Article

Microbial fermented tea-A potential source of natural food preservatives

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  • henan Institute of science and technology, china, xinxiang
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Abstract

Antimicrobial activities of microbial fermented tea are much less known than its health beneficial properties. These antimicrobial activities are generated in natural microbial fermentation process with tea leaves as substrates. The antimicrobial components produced during the fermentation process have shown inhibitory effects against several food-borne and pathogenic bacteria. With the trend of increasing use of natural and biological preservatives in food products, natural antimicrobial agents from microbial fermented tea may offer an innovative and interesting measure for such applications. However, a breakthrough in this field can only be realised after several critical aspects are clarified and further studied. Only then, the application of these potential, novel and natural antimicrobial substances from microbial fermented tea can be industrialized. The present review describes some unique microbial fermentation of tea and the antimicrobial activities formed during the fermentation process. Moreover, future needs in research and development of these antimicrobial compounds from microbial fermentation of tea are discussed for potential industrial applications.

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... The strain generating yellow color cleistothecia is termed as the "golden flower fungus" (Mo, Zhu, & Chen, 2008;Mao, Wei, Teng, Huang, & Xia, 2017). The species within the genera Aspergillus, Eurotium, and Penicillium are main fungal taxa isolated from the postfermentation of dark tea (Mo et al., 2008). ...
... The strain generating yellow color cleistothecia is termed as the "golden flower fungus" (Mo, Zhu, & Chen, 2008;Mao, Wei, Teng, Huang, & Xia, 2017). The species within the genera Aspergillus, Eurotium, and Penicillium are main fungal taxa isolated from the postfermentation of dark tea (Mo et al., 2008). Aspergillus cristatus and Eurotium cristatum are golden flower fungi involved in the fermentation of Chinese fu-zhuan tea (Ge et al., 2016;Zou et al., 2014). ...
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Storage environment caused the difference between Jinhua Pu‐erh tea (JPT) and General Pu‐erh tea. In this study, fungal flora and chemical compositions were analyzed. The results showed that storage environment caused significant (p < .05) differences of theaflavins (TF), theabrownins (TB), tea polyphenols (TP), and water‐soluble sugars (WSS), and a highly significant (p < .01) difference of thearubigins (TR). Aspergillus niger, Aspergillus pallidofulvus, Aspergillus sesamicola, Penicillium manginii, and Aspergillus tamarii were isolated from Pu‐erh teas and identified based on colony characteristics and ITS, β‐tubulin, and calmodulin gene sequences, respectively. A. pallidofulvus, A. sesamicola, and P. manginii were dominant fungi in JPT and generated macroscopic yellow cleistothecia after a long‐term storage. Correlation analysis showed that dominant fungi exhibited significantly (p < .05 or p < .01) positive or negative corrections with TF, TB, TP, WSS, TR, and gallic acid. This study revealed dominant fungi including A. pallidofulvus, A. sesamicola, and P. manginii and their effects on given chemical compositions.
... sinensis), a traditional fermented Chinese drink, has been demonstrated to contain a mixed microscopic fungal population producing anthraquinones (mainly emodin and physcion; Figure 9.6). The strains are involved in the red color, the flavor, and certainly also in the health benefits, showing antidysenteric effects, anti-food born spoilage, and anti-pathogenic microorganisms , Mo, Zhu, and Chen 2008, Ling et al. 2010, Singh et al. 2005. The manufacturing process implies several steps of tea leaves' treatments (mixing, grinding, steaming, cooling, etc.) followed by a solid-state fermentation step (15-17 days) Chen 2008, Xu et al. 2011 microorganisms involved are Debaromyces, Aspergillus, Verticillium and Eurotium spp. ...
... Several species of Eurotium were identified from the fermented material (10 5 CFU/g dry weight of readymade Fuzhuan brick tea), but Eurotium sp. FZ (Eurotium cristatum) was the predominant strain characterized during the fermentation (Ge et al. 2016, Mo, Zhu, and Chen 2008, Xu et al. 2011, Qi and Sun 1990. Further studies were conducted, aiming at standardizing Fuzhuan tea industrial production, through identifying and optimizing the synthesis of antioxidants and antimicrobial substances during the fermentation (Xu et al. 2011, Liu et al. 2010, Abe et al. 2008, Cao, Zhao, and Liu 1998. ...
... Kombu çayının pekçok metabolik hastalığı iyileştirici ve destekleyici etkisinin olduğu belirlenmiş (diabet, kronik yorgunluk, romatizmal hastalıklar, gut, hemoroid, yaşlılık, atheroskleroz, kolesterol ve kan basıncının düzenlenmesi, kanser ve AIDS gibi hastalıklarda görülen kilo kayıplarının kontrolü, bağışıklık ve sindirim sistemleriyle karaciğer fonksiyonlarını destekleme, yangısal durumları azaltma, gastrointestinal sistemin çalışmasını iyileştirme) olup, fenolik bileşik içeriğinden dolayı serbest radikalleri etkisiz kılıcı ve antioksidan aktivitesinin yanısıra, organik asit içeriğiyle de patojen bakterilere (Salmonella typhimurium, S.enteritidis, Staphylococcus aureus, Helicobacter pylori, Shigella sonnei, E.coli) karşı antibakteriyel etkisi bulunmaktadır [1,[8][9][24][25][26][27][28][29][30][31]. ...
... Çay mantarı olarak bilinen Medusomyces gisevii'nin gelişebilmesi osmofilik mayalar ve bakterilerin çoğalmasına bağlı olup; sakkarozu kullanan asetik asit bakterileri (Acetobacter xylinum) fermentasyon sırasında, selülozik yapıda-kalın "zooglea biyofilm" tabakasını oluşturarak simbiyotik bakteri ve maya topluluğunun bir arada kalmasını sağlamaktadır [10,11,26]. Bakteri ve mayaların oluşturduğu simbiyoz konsorsiyum geliştikçe oluşan selüloz yapı, yüzeydeki mikroorganizmaları hem UV ışınlarından korumakta hem de gelişmeleri için gerekli olan oksijeni sağlamaktadır [1]. ...
Article
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Kombucha is a symbiotic system including synergistic effects of yeasts and acetic acid bacteria, produced by the fermentation of tea leaves and the incorporation of kombucha cultures under aerobic conditions. In this study, kombucha samples were produced using different tea leaves (white, green, oolong, black and pu-erh), and the number of lactic acid bacteria (LAB), total yeast (TM), total acetic acid (TAA) and total gluconobacter (TGB) were determined in these samples during the fermentation of 21 days (30°C, dark conditions). Moreover, the survival rates of the present microbiota were investigated by using the in vitro artificial gastrointestinal model depending on the various fermentation periods. On the 12th day of fermentation, the highest vitality rates were obtained for acetic acid bacteria (91.16-99.61%) and gluconobacteria (90.84-99.37%) in artificial gastrointestinal model. At the end of the fermentation period, TAA and TGB counts were 7.77-10.66 and 7.68-9.68 log cfu/mL, respectively. LAB counts increased first, followed by a reduction of 60% due to high acidity (11.17 g/L, as acetic acid) and a decrease in pH (2.82). In terms of antibacterial activity; E. coli was the most sensitive microorganism and Lactobacillus acidophilus was the most resistant microorganism to the elevated acidity. The Kombucha tea produced by Pu-erh tea leaves had the highest antibacterial effect on the microorganisms investigated (p<0.05). In terms of the industrial production of Kombucha tea and the viability of the probiotics, it was concluded that the ideal fermentation period should be 2 weeks, and the fermentation conditions should be standardized in order to maintain its functional properties.
... Fuzhuan brick tea (FBT, Figure 1B) is a post-fermented tea product mainly made in Hunan Province, China. The manufacturing process in detail has been described in previous literature (Mo et al., 2008;Xu et al., 2011). Briefly, the raw brick tea (RBT; Figure 1A, old and coarse green tea) and the tea stalk were moistened by steaming and piled up for 3-4 h at 75-88 C. Followed by partition according to the weight, the tea was pressed into desired brick sizes at 80 C. ...
... Recently, the special physiological effects of FBT have received increasing attention in China, Korea, Japan and Southeast Asian countries. It was reported that FBT possessed inhibitory effects on certain food-borne spoilage and pathogenic microorganisms (Mo et al., 2008). The previous studies have also shown the potential anti-obesity and hypolipidemic effects of FBT in laboratory models, even in an observational pilot study (Fu et al., 2011;Li et al., 2012). ...
... Its popularity is due to its attractive flavor and putative health benefits, including antiobesity, antioxidative, antihyperlipidemic, and antimicrobial properties [1]. The main manufacturing processes of FBT are steaming, piling, pressing, fermentation, and drying [3]. There is also a special process called "flowering", which is actually the incubation of the spores of a special fungus. ...
... Based on the culture and observation, we surmised this increase of unclassified_g_Aspergillus was caused by Eurotium cristatum. Many previous reports also showed that Aspergillus cristatum (Eurotium cristatum) was the dominant fungus during the manufacturing processes of FBT [3,7]. The fungal genus Eurotium, which is the teleomorph of Aspergillus, has proven to be a rich source of novel bioactive metabolites [28,29]. ...
Article
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Fu brick tea (FBT) is one of the major brands of dark tea. Microbial fermentation is considered the key step in the development of the special characteristics of FBT. The systemic corelationship of the microbiome and metabolomics during manufacture of Fu brick tea is not fully understood. In this study, we comprehensively explored the microbiome and metabolite dynamic evolution during the FBT manufacturing processes, and revealed decisive factors for the quality and safety of FBT based on the grouped methods of metabolomics combined with biochemical measurements, microbiome sequencing combined with quantitative polymerase chain reaction (PCR), and multiplex analysis. Both the microbiome and quantitative PCR showed that fungi displayed concentrated distribution characteristics in the primary dark tea samples, while bacterial richness increased during the flowering processes and ripening period. All microorganism species, as well as dominant fungi and bacteria, were identified in the distinct processes periods. A total of 178 metabolites were identified, and 34 of them were characterized as critical metabolites responsible for metabolic changes caused by the corresponding processes. Metabolic analysis showed that most metabolites were decreased during the FBT manufacturing processes, with the exception of gallic acid. Multivariate analysis verified that the critical metabolites were correlated with specific dominant microbial species. All the top fungal species except unclassified_g_ Aspergillus showed positive correlations with six critical metabolites (L-The, epigallocatechin (EGC), Gln, tea polyphenol (TP), tea polysaccharides (TPs) and caffeine). Five of the top bacteria species (Cronobacter, Klebsiella, Pantoea, Pluralibacter, and unclassified_ f_Entero-bacteriaceae) showed positive correlations with epigallocatechins and tea polyphenols, while the other 11 top bacterial species correlated negatively with all the critical metabolites. The content of amino acids, tea polyphenols, tea polysaccharides, and flavonoids was reduced during microbial fermentation. In conclusion, our results reveal that microbial composition is the critical factor in changing the metabolic profile of FBT. This discovery provides a theoretical basis for improving the quality of FBT and enhancing its safety.
... Nowadays, it has become a widely accepted beverage in China and northeastern Asia (Ge et al. 2016). Dark tea or brick tea have been reviewed (Mo, Zhu, and Chen 2008;Zhang et al. 2013;Zheng, Wan, and Bao 2015;Zhu et al. 2020), however, there is no report to summarize recent advances of FBT. Thus, it is necessary to comprehensively summarize the current research works regarding the processing, chemical constituents, and health benefits due to the rapid growing popularity of FBT. ...
... Second-rolling, (6) Drying, (7) Raw dark tea, (8) Screening, (9) In-process product blending, (10) Steam piling and Pile fermentation, (11) Compact shaping, (12) Fungus fermentation, (13) Packaging and storage (Chen 1989;Mo, Zhu, and Chen 2008;Xu et al. 2011). The manufacturing process of FBT can be divided into primary processing stage and reprocessing stage. ...
Article
Fuzhuan brick tea (FBT) is a traditional popular beverage in the border regions of China. Nowadays, FBT has been attracted great attention due to its uniquely flavor and various health-promoting functions. An increasing number of efforts have been devoted to the studies on health benefits and chemistry of FBT over the last decades. However, FBT was still received much less attention than green tea, oolong tea and black tea. Therefore, it is necessary to review the current encouraging findings about processing, microorganisms, chemical constituents, health benefits and potential risk of FBT. The fungus fermentation is the key stage for processing of FBT, which is involved in a complex and unique microbial fermentation process. The fungal community in FBT is mainly dominated by “golden flower” fungi, which is identified as Aspergillus cristatus. A great diversity of novel compounds is formed and identified after a series of biochemical reactions during the fermentation process of FBT. FBT shows various biological activities, such as antioxidant, anti-inflammatory, anti-obesity, anti-bacterial, and anti-tumor activities. Furthermore, the potential risk of FBT was also discussed. It is expected that this review could be useful for stimulating further research of FBT.
... Among them, Fuzhuan-brick tea (FBT), native to the Hunan province of China, is a popular beverage within ethnic groups in the border regions of southern/western China [15]. A unique fungal fermentation process with a mixture of several microorganisms (predominantly Eurotium spp.) controls the aroma, flavor, and the degree of quality of FBT, with a golden "fungal flora" appearing within the tea ( Figure 1A) [16]. Mounting evidence has shown that the fermentation process results in FBT having a unique phytochemical profile, with teapolyphenol, theaflavins, and caffeine being dominant ( Figure 1B, Supplementary Figure S1) compared to other types of tea [15,[17][18][19]. ...
Article
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Ultraviolet B (UVB) irradiation is viewed as the principal inducer of skin photo-aging, associated with acceleration of collagen degradation and upregulation of matrix metalloproteinases (MMPs). The ethnic groups of southern/western China use Fuzhuan brick-tea (FBT) as a beverage and as a nutritional supplement. In this study, we scrutinized the antagonistic effects of aqueous extract of Fuzhuan-brick tea (FBTA) on skin photo-aging in UVB-exposed human keratinocyte (HaCaT) cells. FBTA exhibited strong antioxidant activity and quenched UVB-induced generation of cellular reactive oxygen species (ROS) without showing any toxicity. FBTA was capable of combating oxidative stress by augmenting messenger RNA (mRNA) and protein levels of both phase I and phase II detoxifying enzymes, especially heme oxygenase 1 (HO-1), by upregulating the nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated pathway in HaCaT cells via the phosphorylation of p38 and extracellular signal-regulated kinase (ERK). FBTA also downregulated the expression of matrix metalloproteinase-1 (MMP-1) while upregulating type I procollagen by modulating Nrf2 signaling in UVB-irradiated HaCaT cells. Collectively, our results show that FBTA might be useful as a functional food while being a good candidate in the development of cosmetic products and medicines for the remedy of UVB-induced skin photo-aging.
... The main steps in the Fu brick tea manufacturing process are steaming, piling, pressing, fermentation, and drying (Mo et al., 2008), with microbial fermentation considered the key step in the development of special characteristics of Fu brick tea (Wang et al., 1991). Fungi, including those belonging to the genera Aspergillus, Cyberlindnera, Candida, Penicillium, Eurotium, Beauveria, Debaryomyces, Pestalotiopsis, Pichia, Rhizomucor, and Verticillium, have been identified using culture-dependent and culture-independent methods as important members of the microbial community for the production of Fu brick tea (Qi and Sun, 1990;Wen and Liu, 1991;Xu et al., 2011a;Li et al., 2017). ...
Article
To better understand the effects of bacteria on the characteristics of Fu brick tea, we investigated bacterial community structure as well as the predicted functions of identified bacteria and their correlations with chemical compounds during the manufacturing process. Overall, Klebsiella species dominated during the initial stage of processing, but were quickly replaced by Pseudomonas, Lactococcus, Stenotrophomonas, Enterococcus, and Bacillus species, which remained stable until the end of the manufacturing process. Network analysis identified 11 bacterial genera as keystone taxa, which contributed to the stabilization of the microbial community in the co-occurrence network. Bacterial taxa were grouped into eight modules, with the dominant genera mainly distributed amongst modules I and Ⅵ which were involved in metabolism of carbon and flavor compounds in the Fu brick tea ecosystem. Using bidirectional orthogonal partial least squares analysis, 19 bacterial genera were identified as core functional genera linked to the metabolism of chemical compounds during the manufacturing process, while three genera, namely Klebsiella, Lactococcus, and Bacillus, also dominated the Fu brick tea fermentation process. These findings provide new insights into Fu Brick tea bacterial community variation and increased our understanding of the core functional bacterial genera involved in the manufacture of Fu brick tea.
... In addition, J3 showed considerable potential for converting glucose to pivotal intermediates, such as acetate, ethanol, pyruvate, and acetyl-coA, which might then serve as direct or indirect substrates for JF flavor compounds including ethyl acetate, ethyl butanoate, ethyl propanoate, ethyl 2-hydroxypropanoate, ethyl 2-hydroxyhexanoate, acetic acid, 2-acetylpyridine, hexyl acetate, benzyl acetate ethyl, ethyl 3-methylbutanoate, ethyl benzeneacetate, and 3-methylbutyl acetate (Fan et al., 2012;Wang et al., 2014;Xiao et al., 2016;Gao et al., 2017). The highly expressed enzymes related to glycolysis and pyruvate metabolism were mostly derived from fungal species, some of which have been applied to the production of fermented foods and drugs, such as A. fumigatus (Qin et al., 2012;Wakefield et al., 2017), A. clavatus (Mo et al., 2008;Zutz et al., 2013;Li et al., 2017), and A. oryzae (Park et al., 2018;Son et al., 2018;Zhong et al., 2018). Furthermore, low concentration of ethanol might be generated by several fungi in J3, which to some extent agreed with the earlier finding that a small amount of ethanol could be directly produced by co-culture of fungi (Takano and Hoshino, 2012). ...
Article
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Jiang-flavor (JF) daqu is a liquor starter used for production of JF baijiu, a well-known distilled liquor in China. Although a high temperature stage (70�C) is necessary for qualifying JF daqu, little is known regarding its active microbial community and functional enzymes, along with its role in generating flavor precursors for JF baijiu aroma. In this investigation, based on metatranscriptomics, fungi, such as Aspergillus and Penicillium, were identified as the most active microbial members and 230 carbohydrate-active enzymes were identified as potential saccharifying enzymes at 70�C of JF daqu. Notably, most of enzymes in identified carbohydrate and energy pathways showed lower expression levels at 70�C of JF daqu than those at the high temperature stage (62�C) of Nong-flavor (NF) daqu, indicating lowering capacities of saccharification and fermentation by high temperature stage. Moreover, many enzymes, especially those related to the degradation of aromatic compounds, were only detected with low expression levels at 70�C of JF daqu albeit not at 62�C of NF daqu, indicating enhancing capacities of generating special trace aroma compounds in JF daqu by high temperature stage. Additionally, most of enzymes related to those capacities were highly expressed at 70�C by fungal genus of Aspergillus, Coccidioides, Paracoccidioides, Penicillium, and Rasamsonia. Therefore, this study not only sheds light on the crucial functions of high temperature stage but also paves the way to improve the quality of JF baijiu and provide active community and functional enzymes for other fermentation industries.
... Wines, however, are known and consumed worldwide and rank among the most popular fermented products (WHO, 2014). Of the traditional nonalcoholic fermented products, KT is an extremely popular beverage (Mo et al., 2008). The beverage has acquired significant interest all over the world because of its claimed beneficial effects which range from weight loss to having therapeutic potential as an anticancer drug (Dufresne and Farnworth, 2000;Greenwalt et al., 2000). ...
Chapter
Kombucha tea is a refreshing beverage, obtained by fermenting sugared black tea, made from Camellia sinensis (L.) Kuntze leaves, with a consortium of yeast and predominantly acetic acid bacteria. In recent times, Kombucha tea has seen considerable increase in interest worldwide and can easily be said to be an emerging popular beverage. The fact that today Kombucha tea is available in multiple forms and flavors is a living testament of the massive amounts of transformation this beverage has undergone through the ages. One of the most important reasons behind the rise of the beverage is its claimed health benefits many of which have been established by scientific research. Of the various health benefits of Kombucha tea, its antimicrobial, antioxidant, antidiabetic, and anticancer benefits are most attractive and appealing to ever increasing cohort of scientific investigators and entrepreneurs. The last decade saw noteworthy progress toward understanding the beneficial properties of this fermented tea. Scientific reports claim that drinking Kombucha tea can prevent several types of cancer, cardiovascular diseases, invigorate liver functions, and stimulate the immune system. Moreover, studies show that Kombucha tea is usually more effective than the original unfermented tea with respect to their biological activities. Therefore, Kombucha tea can now be regarded as a health drink and a functional beverage with potential beneficial properties.
... The exact lowest dose of irradiation can depend on the microbial and physiochemical properties of the material to be sterilized. In some spontaneous food fermentations, the core micro-organism will dominate the microflora even without sterilization of substrates and inoculation such as Puer tea fermentation with Aspergillus niger (Mo et al. 2008) and Koji fermentation with Aspergillus oryzae (Zhu and Tramper 2013;Jin et al. 2017). The above information indicated that application of irradiated substrate for SSF in these cases (without strict sterilization or disinfection) can be of potential to shorten the fermentation period that the core fungus grows and becomes dominating. ...
Article
Agricultural or food processing wastes cause serious environmental burden and economic losses. Solid‐state fermentation using these wastes is an attractive option to valorize these wastes. However, conventional autoclaving of substrate may degrade nutrients and generate toxins. Unsterilization of the substrate will cause undesired microbial contamination. Therefore, we compared irradiation with autoclaving to treat citrus wastes as substrate for solid‐state fermentation by Aspergillus aculeatus. By comparing microbial growth, enzymes tested and medium consumption, irradiated substrate had higher biomass and extracellular protein, more sugar consumption and higher enzyme production than those with autoclaved substrate. Irradiation prevented the generation of cell‐inhibiting components such as 5‐hydroxymethylfurfural (5‐HMF) whereas preserved well flavonoids that are often enzyme inducers. These findings suggest that irradiation of agricultural and food processing wastes as substrate has advantages over autoclaving for solid‐state fermentation.
... These data in line with Neffe-Skocińska et al. (2017) who found that the content of ethanol increased with the fermentation time reaching the maximum value of 1.10% on the 10th day at 25°C, while the expected decrease of ethanol due to the conversions into acetic acid was not observed (Chakravorty et al., 2016), probably because of the short period of fermentation. It could be stated that ethanol trend inversion with a total acidity of Kombucha trend, this can be explained with the observation of Mo et al. (2008), who found that yeast converted sucrose into glucose and fructose and produce ethanol through glycolysis then acetic bacteria fermented glucose into gluconic acid and ethanol and producing acetic acid. ...
Article
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Three types of Kombucha fermented tea, rice, and barley were produced in order to study their changes of biological and chemical parameters. About a 2-fold increase in mushroom dry weight after 8 days of growth was observed with Kombucha tea. The optical density of the Kombucha extracts gave the same trend. Moreover, Kombucha tea recorded the highest specific growth rate and lowest doubling time. The total acidity, ethanol content, and total protein content were incremented with the fermentation process to reach the peak after 6–8 days as in descending order: tea > barley ≥ rice. The scavenging abilities of DPPH were in descending order, tea (89.69%) > barley (76.19%) > rice (36.04%). The total phenolic compounds of Kombucha tea (88.8 ppm) have the same trend, which more than 3-fold of Kombucha rice (26.11 ppm). Results revealed that the Kombucha tea preservation method using heat treatment (at 76 and 100 °C for 10 min) was not successful, resulting in a decrease in antioxidant amounts to 71.0 and 53.42% and total phenolic compounds to 40.22 and 45.69 ppm, respectively.
... Ripe Pu-erh tea differs from the other teas as a consequence of the different indigenous microorganisms involved in its solid-state fermentation (Mo et al., 2008). In the manufacturing process of ripe Pu-erh tea, the fresh tea leaves collected from plantations are heat-treated to inactivate the indigenous plant enzymes and dried (Abe et al., 2008). ...
Article
Theabrownins (TB) are polymeric phenolic compounds associated with the multiple bioactivities of Pu‐erh tea, a post‐fermented Chinese dark tea. High‐TB instant Pu‐erh tea was produced via a novel submerged fermentation (SF) using Aspergillus tubingensis and compared with samples produced commercially via the conventional solid‐state fermentation (SSF). Viable microorganisms and microbial toxins, especially aflatoxins B1, G1, B2, G2, cyclopiazonic acid, fumonisins B1, B2, B3 and ochratoxin A, were below the detection limit in all samples. Fewer microbial metabolites were found in SF instant tea compared with the SSF teas. Based on an adult consuming 1 g of instant Pu‐erh tea daily, the dietary intake of investigated elements was below the safe limits recommended by various authorities. Tasters viewed the instant tea infusions as very mild, smooth, mellow and full. This suggested that submerged fermentation using A. tubingensis offers a speedy and safe alternative to commercial production of instant Pu‐erh tea.
... Tea infusions are a source of antioxidants, which can reduce the risk of cancer and cardio-vascular diseases (Michalak-Majewska, 2011). There are four main types of tea: natural (white, green), partly fermented (oolong or blue), post-fermented (Pu-erh or red) and fully fermented (black) (Mo et al., 2008;Tong, 2005). The nutritional merits of tea in conjunction with the tendency of the consumers to find new flavour perceptions in yoghurt products have caused the emergence of new tea-flavoured yoghurts, as well as researchers' increased interest in developing yoghurts with the addition of tea extracts (Granato et al., 2018). ...
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Background: In yoghurt production, additives and flavours are added after the fermentation process, but in the case of yoghurts with the addition of tea extracts all studies concern set-type yoghurts. For this reason, the aim of this study was to analyse the effect of green, black, red (Pu-erh) and white tea extracts addition on sensory characteristics, pH, viscosity and colour of stirred probiotic yoghurts stored for two weeks. Methods: Skim milk powder (10% w/w), sucrose (4% w/w) and typical yoghurt cultures with the addition of Lactobacillus acidophilus LA-5 were applied for yoghurt manufacture. Then yoghurts were stirred and 4, 8, 12% black, red, green and white tea extracts were added. The samples were analysed after 1, 3, 7 and 14 days of storage at 5ºC. Instrumental colour (L*a*b*) determination, rheological measurements and sensory evaluation were carried out. Results: The pH analysis of the final yoghurt samples showed that the type and quantity of tea extract addition had little effect. Apparent viscosity was affected by 12% addition of tea extracts but not by storage time. The instrumental analysis of the colour confirmed the visual assessment. Sensory evaluation revealed that yoghurts with the addition of green tea extract were the most accepted. The addition of extracts made of red, black and white tea resulted in lower values of all the sensory characteristics tested. Conclusions: The stirring method can be applied to the production of probiotic yoghurts with various tea extracts. The acidity of the yoghurts was practically not affected by the addition of the infusion derived from the different types of tea. 4% addition of tea extract did not affect the viscosity of the yoghurts. The best sensory scores among tea yoghurts were obtained by yoghurt with 4% green tea addition.
... Tea infusions are a source of antioxidants, which can reduce the risk of cancer and cardio-vascular diseases (Michalak-Majewska, 2011). There are four main types of tea: natural (white, green), partly fermented (oolong or blue), post-fermented (Pu-erh or red) and fully fermented (black) (Mo et al., 2008;Tong, 2005). The nutritional merits of tea in conjunction with the tendency of the consumers to find new flavour perceptions in yoghurt products have caused the emergence of new tea-flavoured yoghurts, as well as researchers' increased interest in developing yoghurts with the addition of tea extracts (Granato et al., 2018). ...
... Previous study showed that the tea was contained wih catechins such as EC, EGCG, ECG and EGC which attributed to the tea antimicrobial property (Chou et al., 1999). In fermented tea, the fermentation process would produce antimicrobial metabolites such as acids and cause the pH to drop (Greenwalt et al., 1998;Sreeramulu et al., 2000;Mo et al., 2008). Although green tea possessed more catechins than black tea, it showed less antimicrobial activity, thus proving that fermentation played a crucial role. ...
Article
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Kombucha is a traditional fermented drink and has recently gained popularity due to its numerous claims on therapeutic effects. It is prepared by sweetening black tea and fermenting using a symbiotic culture of acetic acid bacteria and yeasts known as SCOBY. The drink can also be brewed using different types of tea and carbon sources. An investigation was conducted to characterize the antioxidant and antimicrobial properties of kombucha by using variation of carbon sources: white sugar (S), jaggery (J) and Kelulut honey (H) in black tea (BT) and green tea (GT) media over a period of 7, 14, 28 and 60 days. The antioxidant and antimicrobial efficacies were tested post fermentation. All samples shown the highest value of 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition for antioxidant activity at 7 days of fermentation but subsequent decrease was observed with longer fermentation time except for the combination of green tea with jaggery (GT+J). Fermentation of green tea with white sugar (GT+S) showed the highest value with 84%. On the other hand, black tea with jaggery (BT+J) showed least DPPH activity of 9%. Fermentation with green tea demonstrated a higher antioxidant activity compared to black tea, whereas fermentation of any tea with jaggery showed the least antioxidant activity in comparison to white sugar and honey. Thus, it could be said that extended periods of fermentation would reduce the DPPH inhibition of kombucha and jaggery itself as carbon source showed an interesting property. Antimicrobial activity was tested using disk diffusion method against E. coli, S. aureus, P. aeruginosa, B. subtilis and S. marcescens. The efficacy was increased with time of fermentation for all combinations. Combination of black tea with all carbon sources was found to exhibit good antimicrobial activity.
... Puer tea extract is known to prevent cardiovascular disease and thus mortality (Mo et al., 2008). Tea has several medicinal properties (Banerjee and Chaudhuri, 2005). ...
Chapter
Fermented foods and beverages are one of the vital components of the dietary culture of every community of different geographical locations of India. Traditional fermentation and smoking, drying, and salting processes were developed by ancient Indian people to preserve foods for long time consumption, an incredible step in the food ethnicity. Food preparation and preservation is unique and distinct due to the geographical location, environmental factors, food preference, and the availability of plant or animal sources. As per the nutritional statistics, approximately 50-400 g per capita of fermented foods and alcoholic beverages are consumed daily worldwide, representing about 5-40% of the total daily food intake. Low-cost, high-value, socially and culturally acceptable fermented foods and beverages are consumed as staple foods, and nonalcoholic beverages. Huge varieties of unlisted major and minor fermented foods and beverages are prepared and consumed by billions of people belonging to different communities and ethnicities across India. Fermented foods and beverages harbor diverse microorganisms from the environment, which include bacteria, mostly lactic acid bacteria, bacilli, and micrococci; mycelial molds and yeasts. Microorganisms convert the chemical constituents of raw materials during fermentation and boost the nutritive value of the products; enrich bland diets with improved flavor and texture; preserve consumable foods; fortify products with essential amino acids, health-promoting bioactive compounds, vitamins, and minerals; degrade detrimental compounds and antinutritive factors; impart 361 Fermented Foods in India: Diversity and Biotechnological Prospects antioxidant and antimicrobial properties; improve digestibility; and stimulate probiotic functions. Most of the ethnic fermented foods and beverages are produced by natural fermentation, except the alcoholic beverages, which are produced by using a consortium of microorganisms in the form of a dry, cereal-based starter. Diversity within the species or strains of several functional genera of dominant microorganisms has created ethnic foods with different sensory characteristics. In this chapter, attempt has been made to document all the diverse fermented foods available in India and their biotechnological prospects.
... Dauguma pridėtų augalų ekstraktų pasižymi antimikrobinėmis, antioksidacinėmis, aromatinėmis savybėmis. Dėl teigiamo augalų poveikio žmogaus organizmui jų panaudojimas maisto produktų gamyboje yra labai svarbus (Mo et al., 2008). Visi augalų ekstraktai buvo priimtino skonio. ...
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The aim of this study was to evaluate the effect of aqueous extracts from different parts of plants such as berries of guelder rose (Viburnum opulus), seeds of cardamom (Elettaria cardamomum), musk (Myristica fragrans) and indian cumin (Cuminum cyminum), rootstock of ginger (Zingiber officinale) and liquorice (Glycyrrhiza glabra) on the quality of curd-type cheese. We produced organoleptically acceptable aqueous plant extracts (1.5% concentration) and evaluated their antimicrobial activity. According to the standard methodology we manufactured curd-type cheese. During the storage we identified physico-chemical properties (pH and colour coordinates), the number of lactic acid bacteria (LAB) and sensoryprofile properties of the final product. The experiment shows that plant extracts extended the shell-life of curd-type cheese, and the substances contained there act as natural preservatives. Curd-type cheese supplemented with plant extracts compared to the control sample is microbiologically safe. The study proves that curd-type cheese can be improved by adding plants rich in biological active substances, to improve the sensory properties, increase the biological value and extend the shell-life as safety by natural means. The effect of plant extracts has shown sensory properties of curd-type cheese – colour, taste, odour and acceptability.
... Although normal black tea is consumed on every continent, however, preferences vary considerably, from region to region. For example, traditionally fermented tea such as "miang" is frequently consumed in Thailand (Tanasupawat, Pakdeeto, Thawai, Yukphan, & Okada, 2007), whereas "puer tea," "fuzhuan brick," and kombucha are more commonly in China (Mo, Zhu, & Chen, 2008). Aspergillus niger is the predominant fungus in puer tea while other fungi Blastobotrys adeninivorans, Asp. ...
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Fermented foods and alcoholic beverages have long been an important part of the human diet in nearly every culture on every continent. These foods are often well‐preserved and serve as stable and significant sources of proteins, vitamins, minerals, and other nutrients. Despite these common features, however, many differences exist with respect to substrates and products and the types of microbes involved in the manufacture of fermented foods and beverages produced globally. In this review, we describe these differences and consider the influence of geography and industrialization on fermented foods manufacture. Whereas fermented foods produced in Europe, North America, Australia, and New Zealand usually depend on defined starter cultures, those made in Asia and Africa often rely on spontaneous fermentation. Likewise, in developing countries, fermented foods are not often commercially produced on an industrial scale. Although many fermented products rely on autochthonous microbes present in the raw material, for other products, the introduction of starter culture technology has led to greater consistency, safety, and quality. The diversity and function of microbes present in a wide range of fermented foods can now be examined in detail using molecular and other omic approaches. The nutritional value of fermented foods is now well‐appreciated, especially in resource‐poor regions where yoghurt and other fermented foods can improve public health and provide opportunities for economic development. Manufacturers of fermented foods, whether small or large, should follow Good Manufacturing Practices and have sustainable development goals. Ultimately, preferences for fermented foods and beverages depend on dietary habits of consumers, as well as regional agricultural conditions and availability of resources.
... Compared with chemical preservatives, food preservatives produced using traditional fermented foods are newer, safer and more effective. Antibacterial substances in natto not only have the advantages of high safety, broad antibacterial spectrum but also rich in nutrition and functionality [11,12]. Nevertheless, there are few reports on the antibacterial activity of B. subtilis natto. ...
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Herein, a bactericide-secreting Bacillus strain, potentially useful as a biocontrol agent, was isolated from the commercial Yanjing Natto food. Following the biochemical and physiological evaluation, the molecular identification was performed using 16S rDNA sequencing of polymerase chain reaction-amplified DNA that confirmed the natto isolate as Bacillus subtilis natto (B. subtilis natto). The biocontrol (microbial inhibitory) capability of B. subtilis natto was investigated against Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, and yeast (Yarrowia lipolytica) and recorded. The antimicrobial activity of B. subtilis natto was further enhanced by optimizing the growth medium for optimal bactericides secretion. Under optimized conditions, B. subtilis natto exhibited much higher inhibitory activity against S. aureus with a zone of inhibition diameter up to 27 mm. After 48 h incubation, the optimally yielded B. subtilis natto broth was used to extract and purify the responsible bactericides by silica gel column chromatography, gel column chromatography, and semi-preparative high-performance liquid chromatography. Structural identification of purified bactericides (designated as NT-5, NT-6, and NT-7) from B. subtilis natto was performed by 13C-nuclear magnetic resonance (NMR) and mass spectral analyses. The NMR comparison also revealed that NT-5, NT-6, and NT-7 had identical structures, except for the fatty chain. In summary, the present study suggests the improved biocontrol and/or microbial inhibitory potential of newly isolated bactericides secreting B. subtilis natto.
... grew as the dominant one initially. But at the end of fermentation, it was predominant by yellow fungi (golden flora) denoting huge production of complex metabolites by fungi (Mo et al., 2008;Xu et al., 2011;Luo et al., 2013;Yue et al., 2014;Zhu et al., 2015). ...
... The antimicrobial and antifungal properties of kombucha are mostly attributed to the presence of powerful symbiosis between bacteria and fungi leading to the production of critical metabolites responsible for the inhibition of contaminating bacteria (Shahbazi et al., 2018). Mo et al., (2008) proposed the possibility of creative and exciting applications of fermented kombucha teas as direct antimicrobial inhibitors, as medicinal and biological preservatives in meat products. ...
... PT was prepared following the method of Mo et al. [21] with modifications. Briefly, 100 kg of dried GT was mixed with 30 L tap water on a wooden board. ...
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Previous reports on phytochemicals in green tea (GT) and processed teas mainly focused on more representative compounds such as catechins. Here, we focus on the insignificantly studied non-catechin components in tea extracts, and explore the multivariate correlation between diverse phenolic compounds in tea and the in vitro antioxidant and anticancer effects. Extracts from GT and four types of processed teas were further divided into hydrophilic and hydrophobic fractions, whose phenolic compositions and antioxidant capacities were quantified using HPLC-MS and three antioxidant assays, respectively. For three types of teas, the anticancer effects of their extracts and fractions were assessed using cancer cell lines. The hydrophobic fractions had lower antioxidant capacities than the corresponding hydrophilic fractions, but exhibited superior antiproliferative effects on cancer cells compared with the whole extract and the hydrophilic fraction. Partial least squares-discriminant analysis revealed a strong correlation between the anticancer effects and the theaflavins and flavonols. Therefore, in addition to catechins, the hydrophobic fraction of tea extracts may have beneficial health effects.
... Researches have showed that natto possesses multiple healthy functions, including anti-thrombotic, anti-hypertensive, anti-osteoporosis and anti-diabetic activities (Kwon et al., 2010;Omura et al., 2005). Furthermore, it was reported that the activities of soybean were elevated with the fermentation process, indicating that this fermentation processing might produce new functional metabolites (Mo et al., 2008). ...
Article
This study is to reveal the variation of five pivotal substances, including polysaccharides, proteins, isoflavones, fatty acids and volatile components during the soybean fermentation process by Bacillus subtilis natto. After 96 hours of soybean fermentation, the polysaccharide contents were significantly decreased, and the glucose and galactose contents showed the greatest decline in all the monosaccharide components. Moreover, isoflavone glycoside levels were decreased, while the isoflavone aglycone levels were increased following the fermentation. In addition, the SCFAs contents were also significantly increased in comparison with the unfermented soybean. Furthermore, 16 amino acids and 36 volatile components were detected in the fermented soybean. Finally, 21 key compounds were identified through PCA and OPLS-DA analysis of total compounds in the fermentation process. These findings demonstrated that Bacillus subtilis natto had a significant influence on the biochemical profiles of soybean fermentation and consequently contributed to its unique quality.
... Such a large number of active compounds explain the rich variety of teas, differences in their organoleptic properties, and effect on the organism. Postfermented teas are not only popular drinks, but also have medicinal properties: they normalize lipid metabolism, and they have antimicrobial, antidiabetic, antioxidant, and antimutagenic effects [10,[13][14][15]. In addition to useful substances, fungi form undesirable or even harmful substances from the point of food microbiology view. ...
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Fungi Eurotium spp. are the main biological agents that ferment the leaves of the Camellia sinensis tea bush to form a popular food product, postfermented tea. The fungus E. cristatum, stored in the collection of the Gause Institute of New Antibiotics under the number INA 01267, was isolated and identified from a briquette of Fujian Chinese tea. The species identification was carried out based on morphocultural characteristics and DNA sequencing. This study is aimed at determining the feasibility of making postfermented herbal teas using E. cristatum and to evaluate their quality. Autofermented herbal teas from Chamaenerion angustifolium (fireweed) and Malus domestica (apple tree) served as the starting material for this study. The change in the concentration of phenolic compounds, organic acids, sugars, and free amino acids was observed for herbal teas subjected to postfermentation with E. cristatum INA 01267. It was found that the E. cristatum INA 01267 strain does not have antimicrobial activity and does not form mycotoxins, which is an indicator of food safety.
... atherosclerosis and cancer models via inhibition of NO production through iNOS, as well as inhibit other proinflammatory mediators such as interleukin-12, monocyte chemoattractant protein (MCP), and tumor necrosis factor-α (TNF-α) [31,40,85]. The result from this study corroborate positive impacts that have been reported for other traditional fermented teas such as Pu-erh, Oolong, Zijuan, and Kombucha, among others, considering the fermentation of both Miang and these teas' is mediated by microbes [6,86]. Flavonoid aglycones such as kaempferol, quercetin, myricetin, apigenin, and their glycosides (flavonoid glycosides) detected in fermented teas such as Tuocha (Chinese bowl tea), Pu-erh, and Oolong tea are suggested to contribute to the bioactivities of these teas [87]. ...
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The study investigated the impact of the fermentation process on the phenolic contents and antioxidant and anti-inflammatory activities in extracts of Miang, an ethnic fermented tea product of northern Thailand. The acetone (80%) extraction of Miang samples fermented by a non-filamentous fungi-based process (NFP) and filamentous fungi-based process (FFP) had elevated levels of total polyphenols, total tannins, and condensed tannins compared to young and mature tea leaves. The antioxidant studies also showed better the half-maximal inhibitory concentration (IC50) values for fermented leaves in both 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity assays as well as improved ferric reducing antioxidant power (FRAP) compared to young and mature tea leaves. Extracts of NFP and FFP samples at concentrations of 50 and 100 ppm showed better protective effects against hydrogen peroxide (H2O2)-induced intracellular reactive oxygen species (ROS) production in HT-29 colorectal cells without exerting cytotoxicity. Additionally, lipopolysaccharide (LPS)-induced production of nitric oxide (a proinflammatory mediator as well as a reactive nitrogen species) was also inhibited by these fermented Miang extracts with an IC50 values of 17.15 μg/mL (NFP), 20.17 μg/mL (FFP), 33.96 μg/mL (young tea leaves), and 31.33 μg/mL (mature tea leaves). Therefore, both NFP-Miang and FFP-Miang showed the potential to be targeted as natural bioactive functional ingredients with preventive properties against free radical and inflammatory-mediated diseases.
Article
This study aimed to investigate the effect of sugar concentration and fermentation time on the antibacterial activity of kombucha beverages prepared with four herbal teas. Four types of herbal teas including, black and green tea, lemon verbena, and peppermint were prepared then sweetened with 2, 5, and 8% sugar. The herbal teas inoculated with actively kombucha culture and after 7, 14, and 21 days, the antibacterial activity of the supernatant of beverages was evaluated against four bacteria based on agar well diffusion method. RSM was used to investigate the effect of fermentation time, sugar concentration, and tea type on the antibacterial activity of beverages. Sugar concentration and fermentation time showed a significant effect on the antibacterial activity of beverages-against all tested bacteria and type of herbal tea affected the antibacterial activity of beverages-against E. coli and S. aureus. Kombucha prepared with black tea at sugar 8% and fermentation time of 21 days showed the most antibacterial activity against B. cereus. The most antibacterial activity against S. aureus was observed in kombucha beverages prepared with green tea and peppermint for fermentation time of 21 days, at 2% and 8% sugar, respectively. Prepared beverages with peppermint and lemon verbena at 8% sugar and 21 days of fermentation showed the most antibacterial activity against E. coli and S. dysenteriae respectively. Generally, to achieve the highest antibacterial activity against the tested bacteria recommended preparation of kombucha beverages at the sugar of 8% and fermentation time of 21 days.
Article
The preventive and therapeutic effects of dark tea fermented by Eurotium cristatum (DTE) in glucose metabolism have been demonstrated. However, few studies have investigated comprehensive changes in the chemical composition and activity in DTE before and after fermentation. In this study, the metabolic profiling of raw samples and fermented samples was determined by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS). Furthermore, a systematic analytical strategy combining global metabolomics and the spectrum-effect relationship based on α-glucosidase inhibition was employed for screening discriminant metabolites. As a result, 15 discriminant metabolites were identified in DTE samples. Among them, 10 metabolites (4 fatty acids, 1 dyphylline derivative, 3 lysophosphatidylcholines, and 2 triterpenes) increased in relative contents and the contents of the other 5 polyphenol metabolites decreased after fermentation. These metabolites were critical constituents possibly associated with DTE's hypoglycemic activity, which also might be suitable as quality evaluation indicators. This study provided a worthy insight into the exploration of representative active constituents or quality indicators of DTE.
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The anti-graying effect of the hexane fraction of Fuzhuan brick tea is investigated in Melan-A cells and C57BL/6 mice. As a result, it is found that reactive oxygen species-induced damage is associated with the reduction of melanogenesis in hair bulb melanocytes when reactive oxygen species generation in Melan-A cells occurred. The results revealed that the hexane fraction of Fuzhuan brick tea could remarkably reduce reactive oxygen species generation in Melan-A cells; meanwhile, it could increase the cellular tyrosinase and melanin content, as well as up-regulate the expression of tyrosinase, tyrosinase related protein-1, tyrosinase related protein-2, and microphthalmia-associated transcription factor, and activate the MAP-kinase pathway through activating the phosphorylation of p38 c-Jun N terminal kinase/extracellular signal-regulated kinase. Furthermore, high-pressure liquid chromatography analysis reveals that the tea’s major ingredients in hexane fraction include gallic acid, theaflavin, theobromine, caffeine, epicatechin, and quercetin. Together, the current results suggest that Fuzhuan brick tea proves to protect from the damage of hydroquinone, which induces hair pigment loss.
Article
Fuzhuan brick tea (FBT) is a post-fermented tea that is intentionally fermented by the fungus Eurotium cristatum. Previous studies have reported the anti-obesity effect of FBT, but the underlying mechanism remains unclear. The present study investigated whether FBT exerts anti-obesity effects through energy expenditure and browning of white adipose tissue. Mice were administered 100 mg or 200 mg FBT/kg body weight along with a high-fat diet (HFD) for 12 weeks; the FBT group had a significantly reduced body weight and adipose tissue mass compared to mice fed an HFD alone. FBT also improved serum biochemical parameters and hepatic steatosis concomitant with obesity. Furthermore, FBT enhanced energy expenditure and promoted browning of subcutaneous adipose tissue by upregulating the expression of brown adipocyte-specific genes, including uncoupling protein 1. Based on these results, we suggest that FBT induces energy expenditure by promoting the browning of subcutaneous adipose tissue, which prevents weight gain.
Article
Background Fuzhuan brick tea (FBT) as a representative type of dark tea is one of the three treasures of the ancient Silk Road in China together with Chinaware and Silk, and has become increasingly popular due to its unique flavors and health benefits. However, the knowledge of FBT is only scattered, and obviously, the more comprehensive study is requisite to reveal the relationship between consumption of FBT and human health, and further prospect the future of FBT-derived products. Scope and approach A more comprehensive review to FBT was reported for the first time, and in this paper, microbiome, aromas and flavors, chemical ingredients and their compositions and nutrition, as well as the future prospects of developing FBT-derived products were reviewed and discussed. Key findings and conclusions FBT contains a rich microbiome environment, where microbial genera represented by characteristic Eurotium cristatum, Debaryomyces, Aspergillus and Klebsiella may grow dynamically during the fermented manufacturing process. Under the actions of microorganisms and their metabolic enzymes, the content of all the major compounds significantly changed, leading to the production of unique aromas and flavors represented by ketones and alcohols, as well as the formation of indispensably new metabolic components with physiological activities. FBT and FBT-derived products owing to its nontoxicity and excellent bioactivities may service as functional food to protect human health and prevent chronic diseases. For the food industrial application, it is believed that the unique post-fermentation with complex mixed microbes mainly contributed by Eurotium cristatum may be conducive to microbial transformation and the formation of the functional compounds.
Chapter
The present chapter shows an overview of the production of bioactive peptides (BAPs) obtained from food matrices, using fermentation processes. It shows that it is possible to obtain BAPs from milk, meat, and vegetable proteins and emphasizes scientific production and the proven benefits that milk protein-derived BAPs provide to health. It also emphasizes a promising outlook in BAP production by fully using meat and vegetable proteins using food industry by-products, which also helps to mitigate waste environmental issue. For viable and safe BAPs industrial production, advances about in vivo research and adaptations of biotechnological processes for this scale of production are required.
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Among the toxin-producing microbes, those that produce mycotoxins are especially problematic due to their broad distribution in the environments and in foods. Several species of Aspergillus, Penicillium, and Fusarium are sources of potent mycotoxins such as aflatoxins, ochratoxins, patulin, deoxynivalenol, and fumonisins. It is, therefore, vital that mycotoxigenic fungi contaminants in food are rapidly and accurately identified for ensuring the safety of consumers. Most of the current methods are based on PCR using gene-specific or species-specific primers. However, contaminating microbes often compose a complex community and PCR-DGGE may provide a better approach than traditional single-gene and/or single-species based methods. It provides “fingerprints” for each microbial flora and has been widely used to analyze environmental and food-associated microbial communities. This review shows the advantages and disadvantages of different molecular methods for the detection of mycotoxigenic fungi including PCR-DGGE as a potent and applicable method that could overcome the difficulties associated with other methods.
Chapter
Fermented food and beverages constitute a significant part of the human diet (5%–40%) worldwide. Fermentation has been used for preservation and to augment the flavor, texture, and nutritional qualities of the food, since antiquity. During fermentation, the bioavailability of vitamins, minerals, and other constituents increases due to the microorganisms’ metabolic activities. Besides enhancing nutritional quality, fermented foods contain live organisms reported to prevent/treat many health disorders. Types of the fermentation process are also classified based on these microorganisms. In developing countries, fermented foods were usually prepared using traditional methods without any standardized techniques. Considering the beneficial effects of fermented foods, industrial-level production requires consistent specific microorganisms, fermentation methods, evaluation of nutritional compositions, and food safety testing. This chapter discusses the fermented foods and associated organisms, different sources available for the consumption of fermented foods, and food component’s effect on microorganism’s efficacy.
Chapter
Polyphenols are important secondary metabolites from plants, largely found in plant-based foods like fruits, vegetables, herbs, legumes spices, and tea. Polyphenols are associated with numerous health benefits such as antiinflammatory, antioxidants, antimicrobial, antidiabetic, cardio-protective, immunoprotective, and antitumor effects. As naturally occurring in diverse chemical structures, polyphenols are divided into many types such as phenolic acids, flavonoids, stilbenes, and lignans. Microbial fermentation leads to hydrolysis and transformation of polyphenol from bound to free form which improves its health benefits. Further, polyphenols are produced using recombinant microorganisms having various advantages over the chemical synthesis process. The interdependent association of polyphenolic compounds and gut microbiota contributes to beneficial health effects in host. The chapter involves the microbial process for production and enhancement of polyphenols during fermentation.
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Emerging evidence supports the health-promoting ability of a special microbial-fermented Fuzhuan brick tea. Epigallocatechin gallate was identified as a dominant flavonoid of Fuzhuan tea aqueous extract (FTE). Mice were treated with 30% high fructose (HF) water feeding alone or in combination with administration of FTE at 400 mg per kg bw for 13 weeks. FTE caused strong inhibition against the elevation of liver weight, serum enzymatic (aspartate aminotransferase, aspartate aminotransferase and alkaline phosphatase) activities and hepatic inflammatory cytokines (interleukin-1, interleukin-6, tumor necrosis factor-α and tumor necrosis factor-β) formation, as well as dyslipidemia (total cholesterol, total triglyceride, low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol) in HF-fed mice (p < 0.05). Hepatic malonaldehyde formation was lowered, while superoxide dismutase and glutathione peroxidase activities were enhanced by FTE treatment, relative to HF-fed mice (p < 0.05), and histopathological evaluation confirmed the protection. As revealed by 16S rDNA gene sequencing, FTE notably increased abundance of Bacteroidetes and Lactobacillus, but reduced population of Firmicutes, Proteobacteria and Tenericutes in HF feeding mice. These findings suggest that FTE exerts a hepatoprotective effect by modifying hepatic oxidative stress, inflammatory response and gut microbiota dysfunction.
Article
Kombucha is a beverage based on a sugared medium fermented by a symbiotic culture of bacteria and yeast. The aim of this study was to produce unfermented and kombucha beverages with Malvaviscus arboreus and Camellia sinensis as substrates, and assess their physico-chemical characteristics, in vivo toxicities, antioxidant activities and antimicrobial properties. The beverages were prepared from infusions (0.5 %, w/v), with sucrose (5.0 %, w/v), kombucha culture (2.5 %, w/v), and 1.0 % (v/v) of the previously fermented beverage, and incubated at 24 ± 2 °C for 14 days. The results showed that both produced kombuchas are within the physico-chemical and microbiological parameters recommended by the Food and Drug Administration. None of the tested samples showed toxicity from the in vivo model of Galleria mellonella larvae. A significant increase of 145 % w/v was observed on the total phenolic content of the Malvaviscus arboreus kombucha when compared to its infusion. Green tea and green tea kombucha showed antifungal activity against the pathogenic fungus Paracoccidioides brasiliensis. Green tea was also the only beverage to present antimicrobial activity against all fungi cultures evaluated and against Staphylococcus aureus and Listeria monocytogenes. Thus, it is possible that the type of substrate used in the kombucha production interferes with its bioactive properties. This report shows the potential use of non-conventional edible plant, such as Malvaviscus arboreus, as substrate for kombucha fermentation and for the first time the use of Galleria mellonella larvae as in vivo model of toxicity in the analysis of kombucha.
Article
The fermentation characteristics of non-Saccharomyces yeasts (Pichia kluyveri FrootZen, Torulaspora delbrueckii Prelude, Williopsis saturnus var. mrakii NCYC2251 and Torulaspora delbrueckii Biodiva) were evaluated in green tea slurry fermentation. Each yeast showed different fermentation performances: strains Prelude and Biodiva utilized sucrose faster than the other two yeasts; strain NCYC2251 was the only species that metabolized xylose. Strain FrootZen increased the caffeine content significantly and strain Prelude showed the opposite trend, both at a statistical level, while theanine contents in four samples were relatively stable. Biodiva and FrootZen significantly improved polyphenols content and the oxygen radical absorbance capacity of fermented teas. Some endogenous volatiles such as ketones, lactones and aldehydes decreased to lower or undetected levels, but one of the key tea aroma compounds methyl salicylate increased by 34-fold and 100-fold in P. kluyveri and W. saturnus samples respectively. Therefore, green tea fermentation by appropriate non-Saccharomyces yeasts can enhance its antioxidant capacity and alter the aroma compound profile.
Article
As the dominant fungus during the fermentation of Fuzhuan brick tea, Aspergillus cristatus is easily induced to undergo a sexual cycle under low-salt stress. However, the underlying regulatory mechanism of sexual reproduction is unclear. Here, we report a P53-like transcription factor AcndtA, which encodes an NDT80 protein and regulates fungal reproduction, pigmentation and the stress response. Both insertion and deletion mutants of AcndtA exhibited a complete blockade of cleistothecium formation, and overexpression AcndtA strains (OE:: AcndtA) exhibited significantly reduced cleistothecium production, indicating that AcndtA plays a vital role in sexual development. Osmotic stress tests showed that overexpression of AcndtA had a negative impact on growth and conidia production. Additionally, AcndtA insertion, deletion and overexpression mutants exhibited reduced pigment formation. All the above developmental defects were reversed by the re-introduction of the AcndtA gene in ΔAcndtA. Moreover, the growth of AcndtA mutants in carbon-limited medium was relatively better than that of the WT and OE:: AcndtA strains, indicating that AcndtA is involved in carbon metabolism. Transcriptional profiling data showed that AcndtA regulated the expression of several genes related to development, osmotic stress and carbon metabolism.
Article
Moringa oleifera is a nutritious herb with a pronounced harsh taste. During microbial fermentation of Fu-brick tea, “flowering” promotes the oxidation, decomposition, and hydrolysis of biochemical components, resulting in a unique flavor. To improve the utilization and flavor of Moringa leaves, we developed a novel blended tea. Moringa-Fu brick tea via microbial fermentation and dark tea blending. We investigated chemical compositions and fungal community structures, and their possible correlations, during eight flowering stages using three blending ratios. Metabolic analysis showed that caffeine, theophylline, and gallic acid levels increased, whereas other key metabolite levels decreased after flowering. The genera Aspergillus, Saccharomycetales incertae sedis, and Candida predominated during the early flowering stage, but Eurotium dominated after 3 days with all three ratios. The fungal taxa were grouped into 14 modules, and six keystone taxa were identified. Three fungal genera (Saccharomycetales incertae sedis, Aspergillus, and Cyberlindnera) were the core functional genera linked to the metabolism of biochemical compounds. Supplementing 15 % moringa tea with dark tea developed the best flavor, suggesting that this substrate’s environment was more suitable for propagating dominant fungi and driving biotransformation. This study can serve as an exemplar for utilizing microbial-fermentation to improve the flavors of harsh-tasting plant resources.
Article
Soymilk fermentation with kombucha was perfomed at 28 °C and 37 °C, and changes in the number of microorganisms, bioactivity and chemical compositions were analyzed during fermentation. Yeast, acetic acid bacteria (AAB), and lactic acid bacteria (LAB) showed substantial growth in the soymilk, and fermentation at 37 °C and 28 °C promoted the growth of LAB and AAB, respectively. The flatulence factors of raffinose and stachyose were entirely and mostly consumed during fermentation, respectively. Nearly all the glucoside isoflavones were transformed into aglycone isoflavones by β-glucosidase hydrolysis. Total phenolic, ferulic, chlorogenic and ascorbic acid (VC) contents significantly increased after fermentation. The antioxidant and inhibition activities to α-glucosidase and α-amylase of kombucha-fermented soymilk significantly increased, and were higher at 37 °C than at 28 °C. In conclusion, fermentation with kombucha can enhance the health-promoting properties of soymilk.
Article
Various dark teas are quite different in their volatile profiles, mainly due to the huge differences in the phytochemical profiles of dark raw tea and the diverse post-fermentation processing technologies. In this study, gas chromatography-mass spectrometry (GC-MS), qualitative GC-olfactometry (GC-O), and enantioselective GC-MS coupled with multivariate analysis were applied to characterise the volatile profiles of various dark teas obtained from the same dark raw tea material. A total of 159 volatile compounds were identified by stir bar sorptive extraction (SBSE) combined with GC-MS, and 49 odour-active compounds were identified. Moreover, microbial fermentation could greatly influence the distribution of volatile enantiomers in tea, and six pairs of enantiomers showed great diversity of enantiomeric ratios among various dark teas. These results suggest that post-fermentation processing technologies significantly affect the volatile profiles of various dark teas and provide a theoretical basis for the processing and quality control of dark tea products.
Article
Fu brick tea is a typical post-fermentation tea known for its special flavor and health benefits. Liquid chromatography-mass spectrometry, and sensory evaluation with multivariate analysis were used to characterize the dynamic changes in metabolite profile and taste characteristics. Seventy-one compounds were identified as critical metabolites, catechins, flavonoids, phenolic acids, terpenoids and others. During the manufacturing process, these compounds exhibited sharp fluctuations in content, the intensities of astringency, bitterness, and sourness of the tea materials reduced greatly, but the mellow intensity increased sharply. Several catechins and phenolic acids were positively related to the ‘astringent’, ‘bitter’, and ‘sour’ tastes attributes. The fungal genera, Aspergillus, Candida, unclassified_o_Hypocreales, unclassified_o_Saccharomycetales and Wallemia and the bacterial genus, Klebsiella, were identified as core functional microorganisms linked to the metabolic variations during the process. Overall, these findings provided a more comprehensive understanding of the formation of the sensory characteristics in Fu brick tea during the manufacturing process.
Article
Aroma is one of the most important criteria of tea quality, but the dynamic changes of aroma profile during the manufacturing process, and the chemical basis of characteristic aroma in Fu brick tea remain largely unknown. In this study, a total of 72 volatiles were identified and quantified, only the esters content increased sharply during the process. Sensory quantitative description analysis revealed that the ‘green’ attribute was dominated in the early processing stage, and the ‘fungal flower’, ‘flower’, ‘mint’ and ‘woody’ attributes became the major contributors to the aroma character in the later processing stages. Indicated by partial least-squares analysis, the linalool, acetophenone, and methyl salicylate were identified as key volatiles contributors to the ‘fungal flower’, ‘flower’, and ‘mint’ attributes, the cedrol contributed to ‘woody’ attribute, and twelve alcohols and aldehydes were related to ‘green’ attribute. Besides, bidirectional orthogonal partial least squares analysis revealed that six fungal genera Aspergillus, Candida, Debaryomyces, Penicillium, Unclassified_k_Fungi, Unclassified_o_Saccharomycetales were identified as core functional microorganisms link to the metabolism of volatiles. Taken together, these findings provide new insights into Fu brick tea aroma profile variation and increase our understanding of the formation mechanism of the characteristic aroma during the manufacturing process.
Article
Fuzhuan Brick‐Tea is a postfermented product with the hypoglycemic effect, which is prepared from the leaves of Camellia sinensis var. sinensis. However, the material basis associated with the hypoglycemic effect was not clear. The present research was designed to explore the hypoglycemic effect of extract/fractions from Fuzhuan Brick‐Tea in streptozotocin‐induced type II diabetic mice. Then an ultra‐high pressure liquid chromatography along with quadrupole time of flight mass spectrometry was used to analyze the phytochemicals in Fuzhuan Brick‐Tea fractions. As a result, the hypoglycemic and hypolipidemic effects were evidently observed from the serum biochemical indexes and liver pathological examination in type II diabetic mice. In addition, there were total of 20 major components including eight lysophosphatidylcholines (Lyso‐PCs), five fatty acids, and seven novel theophylline derivatives tentatively identified in the active fraction from water extract. Therefore, these components were assumed to contribute partly to the hypoglycemic effect of Fuzhuan Brick‐Tea. These findings also give the evidence that the Lyso‐PCs, fatty acids, and novel theophylline derivatives in Fuzhuan Brick‐Tea may provide benefits in ameliorating disorders of glucose and lipid metabolism. Practical Application This study suggests that the Lyso‐PCs, fatty acids, and novel theophylline derivatives in Fuzhuan Brick‐Tea may provide benefits in ameliorating disorders of glucose and lipid metabolism. It can be taken as a beneficial diet additive or nutraceutical.
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Effluent from clarifying the must from wine production was used as a sole medium for kombucha fermentation. Usually, this effluent is disposed in the communal sewage system. This way of use and treating wastewater is certainly ecologically beneficial. The initial substrate for cultivation was prepared by diluting sterilized winery effluent to 70 g/L of total sugars, using boiled tap water. Kombucha starter was prepared using black tea and sucrose and added 10% (vol/vol) to the initial substrate. Fermentation was performed at 25°C. The obtained beverage was appropriate for consummation after 6 days. Obtained kombucha product had an enjoyable taste with wine alike note. The produced beverage had supreme DPPH radical scavenging ability and reducing power compared to traditional black‐ and green‐ tea based kombucha. Hydroxyl radical scavenging ability was also significant. A variety of organic acids was detected. Ascorbic acid content was 3.6 mg/L on the consumption day. Using winery wastewater this way provides benefits for both winemakers and kombucha producers. Winemakers eliminate effluent with a lot of organic compounds for free and kombucha producers ensure raw material for the fermentation. An additional benefit is the eco‐friendly disposal of wastewater that generally goes to communal sewerage.
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Yogurt-flavored bases are widely used in food industry for enhancing flavors. In this study, yogurt-flavored bases by mixed lactic acid bacteria with or without lipase were investigated, which included Streptococcus lactis ACCC 11093 (SL) and Lactobacillus casei subsp. rhamnosus 6013 (LCR), SL and Lactobacillus acidophilus 1.1878 (LAP), and SL and Lactobacillus plantarum DMDL 9010 (LP), respectively. Compared with the combination of SL and LCR and the combination of SL and LAP, the combination of SL and LP had higher production of total amino acids, volatile acids and esters, suggesting that the combination of SL and LP was more efficient to produce yogurt-flavored bases. In addition, lipase significantly increased the production of amino acids associated with sweet and bitter flavors, and resulted in rougher milk globule surface and tighter network structure compared with fermentations without the addition of lipase. Furthermore, a total of 54 volatile compounds were detected in yogurt-flavored bases. The production of volatile compounds in fermentations with and without the addition of lipase, was mainly affected by acids and esters, respectively. Therefore, the lipase is a favorable supplement for producing yogurt-flavored bases.
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Fermentation is an ancient food preservation and processing technology with a long history of thousands of years, that is still practiced all over the world. Fermented foods are usually defined as foods or beverages made by controlling the growth of microorganisms and the transformation of raw and auxiliary food components, which provide the human body with many beneficial nutrients or health factors. As fungus widely used in traditional Chinese fermented foods, molds and yeasts play an irreplaceable role in the formation of flavor substances and the production of functional components in fermented foods. The research progress of molds and yeasts in traditional Chinese fermented foods from traditional to modern is reviewed, including the research on the diversity, and population structure of molds and yeasts in fermented foods. The interaction between fermenting mold and yeast and the latest research results and application development prospects of related industries were discussed.
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Pu-erh tea is a unique post-fermented tea with special quality and unique aroma characteristics, which are achieved by aging as part of the tea-making processing in China. In this work, we developed a new method, based on the combination of the mid-infrared (MIR) spectroscopy of graphene oxide-5,10,15,20-mesotetra (4-aminophenyl) porphyrin hybrid (GO-TAP), with chemometrics, for the variety identification and age prediction of twelve Pu-erh teas. Partial least squares discriminant analysis (PLSDA) and partial least squares regression (PLSR) models were respectively employed to classify the variety of and predict the age of Pu-erh teas based on the collected MIR spectra. Compared with traditional MIR spectroscopy, MIR spectroscopy based on GO-TAP gave better accuracy and specificity in variety classification and age prediction. The GO-TAP complex-based MIR spectroscopy sensor coupled with chemometrics could achieve 100% accuracy for variety classification and predicts storage time of Pu-erh tea. This method can be applied for the accurate identification and prediction of Pu-erh tea storage time, and it might have enormous potential for the application in storage time identification of other food stuff.
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Tea is a popular traditional drink and has been reported to exhibit various health-promoting effects because of its abundance of polyphenols. Among all the tea products, fermented tea accounts for the majority of tea consumption worldwide. Microbiota plays an important role in the fermentation of tea, which involves a series of reactions that modify the chemical constituents and thereby affect the flavor and bioactivities of tea. In the present review, the microorganisms involved in fermented tea and tea extracts in the recent studies were summarized and the modulation effects of microorganisms on tea in fermentation, including polyphenols composition and content, biological activities and sensory characteristics, were also critically reviewed. It is expected that the data summarized could provide some references for the development of microbial fermented tea drinks with specific nutrition and health benefits.
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Chemical compositions and infusion colour differences of seven pu-erh tea samples and their correlation to sensory quality were investigated. The results showed that the pu-erh tea contained 37.1 mg g−1 caffeine, 15.7 mg g−1 amino acids, 67.0 mg g−1 polyphenols and 8.41 mg g−1 total catechins, on average. Among the 17 tested volatile compounds, n-valeraldehyde was not detected. The most abundant volatile was β-ionone and the next was linalool oxide II. Infusion colour analysis showed that the pu-erh tea had deep hue with ΔE ranging from 66.8 to 79.2. Spearman's linear correlation analysis showed that total quality score (TQS) of the pu-erh tea was significantly correlated to concentration of amino acids, linalool oxide II and infusion colour indicator ΔE. Five components were extracted from the 34 tested indicators by principal component analysis and were regressed on the TQS to produce six Pearson's linear regression equations for estimating sensory quality of pu-erh tea, among which two were statistically significant, ie TQS = 57.47 − 0.18geraniol + 0.33polyphenols − 1.14n-caproaldehyde − 1.38linalool oxide I + 0.21caffeine (p < 0.01) and TQS = 57.42-0.03Citral + 0.33polyphenols − 1.14n − caproaldehyde − 1.40linalool oxide I + 0.20caffeine (p < 0.01). Copyright © 2004 Society of Chemical Industry
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The tea fungus (commonly designed as ''kombucha'') is a symbiotic culture of at least three microorganisms : the acetic acid bacteria Acetobacter xylinum and two yeasts Zygosaccharomyces rouxii and Candida sp. in sugared tea (Hesseltine, 1965; Anonymous, 1983). These microorganisms were cultured in their traditional medium and several metabolites were identified and quantified : ethanol, lactic, acetic, gluconic and glucuronic acids. The antibacterial product known as usnic acid was also searched.
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The effect of Kombucha tea (KT) on oxidative stress induced changes in rats subjected to chromate treatment are reported. KT feeding alone did not show any significant change in malondialdehyde (MDA) and reduced glutathione (GSH) levels, but did enhance humoral response and delayed type of hypersensitivity (DTH) response appreciably over control animals. Chromate treatment significantly enhanced plasma and tissue MDA levels, decreased DTH response considerably, enhanced glutathione peroxidase and catalase activities; however, no change in GSH, superoxide dismutase and antibody titres was noticed. KT feeding completely reversed the chromate-induced changes. These results show that Kombucha tea has potent anti-oxidant and immunopotentiating activities.
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The objective of the study was to evaluate toxicity, anti-stress activity and hepato-protective properties of Kombucha tea. Kombucha tea was fed orally for 15 days using three different doses i.e. normal dose, five and ten times the dose. Rats were then sacrificed and various biochemical, and histological parameters were estimated. Anti-stress activity was evaluated either by 1) by exposing animals to cold and hypoxia and estimating the levels of malondialdehyde and reduced glutathione in plasma/blood or 2) by subjecting the animals to restraint stress and recording faecal output. Hepato-toxicity was induced by challenging the animals to an acute dose of paracetamol (1 gm/kg) orally and determining the plasma levels of SGPT, SGOT and MDA. The effect of oral administration of different doses of K-tea to albino rats was examined and the results indicate that K-tea has no significant toxicity as revealed by various biochemical and histopathological parameters. K-tea has been found to prevent lipid peroxidation and fall in reduced glutathione level when rats were exposed to cold and hypoxia in simulated chamber. Further, K-tea has also been found to decrease the Wrap-restraint faecal pellet output in rats. K-tea has also been found to decrease paracetamol induced hepatotoxicity significantly. The study shows that K-tea has anti-stress and hepato-protective activities.
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The antibacterial activities of 10 different plant polyphenols were evaluated by comparing their minimum inhibitory concentrations (MICs) against several food-borne pathogenic bacteria, Staphylococcus aureus (20 strains), some serotypes of the genus Salmonella (26 strains), Escherichia coli (23 strains), and some species of the genus Vibrio (27 strains). The polyphenols examined were epigallocatechin (1), epigallocatechin-3-O-gallate (2), punicalagin (3), tannic acid (4), castalagin (5), prodelphinidin (6), geraniin (7), procyanidins (8), a theaflavin mixture of black tea (9), and green tea polyphenols treated with loquat polyphenol oxidase (10). The average MICs of all polyphenols against S. aureus and the genus Vibrio (192+/-91 and 162+/-165 microg/ml, respectively) were much lower than the values against the genus Salmonella and E. coli (795+/-590 and 1519+/-949 microg/ml, respectively) (p<0.01). The coefficient of variation of the MICs of all polyphenols against S. aureus was the least and that against the genus Vibrio was the greatest. The mean MICs of each plant polyphenol against S. aureus (98-389 microg/ml) and the genus Vibrio (68-488 microg/ml) were similar. The relatively lower mean MIC values of 1, 2, 5, and 6 suggest the importance of 3,4,5-trihydroxyphenyl groups in antibacterial activity.
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The methanolic extract of leaves of Camellia sinensis (L) O. KUNTZE was screened for antimicrobial property against 111 bacteria comprising 2 genera of Gram positive and 7 genera of Gram negative bacteria. Most of these strains were inhibited by the compound at 10-50 microg/ml level and few strains were sensitive even at lower concentrations (5 microg/ml). The bacteria could be arranged in the decreasing order of sensitivity towards the compound in the following manner: Staphylococcus aureus, Vibrio cholerae, Escherichia coli, Shigella spp., Salmonella spp., Bacillus spp., Klebsiella spp. and Pseudomonas aeruginosa. The antibacterial activity of compound could also be confirmed in vivo. When it was given to Swiss strain of white mice at different dosages (30, 60 microg/mouse), it could significantly protect the animals challenged with 50 MLD of Salmonella typhimurium NCTC 74. According to Chi square test the in vivo data were highly significant (p<0.001).
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Flavonoids are ubiquitous in photosynthesising cells and are commonly found in fruit, vegetables, nuts, seeds, stems, flowers, tea, wine, propolis and honey. For centuries, preparations containing these compounds as the principal physiologically active constituents have been used to treat human diseases. Increasingly, this class of natural products is becoming the subject of anti-infective research, and many groups have isolated and identified the structures of flavonoids possessing antifungal, antiviral and antibacterial activity. Moreover, several groups have demonstrated synergy between active flavonoids as well as between flavonoids and existing chemotherapeutics. Reports of activity in the field of antibacterial flavonoid research are widely conflicting, probably owing to inter- and intra-assay variation in susceptibility testing. However, several high-quality investigations have examined the relationship between flavonoid structure and antibacterial activity and these are in close agreement. In addition, numerous research groups have sought to elucidate the antibacterial mechanisms of action of selected flavonoids. The activity of quercetin, for example, has been at least partially attributed to inhibition of DNA gyrase. It has also been proposed that sophoraflavone G and (-)-epigallocatechin gallate inhibit cytoplasmic membrane function, and that licochalcones A and C inhibit energy metabolism. Other flavonoids whose mechanisms of action have been investigated include robinetin, myricetin, apigenin, rutin, galangin, 2,4,2'-trihydroxy-5'-methylchalcone and lonchocarpol A. These compounds represent novel leads, and future studies may allow the development of a pharmacologically acceptable antimicrobial agent or class of agents.
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In the Asian region, indigenous fermented foods are important in daily life. In many of these foods, yeasts are predominant and functional during the fermentation. The diversity of foods in which yeasts predominate ranges from leavened bread-like products such as nan and idli, to alcoholic beverages such as rice and palm wines, and condiments such as papads and soy sauce. Although several products are obtained by natural fermentation, the use of traditional starter cultures is widespread. This minireview focuses on the diversity and functionality of yeasts in these products, and on opportunities for research and development.
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We evaluated the antimicrobial activities of seven green tea catechins and four black tea theaflavins, generally referred to as flavonoids, as well as the aqueous extracts (infusions) of 36 commercial black, green, oolong, white, and herbal teas against Bacillus cereus (strain RM3190) incubated at 21 degrees C for 3, 15, 30, and 60 min. The results obtained demonstrate that (i) (-)-gallocatechin-3-gallate, (-)-epigallocatechin-3-gallate, (-)-catechin-3-gallate, (-)-epicatechin-3-gallate, theaflavin-3, 3'-digallate, theaflavin-3'-gallate, and theaflavin-3-gallate showed antimicrobial activities at nanomolar levels; (ii) most compounds were more active than were medicinal antibiotics, such as tetracycline or vancomycin, at comparable concentrations; (iii) the bactericidal activities of the teas could be accounted for by the levels of catechins and theaflavins as determined by high-pressure liquid chromatography; (iv) freshly prepared tea infusions were more active than day-old teas; and (v) tea catechins without gallate side chains, gallic acid and the alkaloids caffeine and theobromine also present in teas, and herbal (chamomile and peppermint) teas that contain no flavonoids are all inactive. These studies extend our knowledge about the antimicrobial effects of food ingredients.
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Correct spelling of co-author's Kalab first name is Milos or Miloslav. The Chinese green tea extract was found to strongly inhibit the growth of major food-borne pathogens, Escherichia coli O157:H7, Salmonella Typhimurium DT104, Listeria monocytogenes, Staphylococcus aureus, and a diarrhoea food-poisoning pathogen Bacillus cereus, by 44–100% with the highest activity found against S. aureus and lowest against E. coli O157:H7. A bioassay-guided fractionation technique was used for identifying the principal active component. A simple and efficient reversed-phase high-speed counter-current chromatography (HSCCC) method was developed for the separation and purification of four bioactive polyphenol compounds, epicatechin gallate (ECG), epigallocatechin gallate (EGCG), epicatechin (EC), and caffeine (CN). The structures of these polyphenols were confirmed with mass spectrometry. Among the four compounds, ECG and EGCG were the most active, particularly EGCG against S. aureus. EGCG had the lowest MIC90 values against S. aureus (MSSA) (58 mg/L) and its methicilin-resistant S. aureus (MRSA) (37 mg/L). Scanning electron microscopy (SEM) studies showed that these two compounds altered bacterial cell morphology, which might have resulted from disturbed cell division. This study demonstrated a direct link between the antimicrobial activity of tea and its specific polyphenolic compositions. The activity of tea polyphenols, particularly EGCG on antibiotics-resistant strains of S. aureus, suggests that these compounds are potential natural alternatives for the control of bovine mastitis and food poisoning caused by S. aureus.
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The transformation of sucrose into glucose, fructose, gluconic acid, ethanol, and acetic acid was determined during a 60 day tea fungus fermentation. Black tea containing 67.5 g sucrose per litre was inoculated with 10% fermentation broth including the cellulose containing coherent top layer of a previous tea fungus fermentation. The microflora embedded in the cellulose/acetan layer was characterized as a mixed culture of Acetobacter xylinum and Zygosaccharomyces sp., respectively. The yeast cells converted sucrose into glucose and fructose. Fructose was metabolized prior to glucose. The pH value of the kombucha beverage decreased during fermentation from 3.75 to 2.42 as a result of acetic acid and gluconic acid formation. A fermentation balance of the substrates sucrose, glucose, fructose and products ethanol, acetic and gluconic acid and CO2 was calculated based on the carbon-mass (g substrate X number of C-atoms X 12/molecular weight of substrate) as parameter. The total carbon-mass at the start of the fermentation was 30.5 g. The analogous values obtained after 10, 20, 30 and 40 days were 30.7 g, 30.5 g, 28.6 g, and 30.5, respectively. The good stoichiometry implies that all major fermentation products have been accounted for.
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Phenolic compounds like simple phenols, flavonoids, and phenolic acids are commonly in foods of plant origin. Several studies, including animal and epidemiological investigations, have demonstrated that phenolic compounds in foods possess positive attributes such as anticarcinogenesis, antioxidant potential, antiviral activity, antimicrobial activity, and antimutagenic activity. However, other studies have shown that the same phenolics have negative attributes such as carcinogenic activity and antinutritional activity, as well as imparting negative attributes to foods. This review summarizes the information about food phenolics and presents the most current knowledge with respect to its role in human health, food attributes, and toxicity among others.
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Effects of kombucha origins and fermentation time on their antioxidant properties were investigated using in vitro free radical scavenging assays. Kombucha from various sources demonstrated different antioxidant activities, and most showed the time-dependent characteristics. The average antioxidant potentials of kombucha after fermenting for 15 days were raised to about 70%, 40%, 49% determined, respectively, by the assays of DPPH, ABTS radical scavenging, and inhibition of linoleic acid peroxidation, while the ferrous ion binding ability was inversely diminished by 81%. The total phenol content increased up to 98% which implied that thearubigin might be subjected to biodegradation during fermentation, resulting in the release of smaller molecules with higher antioxidant activities.
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Interest in novel biological preservation methods has increased during recent years, supported by research indicating that antagonistic microorganisms or their antimicrobial metabolites may have some potential as natural preservatives to control the growth of pathogenic bacteria in foods, and also to control mycotoxinogenic fungi. To date, nisin is the only bacteriocin that has found practical application in some industrially processed foods. Many other bacteriocins from lactic acid bacteria have recently been characterized, but their efficacy in foods has not been studied extensively. Better understanding of the interactions between antimicrobial metabolites and food components is necessary to evaluate their potential as preservatives.
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Kombucha is a refreshing beverage obtained by the fermentation of sugared tea with a symbiotic culture of acetic bacteria and fungi, consumed for its beneficial effects on human health. Research conducted in Russia at the beginning of the century and testimony indicate that Kombucha can improve resistance against cancer, prevent cardiovascular diseases, promote digestive functions, stimulate the immune system, reduce inflammatory problems, and can have many other benefits. In this paper, we report on studies that shed more light on the properties of some constituents of Kombucha. The intensive research about the effects of tea on health provide a good starting point and are summarized to get a better understanding of the complex mechanisms that could be implicated in the physiological activity of both beverages.
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Fermented tea drink, Kombucha, can inhibit the growth of Shigella sonnei, Escherichia coli, Salmonella enteritidis and Salmonella typhimurium. Several metabolites were analyzed every two days during a 14-day Kombucha fermentation. Levels of acetic acid and gluconic acid were found to increase with fermentation time. No lactic acid or ethanol was detected. Systematic investigation of the antimicrobial activity in Kombucha revealed the presence of antimicrobial compounds other than organic acids or proteins (enzymes) produced during fermentation or the tannins originally present in the tea broth.
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Tea fungus/kombucha, an acetic acid flavoured fermented tea beverage, is widely consumed in various parts of the world and has more recently become a fad in the United States. This is due in part to the fact that it can be produced in the home, and it is reported to be medicinal, effective against arthritis, psoriasis, chronic fatigue, constipation, indigestion and metabolic diseases. Among 264 references from 1852 to 1961, there are reports of antibiotic activity against Agrobacterium tumefaciens and medicinal value against a variety of diseases. The medicinal value appears to be related to that attributed to vinegar, one of our most ancient foods. We decided to test tea fungus/kombucha for its antibiotic activity against Helicobacter pylori, a primary cause of gastritis related to peptic ulcers and gastric carcinoma, Escherichia coli, Staphylococcus (Micrococcus) aureus and Agrobacterium tumefaciens. Tea containing 4.36 g of dry tea per litre and 10% of sucrose and fermented with the tea fungus showed no antibiotic activity in the beverage beyond that caused by acetic acid, a primary product of the fermentation.
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Puer tea is a unique Chinese fermented tea with natural flora manufactured in Yunnan Province of China. Very complex changes take place to form special quality and flavor characteristics in Puer tea due to the coordination of microbial metabolic action and natural oxidation. This paper investigates the isolation and identification of fungi responsible for the fermentation and the development of main volatile compounds of Puer tea during the fermentation process by means of GC/MS. Aldehydes and ketones in parched green tea (raw material) with low boiling-points decreased significantly, while the amount of terpene alcohols – such as linalool and linalool oxides, methoxybenzene and derivatives, and indole – increased remarkably from the parched green tea to the Puer tea product after the manufacturing process. Degradation caused by heat and microbial growth at the piling stage likely played a key role in the generation of these compounds that contributed to the aromatic characteristics of Puer tea. It is hypothesized that the fungus Aspergillus niger plays a decisive role in the development of the volatile compounds.
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The biological action of water extract of pu-erh tea (WEPT) was evaluated by Salmonella mutagenesis assay and bacteria test. Like green tea, oolong tea and black tea, WEPT showed neither cytotoxicity and nor mutagenicity toward Salmonella typhimurium TA98 and TA100 with or without S9 mix (an external metabolic activation system). WEPT at 0.5–5 mg/plate expressed a dose-dependent inhibitory effect against both the mutagenicity of aflatoxin B1 (AFB1), an indirect mutagen which requires metabolic activation, and 4-nitroquinoline-N-oxide (NQNO), a direct mutagen, in Salmonella typhimurium TA98 and TA100. In general, the antimutagenic activity of WEPT against AFB1 and NQNO was weaker than other tea extract because of the least amount of total catechin in WEPT. For antimicrobial action, WEPT, green tea, oolong tea and black tea at 2.0 mg/ml showed inhibitory effect on growth of Staphylococcus aureus and Bacillus subtilis, but no effect on Escherchia coli. Obviously, WEPT has potential antimicrobial effect on gram-positive Staphylcoccus aureus and B. subtilis than that of gram-negative E. coli. In addition, caffeine and epicatechin (EC), main polyphenolic compounds in WEPT, showed both antimutagenic and antimicrobial effect against strains mentioned above, which may partially account for the antimutagenic and antimicrobial action of pu-erh tea.
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Samples of Haipao from three cities of Taiwan were analyzed for their microbial population. Two species of acetic acid bacteria and three species of yeast were isolated from tea fungus Haipao using appropriate isolation media. The isolated bacteria were identified asAcetobacter acetiandAcetobacter pasteurianus, based on their biochemical properties, and compared with those of the type strains of the genusAcetobacter. The yeasts wereSaccharomyces cerevisiae, Zygosaccharomyces bailii, andBrettanomyces bruxellensisaccording to conventional phenotypic characterization combined with the Yeast Identification Program. The brew broth analyzed by high−performance liquid chromatography (HPLC) was shown to contain glycerol, acetic acid and ethanol. The symbiosis phenomenon between the yeast andAcetobacterwas studied. It was found that the autoclaved yeast cells and ethanol produced by yeasts were helpful forAcetobacterto grow or produce acetic acid. The acetic acid produced byAcetobactercould stimulate the yeast to produce ethanol. The ethanol and acetic acid produced by yeasts andAcetobactermight prevent the competition from other micro-organisms.
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Polyphenols of green tea leaf were separated and irradiated at 40 kGy to investigate the effect of irradiation on changes of biological and anti-microbial activities. The major antioxidative activities, including electron donating, inhibition of xanthine oxidase, metal ion chelating, and inhibition of lipid oxidation were maintained through irradiation, except for superoxide dismutase (SOD)-like activity at the 200 ppm level. The anti-microbial activities against Staphylococcus aureus and Streptococcus mutans were higher in the irradiated sample, which showed inhibition of microorganisms tested at a lower concentration than those of the non-irradiated sample. Ranges of the inhibition zone for growth of Escherichia coli, S. aureus, S. epidermidis and S. mutans, at 1 mg/disc, were 9.3, 10.1, 22.5 and 9.3 mm in non-irradiated control but 10.8, 11.0, 25.0, and 11.7 mm in irradiated samples, respectively. Results indicated that irradiation of polyphenols, the major bioactive compounds in green tea, may maintain the biological activities and even increase the anti-microbial activity. The results also demonstrated that irradiation of green tea polyphenols, for removal of dark colour, may be applicable in the food or cosmetic industries.
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Summary Biologically active substances (water soluble vitamins and minerals) were analyzed in ‘Kombucha’—a curative liquor, produced by the so-called ‘Kombucha cultivation’ (Macedonian collection of microorganisms, No 734) in sweet black tea decoct. The water soluble vitamins in the Kombucha drink were separated and identified using thin layer chromatography (TLC) and quantified by the comparison of their chromatographic UV spectra with the reference compounds. Four soluble vitamins have been determinated to have the following concentrations: vitamin B1 0.74 mg ml−1, vitamin B6 0.52 mg ml−1, vitamin B12 0.84 mg ml−1 and vitamin C 1.51 mg ml−1. Mineral elements of nutritional and toxicological importance were determined in dissolved ash using atomic absorption chromatography (AAS). Mineral composition content involved determination of the essential elements: zinc, copper, iron, manganese, nickel and cobalt. Investigations of some toxic elements showed that lead and chromium were present in very small amounts, whereas cadmium was not found.
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The theoretical mathematical models described in this paper are used to evaluate the effects of fungal biomass inactivation kinetics on a non-isothermal tray solid-state fermentation (SSF). The inactivation kinetics, derived from previously reported experiments done under isothermal conditions and using glucosamine content to represent the amount of biomass, are described in different ways leading to four models. The model predictions show only significant effects of inactivation kinetics on temperature and biomass patterns in the tray SSF after long fermentation periods. The models in which inactivation is triggered by low specific growth rates can predict restricted biomass evolution in combination with a fast temperature increase followed by a slower temperature decrease. Such inactivation might occur when substrate is limiting or products are formed in toxic concentrations. Temperature is predicted to be the key parameter. Oxygen concentration is predicted to become limiting only at high heat conduction and low oxygen diffusion rates. Desiccation of the substrate is predicted not to occur.
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A two-phase dynamic model is developed that describes heat and mass transfer in intermittently-mixed solid-state fermentation bioreactors. The model predicts that in the regions of the bed near the air inlet there can be significant differences in the air and solid temperatures, while in the remainder of the bed the gas and solid phases are much closer to equilibrium, although there can be differences in water activity of around 0.05. The increase in the temperature of the gas as it flows through the bed means that it is impossible to prevent the bed from drying out, even if saturated air is used at the air inlet. The substrate can dry to water activities that severely limit growth, unless the bed is intermittently mixed, with the addition of water to bring the water activity back to the desired value. Under the conditions assumed for the simulation, which was designed to mimic the growth of Aspergillus niger on corn, two mixing events were necessary, one at 17.4 and the other at 27.9 h. Even though such a strategy can minimize the restriction of growth by water-limitation, temperature-limitation remains a problem due to the rapid heating dynamics. The model is obviously a useful tool that can be used to guide scale-up and to test control strategies. Such a model, describing the non-equilibrium situation between the gas and solid phases, has not previously been proposed for solid-state fermentation bioreactors. Models in the literature that assume gas-solid temperature and moisture equilibrium cannot describe the large temperature differences between the gas and solid phase which occur within the bed near the air inlet. (C) 2002 Wiley Periodicals, Inc.
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Catechins are flavanols present in a variety of foods such as wine, tea, fruits and chocolate. Catechin, epicatechin and gallates of epicatechin are major catechins with dietary importance for human health. In recent years, catechins have been used as natural antioxidant in oils and fats against lipid oxidation, supplement for animal feeds both to improve animal health and to protect animal products, an antimicrobial agent in foodstuffs and a health functional ingredient in various foods and dietary supplements. This review outlines the novel uses of catechins in foods.
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Early reports onKombucha, a traditional fermented tea beverage, suggested that it has antimicrobial activity against a spectrum of organisms, and that concentrates of unfermented tea components also have anti microbial properties. Therefore, the focus of this study was to determine and characterizeKombucha'santimicrobial activity using an absorbent disc method. Antimicrobial activity was observed in the fermented samples containing 33 g/L total acid (7 g/L acetic acid) against the tested Gram-positive and Gram-negative organisms (Agrobacterium tumefaciens, Bacillus cereus, Salmonella choleraesuisserotypetyphimurium, Staphylococcus aureus, andEscherichia coli.Candida albicanswas not inhibited byKombucha. The contribution of tea itself to the antimicrobial activity ofKombuchaproved to be significant in the tested organisms, even at the highest levels tested, 70 g/L dry tea. As a result, the antimicrobial activity ofKombuchawas attributed to its acetic acid content.
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The inhibitory action of tea polyphenols towards the development and growth of bacterial spores was examined. Among the tested Bacillus bacteria, tea polyphenols showed antibacterial effects towards Bacillus stearothermophilus, which is a thermophilic spore-forming bacterium. The heat resistance of B. stearothermophilus spores was reduced by the addition of tea polyphenols. Clostridium thermoaceticum, an anaerobic spore-forming bacterium, also exhibited reduced heat resistance of its spores in the presence of tea polyphenols. (−)-Epigallocatechin gallate, which is the main component of tea polyphenols, showed strong activity against both B. stearothermophilus and C. thermoaceticum. The heat resistance of these bacterial spores was more rapidly decreased by the addition of tea polyphenols at high temperatures.
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Fuzhuan brick-tea is a popular fermented Chinese dark tea because of its typical fungal aroma. Fungal growth during the production process is the key step in achieving the unique colour, aroma and taste of Fuzhuan brick-tea. To further understand the generation of the characteristic aroma, changes in the main volatile compounds of Fuzhuan brick-tea during the fungal growth stage were studied by gas chromatography/mass spectrophotometry. The results showed that the content of volatile compounds, especially aldehyde compounds with stale aroma such as (E)-2-pentenal, (E)-2-hexenal, 1-penten-3-ol, (E, E)-2,4-heptadienal and (E, Z)-2,4-heptadienal, increased significantly in fermented tea samples. The concentration of terpene alcohols with flower aroma also increased notably during the fermentation process. The compounds with stale and flower aromas in combination with some volatile components of the raw material contributed to the characteristic fungal/flower aroma of Fuzhuan brick-tea. Microbial metabolism during the fermentation process probably played the key role in the generation of characteristic aromatic compounds of Fuzhuan brick-tea.
Article
Microbiological analysis was done on samples from an indigenously fermented tea - Puer. Microbial counting and identification revealed that Aspergillus niger was the dominating microorganism during the fermentation. Antimicrobial activity of fermentation samples showed inhibitory effect on several food borne bacteria, including spore forming bacteria Bacillus cereus, Bacillus subtilis, Clostridium perfringens and Clostridium sporogenes. The antimicrobial activity increased with the course of the fermentation. This implied that certain metabolites of Aspergillus niger growing on tea leaves had the feature of inhibiting certain food borne spoilage and pathogen microorganisms.
Article
A description is given of the solid-state fermentation of wheat bran by Trichoderma reesei QM9414 at constant temperature and relative humidity. Glucosamine, the oxygen consumption rate (OCR), the carbon dioxide production rate (CPR), changes in wheat bran composition and the production of four enzymes were measured during 125 h of fermentation. A C balance was set up between CO2 production, based on CPR measurements, CO2 production as expected on the basis of substrate composition changes and substrate elemental composition in combination with dry-matter weight loss. Glucosamine was used as the measure of biomass. The results indicate that the glucosamine content of fungi in liquid culture cannot be used to estimate the biomass content in solid-state fermentations. Using glucosamine, correlations between fungal growth and respiration kinetics could only partly be described with the linear-growth model of Pirt. A decline in OCR and CPR started the moment the glucosamine level was 50% of its maximum value. After the glucosamine level had reached its maximum OCR and CPR continued to decline. The activities of xylanase and protease are linearly related to the glucosamine level. No clear correlations between glucosamine and carboxylmethylcellulose-hydrolysing enzyme activity and amylase activity were found.
Article
1. Two series of balance experiments were performed with growing rats to test the effect of black tea, green tea, coffee and cocoa on protein and energy utilization. In Expt 1 soya-bean meal was fed as a basal diet and supplemented with freeze-dried materials from 11 black tea, green tea or coffee/500 g dry matter. Cocoa powder, corresponding to 11 of the beverage, was also added to the basal diet. In Expt 2 the procedure was repeated with a barley-based diet. 2. In both experiments both tea varieties and coffee had significantly negative effects on true protein digestibility and biological value, while digestible energy was only slightly affected in the barley-based diet. Cocoa had no effect on protein or energy utilization in either soya-bean meal or barley diets, although the protein in cocoa powder was completely indigestible. 3. As the tannin concentration in both tea varieties and coffee was very high it is assumed that the observed deleterious effects might, in part, be explained by anti-nutritional effects of tannin. 4. The strongest deleterious effect was recorded for black tea.
Article
The tea fungus ‘Kombucha’ is a symbiosis of Acetobacter, including Acetobacter xylinum as a characteristic species, and various yeasts. A characteristic yeast species or genus has not yet been identified. Kombucha is mainly cultivated in sugared black tea to produce a slightly acidulous effervescent beverage that is said to have several curative effects. In addition to sugar, the beverage contains small amounts of alcohol and various acids, including acetic acid, gluconic acid and lactic acid, as well as some antibiotic substances. To characterize the yeast spectrum with special consideration given to facultatively pathogenic yeasts, two commercially available specimens of tea fungus and 32 from private households in Germany were analysed by micromorphological and biochemical methods. Yeasts of the genera Brettanomyces, Zygosaccharomyces and Saccharemyces were identified in 56%, 29% and 26% respectively. The species Saccharomycodes ludwigii and Candida kefyr were only demonstrated in isolated cases. Furthermore, the tests revealed pellicle-forming yeasts such as Candida krusei or Issatchenkia orientalis/ occidentalis as well as species of the apiculatus yeasts (Kloeckera, Hanseniaspora). Thus, the genus Brettanomyces may be a typical group of yeasts that are especially adapted to the environment of the tea fungus. However, to investigate further the beneficial effects of tea fungus, a spectrum of the other typical genera must be defined. Only three specimens showed definite contaminations. In one case, no yeasts could be isolated because of massive contamination with Penicillium spp. In the remaining two samples (from one household), Candida albicans was demonstrated. The low rate of contamination might be explained by protective mechanisms, such as formation of organic acids and antibiotic substances. Thus, subjects with a healthy metabolism do not need to be advised against cultivating Kombucha. However, those suffering from immunosuppression should preferably consume controlled commercial Kombucha beverages. Zusammenfassung. Der Teepilz ‘Kombucha’ ist eine symbiotische Lebensgemeinschaft von Essigsäurebakterien, darunter Acetobacter xylinum als charakteristische Species, und verschiedenen Hefen. Eine charakteristische Hefespecies oder gattung wurde bisher nicht identifiziert. Die Kombucha wird überwiegend in gezuckertem schwarzem Tee zur Herstellung eines leicht säuerlichen, moussierenden Getränkes kultivert, dem verschiedene Heilwirkungen zugeschrieben werden. Das Getränk enthält neben Zucker geringe Mengen an Alkohol sowie verschiedene Säuren, darunter Essig-, Glukon- und Milchsäure, und antibiotisch wirksame Substanzen. Zur Charakterisierung des Hefespektrums unter besonderer Berücksichtigung fakultativ pathogener Hefen wurden zwei im Handel erhältliche sowie 32 Proben aus privaten Haushalten in Deutschland mit Hilfe mikromior-phologischer und biochemischer Methoden analysiert. Hefen der Gattungen Brettanomyces, Zygosaccharomyces und Saccharomyces wurden in 56%, 29% bzw. 26% der Proben identifiziert, nur in Einzelfällen wurden die Species Saccharomycodes ludwigii bzw. Candida kefyr nachgewiesen. Darüber hinaus fanden sich im Probenmaterial die Kahmhefen Candida krusei bzw. Issatchenkia occidentals/orientalis und Species der zu den Apiculatushefen
Article
A bulk acoustic wave (BAW) bacterial growth sensor has been proposed for study of inhibitory effects of tea by continuous monitoring of disturbances in Proteus growth in the aqueous extracts of various teas, e.g. green tea, Fuzhuan brick tea, Oolong tea, Kudin tea, and black tea. The kinetic parameters, e.g. asymptote (A), maximum specific growth rate (microm), lag time (lambda), and generation time (g), accurately estimated by using the growth response model, have been first used to characterize antimicrobial properties of tea. All of the parameters were changed via the inhibitory effects by tea. Green tea gives the weakest inhibitory action while others show stronger inhibitory actions. These inhibitory effects have also been examined by using the pour plate count technique. Both of the results show that, in addition to the antimicrobial properties of tea polyphenols and catechins, etc., the inhibitory effects may be attributed to the metabolites produced during the fermentation processing of these teas except green tea. The conventional disk diffusion test has been used to determine the minimum inhibitory concentration (MIC) against P. rettgeri. The MICs of green tea, Fuzhuan brick tea, Oolong tea, and black tea were found to be 1113, 818.0, 681.2, and 510.4 microg/mL, respectively. The BAW bacterial growth sensor has shown to have advantages over other techniques, including the disk diffusion test, photometry, and the impedance method.