Effect of Preparation conditions on Phenolic Content and Antioxidant Activity of Various Teas and Herbal Teas

Abstract

Phenolic compounds are known for their positive effects on health such as antioxidant activity. Teas and Herbal teas are good source of phenolic compounds, however most studies about phenolic compounds use organic solvents for extraction, which is not able to be applied in real life. Therefore, the aim of this study was to compare the phenolic content of different teas and herbal teas by the usage of boiled water and methanol as solvent extraction and then to investigate the effect of grounding of these teas and herbal teas on the phenolic content. Twelve Teas and herbal teas were investigated to determine the best extraction conditions of phenolic compounds. Methanol/water mixture was compared to boiling water in extracting phenolic compounds from teas and herbal teas before and after grounding. The phenolic content was determined using Folin-Ciocalteu method. Results show that methanol/water mixture was superior to boiling water in extracting phenolic compounds from whole plant parts. However, no significant difference was found in most extracts between the two solvents after grounding the samples. The antioxidant activity of infusions of ground teas and herbal teas in boiling water was subsequently determined using FRAP method. Black tea, green tea, mate tea and Damaskus rose had the highest phenolic content and the highest antioxidant activity using these conditions of extraction. Results showed an overall positive correlation between antioxidant activity and phenolic content.