The heat stability and isoenzyme composition of peroxidases in Ohane grapes

Abstract

Summary Soluble and ionically bound peroxidases have been obtained from homogenized Ohane grapes. The soluble fraction contained the highest level of peroxidase activity and accounted for approximately 87% of the total enzymic activity. Plots of the percentage of heat inactivation for the grape peroxidases against time were non‐linear with approximately 90% of the peroxidase activity being destroyed after 10 min at 80°C. Following heat inactivation there was no significant regeneration of enzymic activity. Using isoelectric focusing six isoperoxidases with isoelectric points ranging from approximately pI 3.5 to 9.8 were detected.