Ascorbic Acid treatments Reduce the Occurrence and Development of Kohansho in Citrus Hassaku and Tangor 'Kiyomi' Fruits

Abstract

Hassaku (Citrus hassaku Hort. ex Tanaka) and tangor 'Kiyomi' (Citrus sinensis×C. tangerina) fruits stored at 5°C for 3 and 2.5 months, respectively, were dipped in 1% L-ascorbic acid (AsA) solution and then held at 20°C to determine the effects of AsA on the occurrence and development of Kohansho, a peel disorder. AsA content was lower and total phenol content was higher in the flavedo of Kohansho peel than in that of sound peel of both Hassaku and 'Kiyomi' fruits. AsA or sodium erythorbate, an analogue of AsA, treatment as well as 50°C hot-water treatment reduced the occurrence and development of Kohansho of Hassaku fruits. All treated Hassaku fruits maintained a higher AsA content in the flavedo than the water-dipped control until day 3 at 20°C. AsA treatment reduced occurrence and development of Kohansho in 'Kiyomi' fruits. but the inhibition was not retained when held in a polyethylene bag after treatment. AsA content in the flavedo did not differ noticeably between water and AsA dipped 'Kiyomi' fruits. AsA treatment was less effective on 'Kiyomi' than Hassaku fruits. Total phenol content in the flavedo of Hassaku and 'Kiyomi' fruits tended to increase during storage at 20°C regardless of treatment. These results indicate that AsA dip treatment helped in reducing occurrence and development of Kohansho in Hassaku and 'Kiyomi' fruits, and the magnitude of the effects depended on the amount of absorbed AsA by the flavedo tissue.