Abstract
Objective
In Asahi-machi, Toyama Prefecture, there is a post-fermented tea called “Batabata-cha”. During fermentation period, steamed tea leaves are placed in a chamber to its fermentation, and a process termed "kirikaeshi"（turning over) is implemented to transfer the leaves to new chambers in order to maintain a consistent fermentation temperature. Throughout fermentation process, the leaves undergo a transformation, suggesting that significant alterations occur in the tea's chemical composition and microflora. However, changes over time during fermentation process have not been studied. Therefore, samples were obtained from the manufacturer at different stages of fermentation and were evaluated for their microbial flora and various components.
Methods
Free amino acids, organic acids, and catechins were analyzed by amino acid analyzer, ion chromatography, and LC-MS, respectively. Aroma components were evaluated by GC/MS/O. ACE inhibitory activity and α-glucosidase inhibitory activity were determined by a commercial assay kit.
Results
The number of viable microorganisms from “Batabata-cha” at each stage of production decreased by steaming the leaves, and then increased markedly after about one month of fermentation. However, it decreased by sun-drying, the final manufacturing step of the tea. Aspergillus were identified predominantly in all processes. Furthermore, Bacillus and Paenibacillus persisted after drying, indicating that aerobic fermentation was promoted by the unique process, “kirikaeshi” specific to the production of the tea, and that the characteristics of fermentation microflora were reflected in the presence of viable bacteria.
Changes in various components were also examined.
