Polyphenol Oxidase from Apple (Malus domestica Borkh. cv Bramley's Seedling): Purification Strategies and Characterization was 30 °C and the enzyme had residual activity of greater than 50% during storage for 72 h at 20 °C to 30 °C and was 30 °C and the enzyme had residual activity of greater than 50% during storage for 72 h at 20 °C to 30 °C and was 30 °C and the enzyme had residual activity of greater than 50% during storage for 72 h at 20 °C to 30 °C and was 30 °C and the enzyme had residual activity of greater than 50% during storage for 72 h at 20 °C to 30 °C and for 24 h at 40 °C to 50 °C.Of the substrates tested, activity was greatest with 4-methylcatechol followed by for 24 h at 40 °C to 50 °C. Of the substrates tested, activity was greatest with 4-methylcatechol followed by for 24 h at 40 °C to 50 °C. Of the substrates tested, activity was greatest with 4-methylcatechol followed by for 24 h at 40 °C to 50 °C. Of the substrates tested, activity was greatest with 4-methylcatechol followed by for 24 h at 40 °C to 50 °C. Of the substrates tested, activity was greatest with 4-methylcatechol followed by catechol, pyrogallol, and (-)-epicatechin. The most effective inhibitors tested were sodium metabisulfite and catechol, pyrogallol, and (-)-epicatechin. The most effective inhibitors tested were sodium metabisulfite and catechol, pyrogallol, and (-)-epicatechin. The most effective inhibitors tested were sodium metabisulfite and catechol, pyrogallol, and (-)-epicatechin. The most effective inhibitors tested were sodium metabisulfite and catechol, pyrogallol, and (-)-epicatechin. The most effective inhibitors tested were sodium metabisulfite and ascorbic acid. ascorbic acid. ascorbic acid. ascorbic acid. ascorbic acid.