Anthocyanin measurement. Three skin discs 9 mm in diameter were collected from individual parts of the treated fruit or skin discs. Anthocyanin was extracted overnight with 10 mL 1% HCl-methanol at 5 °C in the dark, and the absorbance of the extract was measured at 530 nm by a spectrophotometer (Ubest-30; Japan Spectroscopic Co., Ltd., Tokyo).