Determination of some biochemical properties of polyphenol oxidase, pectin methyl esterase, ß-glucosidase and carotenase from some apricot varieties

In this study, effects of polyphenol oxidase (PFO), pectinmethyl esterase (PME), ß-glucosidase and carotenase were investigated on quality of Hacıhaliloğlu, Kabaaşı and Alyanak apricot varieties during ripening and ripen phases in Malatya province, that is an important apricot production center of Turkey. The activities of PFO, PME and ß-glucosidase as well as profiles of total phenol and phenol compounds and changes in browning degree were examined during ripening. In addition biochemical properties of these enzymes were determined with purification.The most common phenolic compound determined in all apricot variety was chlorogenic acid followed by catechin, rutin, procyanidine B1 and procyanidine B2. Hacıhaliloğlu variety was determined to contain the highest amounts of chlorogenic acid, gallic acid, coumaric acid, catechin, epicatechin, procyanidine B1, rutin and kaempferol-3-rutinoside. Hacıhaliloğlu variety also contained the highest amount of total phenol compounds, which was followed by Alyanak and Kabaaşı varieties, respectively.The amounts of phenol compounds and total phenol compounds investigated in the study decreased during the ripening. The highest values of browning degree, specific activity, chlorogenic acid, catechin and total phenol compounds were determined in Hacıhaliloğlu variety, which was followed by Alyanak variety, while the lowest values were observed in Kabaaşı variety. In enzyme purification studies, 3 PFO isoenzymes of Alyanak variety, 4 PFO isoenzymes and 2 ß-glucosidase isoenzymes of Hacıhaliloğlu variety were determined. Specific activities of PFO, ß-glucosidases and PME decreased with ripening in all apricot varieties. In enzyme characterization studies, biochemical properties of enzymes were determined to differ by apricot vatiety, harvest year and isoenzymes. No carotenase activity was determined in carotenase activity measurement performed in all ripening stages of apricot and for all varieties.