Comparison of the Fungal Community, Chemical Composition, Antioxidant Activity, and Taste Characteristics of Fu Brick Tea in Different Regions of China

Abstract

In this study, the fungal community structure, metabolites, antioxidant ability, and taste characteristics of five Fu brick tea (FBT) from different regions of China were determined and compared. A total of 69 operational taxonomic units (OTUs) were identified and assigned into 5 phyla and 27 genera, with Eurotium as the predominant genus in all samples. Hunan (HN) sample had the strongest fungal diversity and richness, followed by Guangxi (GX) sample, and Zhejiang (ZJ) sample had the lowest. GX sample had higher amounts of gallic acid (GA), total catechins, gallocatechin (GC), and epicatechin gallate (ECG) as well as antioxidant activity than the other samples. The levels of total phenolics, total flavonoids, epigallocatechin (EGC), catechin, epicatechin (EC), thearubigins (TRs), and theaflavins (TFs) were the highest in the ZJ sample. Guizhou (GZ) and Shaanxi (SX) samples contained the highest contents of epigallocatechin gallate (EGCG) and gallocatechin gallate (GCG), respectively. Total phenolics, GA, EC, CG, and TFs were positively associated with most of fungal genera. Total phenolic content (TPC), total flavonoid content (TFC), and most of catechins contributed to the antioxidant activities of FBT. HN sample had the strongest sourness and sweetness, ZJ sample had the strongest saltiness, SX sample had the strongest umami, and GZ sample had the strongest astringency, which was ascribed to the varied metabolites. This work reveals that FBT in different regions vary greatly in fungal community, metabolites, antioxidant activity, and taste characteristics, and provides new insight into the quality characteristics formation of FBT in different regions.

Effects of Preharvest Shading on Dynamic Changes in Metabolites, Gene Expression, and Enzyme Activity of Three Tea Types during Processing

“…The extracts were analyzed at 570 nm using a spectrophotometer (NanoDrop 2000). Total phenolic content in tea samples was determined using the Folin-Ciocalteu method in accordance with the literature . The aluminum trichloride technique was used to calculate the flavone content .…”

Discrimination and characterization of the volatile profiles of five Fu brick teas from different manufacturing regions by using HS–SPME/GC–MS and HS–GC–IMS

“…Fungal communities have been reported to be a critical contributor to the drastic effects on the aroma compounds of postfermented FBT ( Li et al, 2020a ). In our previous study, we investigated the fungal communities of diverse FBT samples and found them to be considerably different ( Chen et al, 2022 ). Spearman connection analysis was conducted to clarify the differences in fungal communities (at the genus level) leading to the variation in VOCs in different FBT samples, and the result is shown in Fig.…”

“…6 Network correlation between fungal community and volatile flavor compounds. The abbreviations of fungi are shown in our previous study ( Chen et al, 2022 ). G1: Eurotium , G2: Aspergillus , G3: Thermoascus , G4: Monascus , G5: Saccharomycopsis , G6: Debaryomyces , G7: Saccharomyces , G8: Udeniomyces , G9: Marasmius , G10: Alternaria , G11: Penicillium , G12: Chytridiomycota _unclassified, G13: Saccharomycetales_Incertae _sedis_unclassified, G14: Nectriaceae _unclassified, G15: Chaetothyriales _unclassified, G16: Mortierella , G17: Sporobolomyces , G18: Eurotiomycetes _unclassified, G19: Monosporascus , G20: Wallemia , G21: Agaricomycetes _unclassified, G22: Fungi _unclassified, G23: Thermomyces , G24: Quambalaria , G25: Spizellomycetaceae _unclassified, G26: Malassezia , G27: Ascomycota _unclassified.…”

“…It is gaining popularity worldwide due to its unique flavor and health effects. The main production areas of FBT in China are Hunan, Zhejiang, Guizhou, Guangxi, and Shaanxi Provinces ( Chen et al, 2022 ). Piling, steaming, pressing, fermentation, and drying are the main steps in the manufacture of typical postfermented FBT and contribute to the formation of the distinct aroma features of FBT ( Ling et al, 2010 ).…”

“… Tian et al (2013) revealed that the bacterial community structure of Pu'er tea differed depending on storage conditions and that bacterial diversity was linked to aging time. Our previous study revealed that the fungal communities of FBT samples from different regions of China varied greatly and influenced the metabolites, antioxidant activity, and taste characteristics of the teas ( Chen et al, 2022 ). However, only a few previous studies have focused on the dynamic changes in microbial composition and metabolites during the manufacturing of FBT.…”