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The purpose of this study was to optimize the kefir grains biomass production, using milk as culture media. The kefir grains were cultured at different changed conditions (temperature, time, shaker rotating speed, culture media supplemented) to evaluate their effects. Results showed that optimal culture conditions were using the organic skim milk, incubated at 25°C for 24 hours with a rotation rate of 125 rpm. According to results, the growth rate was 38.9 g/L for 24 h, at 25°C using the organic milk - OSM, 36.87 g/L during 24 hours, optimal time for propagation process gave 37.93 g/L kefir grains biomass when the effect of temperature level was tested. The homogenization of medium with shaker rotating induced a greater growth rate, it was obtained 38.9 g/L for 24 h, at 25°C using rotation rate at 125 rpm. The growing medium (conventional milk) supplemented with different minerals and vitamins may lead to improve the growth conditions of kefir grains biomass. The optimization of the growth environment is very important for achieving the maximum production of kefir grains biomass, substrate necessary to obtain the polysaccharide kefiran

Kefir is a fermented dairy beverage produced by the actions of the microflora encased in the "kefir grain" on the carbohydrates in the milk. Containing many bacterial species already known for their probiotic properties, it has long been popular in Eastern Europe for its purported health benefits, where it is routinely administered to patients in hospitals and recommended for infants and the infirm. It is beginning to gain a foothold in the USA as a healthy probiotic beverage, mostly as an artisanal beverage, home fermented from shared grains, but also recently as a commercial product commanding shelf space in retail establishments. This is similar to the status of yogurts in the 1970s when yogurt was the new healthy product. Scientific studies into these reported benefits are being conducted into these health benefits, many with promising results, though not all of the studies have been conclusive. Our review provides an overview of kefir's structure, microbial profile, production, and probiotic properties. Our review also discusses alternative uses of kefir, kefir grains, and kefiran (the soluble polysaccharide produced by the organisms in kefir grains). Their utility in wound therapy, food additives, leavening agents, and other non-beverage uses is being studied with promising results.

Biodegradable kefiran–whey protein isolate (WPI) nanocomposites were produced using montmorillonite (MMT) and nano-TiO2 as nanoparticles in the percentage of 1, 3, and 5% (w/w) by a casting and solvent-evaporation method. Physical, mechanical, and water-vapor permeability (WVP) properties were determined as a function of nanoparticle concentration. The results revealed that the effect of these nanoparticles was different according to their nature and percentage. The films incorporated with 5% (w/w) MMT showed the highest tensile strength, Young's modulus, puncture strength, and the lowest WVP compared with the control and TiO2 added films. In contrast to MMT, addition of TiO2 nanoparticles due to the plasticizing effect led to a significant change in color and transparency of nanocomposite. Scanning electron microscopy (SEM) observations demonstrated the films’ properties in relation to their microstructures. The surface topography results also showed a considerable increase in roughness parameters by incorporating the nanoparticles in kefiran–WPI matrix.

Biodegradable kefiran-whey protein isolate (WPI)-titanium dioxide (TiO2) blend films were developed and characterized as a function of incorporating amount of TiO2 nanoparticles (1, 3 and 5% wt.). Results showed that the water vapor permeability, moisture content, moisture absorption and water solubility decreased by increasing the nano-TiO2 content. Mechanical tests revealed the plasticizing effect of TiO2 nanoparticles on the kefiran-WPI-TiO2 film. Addition of TiO2 nanoparticles to kefiran-WPI films significantly decreased tensile strength and Young's modulus, while increased its elongation at break. Differential scanning calorimetry data indicated that the glass transition temperature significantly changed by adding nano-TiO2. X-ray diffraction analysis also demonstrated that crystal type in kefiran-WPI was not affected by incorporation of TiO2 nanoparticles. A uniform distribution at 1 and 3% wt. loading levels of TiO2 nanoparticles was observed using scanning electron microscopy (SEM) micrographs.

Kefiran is a neutral polysaccharide constituted by glucose and galactose produced by Lactobacillus kefiranofaciens. It is included into kefir grains and has several health promoting properties. In the present work, shear and extensional properties of different kefiran aqueous dispersions (0.5, 1 and 2% wt.) were assessed and compared to other neutral gums commonly used in food, cosmetic and pharmaceutics industries (methylcellulose, locust bean gum and guar gum). Kefiran showed shear flow characteristics similar to that displayed by other representative neutral gums, although it always yielded lower viscosities at a given concentration. For each gum system it was possible to find a correlation between dynamic and steady shear properties by a master curve including both the apparent and complex viscosities. When studying extensional properties of selected gums at 2% wt. by means of a capillary break-up rheometer, kefiran solutions did not show important extensional properties, displaying a behaviour close the Newtonian. Fil: Piermaria, Judith Araceli. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Bengoechea, Carlos. Universidad de Sevilla; España Fil: Abraham, Analia Graciela. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Hachemi Guerrero, Antonio Munir. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Ciencias Biológicas. Área de Bioquímica y Control de Alimentos; Argentina

The influence of fermentation temperature, agitation rate, and additions of carbon sources, nitrogen sources, vitamins and minerals on production of kefiran by kefir grains lactic acid bacteria was studied in a series of experiments. The main aim of the work was to increase the exopolysaccharide (EPS) production where customised milk was used as fermentation medium. It was proved that the controlling of culturing conditions and the modifying of fermentation medium conditions (i.e., carbon, nitrogen, mineral sources and vitamins) can dramatically enhance the production of the EPS. The temperature and agitation rate were critical for kefiran production during the 24 h cultivation of grains; our optimised conditions being 25°C and 80 rpm, respectively. In addition, when optimising the effects of additional nutrition, it was found that 5% (w/v) lactose, 0.1% (w/v) thiamine, and 0.1% (w/v) FeCl3 led to the maximal production of EPS. The results indicate that nutrients can be utilised to improve the production of EPS and that good kefir grains growth does not appear to be a determining factor for a high production yield of EPS.

In this study, new edible composite films were prepared by blending kefiran with corn starch. Film-forming solutions of different ratios of kefiran to corn starch (100/0, 70/30, 50/50, 30/70) were cast at room temperature. The effects of starch addition on the resulting films’ physical, mechanical and water–vapor permeability (WVP) properties were investigated. Increasing starch content from 0% to 50% (v/v) decreased the WVP of films; however, with further starch addition the WVP increased. Also, this increase in starch content increased the tensile strength and extensibility of the composite films. However, these mechanical properties decreased at higher starch contents. Dynamic mechanical thermal analysis (DMTA) curves showed that addition of starch at all levels increased the glass transition temperature of films. The electron scanning micrograph for the composite film was homogeneous, without signs of phase separation between the components. Thus, it was observed that these two film-forming components were compatible, and that an interaction existed between them.

Ciprofloxacin is a broad-spectrum antibiotic associated with gastric and intestinal side effects after extended oral administration. Alginate is a biopolymer commonly employed in gel synthesis by ionotropic gelation, but unstable in the presence of biological metal-chelating compounds and/or under dried conditions. Kefiran is a microbial biopolymer able to form gels with the advantage of displaying antimicrobial activity. In the present study, kefiran-alginate gel microspheres were developed to encapsulate ciprofloxacin for antimicrobial controlled release and enhanced bactericidal effect against common pathogens. Scanning electron microscopy (SEM) analysis of the hybrid gel microspheres showed a spherical structure with a smoother surface compared to alginate gel matrices. In vitro release of ciprofloxacin from kefiran-alginate microspheres was less than 3.0% and 5.0% at pH 1.2 (stomach), and 5.0% and 25.0% at pH 7.4 (intestine) in 3 and 21 h, respectively. Fourier transform infrared spectroscopy (FTIR) of ciprofloxacin-kefiran showed the displacement of typical bands of ciprofloxacin and kefiran, suggesting a cooperative interaction by hydrogen bridges between both molecules. Additionally, the thermal analysis of ciprofloxacin-kefiran showed a protective effect of the biopolymer against ciprofloxacin degradation at high temperatures. Finally, antimicrobial assays of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhymurium, and Staphylococcus aureus demonstrated the synergic effect between ciprofloxacin and kefiran against the tested microorganisms. Fil: Blandón, Lina M.. Universidade Federal do Paraná; Brasil Fil: Islan, German Abel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Castro, Guillermo Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Noseda, Miguel D.. Universidade Federal do Paraná; Brasil Fil: Thomaz Soccol, Vanete. Universidade Federal do Paraná; Brasil Fil: Soccol, Carlos R.. Universidade Federal do Paraná; Brasil

Потороко Ирина Юрьевна. Доктор технических наук, профессор кафедры «Пищевые и биотехнологии», Южно-Уральский государственный университет (г. Челябинск), irina_potoroko@mail.ru Ускова Дарья Геннадьевна Аспирант кафедры ««Пищевые и биотехнологии» высшей медико-биологической школы, Южно-Уральский государственный университет (г. Челябинск), twins.23@mail.ru Ботвинникова Валентина Викторовна. Старший преподаватель кафедры «Пищевые и биотехнологии» высшей медико-биологической школы, Южно-Уральский государственный университет (г. Челябинск), valens_b@mail.ru Калинина Ирина Валерьевна. Кандидат технических наук, доцент кафедры «Пищевые и биотехнологии», Южно-Уральский государственный университет (г. Челябинск), 9747567@mail.ru. I.Yu. Potoroko, D.G. Uskova, V.V. Botvinnikova, I.V. Kalinina South Ural State University, Chelyabinsk, Russian Federation Все чаще кисломолочные напитки ассоциируются у потребителей с «полезными продуктами», однако в последнее время большинство кисломолочных напитков, реализуемых населению, не способны обеспечить заявленные полезные свойства. Для решения данной проблемы предложено применение акустического воздействия ультразвука, инициируемого с помощью аппарата ультразвукового технологического модель УЗТА-О,4/22-ОМ (частота механических колебаний (22 ± 1,65) кГц). Основными факторами, определяющими потребительские свойства, были приняты структурно-механические характеристики и накопление минорного биологически активного вещества – кефирана. Ультразвуковое воздействие осуществлялось на этапе подготовки молочного сырья в двух режимах мощности 190 и 240 Вт в течение 3 минут. В ходе исследования были получены результаты, подтверждающие использование ультразвукового воздействия (УЗВ) при производстве йогуртовых продуктов как нового подхода, позволяющего обеспечить потребителей функциональной продукцией высокого качества. Так, применение УЗВ в режиме 3 мин при 180 Вт мощности снизило отделение сыворотки от сгустка на 20 %, что согласуется с визуальными наблюдениями. Вязкость в исследуемых образцах йогуртов варьируется в диапазонах: 13,31…15,02 mPas для образцов при УЗВ в режиме 3 мин при 180 Вт мощности и 4,09…4,79 mPas для образцов йогуртов при УЗВ в режиме 3 мин при 240 Вт мощности. Установлено, что УЗВ стимулирует накопление кефирана на 5…30 %, а наиболее интенсивно при режиме УЗВ 3 мин при 240 Вт мощности. Данные, полученные в ходе работы, дают основание для использования УЗВ в технологии йогуртовых продуктов как нового подхода, который позволяет обеспечить потребителей функциональной продукцией высокого качества. Today fermented milk drinks are associated with “healthy products”, but the majority of fermented milk drinks can’t ensure the declared useful properties. To solve this problem it’s suggested to use the acoustic effect of ultrasound initiated with the help of an UZTA-O.4/22-OM ultrasonic technological apparatus (vibration frequency (22 ± 1.65) kHz). The structure mechanical characteristics and accumulation of a minor biologically active substance, i.e. kefiran are accepted as main factors which specify consumer properties. The ultrasonic effect was applied while preparing milk raw materials in two power modes 190 and 240 W during 3 minutes. In the course of research studies the authors have obtained the results which confirm the use of ultrasonic exposure (UE) when producing yoghurt products as a new approach, which enables one to provide consumers with functional products of high quality. The application of UE during 3 minutes at 180 W reduced the whey separation from a clot by 20 %, which agrees with visual observance. The viscosity in the examined samples of yoghurts varies in the ranges: 13.31…15.02 mPas for samples in case of UE during 3 minutes at 180 W and 4.09…4.79 mPas for the yoghurt samples in case of UE during 3 minutes at 240 W. It’s determined that UE stimulates kefiran accumulation by 5…30 %, and more intensively in case of UE during 3 minutes at 240 W. The data obtained in the course of studies give grounds for the use of UE in the technology of yoghurt products as a new approach, which provides consumers with functional high-quality products.

In the presented work, we have developed edible kefiran films containing Lactobacillus plantarum CIDCA 8327 and Kluyveromyces marxianus CIDCA 8154. Thickness, moisture content and optical properties of films were not altered by the incorporation of microorganisms. During the film obtaining, lactobacillus concentration decreased one logarithmic cycle and no loss on yeast viability was detected. Both microorganisms included in glycerol plasticized kefiran films successfully maintained their viability during storage. After 35 days at 20°°C L. plantarum viability decreased less than 1.3 logarithmic cycles and K. marxianus 0.7 logarithmic cycles. The high susceptibility of free cells of lactobacilli to acid was slightly diminished by the inclusion in the kefiran matrix. Inclusion of K. marxianus CIDCA 8154 significantly improved their survival to the sequential acid-bile treatment (36.3%) compared with the corresponding free cells (8.7%). The obtained edible kefiran films have great potential as an alternative way for probiotic delivery. Industrial relevance The edible kefiran films containing probiotics presented in this manuscript are interesting matrices for probiotic administration since the neutral polysaccharide kefiran, produced by lactic acid bacteria, has health-promoting properties itself. Films can be obtained simply and inexpensively. They are transparent, thin and have good mechanical properties among those constituted by biomacromolecules. Likewise, kefiran films can preserve the viability of probiotics in non-refrigerated conditions. Fil: Piermaria, Judith Araceli. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Diosma, Gabriela. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; Argentina Fil: Aquino, C.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Garrote, Graciela Liliana. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Abraham, Analia Graciela. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina

The rheological properties of kefiran film-forming solutions, as well as the structural characterisation of the resulting films, were investigated as a function of various plasticizer types. The behaviours of the storage (G') and loss (G″) moduli as a function of frequency were typical of gel-like material, with the G' higher than the G″. Kefiran-based films, which may find application as edible films, were prepared by a casting and solvent-evaporation method. Possible interaction between the adjacent chains in the kefiran polymer and various plasticizers was proven by Fourier-transform infrared spectroscopy (FT-IR). The crystallinity of plasticized kefiran film was also analysed using X-ray diffraction (XRD); this revealed an amorphous-crystalline structure. These results were explained by the film's microstructure, which was analysed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The present study has helped determine possible interactions of kefiran, plasticizer and water molecules in determining film properties.

This study examined the feasibility of using kefiran, an exopolysaccharide obtained from kefir grains, as a new film-forming material. Kefiran-based films, with and without glycerol as plasticizer, were prepared by a casting and solvent-evaporation method. To study the impact of the incorporation of glycerol into the film matrix, physical, mechanical, and thermal properties of the films were investigated. As expected, the increase of glycerol concentration from 15% to 35% w/w increased extensibility but decreased tensile strength, implying higher mobility of polymer chains by the plasticizing effect of glycerol. Water vapour permeability of films was found to increase as the plasticizer content increased. Glass transition temperatures decreased as a result of plasticization as glycerol content increased. The properties of the films were related to their microstructure, which was observed by scanning electron microscopy. Thus, it was observed that plasticizer is a significant factor in the properties of these films and their food technology applications.

The main goal of this work was to characterise and quantify the exopolysaccharide kefiran and to discover an effective procedure for its isolation from kefir grains, originating from the Caucasian Mountains. Capillary electrophoresis was used for the characterisation and quantification of the d-glucose and d-galactose in our samples at a mass ratio of 1:0.7. The effect of fermentation time on growth of kefir grains and the content of kefiran within the grains were determined. The pH profiles were monitored dynamically. In addition, the influence of fermentation temperature on kefir grains mass concentration (γKG) and the content of kefiran within the grains (wKEF/KG) were studied. The highest values for both were obtained at 30 °C.

Kefiran, an exopolysaccharide produced by microorganisms present in kefir grains, is a glucogalactan that has several health promoting properties. In the present work the effect of different sugars (glucose, galactose, sucrose) and polyols (glycerol and sorbitol) as plasticizers on kefiran film properties was evaluated. Kefiran films were brittle and rigid and all the tested plasticizers improved film properties. They were all transparent with low opacity. Unplasticized kefiran films X-ray diffraction patterns were similar to those of plasticized ones, showing an amorphous-crystalline structure with low crystallinity degree. All films presented low aw values (below 0.5) conferring protection properties against microorganism growth. The lowest permeability value was obtained with glucose as plasticizer whereas the best mechanical properties were obtained with glycerol addition. The relative high intensities of the bands assigned to water molecules stretching and bending modes in ATR/FT-IR average spectra of glycerol–kefiran films were correlated with their relative high water content compared to the other plasticized films. The analysis of the bands due to C–H stretching modes showed that glucose and glycerol could be reducing the interaction between the adjacent chains in the kefiran polymer. It would demonstrate the importance of the analysis of kefiran, plasticizers and water molecules interactions when films properties are studied.

The aim of the present study was to evaluate the effect of the oral administration of kefiran on the balance of immune cells in a murine model. Six week old BALB/c mice were treated with kefiran (300 mg/L) for 0, 2 and 7 days. Kefiran treatment increased the number of IgA+ cells in lamina propria after 2 and 7 days. Percentage of B220+/MHCIIhigh cells in mesenteric lymph nodes (2 days) and Peyer's patches (7 days) was higher compared to untreated control mice. An increase of macrophages (F4/80+ cells) was observed in lamina propria and peritoneal cavity (2 and 7 days). In contrast, at day 7, macrophage population decreased in Peyer's patches. These results show the ability of kefiran to modify the balance of immune cells in intestinal mucosa. This property could be highly relevant for the comprehension of the probiotic effect attributed to kefir. Fil: Medrano, Micaela. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Racedo, Silvia María. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Ciencias Biológicas. Cátedra de Microbiología General; Argentina. Universite de Bordeaux; Francia. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Rolny, Ivanna Sabrina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Ciencias Biológicas. Cátedra de Microbiología General; Argentina Fil: Abraham, Analia Graciela. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Ciencias Biológicas. Área de Bioquímica y Control de Alimentos; Argentina Fil: Perez, Pablo Fernando. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Ciencias Biológicas. Cátedra de Microbiología General; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina

Kefiran, an exopolysaccharide isolated from kefir d’acqua grains, has anti-inflammatory and antimicrobial activities, however, a mechanism of action directly associated with biomembranes is not yet understood. The influence of kefiran on a l -α-Phosphatidylcholine/cholesterol supported bilayer lipid membrane using a Pt electrode was studied by voltammetry and electrochemical impedance spectroscopy. The interaction of the oligosaccharide with s-BLMs promoted the access of Fe ( CN ) 6 3 - / 4 - probe ions to the electrode surface. Kefiran was found to induce molecular pores at the s-BLM surface within 5 min at 11.4 μmol/L. The suggested mechanism seems to involve hydrogen bonding between the carbohydrate and the phosphate head group of the phospholipid with a carpet-like model of interaction. The overall results can be contributed to direct molecular interactions between the prebiotic oligosaccharides and the cell surfaces, which can be related to the biological activity of kefiran in several experimental models.

The feasibility of using kefiran as a new film-forming material was studied. Edible kefiran films were produced using glycerol and sorbitol as plasticizers at the ratio of 10, 15, and 25% (w/w) by the casting method. Physical, mechanical and water vapor permeability (WVP) properties were determined as a function of plasticizer concentration. Dynamic mechanical thermal analysis was used to determine the glass transition temperature. Increased glycerol concentration caused an increase in flexibility and WVP, as expected. However, the plasticizing effect of glycerol became less significant, particularly for puncture deformation and tensile strength. Glycerol was found to be a more suitable plasticizer for kefiran films than sorbitol. The properties of the films were related to their microstructure, which was observed by scanning electron microscopy. It was determined that plasticizers can play an important role in adapting the properties of these films to make them more suitable for food technology applications.

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. ABSTRAKWhey 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%.

Aim: Kefiran is an exopolysaccharide produced by Lactobacillus kefiranofaciens, and has been proposed to have many health-promoting properties. We investigated the antiatherogenic effect of kefiran on rabbits fed a high-cholesterol diet.Methods: Male New Zealand White rabbits were fed a 0.5% cholesterol diet without (control group, n=7) or with kefiran (kefiran group, n=8) for eight weeks. The aorta was analyzed by histochemistry and atherosclerotic lesions were quantified. Lipids and sugars in serum were measured. Foam cell formation of RAW264.7 by βVLDL derived from both groups of rabbits was also investigated.Results: Cholesterol, triglyceride and phospholipids levels of serum and lipoprotein fractions were not significantly different between these groups. Atherosclerotic lesions of the aorta in the kefiran group were statistically lower than those of the control group, with marked differences in the abdominal aorta. T-lymphocytes were not detectable in the aorta of the kefiran group. Cholesterol contents in stools were almost identical in both groups. Cholesterol content in the liver of the kefiran group was statistically lower than in the control group. Galactose content of βVLDL derived from the kefiran group was higher, and the lipid peroxidation level was much lower than in the control group. RAW264.7 macrophages treated with βVLDL from the kefiran group showed a more spherical shape and accumulated statistically lower cholesterol than macrophages treated with βVLDL from the control group.Conclusion: Orally derived kefiran is absorbed in the blood. Kefiran prevents the onset and development of atherosclerosis in hypercholesterolemic rabbits by anti-inflammatory and anti-oxidant actions.

The tolerance of lactic acid bacteria (LAB) from kefir grains to gastrointestinal tract conditions was evaluated in vitro. The effects of pH values and bile salts on the viability of LAB were investigated. The results demonstrated that pH value showed a significant effect on the viability. The viable counts exhibited a reduction of 1.5 to 2 log cycles in 0.3% to 0.5% bile salts after 4 h. The viability of LAB exposure to sequential simulated gastric and intestinal juices was assessed by response surface model (RSM). RSM indicated that the gastric pH and gastric contact time significantly affected the viability (P < 0.05), while the effect of intestinal contact time was not significant. Moreover, RSM revealed the interactions of pH and gastric contact time, and of pH and intestinal contact time. The LAB cells, temporarily damaged by the low pH of gastric juice (pH < 2), could recover in the intestinal juice; and the longer the intestinal contact time, the higher the viability of LAB. RSM proved to be a useful and accurate method to predict the viability of LAB under certain laboratory conditions by the model validation. This study indicated that LAB from kefir grains exhibited excellent tolerance to sequential simulated gastrointestinal tract conditions, and that kefiran possessed a significant protective effect on LAB in hostile environments.

Kefiran, an exopolysaccharide produced by microorganisms present in the kefir grains, is a glucogalactanthat has several health promoting properties. In the present work, the ability of kefiran to form films andthe effect of glycerol addition at different concentrations on film properties was evaluated. Kefiran wasable to form films at concentrations ranging from 5 to 10 g/kg. The concentration 10 g/kg was selectedbecause the films were easily removed from the plate. All film-forming solutions exhibited a pseudo-plastic behavior; glycerol addition did not modify the solution rheological properties.Kefiran films exhibited differential solubility characteristics, at the different assayed temperatures. Thesefilms exhibited good water vapor barrier properties and the addition of 25 g of glycerol per 100 g ofpolysaccharide allowed the optimum value of 4.09 10 11 g/msPa to be obtained.Films without glycerol were brittle and rigid since they showed high elastic modulus and tensile strengthvalues and low deformation at break. Glycerol addition led to extremely high elongation values, allowingflexibilities comparable to those of synthetic materials. 2008 Elsevier Ltd. All rights reserved.

The physicochemical and gelling properties of kefiran, a water-soluble glucogalactan with probed health-promoting properties, were investigated. Gel permeation chromatograms revealed a single distribution of molecular weight corresponding to 10 7 Da. Intrinsic viscosity of kefiran determined using Huggins extrapolations was 6.0 dl/g and using Kramer approximations was 5.95 dl/g. Kefiran has a Newtonian behaviour in diluted solutions, which becomes pseudoplastic at higher concentrations. Rheological behaviour of the solution before and after freeze drying was evaluated by small deformation oscillatory rheological measurements. The mechanical spectrum of solution corresponded to an entangled network behaviour. After freeze–thaw treatment of the solution, a rheological behaviour transition from a liquid-like system to a gel was observed. The storage modulus ( G ′) in cryogels was 35 times higher than the value obtained for the solution. Rheological characteristics of the cryogel were influenced by kefiran concentration. As the polymer concentration increased, higher number of interactions was evident for the increment in both moduli ( G ′ and G ″). The behaviour of kefiran cryogels about 37 °C determines its ability to melt at mouth temperature. These results suggest that kefiran cryogels could be an interesting alternative for its application in food formulations.

BACKGROUND: Kefiran is an exopolysaccharide that is widely used in the food and pharmaceutical industries. The aim of this study was to demonstrate that kefiran with different chemical structures can be obtained by changing the composition of the Lactobacillus kefiranofaciens fermentation medium. RESULTS: When using maltose as the sole carbon source: (1) the average molecular mass of kefiran was 1.5 × 105 Da, only 62.5% of that of the control (with lactose as the sole carbon source); (2) the glucose/galactose molar ratio of kefiran from the optimised medium was 1:10; (3) two variable-angle CH bonds existed in the structure of kefiran; (4) the maximum viscosity of kefiran was [η] = 73.86 ± 5.3 dL g−1 and its specific rotatory power was [α]D = + 68°. Increasing the proportion of maltose in a mixed carbon source (maltose and lactose) from 20 to 100 g L−1 decreased the average molecular mass and glucose/galactose molar ratio of kefiran by 35 and 60% respectively. CONCLUSION: Kefiran with different chemical structures was obtained by changing the composition of the fermentation medium. The results presented here will facilitate further study of the relationship between the chemical structure and biological role of kefiran. Copyright © 2008 Society of Chemical Industry

Low-cost sago starch was used as a carbon source for production of the exopolysaccharide kefiran by Lactobacillus kefiranofaciens. A simultaneous saccharification and fermentation process of sago starch for kefiran production was evaluated. Factors affecting the process such as an initial pH, temperature, starch concentration, including a mixture of α-amylase and glucoamylase were determined. The highest kefiran concentration of 0.85 g/l was obtained at the initial pH of 5.5, temperature of 30 °C, starch concentration of 4% and mixed-enzymes with activity of 100 U/g-starch. The use of a mixture of α-amylase and glucoamylase could enhance the productivity compared to the use of α-amylase alone. The optimal ratio of α-amylase to glucoamylase of 60:40 gave the highest kefiran production rate of 11.83 mg/l/h. This study showed that sago starch could serve as a low-cost substrate for kefiran production.

In a batch coculture of kefiran-producing lactic acid bacteria Lactobacillus kefiranofaciens and lactate-assimilating yeast Saccharomyces cerevisiae, lactate accumulation in the medium was observed, which inhibited kefiran production. To enhance kefiran productivity by preventing lactate accumulation, we conducted lactose-feeding batch operation with feedforward/feedback control during the coculture, so that the lactate production rate of L. kefiranofaciens was balanced with the lactate consumption rate of S. cerevisiae. The lactate concentration was maintained at less than 6 g l(-1) throughout the fed-batch coculture using a 5 l jar fermentor, although the concentration reached 33 g l(-1) in the batch coculture. Kefiran production was increased to 6.3 g in 102 h in the fed-batch coculture, whereas 4.5 g kefiran was produced in 97 h in the batch coculture. The kefiran yield on lactose basis was increased up to 0.033 g g(-1) in the fed-batch coculture, whereas that in the batch coculture was 0.027 g g(-1).

Growth and kefiran production rates of Lactobacillus kefiranofaciens were significantly enhanced in a mixed culture with Saccharomyces cerevisiae as compared with those in a pure culture. Because a positive effect on growth and kefiran production of L. kefiranofaciens in a mixed culture was observed, the elucidation of interaction between L. kefiranofaciens and S. cerevisiae may lead to higher productivity. Hence, microbial performance of each strain was investigated and analyzed by a mathematical model. The mathematical model for kefiran fermentation in a mixed culture of L. kefiranofaciens and S. cerevisiae was established, and the impact of S. cerevisiae on cell growth, kefiran formation, and substrate assimilation of L. kefiranofaciens were considered. The behavior of L. kefiranofaciens in a mixed culture was predicted using a developed mathematical model in this work, and the predictions were compared with the results from mixed culture experiments. The overall mathematical model is capable of describing the behavior of S. cerevisiae in a mixed culture as a lactic acid consumer, nitrogen source competitor and protective function inducer for L. kefiranofaciens. Furthermore, the constructed model described the phenomena in mixed cultures under aerobic and anaerobic conditions. Finally, the optimal inoculation ratios of S. cerevisiae to L. kefiranofaciens at 7-fold and 10-fold under aerobic and anaerobic conditions were obtained by applying the mixed culture model, respectively.

In recent years, there has been a strong focus on beneficial foods with probiotic microorganisms and functional organic substances. In this context, there is an increasing interest in the commercial use of kefir, since it can be marketed as a natural beverage that has health promoting bacteria. There are numerous commercially available kefir based-products. Kefir may act as a matrix in the effective delivery of probiotic microorganisms in different types of products. Also, the presence of kefir's exopolysaccharides, known as kefiran, which has biological activity, certainly adds value to products. Kefiran can also be used separately in other food products and as a coating film for various food and pharmaceutical products. This article aims to update the information about kefir and its microbiological composition, biological activity of the kefir's microflora and the importance of kefiran as a beneficial health substance., Facultad de Ciencias Exactas

In this work, the influence of sucrose and fructose on the gel-forming capacity of kefiran was investigated as well as the physicochemical characteristics of the resulting gels. The addition of sugar to gel-forming solutions did not alter the pseudoplastic flow properties of kefiran solutions and after one freeze-thaw cycle translucent gels with high water-holding capability were obtained. A highly porous matrix was revealed by microscopy whose pore size varied with sugar concentration. Sucrose and fructose had different effects on the rheological characteristics of sugar-kefiran gels. An increment in the strength of the gels with progressive concentrations of sucrose was evidenced by an increase in the elastic modulus (G’), indicating that sucrose reinforces the binding interactions between the polymer molecules (p ≤ 0.05). A drastic reduction in elastic modulus occurred, however, when 50.0 % w/w sucrose was added to kefiran gels, resulting in less elasticity. In contrast, when fructose was added to kefiran gels, elastic modulus decreased slightly with progressive sugar concentrations up to 10 %, thereafter increasing up to 50 % (p ≤ 0.05). Supplementation with up to 30 % sugar contributed to water retention and increased the viscous modulus. The relative increment in the elastic and viscous moduli elevated the loss tangent (tanδ) depending on the type and concentration of sugar. Sugars (sucrose, fructose) present in the matrix of the polysaccharide networks modified water-polymer and polymer-polymer interactions and consequently changed the gels’ physicochemical characteristics, thus allowing the possibility of selecting the appropriate formulation through tailor-made kefiran cryogels. Fil: Zavala, Lucía. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Roberti, Paula. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina Fil: Piermaria, Judith Araceli. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Ciencias Biológicas. Área de Bioquímica y Control de Alimentos; Argentina Fil: Abraham, Analia Graciela. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Ciencias Biológicas. Área de Bioquímica y Control de Alimentos; Argentina

Lactobacillus kefiranofaciens is an indicator microorganism for kefir and a key factor in kefir grain formation and kefiran production. We designed a novel real-time PCR primer and probe set, LKF_KU504, for the rapid detection of L. kefiranofaciens. In inclusivity and exclusivity tests, only 14 L. kefiranofaciens strains were positive among 61 microorganisms, indicating 100 % sensitivity and specificity. The LKF_KU504 set also differentiated kefir milk from 30 commercial nonkefir yogurts. The levels of L. kefiranofaciens in kefir grain and kefir milk were significantly different, indicating L. kefiranofaciens was more concentrated in kefir grain than in kefir milk.

Environmental concern about synthetic polymers and nanoparticles bring about development of the green bionanocomposite. Nanocellulose (NC) as safe nanofiller was prepared from beer industrial residues by acid hydrolysis in this study. ATR-FTIR spectrum showed no change in chemical structure of kefiran and NC after mixing. However, mechanical, visual, and WVP properties of kefiran/NC films improved with NC, but thermal properties and water sensitivity of them declined, simultaneously.

Kefiran is an exogenous microbial metabolite which is produced principally by lactic acid bacteria and fungi and molds throughout growth. Exo polysaccharide of kefiran was extracted from kefir grains and in status of gel was added at 1, 2, 3% concentrations (w/w flour basis) to wheat flour to evaluate its effects on rheological properties of weak wheat dough. The rheological measurements of the dough were investigated using Farinograph and Extensograph instruments. Results of Farinograph evaluation of dough showed that adding of kefiran and increase in its levels leads to increase in the water absorption capacity, dough development time and departure time, while the dough degree of softening after 20 min and mixing tolerance index were decreased in comparison with the control sample. The study on Extensograph behavior of the dough containing kefiran showed that resistance to extension at 45 and 90 min resting times was increased by increasing the percentage of the added kefiran. Longer fermentation time for each level of kefiran led to decrease of resistance to extension. Significant difference was observed in the resistance to extension of the dough containing different levels of kefiran and the control sample. Addition of kefiran to the dough after 45, 90 and 135 min resting times significantly decreased the extensibility, also with an increase in resting time from 45 to 135 min, the extensibility decreased for both the control and kefiran samples. Generally, addition kefiran at 45, 90 and 135 min resting times led to a significantly increase in resistance to extension ratio. Energy input increased at 45 and 90 min resting times, whereas chaotic effect was shown at time of 135 min restig time. Therefore, kefiran can be used to playing an important role in improving of rheological properties of weak dough and its processing conditions.

Kefir is a fermented milk beverage. The milk fermentation is achieved by the of kefir grains, a cluster of microorganisms held together by a polysaccharide matrix named kefiran. Kefir grains are an example of symbiosis between yeast and bacteria. They have been used over years to produce kefir, a fermented beverage that is consumed all over the world, although its origin is Caucasian. A vast variety of different species of organisms forming the kefir grains, comprising yeast and bacteria, have been isolated and identified. Kefir is a probiotic food. Probiotics have shown to be beneficial to health, being presently of great interest to the food industry. Kefir has been accredited with antibacterial, antifungal and antitumoural activities among other beneficial attributes. This review includes a critical revision of the microbiological composition of kefir along with its beneficial properties to human health.

The effects of addition of kefiran, the exopolysaccharide found in kefir grains, on apparent viscosity ( η app ) and dynamic rheological properties of chemically acidified skim-milk gels were investigated. The effect of a heat treatment on kefiran–skim milk mixture was also evaluated. Gels without kefiran showed a pseudoplastic thixotropic behaviour with a small area enclosed between the up and down curves. The addition of kefiran significantly (P⩽0.05) increased the hysteresis loop and the viscosity of the gels. Apparent viscosity of gels increased with kefiran concentration up to 300 mg L−1. Further addition did not modify significantly (P⩽0.05) the apparent viscosity of gels. Gels prepared from heat treated milk–kefiran mixtures showed a significantly higher η app than the ones that were prepared without a heat treatment at all kefiran concentrations assayed. The elastic modulus (G′) and the viscous modulus (G′′) of gels prepared with heat treated milk mixes increased with increasing kefiran concentration, without influencing the loss tangent (G′′/G′). The present results demonstrate that viscosity and viscoelastic properties of acid gels were improved by kefiran addition suggesting a possible application of this natural polysaccharide as an alternative thickening agent in dairy products.

Kefir is a fermented beverage originating form the Caucasian regions composed of a number of bacteria and yeasts living together in polysaccharide grains secreted by them. Kefir can be considered a probiotic source as it presents anti-bacterial, anti-mycotic, anti-neoplasic and immunomodulatory properties. Aiming to appraise a possible anti-inflammatory effect of kefir we conducted cotton-induced granuloma and paw oedema assays in rats, the latter using carrageenan, dextran and histamine as stimuli. Kefir samples were thawed and continuously cultured during 15 days both in a molasses solution (50 g/l) and in cow's milk. A polysaccharide extract isolated from the grains (kefiran) was also tested in cotton-pellet experiments. The results showed significant inhibition in the formation of granuloma tissue for all the test groups, as compared to the blank group. Kefir suspensions in molasses presented an inhibition of 41 +/- 3% for the inflammatory process, fermented milk prepared from kefir showed 44 +/- 6% inhibition and kefiran extract 34 +/- 15%. Rat paw oedema also showed significant decreases with the mediators. Dextran-induced oedema was completely inhibited at 1 h after input, with a 76% inhibition after 2 h. Carrageenan stimulus was inhibited 62% after the 3rd hour, and histamine by 52% after the 2nd hour. These results points to the existence of anti-inflammatory prebiotic compounds present in symbiotic cultures of kefir growing in both aqueous and milky suspensions.

The natural polysaccharide, kefiran (galactoglucan), was studied for the mechanism of its serum cholesterol lowering effect in 2 rat models one, loaded with cholesterol and another given erotic acid. Kefiran accelerated sterol excretion and protected hepatic injuries (GOT, GPT) in both models. In addition, histamine excretion decreased in the cecum content and feces, suggesting that kefiran may have various preventative functions.

Lactobacillus kefiranofaciens was reported to produce an exopolysaccharide named kefiran. In the present study, we developed a new medium, rice hydrolyzate (RH) medium, for the culture of L. kefiranofaciens. Structural analyses revealed that the exopolysaccharide produced by L. kefiranofaciens from RH medium was composed of a hexasaccharide repeating unit, and essentially identical to the kefiran reported in previous studies. A study on the effects of kefiran in animals demonstrated that kefiran significantly suppressed increase of blood pressure and reduced the serum cholesterol levels in SHRSP/Hos rats when subjects consumed excessive dietary cholesterol. Kefiran supplementation demonstrated the ability to significantly lower blood glucose in KKAy mice. In addition, the administration of kefiran in constipated SD rats caused an obvious improvement in the levels of fecal moisture and wet weights of feces. These results suggest that kefiran could be used as a functional food to prevent some commonly occurring diseases.

In a batch mixed culture of Lactobacillus kefiranofaciens and Saccharomyces cerevisiae, which could assimilate lactic acid, cell growth and kefiran production rates of L. kefiranofaciens significantly increased, compared with those in pure cultures. The kefiran production rate was 36 mg l(-1) h(-1) in the mixed culture under the anaerobic condition, which was greater than that in the pure culture (24 mg l(-1) h(-1)). Under the aerobic condition, a more intensive interaction between these two strains was observed and higher kefiran production rate (44 mg l(-1) h(-1)) was obtained compared with that under the anaerobic condition. Kefiran production was further enhanced by an addition of fresh medium in the fed-batch mixed culture. In the fed-batch mixed culture, a final kefiran concentration of 5.41 g l(-1) was achieved at 87 h, thereby attaining the highest productivity at 62 mg l(-1) h(-1). Simulation study considered the reduction of lactic acid in pure culture was performed to estimate the additional effect of coculture with S. cerevisiae. Slightly higher cell growth and kefiran production rates in the mixed culture than those expected from pure culture by simulation were observed. These results suggest that coculture of L. kefiranofaciens and S. cerevisiae not only reduces the lactic acid concentration by consumption but also stimulates cell growth and kefiran production of L. kefiranofaciens.

The characteristics of 58 strains of Lactobacillus spp. isolated from kefir were studied. These strains were tested for adherence to human enterocyte-like Caco-2 cells, resistance to acidic pH and bile acid, antimicrobial activities against enteropathogenic bacteria and inhibition of Salmonella typhimurium attachment to Caco-2 cells. The best probiotic properties were observed in L. acidophilus CYC 10051 and L. kefiranofaciens CYC 10058. L. kefiranofaciens CYC 10058 produced an exopolysaccharide, which revealed that it was closely related to kefiran, a polysaccharide with antitumoral properties. This is the first in vitro study about the antimicrobial characteristics of the Lactobacillus population of kefir.

Lactobacillus kefiranofaciens is known to produce an exopolysaccharide (kefiran) that is either excreted in the growth medium or attaches to the cell wall. In order to achieve high exopolysaccharide production, we developed a new rice hydrolyzate (RH) medium using rice starch hydrolyzate as the carbon source and rice protein hydrolyzate as the peptone source. In this study, three fermentation experiments using RH medium, PYG10 medium and PYL10 medium were carried out, respectively. The highest amount of exopolysaccharide production was obtained from the culture grown in RH medium. Among the three various media compositions compared, rice protein hydrolyzate in the RH medium demonstrated the ability to significantly enhance exopolysaccharide production by L. kefiranofaciens. In addition, the cultivation of L. kefiranofaciens in a 500 l tank was also experimentally conducted, and the maximum yield of exopolysaccharide from the RH culture was 2.5 g/l after a seven-day culture period at pH 5.0 and 33°C. This result indicates that it is possible to produce exopolysaccharide (OSKC) at the level required for large-scale industrial production through the cultivation of L. kefiranofaciens in RH medium.

Physico-mechanical, thermal and structural characteristics of nanocomposite film composed of kefiran-whey protein isolate (WPI)-montmorillonite (MMT; 1, 3 and 5 % w/w) were studied. Incorporation of MMT significantly affected the mechanical attributes of the kefiran-WPI films. The tensile strength and Young’s modulus increased and the percentage of elongation at break decreased as the MMT content increased. Moisture content, moisture absorption and water solubility decreased as the MMT concentration increased. Differential scanning calorimetry indicated that the glass transition temperature for kefiran-WPI film was −12.5 °C and was noticeably affected by an increase in MMT. X-ray diffraction analysis showed formation of an exfoliated structure with the addition of small amounts of MMT to the kefiran-WPI matrix. Intercalation and some exfoliation occurred up to 5 % (wt) increase in MMT. Scanning electron microscopy demonstrated ideal dispersion for MMT nanoparticles into the structure of the bio-nanocomposite films.

In this study, we report the first successful production of kefiran nanofibers through electrospinning process using distilled water as solvent. For this purpose, kefiran was extracted from cultured kefir grains, and homogenous kefiran solutions with different concentrations were prepared and then electrospun to obtain uniform nanofibers. The effect of main process parameters, including applied voltage, tip-to-collector distance, and feeding rate, on diameter and morphology of produced nanofibers, was studied. Scanning electron microscopy (SEM) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy were used to characterize electrospun mats. Rheological behavior of the kefiran solution was evaluated via a cone and plate rheometer too. The results exhibited that diameter of kefiran nanofibers increased with increasing polymer concentration, applied voltage, and polymer feeding rate, while tip-to-collector distance did not have significant effect on nanofiber diameter. ATR-FTIR spectra showed that kefiran has maintained its molecular structure during electrospinning process. Flow curves also demonstrated shear thinning behavior for kefiran solutions.