Abstract—Miang (Thai fermented tea leaves) was made from wild tea leaves (Camellia sinensis var assamica) by traditional process with associated microorganism by natural. In this study we focus on to examine the chemical constituents as tea polyphenols, major catechins, free amino acids (FAAs) and organics acids belong with pH that dynamic changes during traditional Miang processing in various degree of tea leaf maturity (young and mature leaf). To indicate the level of fermentation which is related to Miang quality and provides the potential benefit for human health. This present study is the first report that the organic acids considered to be key components of Miang fermentation are acetic acid, citric acid, fumaric acid and lactic acid. The pH value in mature Miang reduced faster than young Miang, thus astringent Miang should be made by young tea leaves with optimal fermentation time 10-20 d, pH 5.33-5.34, sour Miang could be made by young or mature tea leave, completed fermentation time 30 d, pH 4.49-4.75. The predominant catechin composition in young and mature Miang for 30 d of fermentation are EGCG, C, EGC, EC, ECG and GCG. The highest caffeine content was in young Miang at 20 d (6.24%DW), and in mature Miang at 30 d of fermentation (6.23%DW). The predominant FAAs in young and mature Miang was theanine which was responsible for umami taste in Miang.
 

Index Terms—Miang, fermented tea leaves, chemical constituents, organic acid, caffeine, processing, leaf maturity

Cite: Tunyaluk Bouphun, Xu Wei, Wu Dan, Renliang Zhao, and Zhu Qi, "Dynamic Changes in Chemical Constituents during Processing of Miang (Thai Fermented Tea Leaf) in Various Degree of Tea leaf Maturity," International Journal of Food Engineering, Vol. 4, No. 3, pp. 178-185, September 2018. doi: 10.18178/ijfe.4.3.178-185