ABSTRACT
The present study aimed at examining whether the microencapsulation of Lactobacillus acidophilus LA-5 and Bifidobacterium animalis BB-12 inside hydrogels could prolong their survival in freeze-drying conditions, stored at 4â and in the gastrointestinal medium. Microencapsulation was performed by emulsion with a syringe, while sodium alginate and high methoxyl pectin were used as a carrier material. A relatively high efficiency of encapsulation was obtained (>92%). Z-Average and pdI in samples were not significant (p < .05). In different treatments, changes in the number of bacteria after freeze-drying, 30 days of storage, and gastrointestinal conditions, compared to each other, were significant (p < .05). However, the survival rate after a reduction during storage was higher than 106 cfu/g, indicating the suitability of the microencapsulation process. The surface of microcapsules observed by a scanning electron microscope (SEM) confirmed the success of encapsulation. Finally, a lower decrease in the count of microencapsulated was observed in comparison to the free cells.
ABSTRACT
This study was aimed to optimize the production of bacterial cellulose (BC) by Komagataeibacter xylinus PTCC 1734 using mixture of date syrup and cheese whey as carbon sources as well as ascorbic acid as a supplementary agent and to characterize the properties of produced BC. The results showed the highest BC production on the 10th day. The 50:50 ratio of date syrup and cheese whey lead to the highest BC production. Three samples were selected in optimal cultivation conditions until the 10th day, with different ascorbic acid concentrations (0, 0.1 and 0.4%). SEM results showed no difference in the morphology of BC product in the optimal samples, where the average diameter of cellulose nanofibers produced was in the range of nanometer. The FTIR test results showed no difference in the chemical structure of cellulose product in different ascorbic acid concentrations. According to XRD and TGA analyses, the highest degree of BC crystallinity and thermal resistance was obtained at maximum ascorbic acid concentration (0.04%). Consequently, the 50:50 ratio of date syrup and cheese whey and 10th day of fermentation time were selected as the best conditions for BC production. Though ascorbic acid reduced production efficiency, it improved the physical properties of the BC product.
ABSTRACT
The purpose of this study was to optimize the functional properties of probiotic Ayran. Two-level fractional factorial design with four center points was used to investigate the effect of five independent variables including, reconstructed whey protein (70-90% of milk), salt (0.5-1 g/100 g), Aloe vera gel (0-30 g/100 g), transglutaminase enzyme (0-14 unit/100 g) and storage time (1-21 days). The viability of Lactobacillus acidophilus La-5 and other physicochemical properties such as pH, acidity, viscosity, sedimentation, and color were modeled and then optimized using desirability function method. Results showed that reconstructed whey protein and Aloe vera gel significantly affected the viability of L. acidophilus La-5 and other physicochemical properties (p < 0.05). The viability of L. acidophilus La-5 and viscosity decreased by increasing of whey protein percentage from 70 to 90. Maximum L. acidophilus La-5 count was observed in samples with a minimum level of whey protein and maximum level of Aloe vera gel. Milk replacement with whey protein up to 90% caused to decrease acidity and viscosity significantly but sedimentation increased (p < 0.05). Optimum condition for production of functional Ayran determined as follow: Aloe vera gel concentration: 25.7%, reconstructed whey protein: 70%, salt: 0.58% and transglutaminase enzyme: 5 unit/100 mL.
ABSTRACT
In the present study, vinasse was used to produce bacterial cellulose (BC) by Komagatacibacter xylinus PTCC 1734. Central composite design (CCD) was utilized to evaluate the effects of vinasse concentration (%) and incubation time (Day) on different responses such as thickness as well as wet and dry weights of the produced BC membrane. The increase of vinasse concentration and incubation time caused an increase in the wet weight of BC; however, thickness decreased by increasing incubation time. The BC produced at the optimized conditions (40% vinasse and 10â¯days) was characterized and compared with the BC produced in Hestrin-Schramm medium as a control medium. Scanning electron microscopy (SEM) confirmed 3D network structure of BC. The average diameter of fibrils was in the range of 30-120â¯nm. In addition, the Fourier transform infrared spectroscopy (FT-IR) showed completely similar spectrum for both optimal and control samples. The X-ray diffraction (XRD) analysis approved the crystalline structure of the produced BC. Furthermore, the thermogravimetric analysis (TGA) test revealed no difference in the thermal stability of the optimum and control sample. According to the results, the vinasse, as a by-product, could be used as a cheap and suitable carbon source for the production of BC.
Subject(s)
Acetobacteraceae/growth & development , Acetobacteraceae/metabolism , Biotechnology/economics , Biotechnology/methods , Cellulose/biosynthesis , Costs and Cost Analysis , Culture Media/chemistry , Cellulose/chemistry , Molecular Weight , Temperature , Waste ProductsABSTRACT
In the present study, the effects of different ratios of milk phospholipids, cholesterol and phytosterols (Campesterol) powder (50-100%, 0-50%, and 0-50%, respectively) and sonication time (20, 25, 30, 35 and 40 min) were investigated to produce a new formulation of nanoliposomes for encapsulation of vitamin C. The results showed that increasing the time of sonication and decreasing the ratio of phospholipid to phytosterol significantly decreased nanoliposomes' particle size (p < 0.05). The maximum encapsulation efficiency was obtained at 35 and 40 min of sonication time and 75-25 ratio of phospholipid: phytosterol. Also, reducing the sonication time in the same ratio of phospholipid/phytosterol caused to increase the controlled release. The highest stability of vitamin C during 20 days was obtained in the ratio of 75-25 (phospholipids: campesterol). The results showed a positive effect of cholesterol replacement with campesterol on encapsulation efficiency, control release and stability of vitamin C in nanoliposomes.
ABSTRACT
In this study, the most important variables (incubation temperature, fermentation time and yeast extract concentration) responsible for the exopolysaccharides (EPSs) production by Lactobacillus acidophilus LA5 and Bifidobacterium animalis subsp. lactis BB12 were screened. The EPSs synthesize by LA5, BB12, and their co-culture were successfully optimized and were 349.82⯱â¯5.39, 146.83⯱â¯3.99 and 187.02⯱â¯1.54â¯mg/L, respectively. GC-MS analysis indicated that the purified EPSs are heteropolysaccharide and consisted of glucose, galactose, glucuronic acid, and xylose. The FT-IR analysis was used to investigate functional groups of purified EPSs and NMR analysis was used to study the structure of them. The DSC, TGA and DTG analysis of the extracted EPSs showed that they had high thermal stability and degradation temperature. The results of bioactivity analysis indicated that maximum DPPH and hydroxyl radicals scavenging activity were 59.30⯱â¯1.95, 56.76⯱â¯0.79, 62.33⯱â¯1.02% and 59.94⯱â¯1.68, 46.40⯱â¯0.73, 53.54⯱â¯0.76%, respectively for the EPSs of LA5, BB12, and their co-culture. Additionally, reducing power of the produced EPSs by LA5, BB12, and their co-culture were 1.047⯱â¯0.001, 1.270⯱â¯0.045 and 1.139⯱â¯0.018, respectively. Consequently, all these results showed that the EPSs produced by LA5, BB12, and their co-culture had a high potential as natural antioxidants or bioactive additive in the food industry.
