Polyphenolic Compound and the Degree of Browning in Processing Apple Varieties

Polyphenolic compound in processing apple (Malus dornestica Borkh.) varieties and the relationship between polyphenol content and enzymatic browning were studied to provide reference for raw material selection and processing method optimization. The content of polyphenol compound in 10 processing apple varieties (4 cider and 6 juice varieties) were analyzed using the Folin-Ciocalteu method and HPLC. The degree of browning and the activities of polyphenol oxidase were also studied. The content and proportion of the polyphenol varied depending on the variety. Bitter varieties globally showed a higher polyphenol concentration than sweet or acid varieties. Proanthocyanidins, chlorogenic acid, (+)-catechin, (-)-epicatechin were high-concentrated polyphenols in apple fruits. Phloridzin, the unique polyphenol of apple, was abundant in the bitter variety Frequin rouge fruit. Total polyphenols, proanthocyanidins, (+)-catechin, and phloridzin had higher correlations with browning. The correlation was low between chlorogenic acid and browning. The polyphenolic profiles were correlated with the apple types. Cider apples contained more polyphenol than juice apple varieties. The content of flavan-3-01 has a close relationship with fruit browning.