摘要：Previous investigations demonstrated that crude peroxidase (POD) obtained from onion solid wastes has the ability to catalyse the formation of the aurone aureusidin (ARS), using 2´,4´,6´,3,4-pentahydroxy chalcone (PHC) as substrate, although this reaction under physiological conditions is mediated by a polyphenol oxidase-like enzyme, called aureusidin synthase (AS). In this study, a crude onion POD preparation was used to study the effect of some critical factors affecting the reaction, including reaction time, pH and temperature. The optimal set of conditions was identified by deploying central composite factorial design and response surface methodology. The results obtained showed that the optimum values for pH and temperature were 5 and 20°C, respectively, while time was found to exert a statistically non-significant effect. These values were the same or very close to optimal conditions found for structurally different onion POD substrates. The outcome was discussed with regard to the applicability of the onion POD as a versatile tool of biocatalysis.
