Enhancement of the recovery of antioxidants from Oenanthe javanica herbal teas by optimizing the fermentation, steaming and rolling processing procedures

There is still a lack of studies evaluating the effect of different methods in processing of herbal tea from Oenanthe javanica. The present study aims to optimize the processing methods for the optimal recovery of antioxidant in the herbal tea. The aerial part of this plant was processed according to the standard manufacturing procedure to produce unfermented, partially-fermented and fully-fermented teas. The highest Ferric Reducing Antioxidant Potential (FRAP) and 1,1-diphenyl-2-picryhydrazyl (DPPH) scavenging activities were indicated by the infusion of unfermented tea with EC50 values of 94.99 ± 0.32 μg/mL and 244.28 ± 11.72 μg/mL, respectively. The aerial part was subjected to steaming for seven different time durations and two rolling conditions. The maximum extraction recovery of total antioxidant (on the basis of FRAP analysis) was achieved from the machine rolled sample that was steamed for 60 min. The FRAP activity (EC50 67.00 ± 0.16 μg/mL) was correlated with the highest total phenolic content (TPC) (10.98 ± 0.41 μg GAE/mg tea), total flavonoid content (TFC) (8.12 ± 0.20 μg QE/mg tea) and persicarin content (96.59 ± 5.32 μg persicarin/mg tea) with r values ranging from -0.627 to -0.817 (p < 0.05). Thus, the findings have highlighted the optimization of steaming and rolling conditions are important procedures to produce herbal tea with high antioxidant ingredients. © 2022 SAAB