جستجوی مقالات مرتبط با کلیدواژه "kefiran" در نشریات گروه "مکانیزاسیون کشاورزی"

In this study, biodegradable film based on starch-kefiran-ZnO was made by casting method. The produced films contain different content of nano ZnO (ZN) (1%, 3%, and 5% wt.). Also ZN dispersed by ultrasonic homogenizer and added to the starch-kefiran solution. Surface characteristics, thickness, moisture content, water vapor permeability and mechanical properties were investigated. In the images of water droplets, it was observed that the contact angle of starch-kefiran was 89.67 degrees. By increasing the amount of zinc oxide nanoparticles up to 1%, the contact angle increased significantly to 95.63 degrees, which means improving the surface properties and hydrophobicity. The water vapor permeability for starch-kefir film (×10−10 g m-1s−1Pa−1) was 3.12, which was increased to 2.03 (×10−10 g m-1s−1Pa−1) by increasing the concentration of zinc oxide up to 3%. Tensile strength and Young’s modulus of the specimens were increased by increasing ZN content up to 3%. On the other hand, elongation at break of the nanocomposites was decreased, simultaneously. It is obvious that, ZN was improved some of the packaging properties of the starch-kefiran film.

The use of fat replacers in foods plays an important role in human health, especially cardiovascular diseases. In this study, three levels of kefiran (0.2, 0.5, 0.8 %) was used in fruit yogurt as fat replacer. Their physicochemical (pH, synersis, rheological), microbial (number of lactic acid bacteria, molds and yeasts) and sensory properties were compared with three control fruit yogurt (non -fat, low-fat (fat 1.5%) and fat (fat 3%). Samples were prepared in the same conditions. The results showed that concentrations of kefiran had no effect on the acidity yogurt The lowest level of synersis was obtained in the presence of 0.5% kefiran. This sample also received the highest score of sensory evaluation. With the increase of kefiran concentration increased consistency index and decreased the growth of mold and yeast, while no effect on the number of lactic acid bacteria shown.

Production of Biopolymers by different microorganisms for industrial applications has been considered in recent years. Lactobacillus kefiranofaciens bacterium produces exopolysaccharid exists in kefir grains called kefiran. The objective of this study was optimization of environmental conditions to produce kefiran polysaccharide in a synthetic media based on whey substrate by using response surface methodology (RSM). Therefore, different combinations of factors including pH (4.7-6.3), temperature (23-37º C) and agitation rate (70-170 rpm) on production of kefiran (g/L) were studied. According to the results, the optimum condition for production of kefiran included pH equal to 5.7, 31º C and agitation rate of 127 rpm which led to producing 1.14 g/L kefiran after five days incubation period. Furthermore, the molecular weight of produced kefiran in pure culture of L.kefiranofaciens measured by gel filtration chromatography was 1.1× 106 Da.

Kefiran is an exopolysaccharide produced by microorganisms present in the kefir grains that has several health promoting properties. In this research, physico-mechanical and thermal characteristics of nanocomposite film composed of kefiran-montmorillonite (MMT; 1, 3 and 5% w/w) were studied. Results showed that the thickness and the tensile strength of the films increased by increasing the nanoclay content but its effect on the elongation at break, glass transition temperature and melting temperature in various concentrations is different, so that these factors increase until concentration of 3% of the nanoclay and decrease in higher concentrations(5%). X-ray diffraction analysis showed that formation of an exfoliated structure with the addition of small amounts of MMT to the kefiran matrix. Scanning electron microscopy and the surface topography results showed ideal dispersion for MMT nanoparticles into the structure of the bio-nanocomposite films and a considerable increase in roughness parameters by incorporating the nanoparticles in kefiran matrix,respectively.

This study prepared new edible composite film by blending kefiran with whey protein. The film-forming solutions used different ratios of kefiran to whey protein (70/30, 50/50, 30/70, 10/90) and were cast at room temperature. The effects of the addition of whey protein on the physical, mechanical and water-vapor permeability (WVP) properties of the film were investigated. It was found that an increase in whey protein content from 0% to 50% (v/v) decreased WVP; however, further addition of whey protein increased WVP. This increase in whey protein content increased the tensile strength and extensibility of the composite film; however, these mechanical properties decreased at higher whey protein contents. Electron scanning micrography of the composite film showed it was homogeneous with no sign of phase separation between components. It was observed that these two film-forming components were compatible and that an interaction existed between them.

Kefiran، extracted from kefir grains، is a water-soluble، glucogalactan containing almost equal amounts of D-glucose and D-galactose residues. Throughout this research، Kefiran and Xanthan were added at concentrations of 3% (w/w flour basis) to two wheat dough samples to investigate the effects on the rheological and physical properties of French bread. Physicochemical properties of wheat and its flour were analyzed though Inframatic، the rheological of wheat dough by Farinograph، the stalingof bread by Instron texture analyzer apparatus. Results of Farinograph evaluation of the dough showed، adding of 3% level Kefiran and Xanthan led to a significant increase (p<0. 05) in the water absorption capacity، dough development time، dough stability in comparison with control، although the dough degree of softening after 10 and 20 minutes and Mixing tolerance index got decreased significantly (p<0. 05). Based on the results of staling tests done within the three times of: 24، 48 and 72 hours، it was characterized that an addition of levels of Kefiran 3% and Xanthan 3% to wheat dough، the rate of bread’s crumb staling decreased significantly (p<0. 05)، whereas the 3% xanthan sample had a lower rate of staling as well as higher hardness than the control samples. As a result، although Xanthan (like Kefiran) exerted a positive effect on the rheological properties of dough، but the hardness of breads in comparison with control and with samples containing Kefiran got increased.

The presence of unsaturated fatty acids and phytosterols in hazelnuts and hazelnut products, including hazelnut milk, are useful for health, especially for preventing cardiovascular disease. Fermentation with probiotic microorganisms present in kefir grain increases the functional properties of the products. Hazelnut milk is nutritious and can be used in drinks in addition to whey. The present study produced a novel kefir-like beverage using hazelnut and whey. The effects of fermentation, type of kefir grain, milk ratio and fermentation temperature on the antioxidant power, acidity, kefiran content, apparent viscosity and microflora composition were evaluated to determine the most appropriate functional and organoleptical properties. Results showed that fermentation using kefir grains changed these properties in hazelnut milk; the amount of change increased as the kefir grain content increased. Hazelnut milk fermented with 8% kefir grain at 25°C showed the highest functional properties, especially in antioxidant power and probiotic count. Although the highest concentration of polysaccharide in the media was observed at 30 C, this temperature has a destructive effect on the kefir grain.

Kefiran is an exogenous microbial metabolite produced mainly by bacteria and fungi during growth. The present study investigated the effects of the addition of 3% kefiran and 3 xanthan on the extensographic characteristics of wheat dough and the shelf life of raised bread. Kefir grain was cultivated in a shaking incubator and kefiran extraction was carried using a centrifugalrefrigerator. The physicochemical properties of Sardari and Parsi wheat and their respective flours were analyzed using an Inframatic analyzer. The rheological properties of the wheat dough were measured using an extensograph and the shelf life was recorded from samples preserved in an Incobatore. Sardari wheat recorded lower values for 1000-seed weight, falling number,Zeleny index, protein, water absorption and rigidity, but higher gluten and hectoliter weights than for Parsi wheat. The addition of 3% xanthan significantly decreased (p < 0.05) wheat dough extensibility and significantly increased resistance-to-extension and energy. The addition of 3% kefiran to Sardari dough significantly increased (p < 0.05) resistance-to-extension (each period) and energy (in periods of 45 and 90 min) over the Parsi wheat and significantly decreased (p < 0.05) extensibility in both wheat doughs. The results of staling tests done at 24, 48 and 72 h showed that the addition of 3% kefiran and 3% xanthan significantly decreased crumb staling (p < 0.05). The addition of 3% xanthan decreased staling and increased hardness over the control samples. The addition of 3% kefiran and 3% xanthan extended the shelf life of Parsi wheat bread by 13 and 11 d, respectively, and the shelf life of Sardari wheat bread by 12 and 10 d, respectively.