樹冠内•外層の着果位置別にみたウンシュウミカン果実の貯蔵中における品質の変化

Abstract

Changes in fruit quality and some other components during storage at 5°C and 15°C were investigated in satsuma mandarin (Citrus unshiu Marc. cv. Hayashi) fruits harvested from exterior and interior canopy of 21-year-old trees.1. The rate of microbial decay including stem-end rot was much higher in the fruit from interior canopy than from exterior canopy during storage at 15°C. On the other hand, no decay was observed at 5°C except in a few fruit infected with blue and green mold. The peel of fruits from exterior canopy tended to puff during first 60 days of storage at 5°C and 15°C in contrast to fruits from interior canopy.2. The respiratory rate of fruits from exterior canopy was higher than that from interior canopy during storage at 5°C and 15°C.3. Peel color (a/b value) of the fruits from exterior canopy showed a marked increase compared with the fruits from interior canopy during storage at 5°C and 15°C. The difference in a/b value between the fruits from the two positions tended to increase significantly at 5°C.4. The reduction in titratable acid content of the juice was less in the fruits from exterior canopy than from interior canopy during storage at 5°C and 15°C. The difference in the content between the fruits from the two positions of canopy tended to increase at 5°C in the later period of storage.5. The content of sugars in a fruit (g/juice of one fruit), which were glucose, fructose and sucrose, showed no significant change in the fruits from either position of canopy during storage at 5°C and 15°C. The fruits from exterior canopy maintained notably higher content of sugar in the juice than those from interior canopy. The rate of decreasing total sugar in the flavedo was higher in the fruit from interior canopy than from exterior canopy during storage at 5°C, although there was no significant difference in total sugar in the flayed flavedo of fruits from the two positions at 15°C.6. Ascorbic acid (AsA) content in a fruit (mg/juice of one fruit) remained nearly constant at 5°C, but decreased gradually during storage at 15°C. The exterior fruits that had received more sunlight during development maintained a higher AsA content in the juice throughout storage period for 110 days than did the shaded interior fruits. AsA content in the flavedo of fruits showed a continuous decrease at 5°C and 15°C. The reduction in AsA content in the flavedo of exterior fruits was greater at the end of storage than in interior fruits.