Search Results (21)

Kefiran, the extracellular polysaccharide produced from the Generally Recognized as Safe (GRAS) bacteria in kefir grains, with its well-documented functional and health-promoting properties, constitutes a promising biopolymer with a variety of possible uses. Its compatibility with other biopolymers, such as milk proteins, and its ability to form standalone cryogels allow it to be utilized for the fabrication of films with improved properties for applications in the food and biomedical–pharmaceutical industries. In the present work, the properties of kefiran films were investigated in the presence of milk proteins (sodium caseinate, native and heat-treated whey proteins, and their mixtures), alongside glycerol (as a plasticizer) and cryo-treatment of the film-forming solution prior to drying. A total of 24 kefiran films were fabricated and studied for their physical (thickness, moisture content, water solubility, color parameters and vapor adsorption), mechanical (tensile strength and elongation at break), and optical properties. Milk proteins increased film thickness, solubility and tensile strength and reduced water vapor adsorption. The hygroscopic effect of glycerol was mitigated in the presence of milk proteins and/or the application of cryo-treatment. Glycerol was the most effective at reducing the films’ opacity. Heat treatment of whey proteins proved to be the most effective in increasing film tensile strength, reducing, at the same time, the elongation at break, while sodium caseinates in combination with cryo-treatment resulted in films with high tensile strength and the highest elongation at break. Cryo-treatment, carried out in the present study through freezing followed by gradual thawing of the film-forming solution, proved to be the most effective factor in decreasing film roughness. Based on our results, proper selection of the film-forming solution composition and its treatment prior to drying can result in kefiran–glycerol films with favorable properties for particular applications. Full article

This study reports on the design and development of novel porous biomaterials based on chitosan, water kefiran, and paramylon, enriched with various concentrations of juniper berry oil (JBO). The materials were obtained by freeze-drying and comprehensively characterized. The analyses included morphological evaluation (SEM and porosity), physicochemical tests (swelling rate, water vapor transmission rate, and roughness), mechanical tests (tensile strength, Young’s modulus, and elongation at break), and biodegradability under physiological conditions. Moreover, the functional behavior of the materials was evaluated by assessing their antioxidant and anti-inflammatory activity, as well as interactions with selected proteins (human serum albumin and fibrinogen) relevant to biological responses. It was found that the presence of JBO affects the internal structure and improves selected properties in a concentration-dependent manner. This study is the first to investigate the combined use of chitosan, water kefiran, and paramylon in a single porous system enriched with JBO. The results confirm the importance of such biopolymer sponges as promising platforms for applications where appropriate physicochemical and bioactive properties are desired. Full article

Obesity is a global epidemic and a significant risk factor for various diseases. Obesity and dysbiosis are associated, drawing attention to the mechanisms that regulate the gut microbiota. In this study, we focused on the postbiotic effects of rice kefiran (Kef), a functional product of Lactobacillus kefiranofaciens cultured in a rice-based medium, on obesity and its complications. Although Kef has the potential to improve obesity, the underlying mechanisms remain unknown. Therefore, we aimed to elucidate the mechanisms underlying changes in gut microbiota. The administration of Kef significantly suppressed diet-induced body weight gain, reduced liver fat accumulation, and modestly improved insulin resistance. Among the gut bacteria, Lachnospiraceae and Lachnoclostridium, which were positively correlated with obesity, decreased in mice administered Kef. In contrast, Bacteroides and Alistipes, both reported to ameliorate obesity, were increased. Consistent with the changes in the gut microbiota, Kef increased fecal acetate levels, which ameliorated obesity and hepatic steatosis. Predictive metagenomic analysis suggested that Kef administration increased the abundance of KEGG orthologs, associated with carbohydrate metabolism and improvements in insulin resistance. In conclusion, Kef improves diet-induced obesity, hepatic steatosis, and insulin resistance by regulating the gut microbiota’s composition. Full article

The beneficial effect of milk kefir on respiratory heath has been previously demonstrated; however, water kefir and kefiran in the context of respiratory viral infections have not been investigated. Water kefir and kefiran could be alternatives to milk kefir for their application in persons with lactose intolerance or milk allergy and could be incorporated into vegan diets. Using mice models, this work demonstrated that the oral administration of water kefir or kefiran can modulate the respiratory Toll-like receptor (TLR3)-mediated innate antiviral immunity and improve the resistance to respiratory syncytial virus (RSV) infection. The treatment of mice with water kefir or kefiran for 6 days improved the production of interferons (IFN-β and IFN-γ) and antiviral factors (Mx2, OAS1, RNAseL, and IFITM3) in the respiratory tract after the activation of the TLR3 signaling pathway, differentially modulated the balance of pro- and anti-inflammatory cytokines, reduced RSV replication, and diminished lung tissue damage. Maintaining a proper balance between anti-inflammatory and pro-inflammatory mediators is vital for ensuring an effective and safe antiviral immune response, and the results of this work show that water kefir and kefiran would help to maintain that balance promoting a controlled inflammatory response that defends against infection while minimizing tissue damage. Full article

Microbial exopolymers are gaining attention as sources for the development of biodegradable materials. Milk kefir, a fermented dairy product produced by a symbiotic community of microorganisms, generates milk kefir grains as a by-product, consisting of the polysaccharide kefiran and proteins. This study develops two materials, one from whole milk kefir grains and another from purified kefiran. Film-forming dispersions were subjected to ultrasonic homogenisation and thermal treatment, yielding homogeneous dispersions. Kefiran dispersion exhibited lower pseudoplastic behaviour and higher viscous consistency, with minimal effects from glycerol. Both films exhibited continuous and homogeneous microstructures, with kefiran films being transparent and milk kefir films displaying a yellowish tint. Analysis revealed that milk kefir films comprised approximately 30% proteins and 70% kefiran. Kefiran films demonstrated stronger interpolymeric interactions, as evidenced using thermogravimetric and mechanical tests. Glycerol increased hydration while decreasing thermal stability, glass transition temperature, elastic modulus, and tensile strength in both films. However, in kefiran films, elongation at the break and water vapour permeability decreased at low glycerol content, followed by an increase at higher plasticiser contents. This suggests an unusual interaction between glycerol and kefiran in the absence of proteins. These findings underscore differences between materials derived from the whole by-product and purified kefiran, offering insights into their potential applications. Full article

Kefiran is a heteropolysaccharide that is considered a postbiotic and is obtained by kefir grains fermented in cow’s milk, while little is known about the donkey milk (DM) variety. Postbiotics are recognised as having important human health benefits that are very similar to probiotics but without the negative effects associated with their ingestion. Donkey is a monogastric animal, as are humans, and when used as an alternative food for infants who suffer from cow milk protein allergies, DM could therefore display more biocompatibility. In this study, the DM kefiran was extracted by ultrasound from kefir grains cultured in donkey milk and fully characterized for its structural and physicochemical properties by Fourier-transform infrared spectroscopy (FT-IR), High-Performance Liquid Chromatography- Refractive Index (HPLC-RI), Scanning electron microscope (SEM), Differential Scanning Calorimeters (DSC) and rheological analyses. In addition, tests were conducted on keratinocytes cell lines and human red blood cells to assess the nontoxicity and haemolysis degree of the polymer. The extraction yield of the DM kefiran was 6.5 ± 0.15%. The FT-IR analysis confirmed the structure of the polysaccharide by showing that the stretching of the C-O-C and C-O bonds in the ring, which formed two bands at 1157 and 1071 cm⁻¹, respectively, and the anomeric band at 896 cm⁻¹ indicates the β configuration and vibrational modes of glucose and galactose. Results were confirmed by HPLC-RI analysis indicating that the ratio glucose/galactose was 1:0.87. Furthermore, the SEM analysis showed a porous and homogeneous structure. The rheological analysis confirmed the pseudoplastic nature of the polymer, while the DSC analysis highlighted excellent thermal resistance (324 °C). Finally, DM kefiran was revealed to have biologically acceptable toxicity, showing a haemolytic activity of less than 2% when using fresh human red blood cells and showing no cytotoxicity on human keratinocytes. Therefore, kefiran obtained by DM shows an excellent biocompatibility, establishing it as a promising polymer for bioengineering human tissue for regenerative applications. Full article

Exopolysaccharides (EPSs) are a diverse class of biopolymers synthesized by microorganisms under environmental stress conditions, such as pH, temperature, light intensity, and salinity. They offer biodegradable and environmentally friendly alternatives to synthetic polymers. Their structural versatility and functional properties make them unique in various industries, including food, pharmaceuticals, biomedicine, cosmetics, textiles, petroleum, and environmental remediation. In this way, among the well-known EPSs, homopolysaccharides like dextran, bacterial cellulose, curdlan, and levan, as well as heteropolysaccharides like xanthan gum, alginate, gellan, and kefiran, have found widespread applications in numerous fields. However, recent attention has focused on the potential role of extremophile bacteria in producing EPSs with novel and unusual protective and biological features under extreme conditions. Therefore, this review provides an overview of the functional properties and applications of the commonly employed EPSs. It emphasizes their importance in various industries and scientific endeavors while highlighting the raised interest in exploring EPSs with novel compositions, structures, and properties, including underexplored protective functionalities. Nevertheless, despite the potential benefits of EPSs, challenges persist. Hence, this review discusses these challenges, explores opportunities, and outlines future directions, focusing on their impact on developing innovative, sustainable, and functional materials. Full article

Many lifestyle-related diseases such as cancer, dementia, myocardial infarction, and stroke are known to be caused by aging, and the WHO’s ICD-11 (International Classification of Diseases, 11th edition) created the code “aging-related” in 2022. In other words, aging is irreversible but aging-related diseases are reversible, so taking measures to treat them is important for health longevity and preventing other diseases. Therefore, in this study, we used BioBran containing rice kefiran as an approach to improve aging. Rice kefiran has been reported to improve the intestinal microflora, regulate the intestines, and have anti-aging effects. BioBran has also been reported to have antioxidant effects and improve liver function, and human studies have shown that it affects the diversity of the intestinal microbiota. Quantitative measures of aging that correlate with disease risk are now available through the epigenetic clock test, which examines the entire gene sequence and determines biological age based on the methylation level. Horvath’s Clock is the best known of many epigenetic clock tests and was published by Steve Horvath in 2013. In this study, we examine the effect of using Horvath’s Clock to improve aging and report on the results, which show a certain effect. Full article

Kefiran is an exopolysaccharide produced by milk fermentation that is widely used in the food industry, mainly to improve the rheological properties of foods, as well as for the formation of biofilms. Most of these properties are related to its interaction with milk proteins. It has been reported that kefiran has a molecular weight of up to 10⁷ Da and that it is formed by glucose and galactose molecules in equimolar quantities; however, its folding form is not completely understood. In this work it was elucidated that a model of the 20 kDa kefiran folds in a helical shape. In addition, it was determined that whey proteins can form complexes with kefiran. Full article

A novel kefir exopolysaccharides (KEPS) derived from kefir grain fermentation were found to have a small molecular weight (12 kDa) compared to the traditionally high molecular weight (12,000 kDa) of kefiran (KE). KE has been shown to possess antioxidant, blood pressure-lowering, and immune-modulating effects. In this study, we characterized KEPS and KE and evaluated their anti-inflammatory properties in vitro using RAW264.7 macrophages. The main monosaccharide components were identified as glucose (98.1 ± 0.06%) in KEPS and galactose (45.36 ± 0.16%) and glucose (47.13 ± 0.06%) in KE, respectively. Both KEPS and KE significantly reduced IL-6 secretion in lipopolysaccharide (LPS)-stimulated macrophages. We further investigated their effects in LPS-induced systemic injury in male and female NF-κB-luciferase^+/+ transgenic mice. Mice received oral KEPS (100 mg/kg) or KE (100 mg/kg) for seven days, followed by LPS or saline injection. KEPS and KE inhibited NF-κB signaling, as indicated by reduced luciferase expression and phosphorylated NF-κB levels. LPS-induced systemic injury increased luciferase signals, especially in the kidney, spleen, pancreas, lung, and gut tissues of female mice compared to male mice. Additionally, it upregulated inflammatory mediators in these organs. However, KEPS and KE effectively suppressed the expression of inflammatory mediators, including p-MAPK and IL-6. These findings demonstrate that KEPS can alleviate LPS-induced systemic damage by inhibiting NF-κB/MAPK signaling, suggesting their potential as a treatment for inflammatory disorders. Full article

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. Full article

Hydrogels based on natural polysaccharides can have unique properties and be tailored for several applications, which may be mainly limited by the fragile structure and weak mechanical properties of this type of system. We successfully prepared cryogels made of newly synthesized kefiran exopolysaccharide-chondroitin sulfate (CS) conjugate via carbodiimide-mediated coupling to overcome these drawbacks. The freeze-thawing procedure of cryogel preparation followed by lyophilization is a promising route to fabricate polymer-based scaffolds with countless and valuable biomedical applications. The novel graft macromolecular compound (kefiran-CS conjugate) was characterized through ¹H-NMR and FTIR spectroscopy—which confirmed the structure of the conjugate, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)—which mirrored good thermal stability (degradation temperature of about 215 °C) and, finally, gel permeation chromatography–size exclusion chromatography (GPC-SEC)—which proved an increased molecular weight due to chemical coupling of kefiran with CS. At the same time, the corresponding cryogels physically crosslinked after the freeze-thawing procedure were investigated by scanning electron microscopy (SEM), Micro-CT, and dynamic rheology. The results revealed a prevalent contribution of elastic/storage component to the viscoelastic behavior of cryogels in swollen state, a micromorphology with micrometer-sized open pores fully interconnected, and high porosity (ca. 90%) observed for freeze-dried cryogels. Furthermore, the metabolic activity and proliferation of human adipose stem cells (hASCs), when cultured onto the developed kefiran-CS cryogel, was maintained at a satisfactory level over 72 h. Based on the results obtained, it can be inferred that the newly freeze-dried kefiran-CS cryogels possess a host of unique properties that render them highly suitable for use in tissue engineering, regenerative medicine, drug delivery, and other biomedical applications where robust mechanical properties and biocompatibility are crucial. Full article

Kefiran is an exopolysaccharide produced by the microflora of kefir grains used to produce the fermented milk beverage kefir. The health-promoting and physicochemical properties of kefiran led to its exploration for a range of applications, mainly in the food industry and biomedical fields. Aiming to explore its potential for tissue engineering and regenerative medicine (TERM) applications, the kefiran biopolymer obtained through three different extraction methodologies was fully characterized and compared. High-quality kefiran polysaccharides were recovered with suitable yield through different extraction protocols. The methods consisted of heating the kefir grains prior to recovering kefiran by centrifugation and differed mainly in the precipitation steps included before lyophilization. Then, kefiran scaffolds were successfully produced from each extract by cryogelation and freeze-drying. In all extracts, it was possible to identify the molecular structure of the kefiran polysaccharide through ¹H-NMR and FTIR spectra. The kefiran from extraction 1 showed the highest molecular weight (~3000 kDa) and the best rheological properties, showing a pseudoplastic behavior; its scaffold presented the highest value of porosity (93.2% ± 2), and wall thickness (85.8 µm ± 16.3). All extracts showed thermal stability, good injectability and desirable viscoelastic properties; the developed scaffolds demonstrated mechanical stability, elastic behavior, and pore size comprised between 98–94 µm. Additionally, all kefiran products proved to be non-cytotoxic over L929 cells. The interesting structural, physicochemical, and biological properties showed by the kefiran extracts and cryogels revealed their biomedical potential and suitability for TERM applications. Full article

Kefiran, which was isolated from kefir grains, was used for the fabrication of cryogel-films in the presence of plasticizers, such as glycerol and sorbitol. Varying concentration ratios of the exopolysaccharide/plasticizer system were employed in the process of the cryogel-film formulation and their effect on the physical (film thickness, moisture content, and solubility) and the mechanical (tensile strength and elongation at break) properties of the films was monitored. Kefiran-film vapor adsorption isotherms were calculated, and a thermal analysis of the samples was also performed. The structural characteristics of the cryogel-films were observed using confocal laser scanning microscopy. The cryo-treatment, alongside the plasticizer addition, affected the physical and mechanical properties of the kefiran films, as well as their morphology. Increasing kefiran concentration resulted in increasing the film thickness, the moisture content, and the tensile strength, while decreased their solubility and their elongation at break. Kefiran-film adsorption isotherms were affected by the cryo-treatment, the kefiran concentration, and the plasticizer use and concentration. The thermal analysis of the kefiran films showed thermal stability. The presence of the plasticizers and their increment concentration resulted in decreasing the glass transition and the melting temperatures. The cryo-treatment and the presence of plasticizers resulted in the films appearing smoother. Glycerol proved to affect more than the sorbitol–water vapor adsorption and the morphology of kefiran films. Full article

Kefiran is a heteropolysaccharide biopolymer usually extracted from kefir grains cultured in cow milk. Due to the lack of information on exopolysaccharides from other types of animal milk, in the present study, cow, buffalo and goat milks were used as raw materials for fermentation. The kefiran extractions from kefir grains were carried out with cold water (method I), hot water (method II) and mild heated water-ultrasound (method III), and then the recovery yield and the physicochemical properties of the kefirans were evaluated to establish the influence of both the extraction conditions and the type of milk. The highest yield was recorded for the cow kefiran using method III (4.79%). The recoveries of goat and buffalo kefirans with methods II and III were similar (2.75–2.81%). Method I had the lowest yields (0.15–0.48%). The physicochemical characteristics were studied with Fourier Transform-Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC). Fourier-transform infrared spectroscopy showed the same qualitative profile for all the samples, regardless of the method and the type of milk, confirming that the extraction methods did not affect the chemical structure of the kefirans. Otherwise, the thermal and morphological features of the samples showed differences according to both the type of the milk and the extraction method. The kefiran samples were very thermally stable, having a temperature of degradation (T_d) in the range from 264 to 354 °C. The resulting morphological and thermal differences could lead to different practical applications of kefirans in the fields of nutrition and pharmacology. Full article