Improved extraction of green tea components from teabags using the microwave oven

Abstract

The green tea (Camellia sinensis) catechins are strong antioxidants linked with potential health benefits. Based on previous studies, it was hypothesised that the typical household conditions for brewing green tea in a teabag – 200mL freshly boiled water for 2–3min, as per the manufacturers’ instructions – were not sufficient to extract all the catechins and that a household microwave oven could be used to improve the extraction. The catechins and the two other main green tea components, caffeine and theanine, were monitored by HPLC. The typical household conditions only extracted 62% (61mg/g tea), 76% (24mg/g) and 80% (10mg/g) of the catechins, caffeine and theanine, respectively, from the five varieties of teabags analysed. However, using microwave assisted extraction (MAE) by first brewing a teabag in 200mL freshly boiled water for 0.5min before irradiation for 1min in a microwave oven (hot MAE), improved the extraction of the catechins and caffeine to 80% (80mg/g) and 92% (29mg/g), respectively, although the extraction of theanine was not affected. Therefore, the hot MAE technique could help maximise the extraction of the catechins for those who consume green tea for the potential health benefits of the catechins.