Optimization of the Effect of Temperature, Concentration and pH on Antioxidant Capacity by Gallic Acid by Response Surface Methodology (RSM)
Gilberto Mercado-Mercado
*
Departamento de Ciencias Químico Biológicas, Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Anillo Envolvente Pronafy Estocolmo, Zip Code 32310, Ciudad Juárez, Chihuahua, México.
Elsa Carolina Núñez-Brito
Departamento de Ciencias Químico Biológicas, Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez, Anillo Envolvente Pronafy Estocolmo, Zip Code 32310, Ciudad Juárez, Chihuahua, México.
*Author to whom correspondence should be addressed.
Abstract
The antioxidant capacity of gallic acid (GA) is affected by temperature and pH.
Aim: To understand this phenomenon, we evaluated the optimization of conditions between temperature (2°C, -20 °C, 40 °C), pH (3,7,10) and concentrations (1 mM, 4 mM and 7 mM) to have a better antioxidant capacity by response surface methodology (RSM).
Methods: The DPPH method was used to measure the percentage inhibition (%Inh). Concentrations, 23 °C and pH 7 were evaluated, respectively. Three temperatures (2°C, -20 °C, 40 °C) were combined with the same concentrations and pH in a Box-Behnken design model.
Results: The combination of the three factors significantly influenced the %Inh. The factor levels that resulted in higher %Inh were 2 °C, acidic pH and 4 mM concentration. The RSM showed that the optimum conditions had %Inh values of DPPH of 87.66%, 87.11% and 88.29%, respectively.
Conclusion: the antioxidant capacity of GA. at 2 °C and pH 2 creates highest antioxidant capacity of GA.
Keywords: Gallic acid, antioxidant capacity, DPPH, response surface methodology