A fermented tea with high levels of gallic acid processed by anaerobic solid-state fermentation

Dynamic Changes in Chemical Constituents during Processing of Miang (Thai Fermented Tea Leaf) in Various Degree of Tea leaf Maturity

“…However, during fermentation period 30 d, the flavonoids content in young Miang was a steady decrease until at the end of the fermentation, at 30 d, whereas the flavonoids content of mature Miang was a dramatic fluctuate for the following steamed tea leaves to the end of fermentation, at 30d. Notably, the amounts of flavonoid of young and mature Miang decreased and closely values at 30d of fermentation time, these results are in good agreement with the previous report of pickled tea that fermented by anaerobic solid-state in controlled condition [5] and similar to the changes in flavonoid content in Pu-erh tea during pile fermentation [23]. Decreasing in flavonoids content and changing of tea polyphenol content in Miang tea by natural fermentation might be only related to the extracellular enzymes derived from the microorganisms appearing in the fermentation process, because of the indigenous enzymes in fresh tea leaves are inactivated by streaming which is the heat treatment before they are started to the beginning of fermentation [19].…”

“…After this, the pH of the young Miang remained stable at around 5.33 until at 20d and finally decreased rapidly to 4.49 (p<0.05) by the end of fermentation at 30 d, whereas the pH of the mature Miang decreased from 5.86 to 4.83 (p<0.05) between 10 d and 20 d, and finally remained stable by 4.75 at 30d of fermentation period. These results are similar to those in pickle tea, in which the pH value was 4.67 remain stable from 30d to 60d [5] and also reported a pH of Miang between 4.1 and 4.6 which fermented for a week or many months [20]. Interestingly,in this study the pH value in young Miang was in the range 5.33-5.34 between 10d and 20 d in fermentation time, which should be classified as astringent Miang,but the pH in mature Miang was in the range 4.83-4.75 from 20d to 30d of fermentation period, it could be as sour Miang, however at the 30d both of young and mature Miang has closely pH value (4.49 and 4.75 as sour Miang).This study was in good agreement with previous study [3] that indicated the astringent Miang often produced from young tea leaves but it has not been reported the actual period of fermentation, thus we can suggest the optimal fermentation time for production astringent Miang and sour Miang.…”

“…There were a similar trends changing between young and mature tea leaves during Miang processing, the highest of soluble sugar contents in young and mature steamed tea leaves by 32.86% and 29.82 % respectively, then they decreased sharply at 10 d of fermentation period, after this the contents of soluble sugar were a steady hold between 10 d and 30 d of fermentation with 13.73% and 12.87% in young and mature Miang, respectively. Decreasing trends of soluble sugar contents in Miang tea during fermentation were similar to that pickle tea which produced in controlled condition [5]. Additionally, we observed stream-heating in Miang processing having influence on the flavonoids and soluble sugar which were released and were easy using for microorganisms during fermentation process.…”

“…There are different names in each country, include: Suancha, Yancha and Liangpan-tea in China, Awabancha and Goishi-cha in Japan, Laphet in Myanmar and Miang in Thailand and Laos [5]. Recently reports show the high levels of gallic acid in pickled tea by anaerobic solid-state fermentation reached to the level in Galla chinensis as can be functional tea was reported [5], the resorcinol, a specific-antioxidant in Awa-ban tea, was identified as a novel antioxidant [6], the caffeine and the catechins contents in Miang tea produced in Thailand were analyzed [3]; [7] as well as the polyphenol content of Laphet was also analyzed [8]. Besides the aroma components of Miang examined [9].…”

Effects of roasting treatment on non‐volatile compounds and taste of green tea

“…They were trained to evaluate and quantify the intensity of sweet, sour, bitterness, umami and astringency taste using the following compounds dissolved in deionised water: sucrose (50 mM) for sweet taste; lactic acid (20 mM) for sour taste; caffeine (1 mM) for bitter taste; sodium glutamate (3 mM) for umami taste; and EGCG (0.8 mM) for astringency taste as standard judgments. The sensory score (total points 100) was marked according to the scoring criteria in Table S2 (Huang et al, 2016). For sensory analysis of green tea, leaves were infused according to ISO standard (ISO 3103:1980) with a slight modification.…”