Influence of Preparation Methods on the DPPH Radical Scavenging Activity of Commercial Teas

The antioxidant activity of tea infusions may vary depending on commercial formulation and preparation conditions, including temperature, extraction time, and extraction system. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay allows the radical inhibition capacity to be assessed, enabling comparisons of the antioxidant performance of beverages prepared using different methods. This study aimed to compare the antioxidant activity of seven commercial tea formulations prepared using four different systems and to identify the conditions associated with the highest percentages of DPPH radical inhibition. Seven commercial formulations were evaluated under four preparation conditions: conventional infusion of a commercial tea bag (TS), machine extraction from a commercial capsule (TC), conventional infusion of the contents of a capsule (CS), and machine extraction of tea bag contents transferred to a reusable capsule (SC). Conventional infusions were prepared using 200 mL of water at approximately 90 °C for 5 min, whereas machine extractions used approximately 200 mL of water at 68 °C for approximately 18 s. Antioxidant activity was determined using the DPPH assay and expressed as the percentage of radical inhibition (%AA). The results were analyzed descriptively, and the four preparation methods were compared using the Friedman test, with the seven formulations treated as blocks and a significance level of 5%. Antioxidant activity varied according to both formulation and preparation system. The highest individual values were observed for red berry tea prepared using CS (91.71%), apple, hibiscus, and cinnamon tea prepared using SC (90.14%), red berry tea prepared using SC (88.64%), and peach mate tea prepared using SC (88.58%). Considering the mean values across the seven formulations, SC exhibited the highest percentage of radical inhibition (72.77%), followed by CS (67.22%), TC (58.73%), and TS (51.70%). The difference between SC and TS was approximately 21.07 percentage points, indicating higher mean antioxidant activity in infusions prepared by transferring tea bag contents to a reusable capsule. However, the response was not consistent across all formulations, demonstrating that the performance of each system also depends on the characteristics of the product. The Friedman test revealed no statistically significant differences among the methods (p = 0.166).  Therefore, although SC showed the best descriptive performance, its statistical superiority could not be established under the conditions evaluated The SC system exhibited the highest mean antioxidant activity among the four preparation methods, followed by CS, TC, and TS. Despite this trend, the absence of statistically significant differences indicates that the results should be interpreted with caution. The variability observed among formulations highlights the importance of considering both tea characteristics and preparation conditions when comparing DPPH radical scavenging capacity.