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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.

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. [ABSTRACT FROM AUTHOR]

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.

ABSTRACT: Kefir is a fermented dairy product with well recognized probiotic properties. Recently, consumer interest in fermented products with probiotic microorganisms has increased due to the accumulating evidence of the effects of kefir microorganisms on the modulation of gut microbiota and their antimicrobial activity. Although the health properties of kefir have been reviewed in other works, the present review addresses the antimicrobial effects of kefir microbiota and associated compounds. The antimicrobial activity of kefir microorganisms could derive from different mechanisms. The microorganisms' capacity to adhere to the intestinal epithelium, preventing the adhesion of pathogens, and their immunomodulation properties are among the mechanisms suggested. Bacteria and yeast isolated from kefir have been shown to have in vivo and in vitro antimicrobial activity against enteropathogenic bacteria and spoilage fungi. However, most reports have focused their approach on single-strain antimicrobial properties; evaluation of antimicrobial activity of cocultures of kefir microbiota and their potential mechanisms of action has been neglected. Kefir microbiota and associated compounds have shown promising antimicrobial effects; however, more research needs to be done to discern the mechanisms of action.

In this study, needleless electrospinning technology was used to obtain flexirubin (F)‐loaded polyvinyl alcohol (PVA)_kefiran (KF)/polycaprolactone (PCL) electrospun nanofibers. The SEM images of PVA_KF_ F and PCL_F nanofibers displayed beadless morphology with average diameters of 211.90 ± 96.08 and 1610.71 ± 996.68 nm, respectively. FTIR‐ATR analysis revealed increased intensity at specific wavelengths, after pigment incorporation. The high porosity exhibited by each layer and the mechanical properties of the double‐layered nanofibrous material remained unaffected after flexirubin‐type pigment incorporation. In addition, PVA_KF_F/PCL_F nanofibers showed antioxidant activity of 41.03 ± 0.29%, evaluated by the scavenging of the ABTS radical as well as the ability to reduce enzymatic browning of apple slices. Thus, we believe that the fabricated PVA_KF_F/PCL_F double‐layered material can be considered for application in active food packaging systems. [ABSTRACT FROM AUTHOR]

Introduction. Kefir is a symbiotic association of microorganisms prepared from Kefir grains. Objective. The antibacterial, antifungal, and healing activity of Kefir was evaluated. Material and methods. Antibacterial and antifungal properties was carried out against some pathogenic microbial species, such as Staphylococcus aureus, Pseudomonas aeruginosa, Eschirichia-coli, Salmonella typhi, enterobacterococcus faecalis, Klebsiella pneumoniae, and Candida albicans, by the agar disk diffusion method and by well. Healing experiments were carried out in adult Wistar rats, with skin burns, using a topical application of two milk, and fruit kefir gels, and silver sulfadiazine. Results. Kefiran, an exopolysaccharide of Kefir, had antibacterial anti Staphylococcus activity and anti-candidal antifungal activity. Kefir gels had better wound healing compared to silver Sulfadiazine, with a protective effect on skin, and connective tissue, after a 15-day treatment ofrats. Conclusion. Kefir is a natural probiotic with multiple virtues. Indeed, Kefiran has an anti staphylococcus activity, and an anti candidias activity. Healing activity of Kefir gel is an effective therapeutic approach to improve healing, after a severe burn, compared to a conventional treatment with silver Sulfadiazine.

Trends to ready -to -eat foods such as pizzas and reduced daily physical activity have increased the need to reduce calories and dietary fat. Therefore, the production of low -fat mozzarella cheese by substituting it with beneficial microbial polysaccharides such as kefir and dietary fiber such as inulin can be profitable. In this study, the effect of adding inulin at concentrations of 6 and 7% and kefir at concentrations of 0.6 and 0.7% was investigated and physicochemical tests, color parameters and textural properties of cheese were examined as functions of inulin /Kefirs. The results showed that the most changes in acidity and pH was occurred at the ratio 10:1 inulin to kefir, whereas increasing the kefir content did not have any effect on acidity, which could be related to the neutral structure of kefir polysaccharide. In the study of cheese dry matter, the addition of inulin/kefir did not show a significant effect on the results (P<0.05). In contrast, the melting area was the highest in the control sample and the lowest in the sample B (the lowest ratio of inulin to kefir). In the other words, the addition of inulin/kefir did not show any effect on the melting area of the cheese. In examining the color characteristics of mozzarella cheese, by changing the level of inulin to kefir, no change in brightness, a* and b* was observed. However, for general color change, the most change was observed in sample and the lowest color change was observed in control. The addition of inulin and kefir did not also have a significant effect on the organoleptic and textural properties of mozzarella cheese. Therefore, it is possible to use this combination in the formulation of mozzarella cheese without making undesirable changes in the product. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Active packaging films based on kefiran-gelatin were developed and characterized using Zhumeria majdae essential oil nanoemulsion (ZMEO-NE) at concentrations of 0 (control), 1, 2 and 3 %. The main compounds of the essential oil (EO) of Zhumeria majdae (ZM) plant were linalool (61.44 %) and camphor (20.67 %). Adding the ZMEO-NE to the films decreased permeability to water vapor (from 7.82 × 10 -7 to 4.09 × 10 -7 g·m/m 2 ·Pa·h), ultimate tensile strength (from 38.44 to 33.48 MPa), percentage of light transmission, and increased thickness (from 0.085 to 0.121 mm), opacity (from 2.11 to 2.79), and elongation at break (from 19.97 to 34.73 %), and changed color parameters. The establishment of hydrogen bonds between the ZMEO-NE and polymer network was confirmed. The ZMEO-NE decreased the storage modulus and glass transition temperature. Distinct variations in the films' surface morphology and a reduction in the crystalline structure were observed due to the presence of the ZMEO-NE. Elevating the concentration of the ZMEO-NE increased antioxidant capabilities of the films. The films incorporating the ZMEO-NE exhibited notable antibacterial efficacy against Staphylococcus aureus (reductions ≥4 log CFU/cm 2 ) and Escherichia coli (reductions ≥2 log CFU/cm 2 ) bacteria. The films also demonstrated suitable antifungal properties during storage of sponge cakes for 16 days., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

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.

Kefiran is a polysaccharide present in kefir grains that have been widely explored due to its potential health benefits. The objective of this work was to characterize and quantify the components present in the ethanolic extract of milk kefir grains; to study its pharmacokinetic and toxicological properties in silico and evaluate the acute toxicity of the kefiran in zebrafish. The prediction of pharmacokinetic properties was performed by QikProp software. In silico toxicity assessment was performed using the DEREK (deductive estimate of risk from existing knowledge) software. In the chromatographic, kefiran was identified as the major component. Results showed that the kefiran had low human oral absorption and intestinal absorption its due poor solubility profile; low logP value, indicating its lipophilicity and the low MDCK and Caco-2 cells permability, and unable to cross the blood–brain barrier. Kefiran did not present any structural warning for in silico toxicity. In zebrafish, the dose of 2,000 mg/kg of kefiran produced nonsignificant alterations in the analyzed organs. It can be said then that kefiran has an acceptable degree of safety for use in the development of drugs or functional foods. Further research such as in vivo testing to confirm its pharmacological potential is currently underway. [ABSTRACT FROM AUTHOR]

Kefir is a fermented dairy product with well recognized probiotic properties. Recently, consumer interest in fermented products with probiotic microorganisms has increased due to the accumulating evidence of the effects of kefir microorganisms on the modulation of gut microbiota and their antimicrobial activity. Although the health properties of kefir have been reviewed in other works, the present review addresses the antimicrobial effects of kefir microbiota and associated compounds. The antimicrobial activity of kefir microorganisms could derive from different mechanisms. The microorganisms' capacity to adhere to the intestinal epithelium, preventing the adhesion of pathogens, and their immunomodulation properties are among the mechanisms suggested. Bacteria and yeast isolated from kefir have been shown to have in vivo and in vitro antimicrobial activity against enteropathogenic bacteria and spoilage fungi. However, most reports have focused their approach on single-strain antimicrobial properties; evaluation of antimicrobial activity of cocultures of kefir microbiota and their potential mechanisms of action has been neglected. Kefir microbiota and associated compounds have shown promising antimicrobial effects; however, more research needs to be done to discern the mechanisms of action. [ABSTRACT FROM AUTHOR]

The use of biopolymers in medicine and pharmacology is of great scientific, technological, and commercial interest. A possibility of biopolymer for use in pharmacological applications is the kefiran, an exopolysaccharide (EPS) produced by bacteria that form kefir grains during the milk fermentation process in which the grains are growing. The EPS extraction method can modify its concentration and structure. To establish the most appropriate kefiran extraction protocol and standardize this method, three different extraction processes were evaluated, which differ in the boiling times and in the presence (or not) of agitation. Kefiran obtained by different methods were characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), electron scanning field emission microscopy (FESEM), and determination of antimicrobial potential. The samples showed differences in yield, chemical composition, degree of purity, thermal properties, and antimicrobial capacity. The results analyzed indicated that extraction protocol 1 (EP 1) with a longer heating time and constant agitation was able to provide the best thermal resistance, with a high degree of purity (93%), and yield (22.18 mg of kefiran obtained for each gram of kefir grains used). In addition, this method provides good biological activity as a potential antimicrobial agent and can be a potential biopolymer for pharmacological application.

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 (Td) 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. [ABSTRACT FROM AUTHOR]

Kefiran is an exopolysaccharide (EPS) produced by specific microorganisms in the kefir grain. In this research, kefir grain was activated in various carbon sources (glucose, galactose or lactose) containing medium. The monosaccharides composition of the formed kefiran were determined by a high performance liquid chromatography (HPLC). HPLC with refractive index (RI) detector was used in order to make qualitative and quantitative analysis of sucrose, glucose, galactose, arabinose, xylose, and ribose present in kefiran. Also, the physical properties of differently kefiran formed were determined. The amount of kefiran in the control group and in the sample from the galactose containing medium were determined to be 511.00 and 610.55 mg/L, respectively. The kefiran form obtained from the medium containing galactose was more positively affected than in other media. The apparent viscosity, at a shear rate of 66.0 s-1of the kefiran produced in glucose containing medium, was determined to be 29.2 mPas. The surface morphologies of different kefirans were analysed and roughness parameters were determined by atomic force microscopy (AFM); the maximum height of lumps ranged from 16.80 to 22.10 nm. In this study, of sucrose, glucose, galactose, arabinose, xylose, and ribose were found in sugar composition in all kefiran samples.

Kefir is produced from the fermentation of milk by microorganisms in kefir grains. Kefir grains include lactic acid bacteria, yeast, and acetic acid bacteria surrounded by a protein matrix and polysaccharide called kefiran. One of the most important antibacterial compounds of this beverage is microbial exopolysaccharide of kefiran. The present study aimed to investigate the effect of milk type, fermentation time, temperature, and stirring conditions on the production of kefiran by kefir grains. Activated kefir grains were added to full-fat and non-fat milk. Fermentation was carried out at 25 and 37 °C under stirred and non-stirred. After 24, 48, 72, and 120 h of fermentation, the grains were separated from kefir extract and kefiran exopolysaccharide was extracted from kefir grains. The effect of these variables and their interaction on the production of kefiran using Design-Expert software and full factorial design have been analyzed. Also, the MIC and MBC of extracted kefiran were determined against Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Shigella dysenteriae. All fermentation conditions and their interactions had a significant effect on kefiran production. Considering all fermentation conditions and interaction of all factors, more kefiran were produced in fermented kefir grains at 37 °C compared to 25 °C, in full-fat milk compared to non-fat milk, under stirred conditions compared to non-stirred and fermented beverages for 48 and 120 h. MIC and MBC of extracted kefiran for tested bacteria were determined in the range of 1.4-11.25 mg/mL.

Kefiran is a water soluble polysaccharide produced by Lactobacillus kefiranofaciens ATCC 43761. It has wide potential applications in food, pharmaceutical and nutraceutical industries. To the best of our knowledge, there have been no previous reports on the effect of osmotic stress and ionic surfactants on kefiran production by L. kefiranofaciens ATCC 43761. Accordingly, the current work aimed at optimizing kefiran production as affected by osmotic stress and nonionic surfactants in submerged cultivation system. Afterwards, the work was extended to investigate cytotoxic as well as antioxidant potentials of kefiran. Firstly, different osmolarities, different ionic surfactants (Triton X-100, Tween 20, Tween 80) as well as their concentrations and addition time were evaluated. The kinetics of cell growth and kefiran production were evaluated before and after the addition of surfactants. Results clearly demonstrated that osmotic stress and surfactant addition had a stimulatory effect on kefiran production. Using the optimal medium osmolality, 550 mOsmol.kg−1, kefiran production was enhanced from 1.29 to about 1.38 g.L−1. Furthermore, Triton X-100 was found to be the best surfactant stimulating kefiran production when added at a concentration of 1.0 g.L−1 at the onset of cultivation process (0 h). This increased kefiran production from 1.38 g.L−1 to 1.62 g.L−1. To summarize, the maximal kefiran production can be enhanced using 550 mOsmol.kg−1 and by adding 1.0 g.L−1 of Triton X-100 at 0 h. The new optimized medium showed an increase of about 25.6% in kefiran production (1.29 up to 1.62 g.L−1). After this step, the process was further optimized in 16-L stirred tank bioreactor. Maximal kefiran production reached 2.32 g.L−1 and 1.87 g.L−1 in bioreactor under control and un-controlled pH conditions, respectively, corresponding to 72.9 and 45.0% increase from the initial production titer, respectively. The produced kefiran exhibited promising anticancer activity against breast cancer (MCF-7) cells, with an IC50 value of 193.89 μg.mL−1. Also, kefiran showed 96.58% radical scavenging activity at 100 μg/mL, with an ED50 recorded of 12.29 ± 0.98 μg.mL−1.

Kefir; is a fermented milk product which is produced by granules containing a wide variety of microorganisms such as lactic acid bacteria, acetic acid bacteria and yeasts. It is traditionally consumed in many countries. It has been shown in many studies that the polysaccharide structure surrounding the granules which is composed mainly of kefiran molecule has antimicrobial effect against various pathogens as well as many health promoting effects. In this study, 24 h fermented kefir was used with two types of kefir granules for production of kefiran extract. One of them is being sold commercially and the other was collected from private households in a different region of Turkey. Kefiran extraction was carried out from matured kefir granules using three different temperatures, 80°C, 90°C and 100°C. Also, the protein contents of the extracted solutions were determined by Bradford method. Protein content of the extract solutions obtained were measured as 0.001 g/ml. The antibacterial effect of 0.05, 0.1, 1 and 2 mg of this extract against several plant pathogenic bacterial strains belonging to genus Pseudomonas, Xanthomonas, Erwinia ve Clavibacter was investigated in vitro for the first time. For this purpose, two methods, disc diffusion method and spreading method were used. The AN and SD kefir supernatants used as the positive controls in the experiments showed an average of 13-17 mm and 10-14 mm inhibition zones on the isolates, respectively, but the antibacterial effect of kefiran extracts was not observed.

Research background. Pectinase enzyme has become a valuable compound in beverage industry. One of the most significant concepts to overcome the drawbacks of using industrial enzymes is their immobilization. In the present study, magnetic chitosan microparticles were utilized as a substrate for pectinase immobilization. New methods of enzyme immobilization involve the use of non-chemical cross-linkers between the enzyme and the substrate. The aim of this study is to immobilize the pectinase enzyme using polyaldehyde kefiran as a macromolecular cross-linker on magnetic particles. Experimental approach. Pectinase was immobilized in four steps: relative oxidation of kefiran and its application as a cross-linker, production of magnetic iron(II) iron(III) oxide (Fe3O4) microparticles, coating of magnetic Fe3O4 microparticles with chitosan, and immobilization of the enzyme on the substrate, prepared by the use of oxidized kefiran cross-linker. Parameters such as cross-linking concentration, time and ratio of chitosan magnetic microparticles to enzyme were optimized. Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering, transmission electron microscopy, and vibrating sample magnetometer were used to identify the groups and investigate the structures. The biochemical properties (stability of enzyme activity at different pH, temperature and time), enzyme reusability, kinetic parameters (Km and νmax) and apple juice turbidity, using free and immobilized pectinase enzymes, were also measured. Results and conclusions. Cross-linker concentration, cross-linking time and the ratio of magnetic Fe3O4 microparticles with chitosan to enzyme were important factors in activity recovery of pectinase. FTIR analysis correctly identified functional groups in the structures. The results showed that after enzyme stabilization, the particle size and molecular mass, respectively, increased and decreased the magnetic saturation strength. According to the thermal kinetic study, the activity of the immobilized pectinase was higher than of its free form. The findings of this study indicate excellent stability and durability of the immobilized pectinase. Finally, a magnetic pectinase micro-biocatalyst was used to clarify apple juice, which reduced turbidity during processing. Novelty and scientific contribution. This study investigates the usage of kefiran oxidized as a new cross-linker for the immobilization of pectinase enzyme. Magnetic pectinase micro-biocatalyst has a good potential for industrial applications in the food industry, with high thermal stability.

Anahita Jenab, Rasoul Roghanian, Najmeh Ghorbani, Kamran Ghaedi, Giti Emtiazi Department of Biology, Faculty of Science, University of Isfahan, Hezar Jerib, Isfahan, IranCorrespondence: Anahita Jenab Tel +983137932455Fax +983137932456Email anahitajenab@gmail.comBackground: Kefiran is a useful polysaccharide made of branched glucogalactose which is produced by microorganisms. Here the anti-MCF-7 breast cancer cells activity of kefiran and cytokine productions (IL-6) of peripheral blood mononuclear cells (PBMC) treated by kefiran was studied. Also, the effect of using kefiran as a useful and cost-effective scaffold in neural stem cell culture (PC12 cell culture) was investigated.Material and Methods: Kefiran was produced from raw milk with 0.5% fat and 10 g of kefir grains. After incubation for 48 hrs at room temperature, the solvent collected (crude kefiran). These samples were kept at 100°C for 1 hr (boiled kefiran) and the supernatant was precipitated by ethanol (pure kefiran). Then, the electrospun nanofibers, pure polyacrylonitrile (PAN), PAN/kefiran 5%, and PAN/kefiran 10% were fabricated and used as scaffolds in the cell culture. The structure of fabricated was studied by SEM and the cytokine production (IL-6) in vitro in the cell culture supernatant of PBMC line after treatment with kefiran (1mg/mL, 5 mg/mL) and kefiran-PAN 5% and 10% were carried out by enzyme-linked immunosorbent assay (ELISA). The attachment of PC12 cells was examined by inverted microscope. Also, cytotoxicity of kefiran for PC12 and MCF7 cells and morphological changes of PC12 cells were evaluated by MTT and Cresyl violet staining (Nissl staining) respectively.Results: The mean diameter of fabricated PAN/kefiran 5% and 10% nanofibers were 310.2± 43.97 nm. The contact angle measurement results (26.9± 1.9 for the pure PAN scaffold vs 12.3± 1.13 for the PAN/kefiran) revealed enhanced hydrophilicity of scaffolds upon the incorporation of kefiran and PAN. Seeding of PC12 cells on the scaffolds showed that fabrication of kefiran into PAN led to the enhancement of cell attachment, proliferation, and morphological changes. Also, the promotion of PBMC growth and decreasing of MCF7 cell lines viability were shown through MTT assay. No significant changes were measured for the level of IL-6 in PAN/kefiran 5% treated cells compared to the control (p ≥ 0.05).Conclusion: These results suggest superior properties of kefiran/PAN nanofibrous scaffolds for the neural stem cell culture especially for repairing injured spinal cord. Also, the pure kefiran could be used for the enhancement of PBMC growth and reducing the MCF7 cancerous cells growth. So, using biocompatible, anti-bacterial, and anti-tumor kefiran/PAN nanofibers for regenerative medicine seems promising.Keywords: kefiran, polyacrylonitrile nanofibers, electrospinning, tissue engineering, PC12 cells

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.

This study was carried out to characterize the physical, mechanical and barrier properties of kefiran-carboxy methyl cellulose (CMC) biocomposite films in function with CMC content. Films were prepared by combining these two biopolymers and adding glycerol as plasticizer. Film-forming solutions of different ratios of kefiran to CMC were cast at room temperature. Increasing CMC content from 0 to 50 % (v/v) increased the tensile strength and extensibility of the composite films; however, with further CMC addition these mechanical properties decreased. The water-vapor permeability (WVP) of the films first decreased and then increased with CMC addition. The microstructure of the films was observed by scanning electron microscopy and atomic-force microscopy. The morphology study of the films showed rougher surfaces with increasing CMC amounts. Dynamic mechanical thermal analysis (DMTA) curves showed a single Tg, and addition of CMC at all levels increased the glass-transition temperature of films. These results indicated that these two film-forming components were compatible, and that an interaction existed between them.

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 (Td) 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.

Summary: The goal of this work has been to assess the influence of a health‐promoting hydrocolloid, such as kefiran, in oil‐in‐water emulsions (O/W: 50/50) containing whey protein isolate (1.0% wt.). Different kefiran concentration levels (0%, 0.25%, 0.5%, 1% wt.) were studied, observing a shift from a fluid‐like to a solid‐like behaviour and higher viscosities when kefiran content increased. A pseudoplastic behaviour was detected for all systems studied. The observed evolution is attributed to the thickening effect exerted by kefiran, which promoted stability, in spite of observing a certain flocculation degree within the emulsion systems, demonstrated through the addition of sodium dodecyl sulphate (1% wt.). Furthermore, short‐term stability of these pseudoplastic emulsions has been verified by laser‐scattering techniques. Thus, a Sauter diameter around 1 µm remained unaltered up to 7 days since preparation. The addition of kefiran in the formulation would benefit from their well‐known health‐promoting effects. [ABSTRACT FROM AUTHOR]

Kefiran is an exopolysaccharide (EPS) produced by specific microorganisms in the kefir grain. In this research, kefir grain was activated in various carbon sources (glucose, galactose or lactose) containing medium. The monosaccharides composition of the formed kefiran were determined by a high performance liquid chromatography (HPLC). HPLC with refractive index (RI) detector was used in order to make qualitative and quantitative analysis of sucrose, glucose, galactose, arabinose, xylose, and ribose present in kefiran. Also, the physical properties of differently kefiran formed were determined. The amount of kefiran in the control group and in the sample from the galactose containing medium were determined to be 511.00 and 610.55 mg/L, respectively. The kefiran form obtained from the medium containing galactose was more positively affected than in other media. The apparent viscosity, at a shear rate of 66.0 s-1of the kefiran produced in glucose containing medium, was determined to be 29.2 mPas. The surface morphologies of different kefirans were analysed and roughness parameters were determined by atomic force microscopy (AFM); the maximum height of lumps ranged from 16.80 to 22.10 nm. In this study, of sucrose, glucose, galactose, arabinose, xylose, and ribose were found in sugar composition in all kefiran samples. [ABSTRACT FROM AUTHOR]

In this study, kefiran was esterified with octenyl succinic anhydride (OSA). The esterification reaction variables including pH (8.5), kefiran concentration (5% (w/w)), OSA concentration (12% (w/w)), temperature (~38 °C) and reaction time (~80 min) were found as optimum points to achieve the maximum degree of substitution (DS) (0.041 ± 0.002). Kefiran-OSA samples with DS of 0.021 (FDA suggested DS) and 0.041 (maximum DS) were prepared and compared with unmodified kefiran in all experiments. FTIR and 1H NMR spectroscopies proved the grafting of OSA on kefiran structure. XRD analysis revealed that with increase in DS, the physical state of kefiran to be more amorphous. In addition, the esterification modification led to a decrease in the degradation temperature and an increase in the apparent viscosity based on the obtained data from thermal analysis and viscosity measurement. The results of the foaming and emulsifying properties confirmed the improvement in surface properties of the modified kefiran. The frequency sweep test illustrated that with an increase in DS, the viscoelastic behavior of the kefiran cryogels to be more viscous. It can finally be stated that the modification with OSA was a high potential strategy to extend the industrial applications of the kefiran. [ABSTRACT FROM AUTHOR]

Kefiran is a water-soluble polysaccharide well recognized as a bioactive ingredient to enhance nutritional and health-promoting features. Also, some therapeutic properties have made this macromolecule an active ingredient in ointments and oral anti-inflammatory drugs. However, the details of the molecular and cellular aspects of these effects have not been addressed. In this study, lipopolysaccharides (LPS)-induced monocytes, lymphocytes, and monocyte-derived dendritic cells (MDDCs) as representative cells for both innate and adaptive immunity were treated with kefiran for 2 h. Kefiran had an anti-inflammatory effect on monocytes to reduce pro-inflammatory cytokines, interleukin 1 β (IL-1β) & tumor necrosis factor α (TNF-α), as well as nuclear factor kappa b (NF-kb). However, it did not affect lymphocytes. Overexpression of Toll-like receptor 4 (TLR4) in LPS-induced cells was not reduced after kefiran treatment. Kefiran balanced MDDCs secretion of pro/anti-inflammatory cytokines by reducing and enhancing the expression of IL-1β and interleukin 10 (IL-10), respectively. Also, kefiran decreased the number of apoptotic immature MDDCs and promoted dose-dependent phagocytosis capacity of MDDCs. According to the results of the current study, it may be concluded that the immunomodulatory effects of kefiran are due to antagonist against innate immune receptors especially TLR4. The results of this study can be used as a guide to developing kefiran-based non-aggressive anti-inflammatory drugs. Furthermore, understanding the immunobiological effects of kefiran on monocytes and lymphocytes was another outcome of this study. Unlabelled Image [ABSTRACT FROM AUTHOR]

Kefiran is a water soluble polysaccharide produced by Lactobacillus kefiranofaciens ATCC 43761. It has wide potential applications in food, pharmaceutical and nutraceutical industries. To the best of our knowledge, there have been no previous reports on the effect of osmotic stress and ionic surfactants on kefiran production by L. kefiranofaciens ATCC 43761. Accordingly, the current work aimed at optimizing kefiran production as affected by osmotic stress and nonionic surfactants in submerged cultivation system. Afterwards, the work was extended to investigate cytotoxic as well as antioxidant potentials of kefiran. Firstly, different osmolarities, different ionic surfactants (Triton X-100, Tween 20, Tween 80) as well as their concentrations and addition time were evaluated. The kinetics of cell growth and kefiran production were evaluated before and after the addition of surfactants. Results clearly demonstrated that osmotic stress and surfactant addition had a stimulatory effect on kefiran production. Using the optimal medium osmolality, 550 mOsmol.kg−1, kefiran production was enhanced from 1.29 to about 1.38 g.L−1. Furthermore, Triton X-100 was found to be the best surfactant stimulating kefiran production when added at a concentration of 1.0 g.L−1 at the onset of cultivation process (0 h). This increased kefiran production from 1.38 g.L−1 to 1.62 g.L−1. To summarize, the maximal kefiran production can be enhanced using 550 mOsmol.kg−1 and by adding 1.0 g.L−1 of Triton X-100 at 0 h. The new optimized medium showed an increase of about 25.6% in kefiran production (1.29 up to 1.62 g.L−1). After this step, the process was further optimized in 16-L stirred tank bioreactor. Maximal kefiran production reached 2.32 g.L−1 and 1.87 g.L−1 in bioreactor under control and un-controlled pH conditions, respectively, corresponding to 72.9 and 45.0% increase from the initial production titer, respectively. The produced kefiran exhibited promising anticancer activity against breast cancer (MCF-7) cells, with an IC 50 value of 193.89 μg.mL−1. Also, kefiran showed 96.58% radical scavenging activity at 100 μg/mL, with an ED 50 recorded of 12.29 ± 0.98 μg.mL−1. [ABSTRACT FROM AUTHOR]

Research background. Pectinase enzyme has become a valuable compound in beverage industry. One of the most significant concepts to overcome the drawbacks of using industrial enzymes is their immobilization. In the present study, magnetic chitosan microparticles were utilized as a substrate for pectinase immobilization. New methods of enzyme immobilization involve the use of non-chemical cross-linkers between the enzyme and the substrate. The aim of this study is to immobilize the pectinase enzyme using polyaldehyde kefiran as a macromolecular cross-linker on magnetic particles. Experimental approach. Pectinase was immobilized in four steps: relative oxidation of kefiran and its application as a cross-linker, production of magnetic iron(II) iron(III) oxide (Fe3O4) microparticles, coating of magnetic Fe3O4 microparticles with chitosan, and immobilization of the enzyme on the substrate, prepared by the use of oxidized kefiran cross-linker. Parameters such as cross-linking concentration, time and ratio of chitosan magnetic microparticles to enzyme were optimized. Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering, transmission electron microscopy, and vibrating sample magnetometer were used to identify the groups and investigate the structures. The biochemical properties (stability of enzyme activity at different pH, temperature and time), enzyme reusability, kinetic parameters (Km and vmax) and apple juice turbidity, using free and immobilized pectinase enzymes, were also measured. Results and conclusions. Cross-linker concentration, cross-linking time and the ratio of magnetic Fe3O4 microparticles with chitosan to enzyme were important factors in activity recovery of pectinase. FTIR analysis correctly identified functional groups in the structures. The results showed that after enzyme stabilization, the particle size and molecular mass, respectively, increased and decreased the magnetic saturation strength. According to the thermal kinetic study, the activity of the immobilized pectinase was higher than of its free form. The findings of this study indicate excellent stability and durability of the immobilized pectinase. Finally, a magnetic pectinase micro-biocatalyst was used to clarify apple juice, which reduced turbidity during processing. Novelty and scientific contribution. This study investigates the usage of kefiran oxidized as a new cross-linker for the immobilization of pectinase enzyme. Magnetic pectinase micro-biocatalyst has a good potential for industrial applications in the food industry, with high thermal stability. [ABSTRACT FROM AUTHOR]

Kefir is produced from the fermentation of milk by microorganisms in kefir grains. Kefir grains include lactic acid bacteria, yeast, and acetic acid bacteria surrounded by a protein matrix and polysaccharide called kefiran. One of the most important antibacterial compounds of this beverage is microbial exopolysaccharide of kefiran. The present study aimed to investigate the effect of milk type, fermentation time, temperature, and stirring conditions on the production of kefiran by kefir grains. Activated kefir grains were added to full-fat and non-fat milk. Fermentation was carried out at 25 and 37 °C under stirred and non-stirred. After 24, 48, 72, and 120 h of fermentation, the grains were separated from kefir extract and kefiran exopolysaccharide was extracted from kefir grains. The effect of these variables and their interaction on the production of kefiran using Design-Expert software and full factorial design have been analyzed. Also, the MIC and MBC of extracted kefiran were determined against Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Shigella dysenteriae. All fermentation conditions and their interactions had a significant effect on kefiran production. Considering all fermentation conditions and interaction of all factors, more kefiran were produced in fermented kefir grains at 37 °C compared to 25 °C, in full-fat milk compared to non-fat milk, under stirred conditions compared to non-stirred and fermented beverages for 48 and 120 h. MIC and MBC of extracted kefiran for tested bacteria were determined in the range of 1.4-11.25 mg/mL. [ABSTRACT FROM AUTHOR]

Objective(s): This paper investigates the validity of Artificial Neural Networks (ANN) model in the prediction of electrospun kefiran nanofibers diameter using 4 effective parameters involved in electrospinning process. Polymer concentration, applied voltage, flow rate and nozzle to collector distance were used as variable parameters to design various sets of electrospinning experiments for production of electrospun kefiran nanofibers. Methods: The Scanning Electron Microscopy (SEM) was used to investigate the morphology and evaluate the size of the nanofiber. Data set was drawn using k fold cross-validation method, which was the most suitable scheme for the volume of the data in this work. Data were partitioned into the five series and trained and tested via ANN method. Results: The Scanning Electron Microscopy (SEM) images of the generated nanofiber samples were confirmed that all of the samples were fine and defect-free. Our results indicated that the network including four input variables, three hidden layers with 10, 18 and 9 nodes in each layer, respectively, and one output layer obtained the highest efficiency in the testing set. The mean squared error (MSE) and linear regression (R) between observed and predicted nanofibers diameter were 0.0452 and 0.950, respectively. Conclusions: The results demonstrated that the proposed neural network was appropriately performed in assessing the input parameters and prediction of nanofibers diameter.

Cheese whey is a waste product in cheese processing which contains 4–5% of lactose. Having high carbon source, this material could be a potential fermentation medium for kefir grains. During fermentation of kefir grains, alcohol, lactic acid and exopolysaccharide (kefiran) were produced. The kefir grains fermentation also affected by nitrogen source. Therefore, effects of different composition of lactose and nitrogen sources (including yeast extract, urea and mung bean sprouts extract) in the fermentation were examined in this study. The results showed that after 24 hours of incubation, kefir grains biomass reached 21.30-27.15 g (dry wt, g/250mL medium) from 25 g of intial kefir grains biomass. Fermentation broth showed pH values ranged from 3.49–3.94; alcohol level ranged from 0.11-0.31%; and lactic acid content ranged from 0.49–1.47%. The total of kefiran extracted from kefir grain and fermentation broth ranged from 0.63-1.76 g/L. This study indicated that cheese whey can be used as fermentation medium to produce alcohol, lactic acid and kefiran by kefir grains. The highest production of kefiran was achieved in the medium containing 1.2% of whey lactose and 4% of mung bean sprouts extract.Cheese whey is a waste product from cheese processing industry which still has lactose content of 4-5%, so that it can be used as a carbon source in the fermentation medium of kefir grains. During fermentation of kefir grains, alcohol, lactic acid and exopolysaccharide commonly called as kefiran were produced. The kefir grains fermentation also affected by nitrogen source. Furthermore, fermentation medium composition were varied at whey lactose concentration and nitrogen source composition (yeast extract, urea and mung bean sprouts extract) for kefir grains fermentation. The results showed that after 24 hours fermentation, kefir grains biomass ranged from 21.30-27.15 g; pH values ranged from 3.49-3.94; alcohol level ranged from 0.11-0.31%; lactic acid content ranged from 0.49-1.47%; and the total of kefiran ranged from 0.63-1.76 g/L. Fermentation medium composition that produced the higher total of kefiran was 1,2% whey lactose and 4% mung bean sprouts extract as nitrogen source. ABSTRAK Whey keju adalah produk sampingan dari industri pengolahan keju yang masih memiliki kandungan laktosa sebesar 4–5% sehingga dapat dimanfaatkan sebagai sumber karbon pada media fermentasi oleh biji kefir. Selama proses fermentasi menggunakan biji kefir terjadi pembentukan alkohol, asam laktat dan eksopolisakarida (kefiran). Sumber nitrogen juga dapat mempengaruhi proses fermentasi. Oleh karena itu, dalam penelitian ini dilakukan variasi perlakuan, yaitu variasi konsentrasi laktosa pada whey dan variasi komposisi sumber nitrogen (yeast extract, urea dan ekstrak tauge kacang hijau) sebagai media fermentasi oleh biji kefir. Setelah fermentasi biji kefir selama 24 jam, jumlah biomassa biji kefir berkisar antara 21,30–27,15 g (berat kering g/250 mL medium fermentasi) dari jumlah biomassa awal 25 g. Cairan fermentasi menunjukkan nilai pH berkisar antara 3,49–3,94; kadar alkohol berkisar antara 0,11–0,31% dan kadar asam laktat berkisar antara 0,49–1,47%. Total rendemen kefiran yang didapatkan dari ekstraksi biji kefir dan cairan fermentasi berkisar antara 0,63–1,76 g/L. Hasil penelitian ini mengindikasikan bahwa whey keju dengan penambahan sumber nitrogen dapat digunakan sebagai medium fermentasi oleh biji kefir untuk menghasilkan metabolit berupa alkohol, asam laktat dan kefiran. Variasi formulasi media fermentasi yang menghasilkan kefiran dalam jumlah tertinggi adalah penggunaan konsentrasi laktosa whey keju 1,2% dan sumber nitrogen dari ekstrak tauge kacang hijau sebesar 4%.

One of the main lactic acid bacterial species found in the kefir grain ecosystem worldwide is Lactobacillus kefiranofaciens, exhibiting strong auto-aggregation capacity and, therefore, being involved in the mechanism of grain formation. Its occurrence and dominance in kefir grains of various types of milk and geographical origins have been verified by culture-dependent and independent approaches using multiple growth media and regions of the 16S rRNA gene, respectively, highlighting the importance of their combination for its taxonomic identification. L. kefiranofaciens comprises two subspecies, namely kefiranofaciens and kefirgranum, but only the first one is responsible for the production of kefiran, the water-soluble polysaccharide, which is a basic component of the kefir grain and famous for its technological as well as health-promoting properties. L. kefiranofaciens, although very demanding concerning its growth conditions, can be involved in mechanisms affecting intestinal health, immunomodulation, control of blood lipid levels, hypertension, antimicrobial action, and protection against diabetes and tumors. These valuable bio-functional properties place it among the most exquisite candidates for probiotic use as a starter culture in the production of health-beneficial dairy foods, such as the kefir beverage.

The Poly (vinyl alcohol)/Kefirane nanofiber membrane was successfully fabricated for the first time using electrospinning of the polyvinyl alcohol (PVA) and Kefirane blend solution. Scanning electron microscope (SEM), attenuated total reflectance Fourier transform infrared (ATR FT-IR), and differential scanning calorimetry (DSC) were used to characterize the electrospun Poly (vinyl alcohol)/Kefirane fiber membranes. Similar analysis was done for polyvinyl alcohol nanofibers. Then, the results were compared with each other. Rheological behavior of the Poly (vinyl alcohol)/Kefirane solution was evaluated using a cone and plate rheometer. The flow curves of 6% Kefiran solution and Poly (vinyl alcohol)//Kefiran blend solution showed sufficient viscosity for electrospinning. Viscosity decreased as the shear rate has increased in two samples, with both demonstrating shears thinning behavior. Electrospinnability of Poly (vinyl alcohol)/Kefiran solution at different process conditions and Kefiran concentrations was studied. Scanning electron microscope analysis exhibited that diameter of polyvinyl alcohol nanofibers increased with increasing Kefiran. Increasing the Kefiran concentration to 6% led to the disappearance of nodes in nanofibers. Attenuated total reflectance Fourier transform infrared spectra showed that Kefiran has maintained its molecular structure during the electrospinning process. Differential scanning calorimetry of Poly (vinyl alcohol)/Kefirane nanofibers revealed lower melting point than polyvinyl alcohol nanofibers.

Hydrogel application feasibility is still limited mainly due to their low mechanical strength and fragile nature. Therefore, several physical and chemical cross-linking modifications are being used to improve their properties. In this research, methacrylated Kefiran was synthesized by reacting Kefiran with methacrylic anhydride (MA). The developed MA-Kefiran was physicochemically characterized, and its biological properties evaluated by different techniques. Chemical modification of MA-Kefiran was confirmed by 1H-NMR and FTIR and GPC-SEC showed an average Mw of 793 kDa (PDI 1.3). The mechanical data obtained revealed MA-Kefiran to be a pseudoplastic fluid with an extrusion force of 11.21 ± 2.87 N. Moreover, MA-Kefiran 3D cryogels were successfully developed and fully characterized. Through micro-CT and SEM, the scaffolds revealed high porosity (85.53 ± 0.15%) and pore size (33.67 ± 3.13 μm), thick pore walls (11.92 ± 0.44 μm) and a homogeneous structure. Finally, MA-Kefiran revealed to be biocompatible by presenting no hemolytic activity and an improved cellular function of L929 cells observed through the AlamarBlue® assay. By incorporating methacrylate groups in the Kefiran polysaccharide chain, a MA-Kefiran product was developed with remarkable physical, mechanical, and biological properties, resulting in a promising hydrogel to be used in tissue engineering and regenerative medicine applications.

Rice kefiran is superior in functionality, has high concentration of mucilaginous polysaccharide, and low lipid content, compared to conventional kefiran. However, reports on its physiological functionality, especially studies on life expectancy and aging, in model organisms are rare. In this study, nematodes were used as model organisms that were fed rice kefiran, along with Escherichia coli OP50, as a result of which, the lifespan of nematodes was extended and age-related retardation of mobility was suppressed. It also increased the heat stress resistance in nematodes. Experiments using daf-16 deletion mutant revealed that rice kefiran functions via DAF-16. Thus, this study revealed the longevity, anti-aging and heat stress tolerance effects of rice kefiran in nematodes. Rice kefiran fed C. elegans prolonged life span, increased motility and enhanced heat stress tolerance. These anti-aging effects was mediated through DAF-16. [ABSTRACT FROM AUTHOR]

Abstract In this work, an alternative matrix for probiotics delivery constituted by whey proteins and polysaccharide kefiran was investigated. Edible transparent and homogeneous films containing the microorganisms Lactobacillus paracasei CIDCA 8339 and Kluyveromyces marxianus CIDCA 8154 with probiotic characteristics have been developed. Inclusion of microorganisms did not modify thickness, color or mechanical characteristics of films. This matrix showed good capability protecting the included probiotics from stress during film obtaining process and through gastrointestinal passage simulation. At the end of the applied gastrointestinal tract model, 7.1.105 CFU/cm2 K. marxianus CIDCA 8154 and 1.65.107 CFU/cm2 L. paracasei CIDCA 8339 remain viable, having decreased less than 0.6 logarithm cycle with respect to those originally included, even after 57 days of films storage. Highlights • Edible wpi-kefiran films are adequate carrier for probiotic delivery. • Mechanical properties of films are not modified by microorganisms inclusion. • Films protect microorganisms through gastrointestinal simulation. • Degradation of proteins constituent of films occurs in intestinal stage. [ABSTRACT FROM AUTHOR]

Abstract A factorial experiment was designed to analyze nanobiocomposite films based on kefiran–carboxymethyl cellulose carbohydrates with copper oxide nanoparticles (CuONPs) (0, 1, 1.5 and 2%) and Satureja khuzestanica essential oil (SEO) (0, 1, 1.5 and 2%) as well as their combination in order to investigate their physical, mechanical, antioxidant, antimicrobial, optical, color, dynamic mechanical thermal, and morphological properties. It was generally found that the separate addition of CuONPs and SEO to the film improved its properties. In addition, results showed that the simultaneous application of CuONPs and SEO had substantially improved the physical and mechanical properties of the films. Besides the nature of CuONPs and SEO, this effect was due to the formation of hydrogen interactions between them and the biopolymer matrix, as supported by Fourier transform infrared spectroscopy (FTIR). The simultaneous application of CuONPs and SEO had a synergistic effect on antimicrobial properties against Staphylococcus aureus and Escherichia coli bacteria and further made a significant change in color parameters and percentage of light transmission within the visible and ultraviolet light spectral ranges. The results of the dynamic mechanical thermal analysis (DMTA) showed that the films containing simultaneous combinations of CuONPs and SEO had the highest storage modulus and glass transition temperature. Results of electron microscopy images indicated that the simultaneous presence of CuONPs and SEO in films was consistent with the biopolymer matrix and distributed properly in the medium. In summary, the results of this study showed that nanobiocomposite films containing the simultaneous combination of CuONPs and SEO may be useful in food packaging. Highlights • Novel nanobiocomposite films based on kefiran-CMC were produced and characterized. • Films were incorporated with CuO nanoparticles and Satureja Khuzestanica essential oil. • Clear improvements were observed in various physicochemical properties of the films. • The films showed significant antimicrobial characteristics against S. aureus and E. coli. • The biodegradable films might have a potential to be used as food packaging materials. [ABSTRACT FROM AUTHOR]

Abstract Biodegradable kefiran films, containing different concentrations of Al 2 O 3 (alumina) (1, 3 and 5% w/w), were prepared by casting method and their physical, mechanical, and thermal properties were studied. Based on the results, the increase of the nano-Al 2 O 3 content led to a decrease in the water vapor permeability, moisture content, moisture absorption, and water solubility. The addition of nanoparticles did not affect the lightness of the films significantly (P > 0.05). The mechanical tests revealed that the addition of Al 2 O 3 nanoparticles to the kefiran films significantly increased both tensile strength and elastic modulus, while had no effect on the elongation at break (P > 0.05). Thermogravimetric analysis (TGA) indicated the improvement of the films' thermal stability by adding alumina. The results of X-ray diffraction (XRD) confirmed the effect of Al 2 O 3 on the semi-crystalline structure of kefiran. Scanning electron microscopy (SEM) images approved a uniform distribution of nanocomposites containing 1 and 3% w/w of Al 2 O 3. The obtained results suggested that Al 2 O 3 was able to improve the characteristics of the kefiran-based films for using as food packaging material. Highlights • Kefiran/Al 2 O 3 nanocomposite films were prepared by solution casting method. • Al 2 O 3 caused to increase water barrier and mechanical properties of kefiran films. • Uniform distribution of Al 2 O 3 nanoparticles at lower concentrations was approved. • Al 2 O 3 had different effects on mechanical properties at different concentrations. • Kefiran films with up to 3% Al 2 O 3 are suitable for food packaging applications. [ABSTRACT FROM AUTHOR]

Efficient reconstitution followed by fermentation of nonfat (skimmed) dry milk is one of the most important aspects in manufacturing of various dairy products. As a first stage, dry milk is normally being reconstituted using conventional approaches such as heating and stirring the mixture. Nevertheless, we demonstrated, that low-frequency (22 ± 1.65 kHz) ultrasound can be used as an alternative to the traditional methods of milk recovery. Low-frequency ultrasound was applied during pre-fermentation stage to improve the dispersity of the resulting milk product and to create good conditions for a post-ultrasound bacterial fermentation of milk. The applied ultrasound power was set in the range of 60–120 W/L. For the fermentation process we used: kefir fungi, fermenter of direct inoculation for yogurt LYOBAC YOYO and mixed culture for kefir LAT LC K. The effectiveness of ultrasound treatment was evaluated based on the accumulation of exopolysaccharides (EPS), vitamin C content, as well as antioxidant activity of the resulting milk product. The effect of ultrasound on microflora and the role of the specific types of bacteria such as Lactobacillus on the accumulation of biologically active compounds in the fermented milk products was studied with use of electron microscopy and MALDI – to FMS method. Overall, our results showed that reconstitution of dry milk with use of ultrasound improves further accumulation of biologically active compounds and rises the nutritional quality of the fermented product. [ABSTRACT FROM AUTHOR]

Lactobacillus kefiranofaciens is non-pathogenic gram positive bacteria isolated from kefir grains and able to produce extracellular exopolysaccharides named kefiran. This polysaccharide contains approximately equal amounts of glucose and galactose. Kefiran has wide applications in pharmaceutical industries. Therefore, an approach has been extensively studied to increase kefiran production for pharmaceutical application in industrial scale. The present work aims to maximize kefiran production through the optimization of medium composition and production in semi industrial scale bioreactor. The composition of the optimal medium for kefiran production contained sucrose, yeast extract and K2HPO4 at 20.0, 6.0, 0.25 g L−1, respectively. The optimized medium significantly increased both cell growth and kefiran production by about 170.56% and 58.02%, respectively, in comparison with the unoptimized medium. Furthermore, the kinetics of cell growth and kefiran production in batch culture of L. kefiranofaciens was investigated under un-controlled pH conditions in 16-L scale bioreactor. The maximal cell mass in bioreactor culture reached 2.76 g L−1 concomitant with kefiran production of 1.91 g L−1.

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Background and Objectives: Kefiran (Kef) is a water-soluble polysaccharide that can form transparent film; however, it is brittle. Therefore, in order to improve the mechanical properties of kefiran film, a mixture with other polymers can be offered. The expansion of mixed systems can propose kefiran and polyvinyl alcohol (PVOH) as a new composite film. Materials and Methods: Solutions of 20 gram per liter kef and 40 gram per liter of PVOH were prepared. A mixture of film-forming solutions of different ratios of Kef/PVOH (100/0, 68/32, 50/50, 32/68) was prepared. In this study, different experiments including the physical properties (thickness, moisture content, and film solubility in water), water vapor permeability, and mechanical properties (tensile strength, elongation at break, puncture strength, and puncture deformation) of composite films as well as the rheological properties of film forming solutions were investigated. Results: The results of physical properties such as thickness, moisture content, solubility in water and mechanical properties such as tensile strength, elongation at break, puncture deformation, puncture strength and water vapor permeability indicated that the mechanical properties, thickness and solubility in water increase with increase in PVOH content; however, moisture content and water vapor permeability decrease. Rheological characterization of different film forming solutions exhibited Newtonian fluid behavior. Conclusions: These results contribute to the establishment of an approach to optimize films’ composition based on the interactions between polymers, aiming at improving the properties of polysaccharide-based films. Keywords: Kefiran, Polyvinyl alcohol, Physical properties, Mechanical properties, Rheological properties

This paper reports on an experiment in which starch/kefiran/TiO 2 (SKT)-based bio-nanocomposite films were developed and modified by photo-chemical reaction. In so doing, film-forming solutions were exposed to ultraviolet A (UV-A) for different times (1, 6, and 12 h). The obtained results indicated that increasing UV-A exposure time brought about an increase (≈14.9%) in the tensile strength of bio-nanocomposites. However, elongation at break and Young's modulus of irradiated film specimen decreased (≈32%, ≈12%, respectively) by increasing UV-A exposure time, and the moisture-sensitive parameters of specimen decreased using UV-A irradiation. According to the results, the functional properties of irradiated bio-nanocomposite are depended on the ratio of cross-linkages between polymer chains and the potentially produced mono and disaccharide by UV-A. [ABSTRACT FROM AUTHOR]