Studies on Decolorization Characteristics of Crude Peroxidase from Raphanus sativus Using Response Surface Methodology

Abstract

Dye decolorization with the help of a plant based enzyme was investigated. Crude peroxidase (35.58 U/ml) extracted from the pulp of Raphanus sativus (radish) was used for decolorization of a basic dye, safranin. The effect of the influencing parameters of pH, temperature, dye concentration, and enzyme concentration on safranin decolorization was primarily studied using the traditional One Factor At a Time method (OFAT). The optimal values of each influencing parameter for maximum decolorization were obtained via the OFAT approach which can be extended to study factorial interactions by applying range levels statistically. To obtain the optimal operating conditions for decolorization, the influencing process parameters were optimized further by applying Response Surface Methodology based on Box-Behnken Design. A three level four factor design was generated using the Design Expert software version 8.0.7.1. A quadratic model was fitted for the experimental data obtained, and the significance of the model predicted was analyzed through Analysis of Variance (ANOVA) at the 95 % confidence interval. The determination coefficient, R², of the model was found to be 0.8993. The optimal process conditions were found to be a temperature of 30 °C, a dye concentration of 200 mg/l, an incubation time of 60 min, and an enzyme concentration of 26.69 U/ml, producing 30.07 % decolorization at an optimum pH of 7, which is in accordance with the predicted value of 29.24 %. Confirmatory experiments verified the adequacy of the model. The study provides a foundation for further research on enzyme based decolourization of safranin.

Keywords

• Dye
• radish
• enzyme
• safranin
• decolorization
• Box- Behnken design