of the length of brush material (synthetic fiber and natural hairs) and brushing time was hardly significant at 1 percent level, while that of the sort of brush material was highly significant at 5 percent level.
(2) The effect of the interaction of (sort of the material)×(length of the material) was hardly significant, and that of (length of the material)×(revolution of the brush) was highly significant.
As far as the cleaning rate was concerned, we could obtain the best cleaning rate in the following conditions:
sort of the material … human hair
length of the material … 30mm
revolution of the brush … 120r.p.m.
brushing time … 90 seonds
The brushing operation, however, caused an increase in both the percent of decay and the rate of weight loss of fruits. There was a quadratic functional relation between brushing time and percent of decay. Judging from this situation, brushing time should be within 30 seconds.
