Thermal inactivation kinetics of bromelain in pineapple juice

Bromelain, a protease present in pineapple, needs to be inactivated to assu re consumer acceptance and product stability in canned pineapple products. Available literature reports thermal inactivation kinetics of bromelain ext racted from plant stem, not from fruit pulp and juice. Determination of the rmal inactivation kinetics of bromelain in pineapple juice would lead to op timum heat treatment conditions for minimum loss of juice quality when ther mal degradation kinetics of quality factors are also known. Thermal inactiv ation kinetics of bromelain in pineapple juice were characterized by isothe rmal experiments at 55, 60, 63, 65, and 67 degreesC. Thermal inactivation f ollowed first-order kinetics, and isothermal rate constants varied with tem perature in accordance with the Arrhenius equation. The calculated activati on energy was 3.26 10(5) J/mol, and the frequency factor (reference rate co nstant) was 1.37 10(50) min(-1). A model for bromelain thermal inactivation was developed to predict the residual enzyme activity in response to any d ynamic temperature-time heat treatment, and successfully tested with dynami c heating experiments.