Influence of Steep Time on Polyphenol Content and Antioxidant Capacity of Black, Green, Rooibos, and Herbal Teas

Michael Mcalpine,Wendy Ward

doi:10.3390/beverages2030017

Abstract

Potential health benefits of tea consumption are often attributed to the antioxidant activity of polyphenols. Whether steep time, often variable in a real-life situation, makes a biological difference in terms of polyphenol content and antioxidant activity is uncertain. The study objective was to characterize eight popular and commercially available teas for total polyphenol content (TPC) and antioxidant capacity in relation to steep time. Dragonwell (DW), Sencha (S), English Breakfast (EB), Golden Monkey (GM), Green Rooibos (GR), Red Rooibos (RR), Chamomile (C), and Peppermint (P) loose leaf teas were individually steeped in water for 1–10 min at 1 min intervals. TPC increased with longer durations of steep time; however, the majority of polyphenols observed after 10 minutes were extracted in the first 5 min regardless of tea type. After 5 min of steeping, differences (p < 0.05) in TPC were observed across teas (JS~EB~P > DW > GM~GR~RR > C). Different teas also varied in their ability to inhibit the free radical 2, 2-diphenyl-1-picrylhydrazyl (DPPH) when normalized for polyphenol concentration (1 µg/mL) and there was no effect due to steep time. Predicted antioxidant capacity of teas also demonstrated significant differences among teas after 5 and 10 min. In conclusion, steep time modulates TPC but not the antioxidative capacity of tea polyphenols.

Highlights

IntroductionTea is the second most commonly consumed beverage and is only surpassed by water
On a global level, tea is the second most commonly consumed beverage and is only surpassed by water
One method of receiving more polyphenols without consuming a bitter drink is to selectively choose a tea type that has a greater quantity of polyphenols extracted after similar durations of steeping

Summary

Introduction

Tea is the second most commonly consumed beverage and is only surpassed by water. The cultivation and consumption of tea dates back thousands of years, and the health benefits associated with tea consumption have been well documented, including decreased incidence of cancer and cardiovascular diseases [1,2]. Only tea produced from the leaves of Camellia sinensis can be classified as a “true” tea. The particular type of tea produced depends on how the leaves are processed and their relative levels of oxidation. Despite not being from Camellia sinensis, herbal (i.e., Mint, Chamomile) or rooibos teas can have similar health benefits and have been commonly used in traditional medicine [3,4,5]

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