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Fermentation
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New Fermented Tea: Processing Technology, Microbiology and Health Benefits
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New Fermented Tea: Processing Technology, Microbiology and Health Benefits

A special issue of Fermentation (ISSN 2311-5637). This special issue belongs to the section "Fermentation for Food and Beverages".

Deadline for manuscript submissions: closed (30 August 2023) | Viewed by 10262

Special Issue Editor

Dr. Chunwang Dong

E-Mail Website
Guest Editor
Tea Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, China
Interests: tea processing; tea quality; intelligent sensing technology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Tea has acquired increasing attention due to its health-care effects. Among six traditional categories of Chinese tea, black tea (fully fermented tea), oolong tea (semi-fermented tea) and green tea (non-fermented tea) have already been known as a daily drink for years. Now, a novel fermented tea (including Camellia sinensis and other herbal teas) has come out ahead of traditional tea with its special flavour and health efficacy. It is a little different from traditional fermentation methods. The external conditions affecting the degree of fermentation are no longer limited to temperature and humidity. For example, microbial fermentation affects the sensory quality and metabolic profile, creating a novel kind of tea drink, such as dark tea and kombucha. Moreover, the flavour and health benefits of other teas can also be improved by exogenous microorganism inoculation during tea processing.

Moreover, innovative non-destructive detection technology will contribute to solving some of these problems, such as near-infrared spectroscopy (NIRS), machine vision (also called electronic eye (E-eye)), hyperspectral imaging (HIS) and olfactory visualisation (also called colourimetric sensing array (CSA)). A single technology can determine the characteristics related to only one aspect of a sample and analyse the fermentation quality of tea and herbal teas. For instance, NIRS can identify the main non-volatile components in these drinks and E-eyes can capture the appearance-related characteristics of these teas and herbal teas. Based on these features and an artificial intelligence algorithm, the fermentation quality of teas and herbal teas is evaluated qualitatively and quantitatively. These methods are effective, convenient and non-destructive. They have improved the intelligence level of tea fermentation, and it can be expected that the search for intelligent detection of tea fermentation will continue.

This Special Issue aims to reveal the processing technology, non-destructive detection technology of fermentation quality, metabolic mechanism and health benefits of the new fermented tea.

The following topics are welcome:

  • Microbiology and health benefits;
  • Novel fermented tea and herbal teas;
  • New processing technology of daily drinks.

Dr. Chunwang Dong
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Fermentation is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2100 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • new fermented tea
  • manufacturing processes
  • fermented methods
  • flavour
  • microbial action
  • biological mechanism
  • human health

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Published Papers (6 papers)

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Research

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14 pages, 1651 KiB  
Article
Quercus robur and pyrenaica: The Potential of Wild Edible Plants for Novel Kombuchas
by Olaia Estrada, Lucía Gayoso, Gorka Ortega and Blanca del Noval
Fermentation 2023, 9(10), 863; https://doi.org/10.3390/fermentation9100863 - 22 Sep 2023
Viewed by 1157
Abstract
Wild edible plants (WEPs) can be utilised as a substrate to develop novel types of fermented beverages. The aim of this study was to investigate the potential of incorporating Quercus spp. leaves as a substrate to develop new varieties of kombuchas. The physicochemical [...] Read more.
Wild edible plants (WEPs) can be utilised as a substrate to develop novel types of fermented beverages. The aim of this study was to investigate the potential of incorporating Quercus spp. leaves as a substrate to develop new varieties of kombuchas. The physicochemical properties of kombuchas elaborated with Quercus robur (KQR) and Quercus pyrenaica (KQP) leaves’ infusion were compared with traditional black tea kombuchas (KBT). Total acidity (TA), pH, total soluble solids (TSSs), instrumental colour, total phenolic compounds (TPCs), sucrose, fructose, and glucose were analysed for the three types of infusions and kombuchas at 0, 3, 7, 10, and 14 fermentation days. The results revealed that the type of substrate and the fermentation time significantly influenced the biochemical changes that occurred during 14 days. KQP and KQR turned out to be significantly brighter (L*: 53.91 ± 0.12 and 55.66 ± 0.23, respectively) than KBT (L*: 48.79 ± 0.34) and had significantly lower sucrose content (22.06 ± 0.79 g L−1 and 45.69 ± 1.61, respectively) than KBT (59.28 ± 2.25 g L−1). KBT showed significantly higher content of total polyphenols (1.50 ± 0.05 g GAE L−1) than KQR (0.76 ± 0.09 g GAE L−1) and KQP (0.51 ± 0.04 g GAE L−1) after 14 days of fermentation. Regarding the kinetics of sugars, sucrose reduction was significantly lower in KBT samples (11.36 g L−1) than in KQP and KQR samples (47.01 and 28.31 g L−1, respectively) at the end of fermentation. These results suggest that higher content of TPC may slow down the fermentation process. Quercus spp. leaves may be a viable alternative substrate for developing analogues of kombucha with WEPs and for adding gastronomic and sustainable value. Full article
(This article belongs to the Special Issue New Fermented Tea: Processing Technology, Microbiology and Health Benefits)
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13 pages, 8301 KiB  
Article
Real-Time Discrimination and Quality Evaluation of Black Tea Fermentation Quality Using a Homemade Simple Machine Vision System
by Chongshan Yang, Ting An, Dandan Qi, Changbo Yuan and Chunwang Dong
Fermentation 2023, 9(9), 814; https://doi.org/10.3390/fermentation9090814 - 6 Sep 2023
Cited by 1 | Viewed by 1608
Abstract
Fermentation is a key link in determining the quality and flavor formation of black tea. However, during the actual production, the judgment of black tea fermentation quality mainly relies on the sensory evaluation of the tea maker, which is more subjective and prone [...] Read more.
Fermentation is a key link in determining the quality and flavor formation of black tea. However, during the actual production, the judgment of black tea fermentation quality mainly relies on the sensory evaluation of the tea maker, which is more subjective and prone to cause inconsistency in tea quality. Traditional testing methods, such as physical and chemical analyses, are time-consuming, laborious, and costly and are unable to meet the needs of the actual production. In this study, a self-developed machine vision system was used to quickly and accurately identify the degree of black tea fermentation by acquiring color and texture information on the surface of fermented leaves. To accurately control the quality of black tea fermentation and to understand the dynamic changes in key endoplasmic components in the fermented leaves, a quantitative prediction model of the key endoplasmic components in the fermentation process of black tea was constructed. The experiments proved that the system achieved 100% accuracy in discriminating the degree of fermentation of black tea, and the prediction accuracy of catechin components and thearubigin content reached more than 0.895. This system overcomes the defects of accurate measurement of multiple sensors coupled together, reduces the detection cost, and optimizes the experimental process. It can meet the needs of online monitoring in actual production. Full article
(This article belongs to the Special Issue New Fermented Tea: Processing Technology, Microbiology and Health Benefits)
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15 pages, 2400 KiB  
Article
Study on the Synthesis of Theaflavin-3,3′-Digallate Catalyzed by Escherichia coli Expressing Tea Tree Polyphenol Oxidase Isozymes and Its Enzymatic Solution
by Changwei Liu, Jinghui Zhou, Jianan Huang, Wei Xu and Zhonghua Liu
Fermentation 2023, 9(8), 770; https://doi.org/10.3390/fermentation9080770 - 18 Aug 2023
Cited by 3 | Viewed by 1515
Abstract
Polyphenol oxidase and its isoenzymes are crucial enzymes in the tea tree that catalyze the synthesis of theaflavins. In this study, tea tree polyphenol oxidase was used as the research object, and various protein sequence treatments, such as TrxA fusion tag + N-terminal [...] Read more.
Polyphenol oxidase and its isoenzymes are crucial enzymes in the tea tree that catalyze the synthesis of theaflavins. In this study, tea tree polyphenol oxidase was used as the research object, and various protein sequence treatments, such as TrxA fusion tag + N-terminal truncation, were tested for prokaryotic expression through the Escherichia coli expression system. Comparative analyses were conducted on the activities of the different recombinant enzyme proteins on the substrates of tea polyphenol fractions. Additionally, the enzyme with the highest catalytic efficiency on the TFDG substrate was immobilized using polyethylene glycol to investigate the yield of its synthesis of TFDG. Our results demonstrated that after N-terminal truncation and TrxA fusion expression, CsPPO1, CsPPO2, CsPPO3, and CsPPO4 were mostly expressed in the form of inclusion bodies in the cell and exhibited varying degrees of enhancement in substrate activity. Specifically, CsPPO1 exhibited significantly increased activity in EC and ECG, CsPPO2 showed enhanced activity towards ECG and EGCG, and CsPPO2 displayed the highest activity toward TFDG substrates. Homology modeling structural analysis of the polyphenol oxidase isozymes revealed that the active centers of CsPPO1, CsPPO2, and CsPPO3 consisted of double copper ion center structures, while the conserved histidine residues surrounding the active centers formed different catalytic activity centers in different structures. Furthermore, polyethylene glycol immobilization significantly increased the activity recovery of the CsPPO2 enzyme to 74.41%. In summary, our study elucidated that tea tree polyphenol oxidase is expressed as inclusion bodies in prokaryotic expression, and the activity of the recombinant enzyme towards substrates could be enhanced through N-terminal truncation and TrxA fusion expression. Moreover, immobilization treatment of the CsPPO2 enzyme greatly improved enzyme efficiency. These findings offer an important enzymatic basis and theoretical support for the synthesis of theaflavins. Full article
(This article belongs to the Special Issue New Fermented Tea: Processing Technology, Microbiology and Health Benefits)
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14 pages, 2141 KiB  
Article
Interaction and Metabolic Function of Microbiota during Tibetan Tea Fermentation through Bioaugmentation with Aspergillus niger
by Kunyi Liu, Liyan Han, Qi Wang, Liran Yang, Xiangyu Liu, Bin Jiang, Xu Zeng, Yun Liu, Mingyong Li, Wenwen Jiao and Mingli Liu
Fermentation 2023, 9(7), 690; https://doi.org/10.3390/fermentation9070690 - 24 Jul 2023
Cited by 2 | Viewed by 1357
Abstract
Developing an effective method to achieve stability and improve the quality of Tibetan tea has scientific significance. Aspergillus niger K1 isolated and identified from Tibetan tea was inoculated in unsterilized or sterilized tea leaves to develop the bioaugmented fermentation (BF) and normal fermentation [...] Read more.
Developing an effective method to achieve stability and improve the quality of Tibetan tea has scientific significance. Aspergillus niger K1 isolated and identified from Tibetan tea was inoculated in unsterilized or sterilized tea leaves to develop the bioaugmented fermentation (BF) and normal fermentation (NF) processes of Tibetan tea. The results showed that BF resulted in infusions with a deeper color, a stronger aroma, and a thicker taste compared to NF. The dominant bacterium in BF was Staphylococcus (23.76%), while the dominant fungus was Blastobotrys adeninivorans (50.95%). Moreover, 859 metabolites were identified, and the level of 90 differentially changed metabolites (DCMs) in BF increased significantly (VIP > 1, p < 0.05, FC > 2) compared to those in NF, while the level of 37 DCMs in BF decreased significantly (VIP > 1, p < 0.05, FC < 0.5). Correlation analysis demonstrated that A. niger significantly positively correlated with theabrownins, caffeine, and glutamylisoleucine (p < 0.05, |r| > 0.8). B. adeninivorans showed significant negative correlations with 1-(beta-D-ribofuranosyl)-1,4-dihydronicotinamide and 2-hydroxyacetaminophen sulfate (p < 0.05, |r| > 0.8). Consequently, the inoculation of A. niger for BF has the potential to alter the metabolites in tea through a synergistic interaction with other microorganisms, ultimately improving the sensory quality of Tibetan tea. Full article
(This article belongs to the Special Issue New Fermented Tea: Processing Technology, Microbiology and Health Benefits)
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18 pages, 19744 KiB  
Article
Biosynthesis of Silver Nanoparticles from Fermented Bush Tea (Athrixia phylicoides DC) Leaf Extract and Evaluation of Their Antioxidant and Antimicrobial Properties
by Mpho Edward Mashau, Theshano Mamagau, Kgethego Foforane, Bono Nethathe, Maanea Lonia Ramphinwa and Fhatuwani Nixwell Mudau
Fermentation 2023, 9(7), 648; https://doi.org/10.3390/fermentation9070648 - 10 Jul 2023
Cited by 1 | Viewed by 1689
Abstract
Green synthesis is a promising strategy for producing eco-friendly, non-toxic, and less expensive metallic nanoparticles from plants and microorganisms. This research synthesized silver nanoparticles (AgNPs) from fermented leaf extract of bush tea (Athrixia phylicoides DC). The physicochemical characterization of AgNPs was conducted [...] Read more.
Green synthesis is a promising strategy for producing eco-friendly, non-toxic, and less expensive metallic nanoparticles from plants and microorganisms. This research synthesized silver nanoparticles (AgNPs) from fermented leaf extract of bush tea (Athrixia phylicoides DC). The physicochemical characterization of AgNPs was conducted by UV-vis spectroscopy, Fourier Transform Infrared Spectrometry (FTIR), and Differential Scanning Calorimetry (DSC). In addition, the total phenolic and flavonoid contents, antioxidant and antimicrobial activities of AgNPs were evaluated. The results indicated the successful formation of AgNPs by a visual change of color in fermented bush tea leaf extract from black to brown and in unfermented bush tea leaf crude extract from dark brown to light brown. The UV-vis spectrum of the reaction of the mixture of synthesized AgNPs with unfermented and fermented bush tea showed maximum absorbance at 457 nm and 450 nm, which confirmed the formation of AgNPs. FTIR revealed the functional groups of a leaf extract from bush tea that contributed to the reduction and capping process. The thermal properties suggest that low thermal stable compounds contributed to the reduction of Ag+ to Ag° in the phyto compounds found in the extract. The total phenolic content was higher in fermented AgNPs (290.44 mg/g GAE) compared to unfermented AgNPs (171.34 mg/g GAE). On the other hand, the total flavonoid content was higher in unfermented AgNPs (17.87 mg/g CE) than in fermented AgNPs (9.98 mg/g CE). Regarding antioxidant activity values, unfermented AgNPs had the highest FRAP (535.30 TE/mL) and 47.58% for DPPH. Fermented AgNPs had more antimicrobial activity than unfermented AgNPs. The results show that bush tea leaf extract can be used in different industries such as food, cosmetics, and biomedical. Full article
(This article belongs to the Special Issue New Fermented Tea: Processing Technology, Microbiology and Health Benefits)
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Review

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13 pages, 1168 KiB  
Review
Relationship between the Physiological Activity of Japanese Post-Fermented Teas and Lactic Acid Bacteria
by Masanori Horie and Hitoshi Iwahashi
Fermentation 2023, 9(10), 876; https://doi.org/10.3390/fermentation9100876 - 28 Sep 2023
Cited by 1 | Viewed by 1733
Abstract
Post-fermented tea is a beverage or food made by fermenting tea leaves with microorganisms. Four types of post-fermented tea are traditionally produced in Japan. Three of these post-fermented teas are produced by lactic acid fermentation in the Shikoku region. Post-fermented tea has physiological [...] Read more.
Post-fermented tea is a beverage or food made by fermenting tea leaves with microorganisms. Four types of post-fermented tea are traditionally produced in Japan. Three of these post-fermented teas are produced by lactic acid fermentation in the Shikoku region. Post-fermented tea has physiological activities such as antioxidant, antiallergic, and fat accumulation inhibitory effects. The composition of catechins in post-fermented tea differs from that in green tea. Compared to green tea, epigallocatechin, epigallocatechin gallate, epicatechin, and epicatechin gallate are reduced, and catechin polymers are formed in the post-fermented tea. In addition, post-fermented teas contain pyrogallol, γ-aminobutyric acid (GABA), and D-amino acids. The lactate fermentation of post-fermented teas on Shikoku Island involves Lactiplantibacillus plantarum and Lactiplantibacillus pentosus as the dominant species in the fermentation process. L. planratum and L. brevis isolated from Ishizuchi-kurocha, one of the post-fermented teas of Shikoku, contain amino acid racemases that produce D-amino acids. In addition, L. brevis has a high capacity for GABA production. Furthermore, L. plantarum is likely to produce bacteriocin. Lactic acid bacteria, represented by the L. plantarum group, play an essential role in the physiological activity of post-fermented tea, including lactic acid fermentation. An attempt has been made to create new post-fermented tea (brewed tea) based on traditional post-fermented tea production methods. Full article
(This article belongs to the Special Issue New Fermented Tea: Processing Technology, Microbiology and Health Benefits)
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