Optimization and prediction of antioxidant properties of a tea‐ginger extract

A response surface approach was used to investigate the effects of temperature, concentration, and time on the antioxidant properties (total flavonoid ( TF ), total phenol ( TP ), peroxide scavenging activity ( PS ), iron chelating activity ( IC ), DPPH radical‐scavenging ability ( DPPH ), ABTS assay ( ABTS )) of aqueous extract of tea‐ginger (2:1) powder. Color indices, pH , and redox potential of the tea‐ginger powder were also measured and used as independent variables for the prediction of antioxidant properties of the extract using ordinary least square ( OLSR ), principal component ( PCR ), and partial least square ( PLSR ) regression. The R 2 values for TP , TF , ABTS , and PS response surface models were 0.8873, 0.9639, 0.6485, and 0.5721, respectively. The OLSR , PCR , and PLSR were able to provide predictive models for DPPH , TP , and TF of the tea‐ginger extract ( P  < 0.05). The PLSR gave the most parsimonious model with an R 2 of 0.851, 0.736, and 0.905 for DPPH , TP , and TF , respectively.