Optimization of a natural low-calorie antioxidant tea prepared from purple corn (Zea mays L.) cobs and stevia (Stevia rebaudiana Bert.)

Abstract Purple corn (Zea mays L.) is a crop native to Peru and also widely cultivated in some countries around the world. It contains anthocyanins and other phenolic compounds that help reduce the incidence of a variety of chronic diseases. Here, a natural low-calorie antioxidant purple corn cob and stevia-based tea was optimized after being developed from five ingredients: purple corn cob (PCc), quince (Q), stevia (S), cinnamon (C) and cloves (Cv). A corn fiber filtration bag was selected to package single doses of the tea mixtures, based on the porosity, solid leakage during preparation and infusion absorption spectrum of four different types of bag. The tea was then optimized using an I-optimal mixture design to maximize the antioxidant capacity (AC) and total monomeric anthocyanin (TMA) content of the infusions. The optimum formulation given by the regression model consisted of decimal fractions of 0.8672 for PCc, 0.0464 for Q and 0.0864 for S, with a desirability of 91.2%, AC of 9.51 ± 1.21 μmol TE/mL and TMAs of 98.49 ± 6.00 mg C3GE/L, which were validated. The C and Cv contents were set at 0.0333 and 0.0025 of the total mixture, respectively.