Fruit Quality of Mid-and Late Seasons Citrus Harvested from Exterior and Interior Canopy of Trees and Its Changes during Storage

Studies on Vitamin C of Fruits and Vegetables Part VI

Abstract

Changes in peel color and some components of navel orange (Citrus sinensis Osbeck var. brasiliensis Tanaka cv. Yoshida), Iyokan (Citrus iyo Hort. ex. Tanaka cv. Miyauchi-Iyo), hassaku (Citrus hassaku Hort. ex. Tanaka) and natsudaidai (Citrus Natsudaidai Hayata cv. Shin Amanatsu) fruits harvested from exterior and interior canopy of citrus trees were investigated during storage at 5 °C and 15 °C.
1. In navel orange and Iyokan during storage at 15 °C, which showed a significantly greater weight loss among all cultivars, the loss of fruits from exterior canopy was greater than that from interior canopy. On the other hand, a significant difference in the weight loss between the fruits of the two areas was not observed in navel orange and Iyokan at 5 °C and in hassaku and natsudaidai at 5 °C and 15 °C throughout the storage period.
2. The fruits at harvest from exterior canopy were superior in peel color (a/b value) to those from interior canopy in all cultivars, and continued to show better peel color than those from interior canopy during storage at 5 °C and 15 °C.
3. A significant difference in titratable acid content in the juice between the fruits from the two areas was not observed during storage at 5 °C and 15 °C in navel orange, Iyokan and hassaku, whereas the content in natsudaidai from interior canopy was higher than exterior canopy throughout the storage period at both temperatures.
4. There was no significant difference in sugar content in the juice of Iyokan, hassaku and natsudaidai from the two areas during storage at 5°C and 15°C. However navel orange fruits from exterior canopy maintained a higher content of glucose, fructose and sucrose than those from interior canopy throughout the storage period at 5 °C and 15 °C.
5. The exterior fruits contained a high ascorbic acid (AsA) content in the juice at harvest and maintained a higher content in the juice throughout the storage period at 5 °C and 15 °C than did the interior fruits in all cultivars. AsA content in the juice (mg/one fruit) showed no notable change at 5 °C and 15 °C in navel orange, hassaku and natsudaidai, but showed a continuous decrease in lyokan. AsA content in the flavedo of the fruits of all cultivars tended to decrease during storage at 5 °C and 15 °C. AsA content in the flavedo of exterior fruits was higher than that of interior ones at harvest in all cultivars. The exterior fruits of hassaku and natsudaidai retained higher AsA content during storage at 5°C and 15°C in contrast to the interior fruits.