Homepage: http://ifstrj.um.ac.ir Full Research Paper Microwave and traditional brewing methods of Iranian black tea: bioactive compounds, antioxidant activity and heavy metals R. Farahmandfar* 1 , S. Aboutalebzadeh 1 , H. Moniri 1 , M. Kaykhaii 2 Received: 2022.09.21 Revised: 2022.12.22 Accepted: 2023.01.30 Available Online: 2023.03.01 How to cite this article: Farahmandfar, R., Aboutalebzadeh, S., Moniri, H., Kaykhaii, M. (2023). Microwave and traditional brewing methods of Iranian black tea: bioactive compounds, antioxidant activity and heavy metals. Iranian Food Science and Technology Research Journal. 18 (6), 141-151. Abstract Black tea, which is obtained from the leaves of small tree Camellia sinensis, is a popular drink that has been consumed for centuries all around the world. In this study, a sample of Iranian black tea was brewed by two methods of microwave and traditional brewing and their extracts were then assessed using 2,2-diphenyl- 1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays to determine their phenolic and flavonoid contents as well as heavy metal (HM) (copper, nickel, chromium, cadmium and lead) content. It was observed that there is a direct relationship between the antioxidant activity with their phenolic and flavonoid contents. The highest and lowest antioxidant activities were observed for samples brewed by microwave at 360 W for 2.5 min and 900 W for 7.5 min, respectively. As the brewing power and time increased, the antioxidant activity decreased. Brewing tea by microwave and traditional methods caused a significant reduction in the amount of heavy metals, which was lower than the allowable limit according to the Iranian national standards. These results demonstrate the importance of exposure time and radiation power when tea is prepared by microwave. Keywords: Black tea; Tea extract; Brewing; Antioxidant; Heavy metals. Introduction Tea is the most broadly used aromatized beverage worldwide and its consumption has a long record. As a drink, it originates using green leaves of Camellia sinensis, which contain compounds such as polyphenols, caffeine, and catechins, that possess medicinal properties. For example, a group of catechins that are extracted from Camellia sinensis green leaves are shown to exhibit anti-cancer effects and extend the life of healthy cells. Due to its 1. Department of Food Science and Technology, Faculty of Agricultural Engineering, Sari Agricultural Sciences and Natural Resources University, Sari, Iran. 2. Department of Process Engineering and Chemical Technology, Faculty of Chemistry, Gdańsk University of nutritional, specific taste, agricultural and financial value, both tea leaves and its extract are used in several industries, including food, cosmetics and beverages (Chen et al., 2020; Ghasemzadeh-Mohammadi et al., 2017; Li et al., 2020). Because of the importance of these elements, many studies have been carried out on tea plants (Wang et al., 2020; Zhang et al., 2020). Besides the presence of the antioxidant compounds, other ingredients such as essential elements that exist in the tea plant have both Technology, Narutowicza 11/12, Gdańsk 80-233, Poland. (Corresponding Author Email: r.farahmandfar@sanru.ac.ir; re1farahmand@gmail.com) DOI: 10.22067/IFSTRJ.2023.78904.1208 ایرانییع غذایم و صناشهای علو پژوه نشریه جلد18 ، شماره6 ، بهمن- اسفند1401 ، ص.151 - 141 Iranian Food Science and Technology Research Journal Vol. 18, No.6, Feb. Mrch. 2023, p. 141-151