Enzymatic Browning, Polyphenol Oxidase Activity, and Polyphenols in Four Apple Cultivars: Dynamics during Fruit Development

Abstract

<jats:p>Enzymatic browning is one of the most important reactions that occur in fruits and vegetables, usually resulting in negative effects on color, taste, flavor, and nutritional value. The reaction is a consequence of phenolic compounds' oxidation by polyphenol oxidase (PPO), which triggers the generation of dark pigments. This is particularly relevant for apples, which are rich in polyphenols and highly susceptible to enzymatic browning. The objective of the present work was to quantify enzymatic browning and PPO activity and identify and quantify target polyphenols in apple [<jats:italic>Malus</jats:italic> ×<jats:italic>sylvestris</jats:italic> (L.) Mill. var. <jats:italic>domestica</jats:italic> (Borkh.) Mansf.] pulp in the cultivars (cvs.) Aori27, Elstar, Fuji, and Mellow at three fruit developmental stages (FDS). The enzymatic browning was quantified by tristimulus colorimetry; PPO activity was quantified by an enzyme–substrate spectrophotometric assay; phenolic compounds were determined and quantified by reverse-phase high-performance liquid chromatography–ultraviolet/visible–mass spectrometry. Enzymatic browning showed significant difference among cvs. and FDSs and interaction between both factors. PPO activity showed significant difference among cultivars and FDSs. A significant difference was evidenced for polyphenol content among cultivars and FDSs with interaction between both factors. Chlorogenic acid was the major phenolic compound in ‘Aori27’ and ‘Mellow’. In ‘Fuji’, chlorogenic acid and (–)-epicatechin were the major phenolics and in ‘Elstar’ (–)-epicatechin and procyanidin B2 were the major phenolics at different FDSs. The enzymatic browning showed high correlation to polyphenol content in all cultivars and high correlation was observed between browning and PPO activity in ‘Aori27’ and ‘Elstar’. The magnitude of the correlation between browning and polyphenols and PPO activity is genotype-specific. At the commercial harvest, ‘Fuji’ showed the highest polyphenol content and ‘Aori27’ showed the lowest level for enzymatic browning. Chemical names used: 3-(3,4-dihydroxycinnamoyl) quinic acid (chlorogenic acid), (–)-<jats:italic>cis</jats:italic>-3,3′,4′,5,7-pentahydroxyflavane (epicatechin), and <jats:italic>cis,cis″</jats:italic>-4,8″-Bi(3,3′,4′,5,7-pentahydroxyflavane) (procyanidin B2).</jats:p>

Deodorization of Garlic Breath by Foods, and the Role of Polyphenol Oxidase and Phenolic Compounds

“…The major phenolic compounds that are present in the foods tested in this study included rosmarinic acid in mint leaves (Tahira and others ), quercetin in apples (Lee and others ; Holderbaum and others ), and catechin in tea (Nagao and others ). PPO, which is responsible for enzymatic browning and theorized to cause deodorization, was also tested.…”

Effect of abiotic elicitation on the quality and antioxidant potential of lettuce and endive during storage

“…However, it must be noted that in plant cells polyphenol oxidase (located in plastids) is separated from the phenolic compounds that are present in the vacuoles. Therefore, the enzymatic browning reaction only occurs when this barrier in cells is damaged (Holderbaum, ). The instrumental study of the color of the lettuce and endive leaves in the present investigations showed that the significant change in parameter a * during storage may indicate tissue browning only in the endive leaves (Table ).…”

Sugar and phenol content in apple with or without watercore

“…When ROS accumulates, the membranes are damaged and phenolic compounds are oxidised enzymatically, which results in browning disorders . The role of phenolic compounds in enzymatic browning of apple fruits has been investigated; however, no results are available about phenolic contents of tissue with watercore , before browning has occurred.…”