Statistical optimization for enhanced decolorization of Golden Yellow PRA by Citrus reticulata var. kinnow peroxidase and phytotoxicity evaluation of its degraded products

Abstract

In the present study, the decolorization of Golden Yellow PRA by Citrus reticulate var. kinnow peroxidase (GYPRA) was investigated. Optimization of important process parameters viz. pH, temperature, enzyme dose, concentrations of H₂O₂, and dye was done by applying one-factor-at-a-time and response surface methodology. Through OFAT analysis, maximum decolorization (91.77%) of the dye was observed with pH 2.0, temperature 40°C, enzyme dose 24 U/mL, H₂O₂ concentration 0.375 mM, and Golden Yellow PRA concentration of 100 mg/L. The effect of mediators was also investigated and 0.05 mM of vanillin caused 95.98% decolorization, within just 5 min. The presence of metal ions did not exert any drastic influence on the process of decolorization, ensuring it suitable for industrial applications. For statistical optimization, three factors of pH, enzyme dose, and dye concentration were selected. Then, response surface analysis was conducted through central composite design and a second-order polynomial model (0.9894) was generated. ANOVA analysis of this model indicated that the pH, enzyme dose, dye concentration and their interaction were the most significant in decolorization of GYPRA. Optimum condition through RSM was found to be the pH of 3, enzyme dose 26.77 U/mL, and dye concentration of 86.88 mg/L, for enhanced decolorization.

Keywords:

• Decolorization
• Phytotoxicity
• Golden Yellow PRA
• Response surface methodology

Acknowledgments

This work is a part of PhD thesis of Miss Shazia Nouren. The authors are thankful to Higher Education Commission of Pakistan for financial assistance under Indigenous 5000 PhD Fellowship and International Research Support Initiative Programs.