Influence of reflective foil on persimmon (Diospyros kaki Thunb.) fruit peel colour and selected bioactive compounds

The purpose of this work was to investigate how to overcome the negative effect of anti-hail netting on the photosynthetic photon flux density (PPFD) in persimmon trees and persimmon fruit colour, flesh firmness, total soluble solids (TSS) and individual carotenoid and phenolic compound contents (determined via HPLC-MS) under a hail net with the use of reflective foil. Reflective foil increased the PPFD on the lower side of the fruits, while there was no significant difference on the upper side compared to those of the control group. The CIE colour parameters a* and h° indicated more intense red colouration of the fruits in the foil treatment than those in the control. Among carotenoids, the content of β-carotene increased, and the content of zeaxanthin decreased in fruits in the reflective foil treatment group, while the content of other carotenoids was not affected by the reflective foil. Among individual phenolic compounds in the persimmon peel, greater light intensity significantly influenced all three phenolic compound subgroups: phenolic acids, flavan-3-ols and flavonols. The content of gallic acid in the persimmon flesh increased the most, while other phenolics did not show any significant differences in concentrations between the foil and control groups. This study is the first to examine the influence of reflective foil on bioactive compounds in persimmon fruit. The use of reflective foil in persimmon orchards improves persimmon fruit colour and selected bioactive compound contents.