Search Results (110)

This study aimed to determine the caffeine and L-theanine contents in tea infusions prepared under varying fermentation degrees, brewing conditions (temperature and time), and serving methods (tea bag/loose-leaf). Infusions of six tea types (green, white, yellow, oolong, black, and Pu-erh) and various serving forms of green, white, and black tea were brewed at 80 °C and 100 °C for 2, 5, and 10 min. Contents were analyzed using reversed-phase high-performance liquid chromatography. Caffeine levels were highest in black and yellow tea (14 ± 1.0 mg/200 mL and 13.8 ± 0.2 mg/200 mL, respectively), both of which were significantly higher than the levels in green, white, and oolong tea (11 ± 2.1 mg/200 mL; 5.8 ± 0.7 mg/200 mL; and 4 ± 1.6 mg/200 mL, respectively; p < 0.001), whereas Pu-erh tea (13 ± 2.9 mg/200 mL) had caffeine levels comparable to that of black tea (p > 0.05). L-Theanine levels were highest in black and green tea (12.3 ± 2.8 mg/200 mL and 12.5 ± 2.5 mg/200 mL, respectively), and these levels were significantly higher than those in the other tea types (p < 0.001). Brewing temperature only affected caffeine levels n, whereas L-oolong tea (4.4 → 13.5 mg/200 mL, p < 0.05); theanine remained stable (p > 0.05). Longer brewing times significantly raised both components (e.g., yellow tea caffeine levels rose to 53 ± 16.9 mg/200 mL at 10 min; p < 0.05). In black tea, cup-sized bags yielded higher caffeine levels (39 ± 9.9 mg/200 mL) than loose-leaf (24 ± 7.2 mg/200 mL) and teapot bags (p < 0.001). Serving method had no effect on green and white teas (p > 0.05). In conclusion, fermentation rate, brewing conditions, and serving method were found to influence the caffeine and L-theanine levels of tea infusions. Full article

Neonicotinoids (NEOs) are a class of systemic insecticides widely used in agriculture owing to their high efficacy and selectivity. As one of the most globally consumed beverages, tea may represent a potential dietary source of pesticide residues. However, limited research has examined NEO contamination in tea and its implications for human exposure, highlighting the need for further investigation. Therefore, this study comprehensively evaluated the residue characteristics, processing effects, and human exposure risks of six NEOs—dinotefuran (DIN), imidacloprid (IMI), acetamiprid (ACE), thiamethoxam (THM), clothianidin (CLO), and thiacloprid (THI)—in Chinese tea products. According to the findings, the primary pollutants, ACE, DIN, and IMI, accounted for 95.65% of the total NEO residues in 137 tea samples, including green, oolong, white, black, dark, and herbal teas. The highest total target NEO (∑₆NEOs) residue level was detected in oolong tea (mean: 57.86 ng/g). Meanwhile, IMI exhibited the highest residue level (78.88 ng/g) in herbal tea due to the absence of high-temperature fixation procedures. Concentrations of DIN in 61 samples (44.5%) exceeded the European Union’s maximum residue limit of 10 ng/g. Health risk assessment indicated that both the chronic hazard quotient (cHQ) and acute hazard quotient (aHQ) for adults and children were below the safety threshold (<1). However, children required special attention, as their exposure risk was 1.28 times higher than that of adults. The distribution of NEO residues was significantly influenced by tea processing techniques, such as full fermentation in black tea. Optimizing processing methods (e.g., using infrared enzyme deactivation) and implementing targeted pesticide application strategies may help mitigate risk. These results provide a scientific foundation for enhancing tea safety regulations and protecting consumer health. Full article

To address the growing global demand for aquatic protein and the need for sustainable aquaculture, this study explored Aspalathus linearis tea extract as a novel feed additive for Oreochromis mossambicus larvae. Over an eight-week feeding trial, the efficacy of diets supplemented with 30% fermented or green rooibos extract was assessed against a control. Both fermented and green rooibos treatments significantly (p < 0.05) enhanced larval growth, evidenced by improved weight gain and feed conversion ratios (fermented: 1.50 ± 0.25; green: 1.41 ± 0.07). Notably, A. linearis extracts also demonstrated genoprotective potential, as indicated by a marked reduction in micronucleus frequency, most likely attributed to their abundant phenolic compounds. These findings demonstrate that rooibos extract, especially the green variety, can improve growth performance and feed utilization, and also provide genoprotective benefits. The superior outcomes in growth and feed conversion are likely due to the bioactive phenolic compounds, which may enhance palatability, gut health, and nutrient absorption, rather than macronutrient content. This positions rooibos extract as a promising natural functional additive for aquafeed, offering a sustainable strategy to enhance tilapia farming productivity and resource utilization. However, further research is necessary to uncover specific molecular mechanisms, conduct in-depth analyses of gut health and immune responses, and evaluate effects on product quality to facilitate its sustainable and effective integration into aquaculture practices, thereby contributing to both fish health and food security. Full article

Bee-collected pollen (BCP) can serve as an excellent enhancer of functional food bioactivity, particularly when it is fermented. The aim of this study was to prepare a novel kombucha-based beverage (KPE) enriched with fermented monofloral rapeseed (Brassica napus L.) BCP. To characterize the obtained samples, a proximate phytochemical composition analysis (including total phenolic and flavonoid content) was performed, as well as a detailed untargeted UHPLC-Q-ToF-MS profiling of phenolics and phenylamides. To biologically characterize KPE, antioxidant and antimicrobial activities were monitored. The total phenolic and flavonoid content, enhanced by the addition of BCP to the kombucha green tea beverage, was dose-dependent. The control sample showed a strong predominance of flavan-3-ols, distinguishing it from the KPE samples, where flavonol predominance and an increased content of phenolic acids were observed. Notably, the most significant markers of BCP were phenylamides, which were completely absent in the control. Although antioxidant activity was proximately highest in the control sample, KPE samples exhibited significantly improved antimicrobial activity. Full article

Sea buckthorn (Hippophae rhamnoides) is a valuable plant rich in biologically active compounds, mainly found in its berries and leaves. The harvesting process, which includes pruning, freezing, and shaking, leaves behind large amounts of biomass and juice-pressing residues, typically composted. The aim of this study is to expand knowledge of the valorization of sea buckthorn secondary raw materials by applying an innovative pressure cyclic solid–liquid (PCSL) extraction method and to develop value-added functional food products. Extraction was performed in 20 and 60 cycles, each lasting from 2 to 10 min. The highest concentrations of proanthocyanidins (5.51 g_CE/L) and total phenolics (12.42 g_GAE/L) were obtained under prolonged conditions, but the L-4 extract (20 cycles × 2 min) was selected for kombucha production due to its favorable balance between efficiency and sustainability. Microbial safety evaluation showed that kombucha with sea buckthorn leaf extract exhibited significantly stronger antimicrobial activity against tested pathogens compared to green tea kombucha. Additionally, sensory analysis revealed higher consumer acceptability of beverages enriched with sea buckthorn extracts. Shotgun metagenomic analysis identified high microbial diversity in the M. gisevii MI-2 starter culture and fermented kombucha products (227 bacteria and 44 eukaryotes), most of which (92.5% bacteria, 77.8% eukaryotes) remain viable and contribute to fermentation dynamics. New biotechnological strategies and genetic modifications raise concerns about the safe use of microorganisms in food production. To address these issues, these findings provide a foundation for future strategies aimed at the safe application of beneficial microorganisms in food biotechnology and support the long-term goals of the European Green Deal by promoting sustainable biomass valorization and circular economy advancement in the food sector. Full article

Background/Objectives: The rise of bacterial resistance and the search for alternative, biocompatible antimicrobial materials have driven interest in natural-based nanocomposites. In this context, silver nanoparticles (AgNPs) have shown broad-spectrum antibacterial activity, and bacterial cellulose (BC) is widely recognized for its high purity, hydrophilicity, and biocompatibility. This study aimed to develop a bio-based BC–AgNP nanocomposite via green synthesis using Astrocaryum aculeatum (tucumã) extract and assess its antimicrobial performance for wound dressing applications. Methods: BC was biosynthesized via green tea fermentation (20 g/L tea and 100 g/L sugar) and purified prior to use. AgNPs were obtained by reacting aqueous tucumã extract with silver nitrate (0.1 mmol/L) at pH (9) and temperature (40 °C). BC membranes were immersed in the AgNPs dispersion for 7 days to form the nanocomposite. Characterization was performed using UV–Vis, DLS, TEM, SEM–EDS, FTIR, XRD, ICP–OES, and swelling analysis. Antibacterial activity was evaluated using the disk diffusion method against Staphylococcus aureus and Escherichia coli (ATCC 6538 and 4388). Results: The UV–Vis spectra revealed a gradual decrease in the surface plasmon resonance (SPR) band over 7 days of incubation with BC, indicating progressive incorporation of AgNPs into the membrane. ICP analysis confirmed silver incorporation in the BC membrane at 0.00215 mg/mL, corresponding to 15.5% of the initial silver content. Antimicrobial assays showed inhibition zones of 6.5 ± 0.5 mm for S. aureus and 4.3 ± 0.3 mm for E. coli. Conclusions: These findings validate the successful formation and antimicrobial performance of the BC–AgNP nanocomposite, supporting its potential use in wound care applications. Full article

Oxidative stress and inflammation are critical factors in hypertension and type 2 diabetes mellitus (T2DM). Kombucha, a fermented tea beverage, is enriched with bioactive compounds during fermentation. This study evaluated the antihypertensive, antihyperglycemic, antioxidant, and anti-inflammatory activities of kombucha made from mulberry leaf green tea (MLGT) and black tea (MLBT) during in vitro digestion. The bioaccessibility of 1-deoxynojirimycin (DNJ), γ-aminobutyric acid (GABA), phenolics, and flavonoids was assessed through simulated oral, gastric, and intestinal phases. MLGT kombucha exhibited higher initial antioxidant activity, while MLBT showed greater compound stability and ACE inhibitory activity during digestion. Notably, α-glucosidase inhibition declined significantly in the intestinal phase, in parallel with reduced DNJ and flavonoid content. Strong correlations were observed between specific phenolic acids and bioactivity profiles, highlighting ρ-coumaric and sinapic acids in ACE inhibition and DNJ in antiglycemic activity. These findings demonstrate the functional potential of mulberry leaf kombucha as a beverage to support metabolic health, pending confirmation through in vivo studies. Full article

Kombucha, traditionally fermented from black or green tea, is well known for its potential health benefits. However, its high caffeine content may limit consumption for certain individuals. Therefore, this study aimed to develop a low-caffeine kombucha using lotus root tea as an alternative to black or green tea. Lotus root was roasted and brewed to prepare the tea base, to which sugar and a SCOBY were added for primary fermentation. Subsequently, Lactobacillus plantarum (1.0 × 10⁹ and 3.0 × 10⁹ CFU/mL) was inoculated to carry out secondary fermentation. The kombucha samples were assessed for their organic acid composition, antioxidant activity, antimicrobial effects, β-glucuronidase inhibition, and protective effects against Salmonella infection in a Caenorhabditis elegans model. The caffeine concentration of lotus root tea kombucha was significantly lower than that of conventional kombucha. L. plantarum fermentation increased the lactic acid concentration and enhanced antimicrobial activity, particularly against Escherichia coli OP50 and Salmonella typhimurium. Additionally, β-glucuronidase inhibition significantly improved, suggesting potential gut health benefits. In C. elegans, kombucha consumption improved survival rates following Salmonella infection, indicating a protective effect. This study demonstrates that fermentation using Lactobacillus plantarum can enhance the bioactivity of lotus root kombucha, highlighting its potential as a low-caffeine functional beverage. Full article

Sea buckthorn is a unique resource with high nutritional value. The objective of this study was to develop a novel kombucha beverage from sea buckthorn juice by means of inoculation with kombucha (Symbiotic Culture of Bacteria and Yeast, SCOBY). The study investigated and compared the differences in physicochemical properties, antioxidant activity, and sensory evaluation during fermentation at different temperatures with those of traditional cultured green tea kombucha. The findings demonstrated that there were significant variations in physicochemical properties, antioxidant activity, and sensory evaluation among the sea buckthorn kombuchas produced at different temperatures. Among these, the sea buckthorn kombucha produced by fermentation at 28 °C exhibited the strongest antioxidant properties and the most favorable sensory evaluation. Furthermore, changes in the active substances were observed at different temperatures, and correlation analysis revealed that the antioxidant activity of Kombucha tea was correlated with the content of total phenols and total flavonoids. Consequently, the utilization of sea buckthorn juice in the production of kombucha beverages holds considerable promise. Full article

This study evaluated the influence of tea, sucrose, and inoculum concentrations on green tea kombucha’s physicochemical properties and antioxidant capacity to optimize its production. The highest total phenolic content (98.61 mg GAE/100 mL) and radical scavenging activity for ABTS (9647.14 μmol/mL) and DPPH (6640.00 μmol/mL) were observed with 8 g/L of tea, 80 g/L of sucrose, and 30% inoculum. Principal Component Analysis highlighted inoculum as the key factor influencing these parameters. Following this, fermentation was scaled up in 6.5 L bioreactors operating under static and stirred conditions. Monitoring physicochemical properties, antioxidant capacity, and volatile compounds revealed the impact of agitation on fermentation, with the kombucha obtained by static cultivation presenting higher biological activity. Eleven volatile compounds were identified, including carboxylic acids, terpenes, esters, alcohols, and phenols. Notably, α-terpinolene, dodecanoic acid, and 2,4-di-tert-butylphenol, found in kombucha, exhibit antioxidant properties linked to health benefits. Differences in volatile compound profiles were observed between static and stirred processes. This study concluded that kombucha maintains its physicochemical characteristics and bioactivity during scale-up, contributing to a better understanding of large-scale production. It also suggests stirred cultivation as an alternative for kombucha production. Full article

This study aimed to isolate and characterize microorganisms from water kefir beverage for their functional properties. Five lactic acid bacteria (LAB) strains were isolated: three Leuconostoc citreum strains (LB4, LB6, LB13) and two Lactococcus lactis strains (LB5, LB25), identified via 16S rRNA sequencing, along with three Saccharomyces cerevisiae yeast strains (Y7, Y9, Y10), confirmed by 18S rDNA sequencing. Due to the high genetic and phenotypic similarity within each species, one representative strain from each (LB4, LB5, Y9) was selected for further analysis. These strains showed potential probiotic properties, including tolerance to acid and bile, high auto-aggregation, and hydrophobicity. The LAB strains were sensitive to gentamicin, and their supernatants inhibited the growth of tested pathogenic bacteria. The cumulative probiotic potential (CPP) scores were 93.33% for Lc. citreum LB4 and L. lactis LB5, and 100% for S. cerevisiae Y9. Furthermore, the fermentation potential of these strains was evaluated in a green tea beverage using three co-culture formulations. Among the formulations tested, the BF1 beverage, fermented by F1 (40% LB4, 40% LB5, and 20% Y9), demonstrated optimal physicochemical, microbiological, and sensory properties. Notably, while the individual strains did not show anti-inflammatory activity, the BF1 beverage formulation exhibited this effect, suggesting a synergistic interaction during fermentation. Full article

Kombucha is a well-known fermented drink that gained interest due to its gut health benefits. However, it has a harsh taste of acetic acid and is hard to consume. Thai Cannabis leaves (Cannabis sativa sp. Hang Kra Rog Phu phan ST1) contain high protein and phytochemicals which can improve the growth of lactic acid bacteria (LAB) and enhance the organoleptic quality of the Kombucha. This study revealed the effect of infusing assam green tea leaves with cannabis leaves on the fermentation rate, microbial communities, volatile compounds, and overall quality and taste of the kombucha. The high protein content (23.10%) of Cannabis leaves was found. Phytonutrients and phytochemicals found in the leaves promotes LAB growth, which resulted in the higher number of LAB in the treatment with cannabis leaves. At the end of fermentation (day 7), the highest LAB count (5.53 log CFU mL⁻¹) was presented in kombucha infused with 30% cannabis leaves. Kombucha with better quality, higher pH, and less acidity was obtained in a dose manner. The change in microbial communities was detected using metagenomic analysis. The prominence of Dekkera and Komagataeibacter, with low abundance of Zygosaccharomyces and Weissella were identified. These microorganisms improved flavor by lessening strong fermented odor and harsh acidic taste. From volatile compounds, HS-SPME-GCMS revealed that kombucha infused with 30% cannabis leaves possessed less acetic acid, ethanol, and carbon dioxide and gave a better odor and taste. Hence, cannabis leaves was the novel substrate for kombucha fermentation by enhancing LAB growth and improving the overall qualities. Full article

The aim of this study was to use different concentrations of lemon juice and honey to improve the formulation of a green tea water kefir (GTWK) beverage by applying a central composite design (CCD). Honey’s concentration was 10–50% and lemon juice concentration was 1–5%, these were used as the independent factors, whereas pH, bacteria and yeasts’ count, total phenolic content, % DPPH^. scavenging activity, and overall acceptability were used as the dependent factors. The optimal concentration of honey and lemon juice for highest microbial count, antioxidant activities and overall acceptability was 42.85% and 1.771%, respectively. The analysis of variance revealed that the model was well-fitting, with R² ranging from 87.27% to 96.95%, adj-R² ranging from 78.17% to 94.26% and a non-significant lack of fits. The optimized fermented beverage showed antibacterial potential against Echerichia coli ATCC11229, Staphylococcus aureus ATCC6538 and Salmonella typhimirium ATCC14028 strains. The anti-inflammatory activity was evaluated on CaCo-2 and RAW 264.7 cells. According to ELISA assay, a significant decrease (p < 0.05) in TNF-α concentration was found after inflammatory stimulation, from 1205.41 ± 55.87 pg/mL to 478.17 ± 69.12 pg/mL. Full article

Teas derived from Camellia sinensis are traditionally used in kombucha fermentation, a process in which bacteria and yeasts play key roles. This study aimed to evaluate the effects of green, black, and white teas, as well as their combinations, on the physicochemical properties, antioxidant capacity, and total phenolic compound content of kombucha. In addition, the production of kombucha flavored with fruits. Statistical analysis of simplex centroid mixture design indicated that green tea promoted a positive increase in total phenolic content and antioxidant activities against ABTS and DPPH free radicals, being observed at 5868.46 µmol/mL, 705.40 µmol/mL, and 380.77 mg GAE/100 mL in the kombucha prepared using this tea individually. Then, six kombucha beverages were prepared from green tea, flavored with grape, caja, cashew apple, genipap, passion fruit, and tamarind. The phenolic profile analysis revealed the presence of twenty-six compounds, including twenty-five phenolics and one caffeine derivative. Among the beverages, tamarind-flavored kombucha stood out, exhibiting the highest total flavonoid content (156.77 mg EQ/g), which highlights the positive influence of tamarind on the bioactive properties of kombucha beverages. These results provide valuable insights to optimize kombucha production and explore the potential beneficial effects of flavored non-alcoholic beverages. Full article

Tea is a significant source of flavonoids in the diet. Due to different production processes, the amount of bioactive compounds in unfermented (green) and (semi-)fermented tea differs. Importantly, green tea has a similar composition of phenolic compounds to fresh, unprocessed tea leaves. It consists primarily of monomeric flavan-3-ols, known as catechins, of which epigallocatechin gallate (EGCG) is the most abundant. Thanks to its antioxidant, antiproliferative, and antiangiogenic properties, EGCG has attracted the scientific community’s attention to its potential use in preventing and/or combating cancer. In this review article, we summarize the literature reports found in the Google Scholar and PubMed databases on the anticancer effect of EGCG on selected malignant neoplasms in women, i.e., breast, cervical, endometrial, and ovarian cancers, which have been published over the last two decades. It needs to be emphasized that EGCG concentrations reported as effective against cancer cells are typically higher than those found in plasma after polyphenol administration. Moreover, the low bioavailability and absorption of EGCG appear to be the main reasons for the differences in the effects between in vitro and in vivo studies. In this context, we also decided to look at possible solutions to these problems, consisting of combining the polyphenol with other bioactive components or using nanotechnology. Despite the promising results of the studies conducted so far, mainly in vitro and on animal models, there is no doubt that further, broad-based activities are necessary to unequivocally assess the potential use of EGCG in oncological treatment to combat cancer in women. Full article