Abstract—Miang (Camellia sinensis (L.) Kuntze var. assamica (J.W. Mast.) Kitam.) is an Assam tea which is mainly found in northern Thailand. Fermented Miang is made from young and semi-mature Miang leaves by the local wisdom. Briefly, Miang leaves are harvested and steamed for approximately 2 hours prior to cooling down and subsequently packed into a container with close lid. Fermentation process will take place and run for 1-3 months normally. Steaming step renders a high quantity of steamed Miang juices (SMJ) which will be discarded afterwards. Evaluation of this biological waste will bring about ways of making value-added products. The purpose of this study aims to investigate the effects of steaming time and ages of Miang leaves on biological activities of SMJ obtained. Fresh, young and semi-mature, Miang leaves were collected and steamed for 30 minutes, 1, 2 and 3 hours. Meanwhile, young and old Miang leaves were steamed for 2 hours as compared with the conventional method. All SMJ were further evaporated and lyophilized to obtain SMJ crude extracts (CE). The 3-hour SMJ-CE had the highest antioxidant activity and total phenolic content (p<0.05), 548.4±13 μg GAE/ g extract and 460.24±11.8 μg GAE/g extract, respectively. Comparing between SMJ-CE of young and old Miang leaves, the antioxidant activity and total phenolic content of the young leaves SMJ-CE was significantly higher than the old leaves SMJ-CE (p<0.05). Moreover, all SMJ-CE had antibacterial activities to inhibit growth of some gastrointestinal pathogenic bacteria including Bacillus cereus, Escherichia coli, Escherichia coli O157:H7, Salmonella Typhi, Shigella dysenteriae, Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus (MRSA) and Vibrio cholerae with the young leaves SMJ-CE showed the highest activities. The information obtained will be further used as a guideline in food and cosmetic application using SMJ-CE as a raw material.

Index Terms—Antioxidant, Assam tea, Camellia sinensis, Fermented tea, Miang.

Vipanee Chumsai-Na-Ayudhya is with Master of Science Program in Applied Microbiology (International Program), Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand. She is also with Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand and Graduate School, Chiang Mai University, Chiang Mai, 50200, Thailand.
Narumol Thongwai is with Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand. Narumol Thongwai is also with Center of Excellence in Bioresources for Agriculture, Industry and Medicine, Chiang Mai University, Chiang Mai, 50200, Thailand (email: nthongw@hotmail.com).

Cite: Vipanee Chumsai-Na-Ayudhya, Narumol Thongwai, "Biological Activities of Steamed Miang (Camellia sinensis (L.) Kuntze var. assamica (J.W. Mast.) Kitam) Juice Extracts," International Journal of Bioscience, Biochemistry and Bioinformatics vol. 10, no. 2, pp. 66-73, 2020.

Copyright © 2020 by the authors. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).