Microbiological, biochemical, and functional aspects of sugary kefir fermentation - A review

Water kefir in co-fermentation with Saccharomyces boulardii for the development of a new probiotic mead

Mead is an alcoholic beverage obtained by fermenting a dilute solution of honey with yeasts. The aim of this study was to develop and evaluate a probiotic mead from the co-fermentation of water kefir and Sacharomyces boulardii. According to the results, the combination of 10 g/L of water kefir grains and 0.75 g/L of S. boulardii, with a fermentation time of 9 days, produced a probiotic mead with a viable cell count of more than 8 Log10 CFU/mL of S. boulardii and also for lactic acid bacteria, respectively. S. boulardii and lactic acid bacteria showed counts of over 6 Log10 CFU/mL after gastrointestinal simulation in vitro, with a survival rate of over 70%. Probiotic mead has good luminosity (L*), a tendency to yellow color and the presence of total phenolic compounds and antioxidants. In conclusion, the co-fermentation of water kefir and S. boulardii has potential for the development of probiotic mead.

The Production of Water Kefir Drink with the Addition of Dried Figs in the Horizontal Rotating Tubular Bioreactor

Water kefir is a product obtained through the fermentation of sucrose solution, usually with some kind of dried fruit addition, by a combined culture of micro-organisms which are contained within kefir grains. Its popularity is rising because of the simplicity of its preparation and its anti-inflammatory, antioxidant, probiotic, and antibacterial effects. In this research, the water kefir production was studied in 250 mL jars, as well as in a horizontal rotating tubular bioreactor (HRTB). The first part of the research was conducted in smaller-scale (jars), wherein the optimal fruit and fruit portions were determined. These experiments included the addition of dried plums, apricots, raisins, dates, cranberries, papaya, and figs into 150 mL of initial sugar solution. Also, the optimal ratio between dried fruit and sucrose solution (0.2) at the beginning of the bioprocess was determined. The second part of this research was conducted using HRTB. The experiments in the HRTB were carried out by using different operational modes (constant or interval bioreactor rotation). A total of six different bioreactor setups were used, and in all experiments, figs were added at the beginning of the bioprocess (0.2 ratio between dried figs and sucrose solution). On the basis of the obtained results, the interval bioreactor rotation mode proved to be the better HRTB mode for the production of the water kefir, as the yield of the main fermentation products was higher, and their ratios were the most adequate for the quality of water kefir drink. The optimal results were obtained via HRTB setup 3/57 (3 min rotation, 57 min pause within 1 h) and rotation speed of 3 rpm. Furthermore, it is clear that HRTB has great potential for water kefir production due to the fact that HRTB experiments showed shorter fermentation times (at least five times) than water kefir production in jars.

Comparative metatranscriptome analysis of Brazilian milk and water kefir beverages

The present study compared bacterial and fungal diversity of kefir beverages produced using milk (MK) or sugared water (WK) as propagation matrices and grains from the cities of Curitiba (CU) or Salvador (SA), Brazil, by sequencing the complete set of RNA transcripts produced in four products. In Brazil, milk and sugared water are used as matrices to propagate kefir grains. In all beverages, the bacterial community was composed of Lactobacillaceae and Acetobacteraceae. Saccharomycetaceae was the yeast family more abundant in WK, and Dipodascaceae and Pichiaceae in MK. Regarding KEGG mapping of functional orthologs, the four kefir samples shared 70% of KO entries of yeast genes but only 36% of bacterial genes. Concerning main metabolic processes, the relative abundance of transcripts associated with metabolism (energy metabolism) and environmental information processing (membrane transport) had the highest water/milk kefir ratio observed in Firmicutes. In contrast, transcripts associated with genetic information processing (protein translation, folding, sorting, and degradation) oppositely had the lowest water/milk ratios. Concluding, milk and water kefir have quite different communities of microorganisms. Still, the main mapped functional processes are similar, with only quantitative variation in membrane transport and energy acquisition in the water kefir and protein synthesis and turnover in the milk kefir.

Bacillus subtilis SOM8 isolated from sesame oil meal for potential probiotic application in inhibiting human enteropathogens

BACKGROUND

While particular strains within the Bacillus species, such as Bacillus subtilis, have been commercially utilised as probiotics, it is critical to implement screening assays and evaluate the safety to identify potential Bacillus probiotic strains before clinical trials. This is because some Bacillus species, including B. cereus and B. anthracis, can produce toxins that are harmful to humans.

RESULTS

In this study, we implemented a funnel-shaped approach to isolate and evaluate prospective probiotics from homogenised food waste - sesame oil meal (SOM). Of nine isolated strains with antipathogenic properties, B. subtilis SOM8 displayed the most promising activities against five listed human enteropathogens and was selected for further comprehensive assessment. B. subtilis SOM8 exhibited good tolerance when exposed to adverse stressors including acidity, bile salts, simulated gastric fluid (SGF), simulated intestinal fluid (SIF), and heat treatment. Additionally, B. subtilis SOM8 possesses host-associated benefits such as antioxidant and bile salt hydrolase (BSH) activity. Furthermore, B. subtilis SOM8 contains only haemolysin toxin genes but has been proved to display partial haemolysis in the test and low cytotoxicity in Caco-2 cell models for in vitro evaluation. Moreover, B. subtilis SOM8 intrinsically resists only streptomycin and lacks plasmids or other mobile genetic elements. Bioinformatic analyses also predicted B. subtilis SOM8 encodes various bioactives compound like fengycin and lichendicin that could enable further biomedical applications.

CONCLUSIONS

Our comprehensive evaluation revealed the substantial potential of B. subtilis SOM8 as a probiotic for targeting human enteropathogens, attributable to its exceptional performance across selection assays. Furthermore, our safety assessment, encompassing both phenotypic and genotypic analyses, showed B. subtilis SOM8 has a favourable preclinical safety profile, without significant threats to human health. Collectively, these findings highlight the promising prospects of B. subtilis SOM8 as a potent probiotic candidate for additional clinical development.

Nutritional Characteristics, Health Impact, and Applications of Kefir

A global epidemiological shift has been observed in recent decades, characterized by an increase in age-related disorders, notably non-communicable chronic diseases, such as type 2 diabetes mellitus, cardiovascular and neurodegenerative diseases, and cancer. An appreciable causal link between changes in the gut microbiota and the onset of these maladies has been recognized, offering an avenue for effective management. Kefir, a probiotic-enriched fermented food, has gained significance in this setting due to its promising resource for the development of functional or value-added food formulations and its ability to reshape gut microbial composition. This has led to increasing commercial interest worldwide as it presents a natural beverage replete with health-promoting microbes and several bioactive compounds. Given the substantial role of the gut microbiota in human health and the etiology of several diseases, we conducted a comprehensive synthesis covering a total of 33 investigations involving experimental animal models, aimed to elucidate the regulatory influence of bioactive compounds present in kefir on gut microbiota and their potential in promoting optimal health. This review underscores the outstanding nutritional properties of kefir as a central repository of bioactive compounds encompassing micronutrients and amino acids and delineates their regulatory effects at deficient, adequate, and supra-nutritional intakes on the gut microbiota and their broader physiological consequences. Furthermore, an investigation of putative mechanisms that govern the regulatory effects of kefir on the gut microbiota and its connections with various human diseases was discussed, along with potential applications in the food industry.

Integration of Riboflavin-Modified Carbon Fiber Mesh Electrode Systems in a 3D-Printed Catheter Hub

BACKGROUND

Catheter line infection is a common complication within clinical environments, and there is a pressing need for technological options to aid in reducing the possibility of sepsis. The early identification of contamination could be pivotal in reducing cases and improving outcomes.

METHOD

A sensing rationale based on a riboflavin-modified electrode system integrated within a modified 3D-printed catheter needle-free connector is proposed, which can monitor changes in pH brought about by bacterial contamination.

RESULTS

Riboflavin, vitamin B2, is a biocompatible chemical that possesses a redox-active flavin core that is pH dependent. The oxidation peak potential of the adsorbed riboflavin responds linearly to changes in pH with a near-Nernstian behavior of 63 mV/pH unit and is capable of accurately monitoring the pH of an authentic IV infusate.

CONCLUSIONS

The proof of principle is demonstrated with an electrode-printed hub design offering a valuable foundation from which to explore bacterial interactions within the catheter lumen with the potential of providing an early warning of contamination.

Characterization of the Bacterial Composition of 47 Fermented Foods in Sweden

Fermentation has long been utilized to preserve and enhance the flavor and nutritional value of foods. Recently, fermented foods have gained popularity, reaching new consumer groups due to perceived health benefits. However, the microbial composition of many fermented foods re-mains unknown. Here, we characterized the bacterial composition, diversity, and richness of 47 fermented foods available in Sweden, including kombucha, water kefir, milk kefir, yogurt, plant-based yogurt alternatives, kimchi, sauerkraut, and fermented vegetables. Via 16S rRNA gene sequencing, we identified 2497 bacteria (amplicon sequence variants). The bacterial composition was strongly associated with the type of fermented food, and lactic acid bacteria and/or acetic acid bacteria dominated most samples. However, each fermented food had a unique composition, with kombucha and water kefir having the highest diversity across and within samples. Few bacteria were abundant in multiple foods and food groups. These were Streptococcus thermophilus in yogurts and plant-based yoghurts; Lactococcus lactis in milk kefirs and one water kefir; and Lactiplantibacillus plantarum in kimchi, sauerkraut, and fermented cucumber. The broad range of fermented foods included in this study and their diverse bacterial communities warrant further investigation into the implications of microbial compositions for product traits and potential impact on human health.

Multi-omics characterization of the microbial populations and chemical space composition of a water kefir fermentation

In recent years, the popularity of fermented foods has strongly increased based on their proven health benefits and the adoption of new trends among consumers. One of these health-promoting products is water kefir, which is a fermented sugary beverage based on kefir grains (symbiotic colonies of yeast, lactic acid and acetic acid bacteria). According to previous knowledge and the uniqueness of each water kefir fermentation, the following project aimed to explore the microbial and chemical composition of a water kefir fermentation and its microbial consortium, through the integration of culture-dependent methods, compositional metagenomics, and untargeted metabolomics. These methods were applied in two types of samples: fermentation grains (inoculum) and fermentation samples collected at different time points. A strains culture collection of ∼90 strains was established by means of culture-dependent methods, mainly consisting of individuals of Pichia membranifaciens, Acetobacter orientalis, Lentilactobacillus hilgardii, Lacticaseibacillus paracasei, Acetobacter pomorum, Lentilactobacillus buchneri, Pichia kudriavzevii, Acetobacter pasteurianus, Schleiferilactobacillus harbinensis, and Kazachstania exigua, which can be further studied for their use in synthetic consortia formulation. In addition, metabarcoding of each fermentation time was done by 16S and ITS sequencing for bacteria and yeast, respectively. The results show strong population shifts of the microbial community during the fermentation time course, with an enrichment of microbial groups after 72 h of fermentation. Metataxonomics results revealed Lactobacillus and Acetobacter as the dominant genera for lactic acid and acetic acid bacteria, whereas, for yeast, P. membranifaciens was the dominant species. In addition, correlation and systematic analyses of microbial growth patterns and metabolite richness allowed the recognition of metabolic enrichment points between 72 and 96 h and correlation between microbial groups and metabolite abundance (e.g., Bile acid conjugates and Acetobacter tropicalis). Metabolomic analysis also evidenced the production of bioactive compounds in this fermented matrix, which have been associated with biological activities, including antimicrobial and antioxidant. Interestingly, the chemical family of Isoschaftosides (C-glycosyl flavonoids) was also found, representing an important finding since this compound, with hepatoprotective and anti-inflammatory activity, had not been previously reported in this matrix. We conclude that the integration of microbial biodiversity, cultured species, and chemical data enables the identification of relevant microbial population patterns and the detection of specific points of enrichment during the fermentation process of a food matrix, which enables the future design of synthetic microbial consortia, which can be used as targeted probiotics for digestive and metabolic health.

Moving towards in pouch diagnostics for ostomy patients: exploiting the versatility of laser induced graphene sensors

The development of a 3D printed sensor for direct incorporation within stoma pouches is described. Laser induced graphene scribed on either side of polyimide film served as the basis of a 2 electrode configuration that could be integrated within a disposable pouch sensor for the periodic monitoring of ileostomy fluid pH. The graphene sensors were characterised using electron microscopy, Raman spectroscopy, DekTak profilometry with the electrochemical properties investigated using both cyclic and square wave voltammetry. Adsorbed riboflavin was employed as a biocompatible redox probe for the voltammetric measurement of pH. The variation in peak position with pH was found to be linear over pH 3-8 with a sub Nernstian response (43 mV/pH). The adsorbed probe was found to be reversible and exhibited minimal leaching through repeated scanning. The performance of the system was assessed in a heterogeneous bacterial fermentation mixture simulating ileostomy fluid with the pH recorded before and after 96 h incubation. The peak profile in the bacterial medium provided an unambiguous signal free from interference with the calculated pH before and after incubation (pH 5.3 to 3.66) in good agreement with that obtained with commercial pH probes.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10853-023-08881-x.

Nutraceutical Combinational Therapy for Diarrhoea Control with Probiotic Beverages from Fermented Fruits, Vegetables and Cereals to Regain Lost Hydration, Nutrition and Gut Microbiota

This article deals with the condition of irregular bowel movements known as diarrhoea, its pathology, symptoms and aetiology. The information has been presented on causes of diarrhoea that include gut infections, food intolerances and allergies to certain ingredients, problems in the gastrointestinal tract like irritable bowel syndrome, inflammatory bowel disease and, the condition of dysbiosis which occurs due to long-term use of antibiotics, or other medicines, etc. Most cases of diarrhoea can be resolved without needing medical treatment; however, it is still important to avoid dehydration of the body and use some supplements to get necessary nutrients which are lost with frequent bowel movements before they can get absorbed and assimilated in the gastrointestinal tract. Probiotic products are reported as natural therapeutic agents, which can reduce the risk of diarrhoea in both adults and children. The intake of dietary fluid supplements in the form of fermented beverages containing probiotic strains could help in diarrhoea control. The patient would achieve benefits with the consumption of these functional beverages in three ways-by regaining lost fluids to the body, supplementing beneficial gut bacteria to restore diversity in gut microbiota, which was disturbed in the condition of diarrhoea as well as regaining a source of quick nutrition to recoup energy.

Employing alternative culture media in kefiran exopolysaccharide production: Impact on microbial diversity, physicochemical properties, and bioactivities

Kefiran is a biomaterial with potential application in developing novel materials for food technology. In this study, sugarcane sugar (REF), raw sugar (RAS), brown sugar (BRS), soy molasses (SOM), and sugarcane molasses (SCM) were evaluated for the production of kefiran from kefir biomass rather than cow's milk (CMK), the usual medium. The produced kefiran was purified and characterized by colorimetry, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis, and morphology. It was also assayed for antioxidant and antimicrobial activity. SCM had the highest average daily rate of kefir biomass production (29.17 %/day). The composition of the culture medium affected the microbial diversity of kefir grains, and the Lactobacillus genus was the most abundant (39.8 %, 40.0 %, and 83.9 % to SCM, SOM, and CMK, respectively) in the samples that presented the highest biomass production and kefiran extraction yields. FTIR spectra showed that the bands of kefiran produced in REF and RAS were narrower than those of the other samples. Kefiran grew in an alternative culture medium also exhibited higher thermal stability (Tonset and TMax was higher than 250 and 280 °C, respectively). Those grown in SOM and SCM displayed antimicrobial and antioxidant activities similar to those of kefiran produced in CMK. The results indicate that agro-industrial by-products (SCM and SOM) are potential alternatives for kefiran production from kefir biomass.

Physical, chemical, and sensory properties of water kefir produced from Aronia melanocarpa juice and pomace

Water kefir is widely consumed all over the world due to its potential health benefits. The aim of this current study was to compare non-fermented juice and fermented beverage of water kefir produced from Aronia melanocarpa juice and pomace in terms of chemical, physical and sensory quality as well as valorisation of pomace in the production of water kefir. When compared to water kefir made with aronia juice, less reduction in total phenolic content (TPC), total flavonoid content (TFC) and total anthocyanin content (TAC) was observed in samples made with aronia pomace during the fermentation process. Similarly, greater antioxidant activity was demonstrated in water kefir made with aronia pomace than juice. Based on sensory evaluation, no difference was found in overall acceptability, taste, aroma/odor, and turbidity of water kefir made with aronia pomace before and after fermentation. Results indicated that aronia pomace has potential in water kefir production.

Effect of Agave Fructans on Changes in Chemistry, Morphology and Composition in the Biomass Growth of Milk Kefir Grains

Prebiotic effects have been attributed to agave fructans through bacterial and yeast fermentations, but there are few reports on their use as raw materials of a carbon source. Kefir milk is a fermented drink with lactic acid bacteria and yeast that coexist in a symbiotic association. During fermentation, these microorganisms mainly consume lactose and produce a polymeric matrix called kefiran, which is an exopolysaccharide composed mainly of water-soluble glucogalactan, suitable for the development of bio-degradable films. Using the biomass of microorganisms and proteins together can be a sustainable and innovative source of biopolymers. In this investigation, the effects of lactose-free milk as a culture medium and the addition of other carbon sources (dextrose, fructose, galactose, lactose, inulin and fructans) in concentrations of 2, 4 and 6% w/w, coupled with initial parameters such as temperature (20, 25 and 30 °C), % of starter inoculum (2, 5 and 10% w/w) was evaluated. The method of response surface analysis was performed to determine the optimum biomass production conditions at the start of the experiment. The response surface method showed that a 2% inoculum and a temperature of 25 °C were the best parameters for fermentation. The addition of 6% w/w agave fructans in the culture medium favored the growth of biomass (75.94%) with respect to the lactose-free culture medium. An increase in fat (3.76%), ash (5.57%) and protein (7.12%) content was observed when adding agave fructans. There was an important change in the diversity of microorganisms with an absence of lactose. These compounds have the potential to be used as a carbon source in a medium culture to increase kefir granule biomass. There was an important change in the diversity of microorganisms with an absence of lactose, where the applied image digital analysis led to the identification of the morphological changes in the kefir granules through modification of the profile of such microorganisms.

Fermented Beverage Benefits: A Comprehensive Review and Comparison of Kombucha and Kefir Microbiome

Beverage fermentation is an ancient ritual that has been practised for millennia. It was slowly disappearing from households and communities due to the advancement of manufacturing technology and the marketing of soft drinks until the recent revival of the beverage fermentation culture due to an increase in the demand for health drinks amid the COVID-19 pandemic. Kombucha and kefir are two well-known fermented beverages that are renowned for their myriad of health benefits. The starter materials for making these beverages contain micro-organisms that act like microscopic factories producing beneficial nutrients that have antimicrobial and anticancer effects. The materials modulate the gut microbiota and promote positive effects on the gastrointestinal tract. Due to wide variations in the substrates and types of micro-organisms involved in the production of both kombucha and kefir, this paper compiles a compendium of the micro-organisms present and highlights their nutritional roles.

Physico-Chemical, Microbiological and Sensory Properties of Water Kefir Drinks Produced from Demineralized Whey and Dimrit and Shiraz Grape Varieties

Water kefir grains cannot grow in milk. Therefore, the aim of this study was to investigate whether water kefir grains can show activity in demineralized whey, an environment containing lactose as a carbon source. The physicochemical, microbiological and sensory properties of water kefir prepared from demineralized whey containing 2% and 5% lactose and raisins or grape juice from two grape varieties (Dimrit and Shiraz) were investigated. It was found that the protein content of the water kefir increased significantly (p < 0.05), especially when grape juice was added. The total soluble solids and viscosity of the samples with grape addition increased significantly (p < 0.05). Total phenolic content and antioxidant capacity increased significantly with grape addition (p < 0.05), with the effect of Shiraz grape being more pronounced. In general, it was found that the content of K, P, Na, Ca and Mg was higher in the samples with grape addition. The sensory properties of water kefir made from dWhey with 2% lactose and grape juice were better. It was also confirmed that viability of water kefir microbiota is better in water kefir drink made from dWhey with 2% lactose due to higher pH value in comparison to dWhey with 5% lactose.

Influence of Substrate on the Fermentation Characteristics and Culture-Dependent Microbial Composition of Water Kefir

Water kefir is a sparkling fermented beverage produced by fermenting water kefir grains in a sucrose solution containing dried fruits or fruit extracts. The objective of this study was to investigate the influence of substrate composition on the fermentation kinetics and culture-dependent microbial composition of water kefir. First, the impact of different fruit substrates and nitrogen limitation was examined. Fermentation of different fruit-based media with a single water kefir culture demonstrated that the substrate mainly influenced the type and ratio of the organic acids produced. These organic acid profiles could be linked to the culture-dependent microbial composition. In addition, the microbial composition and the associated dominant microorganisms observed were influenced by the water kefir fermentation conditions. Investigation of the effect of nitrogen limitation on the fermentation kinetics of several water kefir cultures showed that under such conditions, the fermentative capacity of the cultures declined. However, this decline was not immediate, and specific water kefir microorganisms may have enabled some cultures to maintain a higher fermentative capacity for longer. Thus, the water kefir fermentation kinetics and characteristics could be linked to the substrate composition, microorganisms present, and the process conditions under which the fermentations were performed.

The Effects of Kefir and Kefir Components on Immune and Metabolic Physiology in Pre-Clinical Studies: A Narrative Review

Kefir, a fermented beverage made from kefir grains, has gained immense popularity around the world due to its potential health-promoting properties. Kefir beverages are both marketed commercially and brewed privately by individuals. Both milk and sugar solutions can be used as substrates with various additives included based on consumer preference. Fermentation occurs via microorganisms including lactic acid bacteria, acetic acid bacteria, and yeasts, which are naturally present in kefir grains. Health-promoting effects of kefir are thought to occur through immune, gastrointestinal, and metabolic regulation. Both clinical trials and mechanistic studies in cell culture and animal models have explored these effects. Studies in vitro and in animals have shown the ability of kefir and kefir components to antagonize pathogens, reduce proinflammatory cytokine production, contribute to cytotoxicity of tumor cell lines and reduce tumor burden, and improve serum glycemic and lipid profiles. However, some data from clinical trials are conflicting, and the precise mechanisms by which kefir promotes well-being are not completely defined. This review summarizes the current body of evidence in both cell culture and animal models that provide insight into the mechanisms by which kefir beverages may protect consumers from enteric infections and improve immune and metabolic health. We believe that readers will gain knowledge helpful for both developing more targeted mechanistic studies and selecting informative outcomes when designing clinical studies.

Screening and evaluation of lactic acid bacteria with probiotic potential from local Holstein raw milk

There are massive bacteria in the raw milk, especially the lactic acid bacteria (LABs), which have been considered probiotics in humans and animals for a long time. Novel probiotics are still urgently needed because of the rapid development of the probiotic industry. To obtain new LABs with high probiotic potential, we obtained 26 LAB isolates, named L1 ~ L26, from local Holstein raw milk collected from a farm whose milk had never been used for LAB isolation. We identified them at the species level by biochemical and 16S rDNA sequencing methods. Their antagonistic activities against four target pathogens (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa PAO1, and Salmonella enterica H9812), co-aggregative ability with these target pathogens, survivability in the simulated gastrointestinal tract conditions and phenol, auto-aggregation and hydrophobicity, hemolytic activity, and antibiotic susceptibility, were evaluated in vitro. Five Lactiplantibacillus plantarum isolates (L5, L14, L17, L19, and L20) showed more promising probiotic potential than others. Specifically, these five isolates conglutinated with and inhibited all the target pathogens, and survived in the simulated gastric juice (92.55 ~ 99.69%), intestinal juice (76.18 ~ 83.39%), and 0.4% phenol (76.95 ~ 88.91%); possessed considerable auto-aggregation (83.91 ~ 90.33% at 24 h) and hydrophobicity (79.32 ~ 92.70%); and were non-hemolytic, sensitive to kinds of common antimicrobials. Our findings demonstrated that these five isolates could be preliminarily determined as probiotic candidates because they have better probiotic potential than those previously reported. Again, this study highlighted the potential of raw milk for probiotic isolating and screening and provided the probiotic industry with five new LAB candidates.

Biopolymer from Water Kefir as a Potential Clean-Label Ingredient for Health Applications: Evaluation of New Properties

The present work aimed to characterize the exopolysaccharide obtained from water kefir grains (EPSwk), a symbiotic association of probiotic microorganisms. New findings of the technological, mechanical, and biological properties of the sample were studied. The EPSwk polymer presented an Mw of 6.35 × 105 Da. The biopolymer also showed microcrystalline structure and characteristic thermal stability with maximum thermal degradation at 250 °C. The analysis of the monosaccharides of the EPSwk by gas chromatography demonstrated that the material is composed of glucose units (98 mol%). Additionally, EPSwk exhibited excellent emulsifying properties, film-forming ability, a low photodegradation rate (3.8%), and good mucoadhesive properties (adhesion Fmax of 1.065 N). EPSwk presented cytocompatibility and antibacterial activity against Escherichia coli and Staphylococcus aureus. The results of this study expand the potential application of the exopolysaccharide from water kefir as a potential clean-label raw material for pharmaceutical, biomedical, and cosmetic applications.

Does probiotic Kefir reduce dyslipidemia, hematological disorders and oxidative stress induced by zearalenone toxicity in wistar rats?

Zearalenone (ZEA) is a toxic metabolite of the genus Fusarium, which causes hepatotoxicity and induces oxidative stress. Kefir is an important probiotic dairy-product showing important in vitro antioxidant potential. In this study, the effect of Kefir supplementation to mitigate ZEA toxicity in rats was investigated. Animals were divided into four groups of five rats each, which received sterile milk (200 μL/day) during the first week. Then, they were switched to Kefir (200 μL/day), ZEA (40 mg/kg b. w./day) and Kefir + ZEA for the second week. Hematological and biochemical parameters, as well as liver histological analysis were determined. Kefir administration prevented the changes occurred in the count of all blood cells, and improved the antioxidant enzymes in the liver, such as catalase, glutathione peroxidase and superoxide dismutase activities that increased by 6, 4.5 and 1.3 folds, respectively, compared to ZEA group. Interestingly, the concurrent regimen Kefir + ZEA removed ZEA residues in the serum and liver. Furthermore, the Kefir + ZEA group showed a reduction in the levels of bilirubin, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and hepatic malonaldehyde by ∼82, 54, 66, 50 and 36%, respectively, compared to the ZEA group. The histopathological analysis showed a normal liver histological architecture in Kefir + ZEA group, while degenerative changes were observed in ZEA group. These results suggest that Kefir as probiotic consortium may have a hepatoprotective effect against ZEA poisoning.

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Zearalenone caused oxidative stress and liver damage in rats.

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Zearalenone induced disruption of hematological and biochemical parameters.

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Kefir improved the antioxidant defense systems in rats subjected to Zearalenone.

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Kefir prevented Zearalenone-induced hepatotoxicity in rats.

Fermentation process optimization, chemical analysis, and storage stability evaluation of a probiotic barley malt kvass

Kvass is a popular low-alcohol beverage produced by the natural fermentation of dark rye bread or malt with complex microbial flora. However, few pieces of research focus on the microflora of traditional bread kvass, and the industrial kvass based on malt concentrate has some disadvantages, including the lack of viable probiotics and containing multiple artificial additives. Therefore, in the present study, based on the different homemade traditional bread kvass, the predominant species including Lacticaseibacillus paracasei, Acetobacter pasteurianus, and Saccharomyces cerevisiae were screened and identified. In addition, barley malt was used instead of bread for kvass production, and the co-fermentation conditions with three different strains were optimized as wort concentration of 7.4°Brix, cell ratio of 2/2/1 (S. cerevisiae/L. paracasei/A. pasteurianus), inoculum amount of 8%, fermentation temperature of 29.5 °C and fermentation time of 24.6 h. Moreover, the physicochemical (pH, total soluble solids, color, and alcohol content) and probiotic (microorganisms counting and antioxidant activity) properties of the barley malt kvass prepared at optimal conditions were symmetrically evaluated. Besides, compared with the commercial kvass products, the produced barley malt kvass exhibited better taste and more desirable antioxidant activity, and also maintained around 6-7 log CFU/mL of viable probiotic microorganisms during a week of storage. The present study not only enriched the biological resource of the traditional kvass, but also promoted the development of the kvass as a live-bacteria beverage.

Potential Probiotic Strains From Milk and Water Kefir Grains in Singapore-Use for Defense Against Enteric Bacterial Pathogens

Kefir grains consist of complex symbiotic mixtures of bacteria and yeasts, and are reported to impart numerous health-boosting properties to milk and water kefir beverages. The objective of this work was to investigate the microbial communities in kefir grains, and explore the possibility of deriving useful probiotic strains from them. A total of 158 microbial strains, representing six fungal and 17 bacterial species, were isolated from milk and water kefir grains collected from a Singapore-based homebrewer. Based on 16S rRNA sequencing, isolated genera included Lactobacillus, Liquorilactobacillus, Lacticaseibacillus, Lentilactobacillus, Leuconostoc, Lactococcus, Acetobacter, Gluconobacter, Oenococcus, Clostridium, Zymomonas, Saccharomyces, Kluyveromyces, Pichia, Lachancea, Candida, and Brettanomyces. To characterize these isolates, a funnel approach, involving numerous phenotypic and genomic screening assays, was applied to identify kefir-derived microbial strains with the highest probiotic potential. Particular focus was placed on examining the pathogen inhibitory properties of kefir isolates toward enteric pathogens which pose a considerable global health burden. Enteric pathogens tested include species of Bacillus, Salmonella, Vibrio, Clostridium, Klebsiella, Escherichia, and Staphylococcus. Well diffusion assays were conducted to determine the propensity of kefir isolates to inhibit growth of enteric pathogens, and a competitive adhesion/exclusion assay was used to determine the ability of kefir isolates to out-compete or exclude attachment of enteric pathogens to Caco-2 cells. Seven bacterial strains of Lentilactobacillus hilgardii, Lacticaseibacillus paracasei, Liquorilactobacillus satsumensis, Lactobacillus helveticus, and Lentilactobacillus kefiri, were ultimately identified as potential probiotics, and combined to form a "kefir probiotics blend." Desirable probiotic characteristics, including good survival in acid and bile environments, bile salt hydrolase activity, antioxidant activity, non-cytotoxicity and high adhesion to Caco-2 cells, and a lack of virulence or antimicrobial resistance genes. In addition, vitamin and γ-aminobutyric acid (GABA) synthesis genes, were identified in these kefir isolates. Overall, probiotic candidates derived in this study are well-characterized strains with a good safety profile which can serve as novel agents to combat enteric diseases. These kefir-derived probiotics also add diversity to the existing repertoire of probiotic strains, and may provide consumers with alternative product formats to attain the health benefits of kefir.

From Milk Kefir to Water Kefir: Assessment of Fermentation Processes, Microbial Changes and Evaluation of the Produced Beverages

The aim of the present study was to investigate the feasibly of using traditional milk kefir grains for the production of water kefir-like beverages and assess the changes in the physicochemical characteristics and the microbial populations of the fermented beverages. To this end, experiments of milk fermentation were primarily conducted at different temperatures and upon selection of the optimal, a gradual substitution of the substrate was performed by replacing milk from a sucrose-based solution. After the successful fermentation of the sucrose substrate, fruit juices were used as fermentation substrates. Sensory evaluation of the sugar-based beverages was also performed in order to access their acceptability for consumption. According to the results, the transition from milk to water kefir is indeed feasible, leading to the production of beverages with relatively higher ethanol concentrations (up to 2.14 ± 0.12% w/v) than milk kefir and much lower lactic acid concentrations (up to 0.16 ± 0.01% w/v). During the fermentation of the sugary substrates, yeasts seemed to be dominant over lactic acid bacteria, in contrast to what was observed in the case of milk kefir, where LAB dominated. The sensory evaluation revealed that all sugar-based beverages were acceptable for consumption, with the fruit-based ones obtaining, though, a better score in all attributes.

Water Kefir Grains vs. Milk Kefir Grains: Physical, Microbial and Chemical Comparison

AIMS

Even though kefir has been known for centuries, there is confusion between the two types of kefir grains, e.g., milk kefir grain and water kefir grain. This study aimed to unravel the differences and similarities between water kefir grain and milk kefir grain.

METHODS AND RESULTS

Microbiological analyses, identification of grains microbiota and enumeration of microbiological content of the grains as well as Scanning Electron Microscope (SEM) imaging, dry matter, protein, ash, and mineral content, and color analyses were carried out for the two types of grains. As a result, significant differences were found in microbiological content, chemical properties, and colors (p<0.05). Additionally, SEM images revealed the different intrinsic structures for the microbiota and the structure of the two types of grains.

CONCLUSIONS

MK grain has more nutritional content compared to WK grain. Despite not as widely known and used as MK grain, WK grain is a good source for minerals and health-friendly microorganisms like lactic acid bacteria (LAB) and yeasts. WK grain is possibly suitable for vegans and allergic individuals to fulfill nutritional requirements. Moreover, in this study, the variety of WK grain microbial consortia was wider than that of MK grains, and this significantly affected the resultant WK products.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first study that comprehensively compares two different kefir grains in microbial, chemical, and physical properties.

Overview of fermentation process: structure-function relationship on protein quality and non-nutritive compounds of plant-based proteins and carbohydrates

Demands for high nutritional value-added food products and plant-based proteins have increased over the last decade, in line with the growth of the human population and consumer health awareness. The quality of the plant-based proteins depends on their digestibility, amino acid content, and residues of non-nutritive compounds, such as phenolic compounds, anti-nutritional compounds, antioxidants, and saponins. The presence of these non-nutritive compounds could have detrimental effects on the quality of the proteins. One of the solutions to address these shortcomings of plant-based proteins is fermentation, whereby enzymes that present naturally in microorganisms used during fermentation are responsible for the cleavage of the bonds between proteins and non-nutritive compounds. This mechanism has pronounced effects on the non-nutritive compounds, resulting in the enhancement of protein digestibility and functional properties of plant-based proteins. We assert that the types of plant-based proteins and microorganisms used during fermentation must be carefully addressed to truly enhance the quality, functional properties, and health functionalities of plant-based proteins.Supplemental data for this article is available online at here. show.

Therapeutic Effects of Kefir Peptides on Hemophilia-Induced Osteoporosis in Mice With Deficient Coagulation Factor VIII

Osteoporosis is a clinically prevalent comorbidity in patients with hemophilia. A preventive effect of kefir peptides (KPs) on postmenopausal osteoporosis has been proved. The aim of this study was to evaluate the therapeutic effect of KPs for the treatment of osteoporosis in coagulation factor VIII (FVIII) gene knockout mice (F8KO), a model of hemophilia A. In this study, male F8KO mice at 20 weeks of age were orally administered different doses of KPs for 8 weeks. The therapeutic effects of KPs were shown in the femoral trabeculae and the 4th lumbar vertebrae, which increased the trabecular bone mineral density (BMD), bone volume (Tb.BV/TV), and trabecular number (Tb.N) and decreased the trabecular separation (Tb.Sp), and they were also observed in the femoral cortical bones, in which the mechanical properties were enhanced in a dose-dependent manner. Characterization of receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), and interleukin 6 (IL-6) demonstrated that the serum RANKL/OPG ratio and IL-6 levels were significantly decreased in the F8KO mice after the KP treatment. Tartrate-resistant acid phosphatase (TRAP) staining of mature osteoclasts indicated that the therapeutic effect of KPs in F8KO mice was associated with the functions of KPs to inhibit RANKL-induced osteoclastogenesis by reducing serum RANKL/OPG ratio and IL-6 secretion. The present study is the first to address the potentials of KPs for the treatment of hemophilia-induced osteoporosis in mice and it also provides useful information for the application of KPs as a complementary therapy for the treatment of osteoporosis in hemophilic patients.

Microencapsulation of Lactobacillus plantarum by spray drying: Protective effects during simulated food processing, gastrointestinal conditions, and in kefir

Probiotics are incorporated into food products because of numerous favorable effects on human health. The viability of probiotics is often affected by unfavorable interference during processing. The encapsulation can provide protection to probiotics during mechanical processing, storage, and gastrointestinal digestion. This study aimed to evaluate the protective effect of whey protein isolate (WPI) and dextran (DX) conjugates for Lactobacillus plantarum. The WPI-DX conjugate was prepared by Maillard-based glycation and confirmed by gel electrophoresis. Extending the heating time from 1 to 5 h decreased the content of tryptophan residues and increased the amide I and amide II bands. The enhanced protective ability of Maillard reaction products (MRPs) for L. plantarum was observed under conditions of stress (pH, heat, and salt) and in vitro digestion. In situ viability tests showed that encapsulation improved the survival of bacteria in kefir during 15 days of storage at 4 °C. Overall, our results provide valuable information for the development of functional probiotic food products.

Exploitation of Yeasts with Probiotic Traits for Kefir Production: Effectiveness of the Microbial Consortium

Kefir is a fermented milk made by beneficial lactic acid bacteria and yeasts inoculated as grains or free cultures. In this work, five yeast strains with probiotic aptitudes belonging to Candida zeylanoides, Yarrowia lipolytica, Kluyveromyces lactis, and Debaryomyces hansenii species were assessed in a defined consortium, in co-culture with a commercial strain of Lactobacillus casei, in order to evaluate the yeasts’ fermentation performance during kefir production, using different milks. The concentration of each yeast was modulated to obtain a stable consortium that was not negatively affected by the bacteria. Furthermore, all yeasts remained viable for five weeks at 4 °C, reaching about 8.00 Log CFU in 150 mL of kefir, a volume corresponding to a pot of a commercial product. The yeasts consortium showed a suitable fermentation performance in all milks, conferring peculiar and distinctive analytical and aromatic properties to the kefirs, confirmed by a pleasant taste. Overall, the panel test revealed that the cow’s and sheep’s kefir were more appreciated than the others; this evaluation was supported by a distinctive fermentation by-products’ content that positively influences the final aroma, conferring to the kefir exalted taste and complexity. These results allow us to propose the yeasts consortium as a versatile and promising multistarter candidate able to affect industrial kefir with both recognizable organoleptic properties and probiotic aptitudes.

Water kefir: Factors affecting grain growth and health-promoting properties of the fermented beverage

Nowadays, the interest in the consumption of healthy foods has increased as well as the homemade preparation of artisanal fermented product. Water kefir is an ancient drink of uncertain origin, which has been passed down from generation to generation and is currently consumed practically all over the world. Considering the recent and extensive updates published on sugary kefir, this work aims to shed light on the scientific works that have been published so far in relation to this complex ecosystem. We focused our review evaluating the factors that affect the beverage microbial and chemical composition that are responsible for the health attribute of water kefir as well as the grain growth. The microbial ecosystem that constitutes the grains and the fermented consumed beverage can vary according to the fermentation conditions (time and temperature) and especially with the use of different substrates (source of sugars, additives as fruits and molasses). In this sense, the populations of microorganisms in the beverage as well as the metabolites that they produce varies and in consequence their health properties. Otherwise, the knowledge of the variables affecting grain growth are also discussed for its relevance in maintenance of the starter biomass as well as the use of dextran for technological application.

The Emerging Scenario of the Gut-Brain Axis: The Therapeutic Actions of the New Actor Kefir against Neurodegenerative Diseases

The fact that millions of people worldwide suffer from Alzheimer’s disease (AD) or Parkinson’s disease (PD), the two most prevalent neurodegenerative diseases (NDs), has been a permanent challenge to science. New tools were developed over the past two decades and were immediately incorporated into routines in many laboratories, but the most valuable scientific contribution was the “waking up” of the gut microbiota. Disturbances in the gut microbiota, such as an imbalance in the beneficial/pathogenic effects and a decrease in diversity, can result in the passage of undesired chemicals and cells to the systemic circulation. Recently, the potential effect of probiotics on restoring/preserving the microbiota was also evaluated regarding important metabolite and vitamin production, pathogen exclusion, immune system maturation, and intestinal mucosal barrier integrity. Therefore, the focus of the present review is to discuss the available data and conclude what has been accomplished over the past two decades. This perspective fosters program development of the next steps that are necessary to obtain confirmation through clinical trials on the magnitude of the effects of kefir in large samples.

Water Kefir and Derived Pasteurized Beverages Modulate Gut Microbiota, Intestinal Permeability and Cytokine Production In Vitro

Fermentation is an ancient food preservation process, and fermented products have been traditionally consumed in different cultures worldwide over the years. The interplay between human gut microbiota, diet and host health is widely recognized. Diet is one of the main factors modulating gut microbiota potentially with beneficial effects on human health. Fermented dairy products have received much attention, but other sources of probiotic delivery through food received far less attention. In this research, a combination of in vitro tools mimicking colonic fermentation and the intestinal epithelium have been applied to study the effect of different pasteurized and non-pasteurized water kefir products on gut microbiota, epithelial barrier function and immunomodulation. Water kefir increased beneficial short-chain fatty acid production at the microbial level, reduced detrimental proteolytic fermentation compounds and increased Bifidobacterium genus abundance. The observed benefits are enhanced by pasteurization. Pasteurized products also had a significant effect at the host level, improving inflammation-induced intestinal epithelial barrier disruption and increasing IL-10 and IL-1β compared to the control condition. Our data support the potential health benefits of water kefir and demonstrate that pasteurization, performed to prolong shelf life and stability of the product, also enhanced these benefits.