The influences of temperature, UV irradiation, pH and copigment concentration on the stability of a copigmentation complex were investigated. The copigments selected for the study included: Catechin, Chlorogenic acid and Gallic acid. Five levels of copigment concentration as: 0, 120, 240, 480, 960 mg L(-1) were examined. The copigmentation effect increased with copigment contain. UV irradiation had a stronger degradation effect on the copigmentation complex than heating at 80 degrees C. The suitable pH for copigmentation complex was in pH 3.5. In this study, catechin predominate among copigments.

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Peroxidase (EC 1.11.1.7; donor: hydrogen-peroxide oxidoreductase, POD) is one of the key enzymes controlling plant growth, differentiation and development. The enzyme participates in construction, rigidification and eventual lignification of cell walls, biosynthesis of ethylene from 1-aminocyclopropane-1-carboxylic acid and H 2 O 2 , regulation of auxin level through auxin catabolism, protection of tissue from damage and infection by pathogenic microorganisms, the oxidation of indoleacetic acid. For peroxidase activity in wild pears extract one pH optimum was observed at 6.5 that probably belong to atleast one isoenzyme. Activity of peroxidase in presence of guaiacol and H 2 O 2 was optimum after incubation at 40 °C. Maximum activity of peroxidase is 300 % .Activity increased to 240 %, 300 %, 70 % and 10 % after 60 minute incubation at 30, 40, 45 and 60 °C for peroxidase. Incubation at high temperature (70 °C) was accompanied with decrease of activity to 10 % peroxidase activity.

Peroxidase (EC 1.11.1.7; donor: hydrogen-peroxide oxidoreductase, POD) is one of the key enzymes controlling plant growth, differentiation and development. The enzyme participates in construction, rigidification and eventual lignification of cell walls, biosynthesis of ethylene from 1-aminocyclopropane-1-carboxylic acid and H2O2, regulation of auxin level through auxin catabolism, protection of tissue from damage and infection by pathogenic microorganisms, the oxidation of indoleacetic acid. For peroxidase activity in wild pears extract one pH optimum was observed at 6.5 that probably belong to atleast one isoenzyme. Activity of peroxidase in presence of guaiacol and H2O2 was optimum after incubation at 40 °C. Maximum activity of peroxidase is 300% .Activity increased to 240%, 300%, 70% and 10% after 60 minute incubation at 30, 40, 45 and 60 °C for peroxidase. Incubation at high temperature (70 °C) was accompanied with decrease of activity to 10% peroxidase activity.