A Review on Kombucha Tea-Microbiology, Composition, Fermentation, Beneficial Effects, Toxicity, and Tea Fungus

Development of kombucha beverage with jackfruit leaves (Artocarpus heterophyllus Lam) and/or soursop leaves (Annona muricata)

Kombucha is a fermented beverage with health effects, made mainly from green tea and black tea; however, it can also be made from other leaves such as those of jackfruit and soursop, which are not used even though they have been reported to have positive health effects. Due to the above, in this work "kombucha" beverages based on jackfruit and/or soursop leaves were developed and analyzed to take advantage of these by-products. It was found that fermentation produced significant changes, being the optimal kombucha formulation green tea with soursop leaves (GTKS), obtaining a higher content of antioxidant compounds (mainly catechin, rutin and shikimic acid) and greater ferric reducing antioxidant power (FRAP) (1.62 ± 0.03 mg TE/mL), increasing acidity and decreasing pH and total soluble solids (TSS), having a better sensory acceptance than a commercial kombucha; in addition to demonstrating safe conditions for human consumption.

Physiological and fermentative performance of non-Saccharomyces yeasts isolated from kombucha for beer production

This study aimed to isolate, identify, and characterize kombucha yeasts for beer production. Nineteen yeasts were isolated, and the species Brettanomyces bruxellensis, Galactomyces candidum, Galactomyces sp., Pichia kluyveri, and Saccharomycodes ludwigii were identified. The strains B. bruxellensis L652, P. kluyveri L472, L231, L431, and L131, and S. ludwigii L331 present desired physiological properties for beer production, including tolerance to 6% ethanol, 100 mg/L of iso-α-acid and flocculation capacity. It was selected for wort fermentation at 10 °C and 20 °C. Beers with different chemical characteristics were produced when evaluated at 10 °C and 20 °C for all strains. Minor carbohydrate residuals and higher ethanol concentrations were observed in the beers fermented at 20 °C. All non-Saccharomyces yeasts evaluated produced alcohol-free beers (<0.5%) at 10 °C. At 20 °C, only the yeast P. kluyveri L431 produced non-alcoholic beer (0.24%). The yeasts P. kluyveri L131, L231, and L472 and B. bruxellensis L652 produced beers with reduced alcoholic content (0.6-1.4%), and the strains S. ludwigii L331 produced alcoholic beer (2.45%). Relating acetic acid, the strains P. kluyveri L431 and L472 presented higher concentrations (0.226 g/L and 0.264 g/L, respectively) at 10 °C, while S. ludwigii L331 showed the highest concentration (0.936 g/L) at 20 °C, demonstrating the potential to produce sour beers. These results indicate that evaluating the yeast strain according to the beer style is crucial.

Physicochemical, microbiology, and sensory characteristics of kombucha prepared with Tommy mango peel flour

Fermented foods are a good option due to the beneficial compounds generated in the fermentation process and the low pH that allows conservation without additives. The objective of the study was to produce and include Tommy mango peel flour in the production of kombucha and evaluate its effects on the physicochemical and sensory properties, antioxidant capacity, and microbiological profile. The kombucha was developed with green tea and the addition of Tommy mango peel flour (10% and 20%). The kombuchas were evaluated in the first fermentation (aerobic) and at the end of the second fermentation (anaerobic), the granulometry and colorimetry of the flour and the antioxidant profile were evaluated. Microbiome analysis was performed by 16S DNA extraction. For sensory analysis, an affective test was performed for global evaluation, flavor, texture, and oral perception. The results showed that the total phenolic content was 4.86 mg EAG/mL in F1, 8.79 mg EAG/mL in F2 with 10% mango peel flour, and 8.83 ± 0.54 mg EAG/mL in F2 with 20% mango peel flour, evidencing a significant increase in the second fermentation with the addition of the flour. In addition, the antioxidant activity was also higher in the second fermentation. The values obtained were F1 = 15.27 µmol TE/mL; F2 with 10% FCMT = 18.80 µmol TE/mL; and F2 with 20% FCMT = 26.76 µmol TE/mL. These findings indicate that the antioxidant capacity increases significantly during the second fermentation, directly correlating with the amount of mango peel flour added. The most abundant bacterial genera were Liquorilactobacillus nagelii (72%), Acetobacter (13%), and Komagataeibacter (12%) and for fungi (90%) Brettanomyces/Dekkera bruxellensis. The beverage obtained different levels of acceptance among consumers and non-consumers only in terms of flavor, proving to be a good alternative for the food industry for applying a mango byproduct to drinks.

Comprehensive survey of kombucha microbial communities of diverse origins and fermentation practices

Kombucha is a unique, naturally fermented sweetened tea produced for thousands of years, relying on a symbiotic microbiota in a floating biofilm, used for successive fermentations. The microbial communities consist of yeast and bacteria species, distributed across two phases: the liquid and the biofilm fractions. In the fermentation of kombucha, various starters of different shapes and origins are used, and there are multiple brewing practices. By metabarcoding, we explored here the consortia and their evolution from a collection of 23 starters coming from various origins summarizing the diversity of kombucha fermentation processes. A core microbiota of yeast and bacteria has been identified in these diverse kombucha symbiotic consortia, revealing consistent core taxa across symbiotic consortium of bacteria and yeasts from different starters. The common core consists of five taxa: two yeast species from the Brettanomyces genus (B. bruxellensis and B. anomalus) and bacterial taxa Komagataeibacter, Lactobacillus, and Acetobacteraceae, including the Acetobacter genus. The distribution of yeast and bacteria core taxa differs between the liquid and biofilm fractions, as well as between the "mother" and "daughter" biofilms used in successive fermentations. In terms of microbial composition, the diversity is relatively low, with only a few accessory taxa identified. Overall, our study provides a deeper understanding of the core and accessory taxa involved in kombucha fermentation.

Kombucha fortified with Cascade hops (Humulus lupulus L.): enhanced antioxidative and sensory properties

In recent years, there has been a surge in the production of kombucha-a functional beverage obtained via microbial fermentation of tea. However, fresh, unpasteurized kombucha is sensitive to quality deterioration as a result of, among other factors, oxidation. The addition of hops seems to be promising, due to their antioxidative properties, which may improve the stability of kombucha. However, aiming at retaining the highest antioxidative properties of kombucha, it remains unclear at which stage of the production process hops should be added. The study investigated the effect of hop supplementation during kombucha production on the basic physicochemical, antioxidative, and sensory properties of kombucha. Cascade hops in the concentrations 0.5 and 2 g/L were added at the onset of tea infusion and to the fresh, unpasteurized kombucha. The addition of hops (particularly at the pre-fermentation stage of production) led to a significant decrease in radical formation in the produced kombucha measured by electron spin resonance spectroscopy (ESR), which correlated with the higher DPPH antiradical activity and the elevated bitter α-acid content. From the sensory perspective, the post-fermentation addition of hops to kombucha resulted in a significantly higher rating of the overall quality. This enhancement was directly associated with heightened bitterness, increased presence of fruity and citrusy aromas, and a simultaneous reduction in the intensities of acetic and tea-related attributes. The data presented in this study are relevant for kombucha producers, who want to deliver a sensory-novel product in combination with an improved oxidative stability. KEY POINTS: • Hop addition in kombucha production improves the antioxidative activity of the beverage. • Hop α-acids display higher antioxidative properties in kombucha than polyphenols. • Oxidative stability of kombucha fortified with hops depends on the timing of hops addition. • Hop addition enriches the taste and aroma attributes of kombucha.

Application of scoby bacterial cellulose as hydrocolloids on physicochemical, textural and sensory characteristics of mango jam

BACKGROUND

The scoby pellicle of symbiotic culture of bacteria and yeast is a by-product from kombucha fermentation. While a portion is used as starter culture, the remainder is often discarded, yet it can be a valuable source of bacterial cellulose.

RESULTS

Scoby from black, green and oolong tea kombucha fermentation was assessed for its hydrocolloid effects in mango jam-making through evaluation of physicochemical, textural and sensory characteristics. Quality of jam was significantly improved with water activity reduction up to 22.22% to 0.679, moisture content reduction up to 37.06% to 19.92%, and a pH drop up to 5.9% to 3.19 with the use of 20 to 100 g kg-1 scoby. In colour analysis, presence of scoby led to a brighter jam due to higherL * values from 30.98 to a range of 31.82 to 40.83. Texture of jam with scoby gave higher gel strength and adhesiveness, with the most prominent effects from the black tea kombucha. Overall acceptability in sensory test scoring was above 70% on a nine-point hedonic scale with the 40 g kg-1 green tea kombucha scoby jam chosen as the most preferred.

CONCLUSION

Scoby gave significant contributions to jam stability, appearance and texture, showing potential as a clean-label food ingredient. © 2024 Society of Chemical Industry.

Functional kombucha production from fusions of black tea and Indian gooseberry (Phyllanthus emblica L.)

The use of alternative ingredients as supplements to or blends with kombucha tea to improve organoleptic properties and health effects has recently increased. Indian gooseberry fruit is among the most promising alternative raw materials for producing functional kombucha since the berries contain several beneficial substances. In this study, the production of functional kombucha beverages from fusions of black tea and Indian gooseberry fruit homogenate (IGH) was investigated, and the chemical and biological properties of kombucha products were evaluated and compared with those of traditional black tea kombucha products. Chemical composition analysis revealed that IGH contains high amounts of polyphenols (627.4 mg GAE/L or 129.51 mg GAE/g dry weight), flavonoids (98.0 mg QE/L or 9.11 mg QE/g dry weight), and vitamins, specifically ascorbic acid (465.72 mg/100 g fresh weight). It also contains several amino acids, fatty acids, and trace elements. Supplementing or blending black tea kombucha with IGH in the range of 10 %-50 % (v/v) increased the total phenolic content (TPC), total flavonoid content (TFC), and total acidity of the fermented beverages. Several volatile organic compounds associated with the flavor, aroma, and health benefits of kombucha were also detected in black tea and IGH fusion kombucha products. Moreover, the black tea and IGH fusion kombucha products also displayed greater antioxidant and antimicrobial activities than the traditional black tea kombucha. Among the different combinations of black tea and IGH, supplementing black tea kombucha with 20 % IGH was the best combination for producing alternative and unique functional kombucha products with notable nutritional and health benefits.

Regular Consumption of Black Tea Kombucha Modulates the Gut Microbiota in Individuals with and without Obesity

BACKGROUND

Kombucha, a fermented beverage obtained from a Symbiotic Culture of Bacteria and Yeast, has shown potential in modulating gut microbiota, although no clinical trials have been done.

OBJECTIVES

We aimed to evaluate the effects of regular black tea kombucha consumption on intestinal health in individuals with and without obesity.

METHODS

A pre-post clinical intervention study was conducted lasting 8 wk. Forty-six participants were allocated into 2 groups: normal weight + black tea kombucha (n = 23); and obese + black tea kombucha (n = 23). Blood, urine, and stool samples were collected at baseline (T0) and after 8 wk of intervention (T8).

RESULTS

A total of 145 phenolic compounds were identified in the kombucha, primarily flavonoids (81%) and phenolic acids (19%). Kombucha favored commensal bacteria such as Bacteroidota and Akkermanciaceae, especially in the obese group. Subdoligranulum, a butyrate producer, also increased in the obese group after kombucha consumption (P = 0.031). Obesity-associated genera Ruminococcus and Dorea were elevated in the obese group at baseline (P < 0.05) and reduced after kombucha consumption, becoming similar to the normal weight group (Ruminococcus: obese T8 × normal weight T8: P = 0.27; Dorea: obese T8 × normal weight T0: P = 0.57; obese T8 × normal weight T8: P = 0.32). Fungal diversity increased, with a greater abundance of Saccharomyces in both groups and reductions in Exophiala and Rhodotorula, particularly in the obese group. Pichia and Dekkera, key microorganisms in kombucha, were identified as biomarkers after the intervention.

CONCLUSIONS

Regular kombucha consumption positively influenced gut microbiota in both normal and obese groups, with more pronounced effects in the obese group, suggesting that it may be especially beneficial for those individuals. This trial was registered at Brazilian Clinical Trial Registry - ReBEC as UTN code U1111-1263-9550 (https://ensaiosclinicos.gov.br/rg/RBR-9832wsx).

SCOBY Cellulose-Based Materials Hydrophobized Using Stearic Acid and Apple Powder

Bacterial cellulose (BC) is a subject of interest for researchers due to its advantageous characteristics, including a straightforward manufacturing process, biocompatibility, and extensive modification potential. The hydrophilic nature of the material is beneficial in some applications, yet a limiting factor in others. This study aimed to develop BC-based materials with goFogureod moisture resistance. The modification of bacterial cellulose (BC) using apple powder, stearic acid, or a combination of these modifiers resulted in the formation of a range of materials, some of which had their surfaces additionally functionalised by coating with a mixture of apple powder and stearic acid (HSt). The nature and type of changes were confirmed by FTIR and theoretical analysis, which was conducted by modelling the interaction between cellulose and homogalacturonan or rhamnogalacturonan using SCIGRESS v.FJ 2.7 software. Changes in hydrogen bonding resulting in a weakening of the interactions between cellulose and water in the presence of pectin were demonstrated by both empirical data and modelling. The effectiveness of BC functionalisation was confirmed by material wettability. The water contact angle changed from 38° for the unmodified material to 125° for the material obtained by modification of the bacterial cellulose with glycerol followed by modification with a mixture of HSt at a concentration of 10% and AP at a concentration of 60%. The modifications produced a material with a robust hydrophobic surface. The results suggest that the surface roughness may not be the primary factor influencing the hydrophilicity or hydrophobicity of these materials but that it is more likely to be related to the interactions of components. None of the tested materials demonstrated antimicrobial activity against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Aspergillus niger, or Candida albicans.

Plant-based probiotic foods: current state and future trends

Abstract

Plant-based probiotic foods (PBPFs) have recently become a notable choice for many consumers. While less recognized than dairy products, these foods offer efficient alternatives for individuals with lactose intolerance, vegans, or those aiming for more sustainable dietary practices. Traditional fermented PBPFs, such as kimchi, sauerkraut, and kombucha, are part of cultures from different countries and have gained more significant popularity in recent years globally due to their peculiar flavors and health benefits. However, new plant-based probiotic products have also been studied and made available to consumers of the growing demand in this sector. Therefore, this review discusses trends in plant-based probiotic production, known benefits, and characteristics. Challenges currently faced in manufacturing, distribution, marketing, consumer acceptance, and legislation are also discussed.

Graphical abstract

Dynamic changes in microbial communities and volatile compounds in kombucha fermentation using Flos sophorae and Elm fruits, compared to black and green tea

The dynamic changes in physicochemical properties, microbial communities, and volatile compounds in kombucha made from Flos sophorae (FLSK) and Elm fruit (EFK) were compared to those of black tea (BTK) and green tea (GTK) over a 12-day fermentation period. The results revealed that overall flavonoid and polyphenol content, as well as antioxidant activity, increased initially and then decreased, accompanied by a steady reduction in pH within the fermentation broths investigated. Notably, the GTK exhibited stronger antioxidant activity than the other fermentation broths. Furthermore, 16S rRNA gene sequencing revealed that Komagataeibacter rhaeticus, Komagataeibacter saccharivorans, and Acidovorax wautersii were the dominating microbial species in the fermentation broths under this study. Komagataeibacter rhaeticus initially reduced and then increased throughout the FLSK fermentation, whereas Komagataeibacter saccharivorans increased from day 0 to day 6, and remain stable by day 12 during the EFK fermentation. Comparative analysis revealed that Komagataeibacter rhaeticus was more abundant in the FLSK and GTK than in the EFK and BTK, whereas Komagataeibacter saccharivorans showed a higher abundance in the EFK relative to the other fermentation broths. Gas chromatography-mass spectrometry identified acetic acid, linalool, ethanol, and ethyl acetate as the major volatile chemicals that rose significantly in fermentation mixtures of the examined substrates. The FLSK had a much higher linalool concentration than the other fermentation broths, although the EFK and GTK had higher ethanol content. Correlation study found that Komagataeibacter rhaeticus was negatively related with alcohol compounds, but Komagataeibacter saccharivorans was positively associated with a diverse spectrum of acids, alcohols, and esters. The study found changes in bioactive chemicals as well as interactions between bacterial populations and volatile compounds throughout fermentation in the substrates investigated.

Phenolic compounds, antioxidant and antileishmanial activities of kombucha as affected by fermentation time

Objective

Study the impact of fermentation time on the phytochemical properties, antioxidant and antileishmanial activities.

Materials and methods

The preparation of Kombucha tea by fermentation was performed under aseptic conditions and symbiotic culture of bacteria and yeast (SCOBY) layer was maintained in culture for continuous growth in a water-sugar (4 L-500 g) mixture for 7, 14, 21, 28 and 35 days. The process of preparation was performed using a decoction. Phenolic compounds, flavonoids, and tannins was determined using standard method. The antioxidant activity was determined using three tests: DPPH•, ABTS• + and FRAP methods. Finally, the antileishmanial activity was performed in vitro on Leishmania donovani promastigote strains.

Results

The qualitative analysis of the constituents showed the kombucha drink was rich in saponins, terpenoids, quinones, phenolic compounds, catechins and coumarins depending on the fermentation times. Depending on the fermentation time (7 days, 14 days, 21 days, 28 days and 35 days), significant quantities of phenolic compounds were obtained in the tea with values ranging from 182.42 to 509.41 mg GAE/g dry extract; 15.83-53.05 mg QE/g dry extract and 6.16-51.82 mg TAE/g dry extract respectively for phenolic compounds, total flavonoids and total tannins. The SC50 values of DPPH• and ABTS• +, were 14.57 μg/mL; and 21.47 μg/mL after 14 and 21 days of fermentation respectively indicating a good antioxidant profile. The inhibition of the promastigote form of Leishmania donovani responsible for visceral leishmaniasis was observed with the samples obtained after 7 days, 14 days and 28 days with inhibitory concentrations 50 of: 131.2, 48.86 and 128.8 μg/mL respectively. The antileishmanial activity was more pronounced with the Kombucha tea after 14 days (KBT14) extract (48.86 μg/mL).

Conclusion

The Kombucha tea revealed the presence of phenolic compounds at different fermentation time. In addition, a good antioxidant profile was observed with the different radicals analyzed. Also, the inhibition of the Leishmania parasite was obtained. Therefore, the Kombucha tea constitutes a source bioactive molecules with antioxidant properties against Leishmania parasite.

Structural and Viscoelastic Properties of Bacterial Cellulose Composites: Implications for Prosthetics

This study investigates the morphological, mechanical, and viscoelastic properties of bacterial cellulose (BC) hydrogels synthesized by the microbial consortium Medusomyces gisevii. BC gel films were produced under static (S) or bioreactor (BioR) conditions. Additionally, an anisotropic sandwich-like composite BC film was developed and tested, consisting of a rehydrated (S-RDH) BC film synthesized under static conditions, placed between two BioR-derived BC layers. Sample characterization was performed using scanning electron microscopy (SEM), atomic force microscopy (AFM), rheometry, and uniaxial stretching tests. To our knowledge, this is the first study to combine uniaxial and rheological tests for BC gels. AFM and SEM revealed that the organization of BC fibrils (80±20 nm in diameter) was similar to that of collagen fibers (96±31 nm) found in human dura mater, suggesting potential implications for neurosurgical practice. Stretching tests demonstrated that the drying and rehydration of BC films resulted in a 2- to 8-fold increase in rigidity compared to other samples. This trend was consistent across both small and large deformations, regardless of direction. Mechanically, the composite (BioR+S-RDH) outperformed BC hydrogels synthesized under static and bioreactor conditions by approx. 26%. The composite material (BioR+S-RDH) exhibited greater anisotropy in the stretching tests compared to S-RDH, but less than the BioR-derived hydrogels, which had anisotropy coefficients ranging from 1.29 to 2.03. BioR+S-RDH also demonstrated the most consistent viscoelastic behavior, indicating its suitability for withstanding shear stress and potential use in prosthetic applications. These findings should provide opportunities for further research and medical applications.

The Impact of Green Tea Kombucha on the Intestinal Health, Gut Microbiota, and Serum Metabolome of Individuals with Excess Body Weight in a Weight Loss Intervention: A Randomized Controlled Trial

Green tea kombucha (GTK) has emerged as a promising probiotic fermented beverage. Few studies have investigated its effect on human health, mainly focusing on intestinal health, microbiota composition, and metabolomics. The present study is a pioneer in investigating the effect of GTK consumption in individuals with excess body weight. This is a randomized controlled trial, lasting ten weeks, with two groups placed under an energy-restricted diet: control (CG, n = 29), kombucha (KG, n = 30; 200 mL/d). Biological samples and questionnaires were collected before and after the intervention. Microbiota analysis used an amplification of the V4 region of 16S rRNA. Serum untargeted metabolomics used HPLC-TOF mass spectrometry. Intestinal permeability considered the urine excretion of lactulose and mannitol, plasma zonulin, and LPS-binding protein. After the intervention, no differences related to intestinal permeability and microbiota were found between groups, but only the CG had increased fecal pH, lactulose/mannitol ratio, and zonulin. In addition to this, the KG reported lower gastrointestinal symptoms related to motility compared to the CG, and discriminant metabolites (e.g., diethyl malonate) were found strictly in the KG. GTK did not significantly improve gut microbiota and intestinal permeability. However, GTK ameliorated gastrointestinal symptoms and positively influenced the serum metabolome, which may contribute to enhancing the metabolic health of individuals with excess body weight.

Exploring the Acetobacteraceae family isolated from kombucha SCOBYs worldwide and comparing yield and characteristics of biocellulose under various fermentation conditions

Bacterial cellulose (BC) is a cellulosic biopolymer produced by specific acetic acid bacteria during kombucha fermentation. In this study, bacterial cellulose-producing strains were isolated from four different global kombucha SCOBY samples obtained from markets in the Netherlands, America, China, and Iran. The strains were identified using biochemical and molecular techniques. The ability of species to produce BC was evaluated under both static and stirred fermentation conditions. Seven dominant strains from the Acetobacteraceae family and the genus of Komagataeibacter and Gluconacetobacter were identified and submitted to NCBI gene bank archives: K. xylinus CH1, K. sucrofermentans IR2, K. intermedius IR3, K. cocois AM2, K. sucrofermentans NE4, K. cocois NE6, and G. liquefaciens NE7. Among these, K. intermedius IR3, isolated from local Iranian SCOBY, exhibited the highest BC production yield at 5.733 ± 0.170 gL-1 under static fermentation conditions. On the other hand, K. xylinus CH1, from Chinese SCOBY, had the highest yield under stirred conditions, producing 12.689 ± 0.808 gL-1 of BC. The BC production yield of both K. xylinus CH1 and K. intermedius IR3 under stirred conditions was 3 and 1.3 times more than static conditions, respectively. Despite the yield differences, static fermentation demonstrated superior physicochemical characteristics; such as moisture content, water holding capacity, and crystallinity degree, compared to stirred. Therefore, depending on the intended application in industry and specific criteria, both products could serve as functional substitutes in food and medicine sectors.

Assessment of Culture Systems to Produce Bacterial Cellulose with a Kombucha Consortium

Bacterial cellulose (BC) is an emerging material for high-end applications due to its biocompatibility and physicochemical characteristics. However, the scale-up production of this material is still expensive, with the culture medium constituting one-third of the total cost. Herein, four different media (yeast nitrogen base, YNB; Murashige and Skoog, MSO; black tea; and NPK fertilizer solution) were compared while using sucrose as an additional carbon source. The yields of BC were best for YNB and fertilizer with 0.37 and 0.34 gBC/gC respectively. These two were then compared using glucose as a carbon source, with improvements in the production of 29% for the fertilizer, while only an 8% increase for YNB was seen; however, as the carbon concentration increased with a fixed N concentration, the yield was lower but the rate of production of BC increased. The obtained BC films were sanitized and showed low molecular weight and all the expected cellulose characteristic FT-IR bands while SEM showed nanofibers around 0.1 μm. Compared to traditional methods for lab-scale production, the use of the fertilizer and the consortium represent benefits compared to traditional lab-scale BC culture methods such as a competitive cost (two times lower) while posing resilience and tolerance to stress conditions given that it is produced by microbial communities and not with a single strain. Additionally, the low molecular weight of the films could be of interest for certain coating formulations.

Enhancing Antioxidant Benefits of Kombucha Through Optimized Glucuronic Acid by Selected Symbiotic Fermentation Culture

Kombucha, a functional beverage rich in glucuronic acid, is fermented in the presence of acetic acid bacteria and yeast as the primary microorganisms. Glucuronic acid is recognized for its various physiological benefits, such as detoxification, antioxidation, and anti-inflammation. To optimize the glucuronic acid content in kombucha, various strain combinations by selecting fermented sources were accomplished. According to the experimental results, kombucha produced through co-fermentation with Pichia anomala and Komagataeibacter hansenii, with glucose-added black tea as the carbon source, exhibited the highest glucuronic acid production. A response surface methodology found that under optimized conditions of a 12.27% (w/v) carbon source concentration, a 10.07% (w/v) substrate concentration, and a 28.4 °C temperature, the highest glucuronic acid production reached 80.16 g/L, which represented a 2.39-fold increase compared to the original kombucha. Furthermore, the total polyphenol content increased by 3.87-fold, while DPPH and ABTS free radical-scavenging capacities increased by 1.86- and 2.22-fold, respectively. To sum up, these observations reveal the potential for commercial production of glucuronic acid-enriched kombucha and contribute to the development of functional food products related to kombucha in the future.

Bacterial nanocellulose by static, static intermittent fed-batch and rotary disc bioreactor-based fermentation routes using economical black tea broth medium: A comparative account

Bacterial nanocellulose was produced here using static, static intermittent-fed batch (SIFB) and rotary disc bioreactor (RDB) mode. Economical black tea broth media with symbiotic consortia of bacteria and yeast (SCOBY) was used towards feasible BNC production (instead of commercial NCIM 2526 strain and conventional HS media). The physicochemical characterization of BNC produced in all three modes via FE-SEM, ATR-FTIR, XRD and TGA results showed a highly porous morphology, mostly Iα form, good crystallinity and thermal stability, respectively. BNC crystallinity lies in the range of 68 % (RDB) to 79.4 % (static and SIFB). Water retention value (86 to 93 %) and moisture content (85 to 93 %) are high for BNC produced in all three modes. Commendable difference in the BNC yield, sugar consumption, conversion yield and residual sugar was observed using different methods. Highest BNC yield 29.4 ± 0.66 gL-1 was obtained under SIFB method as compared to static mode (13.6 ± 0.32 g L-1). Under RDB, a negligible amount of BNC i.e., 1.0 ± 0.2 g L-1 was produced. SCOBY with BTB medium was found unsuitable for BNC production under RDB and needs further investigation. Thus, this comparative study offers a way to produce a commendable amount of low-priced BNC for various techno-industrial usage.

Functional Properties and Sensory Quality of Kombucha Analogs Based on Herbal Infusions

Traditionally, kombucha is produced by the fermentation of black or green tea infusions with the use of SCOBY (Symbiotic Culture of Bacteria and Yeasts). However, SCOBY exhibits the ability to ferment other substrates as well, which can be used to create novel products with new sensory and health-promoting properties. This paper investigates the antioxidant activity, chemical composition, and sensory properties of mint, nettle, and blackcurrant leaf-based kombucha analogs. It has been demonstrated that the fermentation process with SCOBY significantly influenced (p ≤ 0.05) sugar, organic acids, and mineral contents, with the increase in iron, magnesium, and calcium amounts in all tested herbal kombucha. The study shows that the type of herb infusion has a significant influence on the parameters associated with antioxidant potential. The fermentation with SCOBY resulted in an increase in antioxidant activity as measured by the superoxide anion radical (O2•-) inhibition of all three tested herbal infusions, with the greatest changes observed in nettle kombucha. Herbal kombucha was characterized by significantly increased total phenolic content as determined by Folin's reagent and a changed phenolic compound profile by LC-MS/MS (liquid chromatography with tandem mass spectrometry) in comparison to nonfermented infusions. Very high sensory scores were achieved for fermented mint and blackcurrant-based kombucha.

Technological quality and fungal community of Kombucha fermented with hemp leaves and milky mushroom flour (Calocybe indica)

Kombucha is traditionally a non-alcoholic beverage whose production is dependent on culture and the various ingredients used as substrates for fermentation. The goal of our study was to apply hemp leaf and milky mushroom (Calocybe indica) flour as functional ingredients to enhance phytonutrient quality, along with using a microbial consortium highly symbiotic with these ingredients. The study determined the content of phytonutrients (phenolic and flavonoids content), antioxidant activity through percentage inhibition of DPPH radical scavenging activity (%), and microbial communities changes during fermentation. The microbial changes were evaluated by cell viable count (total bacteria, Lactic Acid Bacteria, and Yeast & Mold) and ITS in prepared kombucha (using red tea leaves, pandan leaves, and sucrose) supplemented with functional ingredients: T1 (hemp leaves (control)) and T2 (hemp leaves with milky mushroom flour). The results indicated that microbial consortium changed during fermentation. In the first 7 days, the levels of yeast and mold increased to 6.17 and 6.18 log CFU/mL, respectively. By day 21, the levels of both T1 and T2 continued to rise, reaching 7.78 and 7.82 log CFU/mL, respectively. The viable count of lactic acid bacteria in T1 and T2 gradually increased to 6.79 and 6.70 log CFU/mL, respectively, by day 14. These changes resulted in a marked decrease in pH value, reaching 3.63 and 3.23 in T1 and T2, respectively, by the end of the process (21 days). The total bacterial viable count decreased with an increase in the fermentation time. During fermentation, unique genera of tea fungus observed in T1 and T2 were 64% and 19%, respectively. At the beginning (0 days), the top five genera found in T1 were: g__Setophoma (25.91%), g__Macrocybe (14.88%), g__Cladosporium (7.81%), g__Phaeosphaeria (7.12%), g__Malassezia (6.63%), while the top five genera in T2 were g__Macrocybe (94.55%), g__Setophoma (1.87%), g__Cladosporium (0.77%), g__Phaeosphaeria (0.40%), g__Cordyceps (0.38%). However, on day 21 (end of the process), it was found that g__Dekkera had the highest relative abundance in both T1 and T2. In addition, the supplementation of the two ingredients affected the total phenolic and total flavonoid content of the treatments. At the end of the process, T2 showed values of 155.91 mg GAE/mL for total phenolics and 1.01 mg CE/mL for total flavonoids, compared to T1, which had 129.52 mg GAE/mL and 0.69 mg CE/mL, respectively. Additionally, the DPPH inhibition was higher in T1 (91.95%) compared to T2 (91.03%). The findings suggest that kombucha fermented with these innovative ingredients exhibited enhanced phytonutrients, and served as substrate for LAB and tea fungus fermentation, while limiting the growth of fungal genera and diversity of microbial consortium.

First Characterization of Kombucha Beverages Brewed in Argentina: Flavors, Off-Flavors, and Chemical Profiles

Kombucha is an acidic beverage obtained through the fermentation of sweetened tea by bacteria and yeast. The kombucha market is relatively new and shows sustained growth. Given kombucha's inherent characteristics, compliance with regulations may be challenging. The aim of this study was to characterize the chemical and sensory diversity of commercial kombuchas in Argentina. Acetic acid was the predominant acid, while lactic and glucuronic acids were present in 70% and 50% of the kombuchas, respectively. Only 20% of the kombuchas met the ethanol limit, while all fell within the established pH range. Ninety percent had sugar concentrations exceeding the limit set by Argentinian Law. As assessed by a trained panel, drinkability was positively associated with sweetness and fruity tastes and negatively associated with astringency, bitterness, and off-flavors. This work represents the first comprehensive analysis of kombuchas in Argentina, revealing their variability and providing relevant insights for producers and consumers.

Nature of back slopping kombucha fermentation process: insights from the microbial succession, metabolites composition changes and their correlations

Kombucha, a fermented tea prepared with a symbiotic culture of bacteria and yeast (SCOBY), offers a unique and unpredictable home-brewed fermentation process. Therefore, the need for a controlled kombucha fermentation process has become evident, which requiring a thorough understanding of the microbial composition and its relationship with the metabolites produced. In this study, we investigated the dynamics of microbial communities and metabolites over a 12-day fermentation period of a conventional kombucha-making process. Our findings revealed similarities between the microbial communities in the early (0-2 days) and late (10-12 days) fermentation periods, supporting the principle of back-slopping fermentation. Untargeted metabolite analysis unveiled the presence of harmful biogenic amines in the produced kombucha, with concentrations increasing progressively throughout fermentation, albeit showing relatively lower abundance on days 8 and 12. Additionally, a contrasting trend between ethanol and caffeine content was observed. Canonical correspondence analysis highlighted strong positive correlations between specific bacterial/yeast strains and identified metabolites. In conclusion, our study sheds light on the microbial and metabolite dynamics of kombucha fermentation, emphasizing the importance of microbial control and quality assurance measures in the production process.

A Review on the Interaction of Acetic Acid Bacteria and Microbes in Food Fermentation: A Microbial Ecology Perspective

In fermented foods, acetic acid bacteria (AAB), kinds of bacteria with a long history of utilization, contribute to safety, nutritional, and sensory properties primarily through acetic acid fermentation. AAB are commonly found in various fermented foods such as vinegar, sour beer, fermented cocoa and coffee beans, kefir beverages, kombucha, and sourdough. They interact and cooperate with a variety of microorganisms, resulting in the formation of diverse metabolites and the production of fermented foods with distinct flavors. Understanding the interactions between AAB and other microbes is crucial for effectively controlling and utilizing AAB in fermentation processes. However, these microbial interactions are influenced by factors such as strain type, nutritional conditions, ecological niches, and fermentation duration. In this review, we examine the relationships and research methodologies of microbial interactions and interaction studies between AAB and yeasts, lactic acid bacteria (LAB), and bacilli in different food fermentation processes involving these microorganisms. The objective of this review is to identify key interaction models involving AAB and other microorganisms. The insights gained will provide scientific guidance for the effective utilization of AAB as functional microorganisms in food fermentation processes.

Multidisciplinary advances in kombucha fermentation, health efficacy, and market evolution

Kombucha, a fermented tea beverage, has seen a significant rise in global popularity. This increase is attributed to its reported health benefits and extensive cultural heritage. The comprehensive review examines kombucha through microbiology, biochemistry, and health sciences, highlighting its therapeutic potential and commercial viability. Central to kombucha production is the symbiotic culture of bacteria and yeasts (SCOBY), which regulates a complex fermentation process, resulting in a bioactive-rich elixir. The study examines the microbial dynamics of SCOBY, emphasizing the roles of various microorganisms. It focuses the contributions of acetic acid bacteria, lactic acid bacteria, and osmophilic yeasts, including genera such as Saccharomyces, Schizosaccharomyces, Zygosaccharomyces, Brettanomyces/Dekkera, and Pichia. These microorganisms play crucial roles in producing bioactive compounds, including organic acids, polyphenols, and vitamins. These bioactive compounds confer therapeutic properties to kombucha. These properties include antioxidant, antimicrobial, anti-inflammatory, antidiabetic, antihypertensive, cancer prevention, hepatoprotective, and detoxifying effects. The review also explores the growing market for kombucha, driven by consumer demand for functional beverages and opportunities for innovative product development. It emphasizes the necessity of standardized production to ensure safety and validate health claims. Identifying research gaps, the review highlights the importance of clinical trials to verify therapeutic benefits. Ultimately, this study integrates traditional knowledge with scientific research, providing directions for future studies and commercial expansion, emphasizing the role of kombucha in health and wellness.

Drosophila models of the anti-inflammatory and anti-obesity mechanisms of kombucha tea produced by Camellia sinensis leaf fermentation

Kombucha tea is a traditional beverage originating from China and has recently gained popularity worldwide. Kombucha tea is produced by the fermentation of tea leaves and is characterized by its beneficial properties and varied chemical content produced during the fermentation process, which includes organic acids, amino acids, vitamins, minerals, and other biologically active compounds. Kombucha tea is often consumed as a health drink to combat obesity and inflammation; however, the bioactive effects of kombucha tea have not been thoroughly researched. In this study, we reveal the underlying mechanisms of the beneficial properties of kombucha tea and how they protect against obesity and inflammation by studying Drosophila models. We established an inflammatory Drosophila model by knocking down the lipid storage droplet-1 gene, a human perilipin-1 ortholog. In this model, dysfunction of lipid storage droplet-1 induces inflammation by enhancing the infiltration of hemocytes into adipose tissues, increasing reactive oxygen species production, elevating levels of proinflammatory cytokines, and promoting the differentiation of hemocytes into macrophages. These processes are regulated by the c-Jun N-terminal Kinase (JNK) pathway. Using this unique Drosophila model that mimics mammalian inflammation, we verified the beneficial effects of kombucha tea on reducing tissue inflammation. Our data confirms that kombucha tea effectively improves inflammatory conditions by suppressing the expression of cytokines and proinflammatory responses induced by lipid storage droplet-1 dysfunction. It was found that kombucha tea consumption alleviated the production of reactive oxygen species and activated the JNK signaling pathway, signifying its potential as an anti-inflammatory agent against systemic inflammatory responses connected to the JNK pathway. Kombucha tea reduced triglyceride accumulation by increasing the activity of Brummer (a lipase), thereby promoting lipolysis in third-instar larvae. Therefore, kombucha tea could be developed as a novel, functional beverage to protect against obesity and inflammation. Our study also highlights the potential use of this innovative model to evaluate the effects of bioactive compounds derived from natural products.

Microbiological characterization of kombucha and biocellulose film produced with black tea and cocoa bean shell infusion

The food industry is increasingly striving to produce probiotics-based food and beverages using sustainable processes. Therefore, the use of by-products in product development has been investigated by several authors. The aim of this work was to investigate the effects of cocoa bean shell infusion in the production of kombucha through microbiological and genetic characterization. Three beverage formulations were prepared, one based on black tea (KBT), one based on cocoa bean shell infusion (KCS) and one containing 50 % black tea and 50 % cocoa shell infusion (KBL). The infusions were prepared with water, filtered, and sucrose was added. They were then homogenized and a portion of finished kombucha and SCOBY (symbiotic culture of bacteria and yeast) were added. Fermentation took place for 13 days and aliquots were collected every three days for physicochemical and microbial count analyses. Samples from the last day of fermentation were sent for DNA sequencing, extraction and quantification. The results were subjected to analysis of variance and compared by using Tukey's test (p < 0.05). The results show that there was a significant decrease in pH over time in all samples, while the titratable acidity increased, indicating an acidification of the beverage due to the production of organic acids. There was an increase in lactic acid bacterial colonies in all the formulations, which have a probiotic nature and are not always found in this type of beverage. Regarding the taxonomic classification of the samples, microorganisms of the kingdoms Fungi and Bacteria, of the families Saccharomycetaceae and Acetobacteraceae, were found in KBT, KCS and KBL, but with different microbiological compositions, with different amounts of yeasts and bacteria. Therefore, the use of by-products such as cocoa bean shell in the production of kombucha can contribute to the reduction of waste in the food industry and, at the same time, accelerate fermentation increasing the presence of lactic acid bacteria when compared to black tea.

Production of bacterial cellulose-based peptidopolysaccharide BC-L with anti-listerial properties using a co-cultivation strategy

Bacterial cellulose (BC) has been found extensive applications in diverse domains for its exceptional attributes. However, the lack of antibacterial properties hampers its utilization in food and biomedical sectors. Leucocin, a bacteriocin belonging to class IIa, is synthesized by Leuconostoc that demonstrates potent efficacy against the foodborne pathogen, Listeria monocytogenes. In the current study, co-culturing strategy involving Kosakonia oryzendophytica FY-07 and Leuconostoc carnosum 4010 was used to confer anti-listerial activity to BC, which resulted in the generation of leucocin-containing BC (BC-L). The physical characteristics of BC-L, as determined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), were similar to the physical characteristics of BC. Notably, the experimental results of disc diffusion and growth curve indicated that the BC-L film exhibited a potent inhibitory effect against L. monocytogenes. Scanning electron microscopy (SEM) showed that BC-L exerts its bactericidal activity by forming pores on the bacterial cell wall. Despite the BC-L antibacterial mechanism, which involves pore formation, the mammalian cell viability remained unaffected by the BC-L film. The measurement results of zeta potential indicated that the properties of BC changed after being loaded with leucocin. Based on these findings, the anti-listerial BC-L generated through this co-culture system holds promise as a novel effective antimicrobial agent for applications in meat product preservation and packaging.

Elaboration and Characterization of Novel Kombucha Drinks Based on Truffles (Tuber melanosporum and Tuber aestivum) with Interesting Aromatic and Compositional Profiles

The organoleptic and bioactive properties of truffles place these fungi as interesting materials for use in the of design functional foods based on fruiting bodies outside commercial standards. Moreover, kombucha beverages have become more popular in the Western world, leading to novel drinks using alternative substrates instead of tea leaves. In this work, two truffle species (Tuber melanosporum, TMEL; Tuber aestivum, TAES) and three different symbiotic consortia of bacteria and yeasts (SCOBYs: SC1, SC2, and SC3) were tested. Fermentation (21 days) was monitored in terms of physicochemical (pH, viscosity), biochemical (total carbohydrates, alcohol, soluble proteins, phenolic compounds), and sensory attributes (volatile organic compounds, VOCs). The obtained pH ranges were adequate, alcohol levels were undetectable or very low, and sugar content was lower than in traditional kombuchas or other beverages. In most cases, the usual bottling time could be applied (7-10 days), although longer fermentations are recommended (14 days) to reach higher protein and phenolic compounds contents. Truffle kombuchas produced up to 51 volatile organic compounds (alcohols, acids, esters, ketones, and aldehydes, among others), with TMEL showing a more complex profile than TAES. During the first week, acidic compound production was observed, especially acetic acid. Similar behavior in the VOC profile was reported with different SCOBYs.

Microbiological, Functional, and Chemico-Physical Characterization of Artisanal Kombucha: An Interesting Reservoir of Microbial Diversity

Kombucha is a trending tea fermented via a complex microflora of yeasts and acetic acid bacteria. It can be a valid low-calorie substitute for soft drinks due to its sour, naturally carbonated, and sweet taste. Despite increased interest, the microflora and functional properties of kombucha have not yet been fully understood. The aim of this work was to characterize, from a microbiological, chemico-physical, and functional point of view, three types of artisanal kombucha obtained by fermenting green tea containing sugar by means of different starter cultures. Metagenomic analysis revealed a predominance of yeasts compared to bacteria, regardless of the sample. In particular, Brettanomyces spp. was found to be the dominant yeast. Moreover, the different types of kombucha had different microbial patterns in terms of acetic acid bacteria and yeasts. Ethanol and acetic acid were the dominant volatile molecules of the kombucha volatilome; the samples differed from each other in terms of their content of alcohols, esters, and acids. All the samples showed a high antioxidant potential linked to the high content of phenols. This study confirmed the positive chemico-physical and functional properties of kombucha and indicated that the microflora responsible for the fermentation process can significantly affect the characteristics of the final product.

Spectrofluorimetric Analysis of Riboflavin Content during Kombucha Fermentation

Kombucha is a traditional beverage obtained by the microbial fermentation of tea using a symbiotic culture of bacteria and yeasts. In addition to several documented functional properties, such as anti-inflammatory activity and antioxidant activity, kombucha is often credited with high levels of vitamins, including riboflavin. To our knowledge, the vitamin B2 content in traditionally prepared kombucha has been determined in only two studies, in which the concentration measured by the HPLC technique ranged from 2.2 × 10-7 to 2.1 × 10-4 mol dm-3. These unexplained differences of three orders of magnitude in the vitamin B2 content prompted us to determine its concentration during the cultivation of kombucha under very similar conditions by spectrofluorimetry. The B2 concentrations during the 10-day fermentation of black tea ranged from 7.6 × 10-8 to 3.3 × 10-7 mol dm-3.

Alternative Substrates for the Development of Fermented Beverages Analogous to Kombucha: An Integrative Review

Kombucha is a fermented beverage that originated in China and is spread worldwide today. The infusion of Camellia sinensis leaves is mandatory as the substrate to produce kombucha but alternative plant infusions are expected to increase the opportunities to develop new fermented food products analogous to kombucha, with high technological potential and functional properties. This review gathers information regarding promising alternative substrates to produce kombucha-analogous beverages, focusing on plants available in the Amazonia biome. The data from the literature showed a wide range of alternative substrates in increasing expansion, with 37 new substrates being highlighted, of which ~29% are available in the Amazon region. Regarding the technological production of kombucha-analogous beverages, the following were the most frequent conditions: sucrose was the most used carbon/energy source; the infusions were mostly prepared at 90-100 °C, which allowed increased contents of phenolic compounds in the product; and 14 day-fermentation at 25-28 °C was typical. Furthermore, herbs with promising bioactive compound compositions and high antioxidant and antimicrobial properties are usually preferred. This review also brings up gaps in the literature, such as the lack of consistent information about chemical composition, sensory aspects, biological properties, and market strategies for fermented beverages analogous to kombucha produced with alternative substrates. Therefore, investigations aiming to overcome these gaps may stimulate the upscale of these beverages in reaching wide access to contribute to the modern consumers' quality of life.

Additional advances related to the health benefits associated with kombucha consumption

Kombucha is a fermented, acidic beverage that dates back thousands of years as a remedy for various health problems in East Asia. Due to its health benefits, kombucha has gained popularity and attracted the attention of both consumers and researchers. The health benefits of kombucha are predominantly attributed to its bioactive compounds that have antioxidant, antimicrobial, probiotic, and other positive effects owing to fermentation. Many factors such as the type of the substrate used, the symbiotic culture of the bacterial yeast composition, and fermentation conditions influence the extent of these properties. This review focuses on recent developments regarding the bioactive constituents of kombucha and its potential health benefits (antimicrobial, antioxidant, antidiabetic, hepatoprotective effects) as well as its impact on multiple sclerosis, nephrotoxicity, gastric ulceration and gut microbiota. Additionally, the composition of kombucha, alternative uses of its biofilm, and potential toxicity are also discussed. Kombucha is a healthy and safe beverage with multiple health benefits that are primarily related to the presence of bacteria, yeasts, and other bioactive constituents. Moreover, kombucha has been suggested as a potential source of probiotics and eco-friendly materials (kombucha-derived bacterial cellulose) for several industries including food and textile.

Edge-functionalized coal-derived graphene oxide in bacterial nanocellulose hydrogel for active wound healing

This work presents a comparison of physicochemical and in vitro active wound healing properties of two distinct Graphene Oxides (GOs) from graphite and coal. These GOs are incorporated in Bacterial Nanocellulose (BNC) to form hydrogels. The performance and limitations of the loading fraction of both GOs in BNC are controlled by the processing technology and the source materials from which GOs are derived. Edge functionalization with C-GO offers the advantage of facilitating face-to-edge assembly in the hydrogel leading to better dispersion than the face-to-face assembly of basal functionalized G-GO. The latter leads to more aggregation of G-GO, resulting in a lower optimal loading fraction. Our investigation into the antibacterial properties of the BNC and BNC/GO hydrogels against gram-negative E. coli revealed inhibitory effects of the BNC/GO hydrogels that intensified with an increase in the concentration of GO. Furthermore, an in vitro wound scratch assay demonstrated that BNC/C-GO hydrogels promote better cell migration, confirming their superior biocompatibility and suitability as active wound dressings, albeit limited by loading fraction due to agglomeration. These findings shed light on the performance and limitations of GOs for diverse applications, emphasizing the significance of exploring the influence of different methods and source materials of GOs.

Biological Significance of Probiotic Microorganisms from Kefir and Kombucha: A Review

(1) Background: The human microbiota is essential for maintaining a healthy body. The gut microbiota plays a protective role against pathogenic bacteria. Probiotics are live microorganisms capable of preventing and controlling gastrointestinal and balancing the immune system. They also aid in better nutrients and vitamins absorption. Examples of natural probiotic cultures are kefir and kombucha. (2) Methods: Therefore, the aim of this review was to address the beneficial properties of probiotic kefir and kombucha using a Boxplot analysis to search for scientific data in the online literature up to January 2024: (Latin American and Caribbean Health Sciences (LILACS), PubMed, Medical Literature Analysis (MED-LINE), Science Direct, Google Scholar/Google Academic, Bioline Inter-national and Springer Link). Boxplots showed the summary of a set of data "Index Terms-Keywords" on kefir and kombucha in three languages (English, Portuguese and Spanish). (3) Results: Google Scholar was the database with the highest number of articles found, when the search for the keywords used in the study (containing ~4 × 106-~4 million articles available). This was Followed by the Science Direct database, containing ~3 × 106-~3 million articles available, and the BVS databases-Biblioteca Virtual de Saúde (Virtual Health Library) e Lilacs, both containing a value of ~2 × 106-~2 million articles available. The databases containing the smallest number of articles found were Nutrients and Medline, both containing a value of ≤0.1 × 106-≤100 thousand articles. (4) Conclusions: Scientific studies indicate that kefir and kombucha certainly contain various functional properties, such as antimicrobial, antitumor, anticarcinogenic and immunomodulatory activity, in addition to having a microbiological composition of probiotic bacteria and yeasts. Kefir and kombucha represent key opportunities in the food and clinic/medical fields.

Viability and Diversity of the Microbial Cultures Available in Retail Kombucha Beverages in the USA

Kombucha is a two-stage fermented sweetened tea beverage that uses yeast and lactic acid bacteria (LAB) to convert sugars into ethanol and lactate and acetic acid bacteria (AAB) to oxidize ethanol to acetate. Its popularity as a beverage grew from claims of health benefits derived from this vibrant microbial bioconversion. While recent studies have shed light on the diversity of cultures in Kombucha fermentation, there is limited information on the diversity, and especially viability, of cultures in retail beverages that advertise the presence of Kombucha and probiotic cultures. In this study, 12 Kombucha beverages produced by different manufacturers throughout the US were purchased and microbially characterized. Eight of the beverages contained viable Kombucha cultures, while 3 of the remaining 4 had viable Bacillus cultures as added probiotics. Amplicon profiling revealed that all contained Kombucha yeast and bacteria cells. The dominant yeasts detected were Lachancea cidri (10/12), Brettanomyces (9/12), Malassezia (6/12), and Saccharomyces (5/12). Dominant LAB included Liquorilactobacillus and Oenococcus oeni, and AAB were Komagataeibacter, Gluconobacter, and Acetobacter. One beverage had a significant amount of Zymomonas mobilis, an ethanol-producing bacterium from Agave cactus. While Kombucha beverages differ in the types and viability of cultures, all except one beverage contained detectable viable cells.

Exploring the evolution of bacterial cellulose precursors and their potential use as cellulose-based building blocks

Natural polymers have found increased use in a wider range of applications due to their less harmful effects. Notably, bacterial cellulose has gained significant consideration due to its exceptional physical and chemical properties and its substantial biocompatibility, which makes it an attractive candidate for several biomedical applications. This study attempts to thoroughly unravel the microstructure of bacterial cellulose precursors, known as bioflocculants, which to date have been poorly characterised, by employing both electron and optical microscopy techniques. Here, starting from bioflocculants from Symbiotic Culture of Bacteria and Yeast (SCOBY), we proved that their microstructural features, such as porosity percentage, cellulose assembly degree, fibres' density and fraction, change in a spatio-temporal manner during their rising toward the liquid-air interface. Furthermore, our research identified a correlation between electron and optical microscopy parameters, enabling the assessment of bioflocculants' microstructure without necessitating offline sample preparation procedures. The ultimate goal was to determine their potential suitability as a novel cellulose-based building block material with tuneable structural properties. Our investigations substantiate the capability of SCOBY bioflocculants, characterized by distinct microstructures, to successfully assemble within a microfluidic device, thereby generating a cellulose sheet endowed with specific and purposefully designed structural features.

3D printed kombucha biomaterial as a tissue scaffold and L929 cell cytotoxicity assay

Tissue engineering includes the construction of tissue-organ scaffold. The advantage of three-dimensional scaffolds over two-dimensional scaffolds is that they provide homeostasis for a longer time. The microbial community in Symbiotic culture of bacteria and yeast (SCOBY) can be a source for kombucha (kombu tea) production. In this study, it was aimed to investigate the usage of SCOBY, which produces bacterial cellulose, as a biomaterial and 3D scaffold material. 3D printable biomaterial was obtained by partial hydrolysis of oolong tea and black tea kombucha biofilms. In order to investigate the usage of 3D kombucha biomaterial as a tissue scaffold, "L929 cell line 3D cell culture" was created and cell viability was tested in the biomaterial. At the end of the 21st day, black tea showed 51% and oolong tea 73% viability. The cytotoxicity of the materials prepared by lyophilizing oolong and black tea kombucha beverages in fibroblast cell culture was determined. Black tea IC50 value: 7.53 mg, oolong tea IC50 value is found as 6.05 mg. Fibroblast viability in 3D biomaterial + lyophilized oolong and black tea kombucha beverages, which were created using the amounts determined to these values, were investigated by cell culture Fibroblasts in lyophilized and 3D biomaterial showed viability of 58% in black tea and 78% in oolong tea at the end of the 7th day. In SEM analysis, it was concluded that fibroblast cells created adhesion to the biomaterial. 3D biomaterial from kombucha mushroom culture can be used as tissue scaffold and biomaterial.

Metabolomic kinetics investigation of Camellia sinensis kombucha using mass spectrometry and bioinformatics approaches

Kombucha is created through the fermentation of Camellia sinensis tea leaves, along with sucrose, utilizing a symbiotic consortium of bacteria and yeast cultures. Nonetheless, there exists a dearth of comprehensive information regarding the spectrum of metabolites that constitute this beverage. To explore this intricate system, metabolomics was used to investigate fermentation kinetics of Kombucha. For that, an experimental framework was devised to assess the impact of varying sucrose concentrations and fermentation temperatures over a ten-day period of kombucha fermentation. Following fermentation, samples were analyzed using an LC-QTOF-MS system and a distinctive metabolomic profile was observed. Principal component analysis was used to discriminate between metabolite profiles. Moreover, the identified compounds were subjected to classification using the GNPS platform. The findings underscore notable differences in compound class concentrations attributable to distinct fermentation conditions. Furthermore, distinct metabolic pathways were identified, specially some related to the biotransformation of flavonoids. This comprehensive investigation offers valuable insights into the pivotal role of SCOBY in driving metabolite production and underscores the potential bioactivity harbored within Kombucha.

Evaluation of the probiotic potential of yeast isolated from kombucha in New Zealand

The current study investigated the in vitro probiotic potential of yeast isolated from kombucha, a tea beverage fermented with a symbiotic culture of acetic acid bacteria and yeast. A total of 62 yeast strains were previously isolated from four different commercial kombucha samples sold in New Zealand. Fifteen representative isolates belonging to eight different species were evaluated for their growth under different conditions (temperature, low pH, concentrations of bile salts, and NaCl). Cell surface characteristics, functional and enzymatic activities of the selected strains were also studied in triplicate experiments. Results showed that six strains (Dekkera bruxellensis LBY1, Sachizosaccharomyces pombe LBY5, Hanseniaspora valbyensis DOY1, Brettanomyces anomalus DOY8, Pichia kudraivzevii GBY1, and Saccharomyces cerevisiae GBY2) were able to grow under low-acid conditions (at pH 2 and pH 3) and in the presence of bile salts. This suggests their potential to survive passage through the human gut. All 15 strains exhibited negative enzymatic activity reactions (haemolytic, gelatinase, phospholipase, and protease activities), and thus, they can be considered safe to consume. Notably, two of the fifteen strains (Pichia kudraivzevii GBY1 and Saccharomyces cerevisiae GBY2) exhibited desirable cell surface hydrophobicity (64.60-83.87%), auto-aggregation (>98%), co-aggregation, resistance to eight tested antibiotics (ampicillin, chloramphenicol, colistin sulphate, kanamycin, nalidixic acid, nitrofurantoin, streptomycin, and tetracycline), and high levels of antioxidant activities (>90%). Together, our data reveal the probiotic activities of two yeast strains GBY1 and GBY2 and their potential application in functional food production.

Kombucha Tea-associated microbes remodel host metabolic pathways to suppress lipid accumulation

The popularity of the ancient, probiotic-rich beverage Kombucha Tea (KT) has surged in part due to its purported health benefits, which include protection against metabolic diseases; however, these claims have not been rigorously tested and the mechanisms underlying host response to the probiotics in KT are unknown. Here, we establish a reproducible method to maintain C. elegans on a diet exclusively consisting of Kombucha Tea-associated microbes (KTM), which mirrors the microbial community found in the fermenting culture. KT microbes robustly colonize the gut of KTM-fed animals and confer normal development and fecundity. Intriguingly, animals consuming KTMs display a marked reduction in total lipid stores and lipid droplet size. We find that the reduced fat accumulation phenotype is not due to impaired nutrient absorption, but rather it is sustained by a programed metabolic response in the intestine of the host. KTM consumption triggers widespread transcriptional changes within core lipid metabolism pathways, including upregulation of a suite of lysosomal lipase genes that are induced during lipophagy. The elevated lysosomal lipase activity, coupled with a decrease in lipid droplet biogenesis, is partially required for the reduction in host lipid content. We propose that KTM consumption stimulates a fasting-like response in the C. elegans intestine by rewiring transcriptional programs to promote lipid utilization. Our results provide mechanistic insight into how the probiotics in Kombucha Tea reshape host metabolism and how this popular beverage may impact human metabolism.

Postbiotics: the new horizons of microbial functional bioactive compounds in food preservation and security

In recent decades, consumers, manufacturers, and researchers have been more interested in functional foods, which include probiotics, prebiotics, and postbiotics. Probiotics are live microbes that, when regulated in enough quantities, provide health benefits on the host, while the prebiotics are substrates that host microorganisms selectively use. Postbiotics are metabolites and cell-wall components that are beneficial to the host and are released by living bacteria or after lysis. Postbiotic dietary supplements are more stable than probiotics and prebiotics. Many bioactivities of postbiotics are unknown or poorly understood. Hence, this study aims to present a synopsis of the regular elements and new developments of the postbiotics including health-promoting effects, production, conceptualization of terms, bioactivities, and applications in the field of food safety and preservation. Postbiotics aid in bio preservation and the reduction of biofilm development in food due to their organic acids, bacteriocins, and other antibacterial activities. The present study examines the production of postbiotic metabolites in situ in food and the effects of external and internal food components. The antimicrobial roles, removal of biofilms, and its applications in preservation and food safety have also been discussed. This paper also explored the various aspects like manipulation of postbiotic composition in the food system and its safety measures.

Graphical Abstract

Kombucha as a Potential Active Ingredient in Cosmetics-An Ex Vivo Skin Permeation Study

Kombucha is a non-alcoholic beverage, that is increasingly used in the cosmetic industry. The available literature reports the positive effects of kombucha on the skin, in particular its antioxidant action. However, there is a lack of information on skin permeation and the accumulation of active ingredients showing such effects. Skin aging is largely dependent on oxidative stress, therefore in our study we assessed the ex vivo permeation of two types of kombucha (green and black tea) through porcine skin. The antioxidant activity (DPPH, ABTS, FRAP methods) and total polyphenol content of these extracts were determined before and after permeation testing. Moreover, the content of selected phenolic acids as well as caffeine was assessed. Skin permeation was determined using a Franz diffusion cell. The antioxidant activity of both Kombuchas was found to be high. In addition, gallic acid, chlorogenic acid, protocatechuic acid, coumaric acid, m-hydroxybenzoic acid, and caffeine were identified. A 24-h ex vivo study showed the permeation of some phenolic acids and caffeine and their accumulation in the skin. Our results confirm the importance of studying the skin permeation of what are still little known ingredients in cosmetic preparations. Evaluation of the accumulation of these ingredients can guarantee the efficacy of such preparations.

Volatilome, Microbial, and Sensory Profiles of Coffee Leaf and Coffee Leaf-Toasted Maté Kombuchas

Kombucha is a fermented beverage traditionally made from the leaves of Camelia sinensis. The market has drastically expanded recently, and the beverage has become more elaborated with new, healthy food materials and flavors. Pruning and harvesting during coffee production may generate tons of coffee leaves that are discarded although they contain substantial amounts of bioactive compounds, including those found in maté tea and coffee seeds. This study characterized the changes in volatilome, microbial, and sensory profiles of pure and blended arabica coffee leaf tea kombuchas between 3-9 days of fermentation. Acceptance was also evaluated by consumers from Rio de Janeiro (n = 103). Kombuchas (K) were prepared using black tea kombucha starter (BTKS) (10%), sucrose (10%), a symbiotic culture of Bacteria and Yeasts (SCOBY) (2.5%), and a pure coffee leaf infusion (CL) or a 50:50 blend with toasted maté infusion (CL-TM) at 2.5%. The RATA test was chosen for sensory profile characterization. One hundred volatile organic compounds were identified when all infusions and kombucha samples were considered. The potential impact compounds identified in CL K and CL-TM K were: methyl salicylate, benzaldehyde, hexanal, nonanal, pentadecanal, phenylethyl-alcohol, cedrol, 3,5-octadien-2-one, β-damascenone, α-ionone, β-ionone, acetic acid, caproic acid, octanoic acid, nonanoic acid, decanoic acid, isovaleric acid, linalool, (S)-dihydroactinidiolide, isoamyl alcohol, ethyl hexanoate, and geranyl acetone. Aroma and flavor descriptors with higher intensities in CL K included fruity, peach, sweet, and herbal, while CL-TM K included additional toasted mate notes. The highest mean acceptance score was given to CL-TM K and CL K on day 3 (6.6 and 6.4, respectively, on a nine-point scale). Arabica coffee leaf can be a co-product with similar fingerprinting to maté and black tea, which can be explored for the elaboration of potentially healthy fermented beverages in food industries.

An overview of bio-cellulose derived materials for catalytic water treatment

Bio-cellulose derived materials (BCM) exhibit distinct structural and morphologic properties, which make them suitable for catalytic environmental remediation. In the domain of water treatment, the prospects for BCM remain bright, offering new possibilities for the development of advanced materials with low environmental impact. Research on BCM as catalysts or catalyst immobilization platforms for water treatment is still limited, mostly using laboratory-grown biomaterials for the photocatalytic degradation of dyes. BCM production costs can be significant, which can hinder its application. Thus, cost-effective alternatives using waste materials as substrates for BCM culture media are highly desirable to optimize production, while also decreasing food waste. Moreover, advances in biotechnology can enhance BCM production, tailoring its properties to meet specific requirements. Hybrid catalytic BCM composites can be easily developed, due to the straightforward functionalization of the biomaterial's network, promoting the efficiency of a variety of catalytic systems. Still considering the intrinsic features of the biomaterial, membrane development and application pose as an opportunity for continuous flow evaluations, facilitating long-term usage and reusability. Nevertheless, there are still challenges regarding catalytic BCM for water treatment (i.e., cost-effectiveness, scaling up, and consistent performance in diverse treatment scenarios). Addressing these aspects can lead to innovative environmental remediation options.

The mycobiome as integral part of the gut microbiome: crucial role of symbiotic fungi in health and disease

The gut mycobiome significantly affects host health and immunity. However, most studies have focused on symbiotic bacteria in the gut microbiome, whereas less attention has been given to symbiotic fungi. Although fungi constitute only 0.01%-0.1% of the gut microbiome, their larger size and unique immunoregulatory functions make them significant. Factors like diet, antimicrobials use, and age can disrupt the fungal community, leading to dysbiosis. Fungal-bacterial-host immune interactions are critical in maintaining gut homeostasis, with fungi playing a role in mediating immune responses such as Th17 cell activation. This review highlights methods for studying gut fungi, the composition and influencing factors of the gut mycobiome, and its potential in therapeutic interventions for intestinal and hepatic diseases. We aim to provide new insights into the underexplored role of gut fungi in human health.

Multi-Strain Probiotics Enhance the Bioactivity of Cascara Kombucha during Microbial Composition-Controlled Fermentation

Kombucha is a widely consumed fermented tea beverage with diverse health benefits. In a previous study, we demonstrated that the use of cascara as a substrate results in a special kombucha beverage with high bioactivity. Traditional kombucha fermentation using a symbiotic culture of bacteria and yeast (SCOBY) can lead to inconsistent product quality because of the lack of control over microbial composition. We successfully isolated and identified yeast and bacteria, including Saccharomyces cerevisiae, Komagataeibacter rhaeticus, and Lactobacillus brevis that are appropriate starter cultures for cascara kombucha fermentation. We also demonstrated that a supplementation with lactic acid bacteria (LAB) and a mixture of S. cerevisiae and K. rhaeticus resulted in higher total polyphenol and flavonoid content of cascara kombucha compared with the traditionally fermented product using SCOBY as the inoculum. The free radical scavenging activity, inhibitory effects on α-amylase, tyrosinase activity, and antibacterial properties of cascara kombucha were also enhanced as a result of LAB supplement. These findings provide valuable insights into the controlled microbiological composition required for the fermentation of cascara kombucha, thereby ensuring consistent quality and enhanced bioactivity of the product. Further, the use of cascara as a substrate for kombucha production not only offers various health benefits and biological effects, but also repurposes by-products from the coffee industry, which contributes to sustainable development and is eco-friendly.

Kombucha fermentation as a modern way of processing vineyard by-products into cosmetic raw materials

OBJECTIVE

The wine industry generates large quantities of by-products presenting a remarkably valuable composition in phytochemicals. The process that can significantly increase the content of bioactive compounds is fermentation by yeast and other microorganisms. The current study presents, for the first time, an evaluation of the potential of grape stems extract and its ferments using the Scoby consortium, as a cosmetic raw material for improving the skin care properties of facial cosmetics.

METHODS

Fermentation of grape stems using Scoby consortium was carried out for 10 and 20 days. Unfermented and fermented extracts were analysed for their antioxidant activity and chemical composition, with a particular emphasis on biologically active substances. Additionally, the influence of the addition of the obtained ferments to the model cosmetic creams on hydration, transepidermal water loss and skin pH were assessed.

RESULTS

The obtained results revealed that grape stems extract and its ferments are a rich source of phenolic compounds and show antioxidant activity, with the highest values observed for extracts on the 20th day of fermentation. Furthermore, the addition of the extract, as well as ferment, to the cream has a positive effect on skin hydration and reduces transepidermal water loss.

CONCLUSION

These results suggest that grape stem extracts are a prospective source of active compounds that may be valuable ingredients for the cosmetic industry. Unfermented and fermented extracts can be used in moisturizing cosmetic formulations and also to complement the treatment of dry and sensitive skin.

Understanding the effect of fermentation time on physicochemical characteristics, sensory attributes, and volatile compounds in green tea kombucha

Kombuchas are a trend in the fermented beverage field and the effect of fermentation time on their characteristics is necessary to better understand the process, mainly concerning volatile compounds, which are scarce information in the current literature. Thus, the present work aimed to evaluate the features of green tea kombucha during fermentation, monitoring the changes in pH, acidity, turbidity, polyphenols, ethanol, acetic acid, volatile compounds, and sensory profile and acceptance up to 14 days of fermentation. Kombuchas' pH and acidity decreased through time as expected, but after 4 days of fermentation, the beverage exceeded the Brazilian legal limits of acidity (130 mEq/L) and produced more than 0.5% AVB, which labels the beverage as alcoholic. Total polyphenols and condensed tannins content enhanced until the seventh day of fermentation and remained constant. Fermentation highly impacted the aroma of the infusion with a high formation of volatile acids, such as alcohols, esters, and ketones. Aldehydes were degraded during the bioprocess. Sensory characterization of kombucha showed that fermentation of 4 days increased perceived turbidity; vinegar, citric fruit, acid, and alcoholic aroma; and produced the beverage with sour, bitter, and vinegar flavor. Thus, the fermentation time of kombuchas must be controlled as they rapidly change and impact on the physicochemical parameters and sensory profile of the beverage can be negative.

Dynamic Changes in Microbial Communities, Physicochemical Properties, and Flavor of Kombucha Made from Fu-Brick Tea

In this study, Fu-brick tea (FBT) was used for kombucha preparation. The succession of microbial community structures, changes in physicochemical properties, and the volatiles were investigated during the kombucha fermentation. The sequencing analysis showed that Komagataeibacter was the most predominant bacterium. Aspergillus and Zygosaccharomyces were the dominant fungi before fermentation whereas Zygosaccharomyces and Derkella were the dominant fungi after 3 days of fermentation. The physicochemical analysis revealed that acetic acid, glucuronic acid, and polyphenols increased by 10.22 g/L, 0.08 g/L, and 177.40 mg/L, respectively, by the end of fermentation. The GC-MS analysis showed that a total of 49 volatile compounds were detected during the fermentation. Moreover, there were great differences in volatile components among the kombucha samples with different fermentation times. Furthermore, the relevance among microbial community and volatile compounds was evaluated through correlation network analysis. The results suggested that Komagataeibacter, Aspergillus, Zygosaccharomyces, and Dekkera were closely related to the main volatile compounds of FBT kombucha. The results in this study may provide deep understanding for constructing the microbiota and improving the quality of FBT kombucha.