Effects of domestic cooking on the bioactive compounds of pohpohan leaves (Pilea trinervia L)

Abstract

This study aimed to analyze the influence of domestic cooking methods on the total phenolic content (TPC), antioxidant activity, and bioactive compounds of pohpohan leaves. This is the first study to examine the effect of domestic processing on the bioactive compounds of pohpohan leaves. The cooking methods included boiling for 5 and 15 mins at 100°C, boiling for 5 and 15 mins at 70°C, steaming for 5 and 15 mins, and heating by microwave for 1 and 3 mins. The TPC was determined by using the Folin-Ciocalteu method, while the antioxidant activity analysis was conducted by 2,2-diphenyl-1- picrylhydrazyl assay. Moreover, the bioactive components (caffeic and ferulic acids) were analyzed by a reversed phase-ultra high-performance liquid chromatography. The results showed that domestic cooking significantly decreased the TPC and antioxidant activity of pohpohan leaves, with the lowest changes recorded for steaming and microwave heating. The highest TPC was observed in raw leaves extract, measuring about 84.43±3.43 mg GAE/100 g wet basis, followed by microwave heating, steaming, and boiling, respectively. The highest antioxidant activity was measured in raw leaves extract, followed by steaming and boiling. Additionally, microwave heating significantly enhanced the antioxidant activity of pohpohan leaves and preserved the ferulic and caffeic acid content. In summary, domestic processing methods have different effects on the preservation of TPC, antioxidant activity, and bioactive compounds and these results are implied in the functional properties of pohpohan leaves.