Abstract
The resistivities to impact and compression of Japanese pear, ‘Kikusui’ and Chojuro and oriental persimmon, ‘Fuyu’ were investigated.
1. As for resistivity of ‘Kikusui’ pear to compression, fruts were injured more severely as the fruit stiffness lowered 15 days after storage at 20°C. How ever, the resistivity to impact was not connected with flesh firmness.
2. ‘Kikusui’ fruits were more sensitive than ‘Chojuro’, to impact and compression.
3. Concerning the impact position on the fruit, ‘Kikusui’ fruits were apt to be injured more severely at the stem end of fruit.
4. In ‘Kikusui’ pears, shapes of bruised portions by impact were different from those by compression.
In both cases, however, fleshy tissues immediately under the skin were very sensitive to bruising. On the other hand, shapes of bruised portions in persimmon changed with fruit maturation, and fleshy tissues immediately under the skin were not injured except those of overripe fruits.
5. When ‘Fuyu’ fruits were dropped onto a hard board 2.7cm thick from the height of 20cm, the allowable flesh firmness for resisting impact injuries with sodden brusises was about 15lb. by Magness-Taylor pressure tester with 5/12 in. diameter plunger. In case fruits were loaded to 20kgw at a speed of 2mm/min by Instron material testing machine the allowable fruit stiffness for resisting compressed injuries was about 2.3-2.4kg/mm.
