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1.  Optimization of Effective Minerals on Riboflavin Production by Bacillus subtilis subsp. subtilis ATCC 6051 Using Statistical Designs 
Background:
Riboflavin (vitamin B2) is an essential component of the basic metabolism, and an important nutritional and growth factor in humans, animals, plants and micro-organisms. It has been widely used in the fields of pharmaceuticals, feed and food additives. The industrial production of riboflavin mostly relies on the microbial fermentation. Designing an appropriate fermentation medium is of crucial importance to improve the riboflavin production.
Methods:
In this study, sequential methodology combining a screening test of minerals by Plackett-Burman (PB) and an optimization test by Central Composite Design (CCD) was applied to enhance riboflavin production by Bacillus subtilis ATCC 6051 in shake flasks.
Results:
Initially, one-factor-at-a-time approach was applied to evaluate the effect of different carbon sources. The results showed that fructose was significantly most effective on biomass and riboflavin production. After that, 13 minerals [CaCl2, CuCl, FeCl3, FeSO4, AlCl3, Na3MoO4, Co(NO3)2, NaCl, KH2PO4, K2HPO4, MgSO4, ZnSO4, and MnSO4] were studied with the screening test. The results revealed that concentration of MgSO4, K2HPO4, and FeSO4 had greater influence on riboflavin production (p< 0.05). A CCD with five factors (concentration of fructose, MgSO4, K2HPO4, FeSO4, and yeast extract) at five levels was then used to determine the maximum riboflavin concentration. The optimal concentrations (g/l) of these variables determined by Response Surface Methodology (RSM) were fructose, 38.10; MgSO4, 0.85; K2HPO4, 2.27; FeSO4, 0.02; and yeast extract, 4.37.
Conclusion:
Statistical experimental design offers a practicable approach to the implementation of medium optimization. From an industrial view point, our optimum medium, besides fructose and a small amount of yeast extract, is mainly composed of common and cheap inorganic salts, which are available to the industrial riboflavin production.
PMCID: PMC5742654
Bacillus subtilis ATCC 6051; Minerals; Riboflavin
2.  Modification of functional properties of pullulan–whey protein bionanocomposite films with nanoclay 
In this study, biodegradable nanocomposite film composed of pullulan – whey protein isolate (WPI) – montmorillonite (MMT) were developed and characterized as a function of incorporating various amounts of MMT nanoparticles (0, 1, 3 and 5 % wt). Results showed that the water-vapor permeability, moisture content, moisture absorption and water solubility decreased when the nano-MMT content was increased. Tensile strength improved and elongation at break simultaneously decreased with increasing MMT content. The glass transition temperature (Tg(and melting-point temperature (Tm) increased with increasing nano-MMT content. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis revealed uniform distribution of MMT into the polymer matrix. Atomic force microscopy (AFM) showed enhancement of films’ roughness with increasing MMT content.
doi:10.1007/s13197-015-1778-3
PMCID: PMC4837720  PMID: 27162410
Whey protein; Pullulan; Nano clay; Nanocomposite; Film
3.  Total phenolic content and antioxidant activities of pomegranate juice and whey based novel beverage fermented by kefir grains 
Mixture of pomegranate juice and whey was evaluated as a potential substrate for production of a novel beverage by kefir grains. The effects of two different variables, fermentation, temperature (19 and 25 °C) and kefir grain amount (5 %w/v and 8 %w/v), on total phenolic content (TPC) and antioxidant activities of beverage were examined during a fermentation time of 32 h. TPC and antioxidant activities including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power, inhibition effect upon linoleic acid autoxidation and inhibition effect upon ascorbate autoxidation increased significantly (p < 0.05) during fermentation, but metal chelating effect showed no significant difference. The highest increases were observed when the temperature of 25 °C and kefir grain amount of 8 %w/v were applied. Results proved antioxidant activities of beverages were desirable and fermentation by kefir grains has the ability to enhance these antioxidant activities, as compared with unfermented beverage. Also pomegranate juice and whey were suitable media for producing a novel dairy-juice beverage.
doi:10.1007/s13197-015-2029-3
PMCID: PMC4711455  PMID: 26787994
Pomegranate juice; Whey; Kefir grain; Fermentation; Total phenolic content; Antioxidant activity
4.  Development of a novel yoghurt based on date liquid sugar: physicochemical and sensory characterization 
Journal of Food Science and Technology  2015;52(10):6583-6590.
The addition effect of date liquid sugar (DLS, 1–9 % v/v) to yoghurt milk on the physical (colour, firmness and syneresis), chemical (pH, total titratable acidity (TTA), total phenolic content (TPC) and antioxidant activity), rheological (viscosity and flow behaviour), and sensory attributes was scrutinized. Results showed that the pH value decreased by increasing DLS concentration from 1 to 6 %, while the TTA decreased with an increase in DLS from 6 to 9 % (p < 0.05). The whey syneresis, firmness and viscosity values were considerably influenced by the DLS content and acidity of the yoghurts (p < 0.05). A noticeable increase in antioxidant activity and TPC was found by the increasing DLS content (p < 0.05). Yoghurts containing 6 % v/v DLS also had the lowest syneresis and the highest firmness among the different samples. Moreover, a pseudoplastic rheological behaviour was detected for all the produced yoghurts. An increase in DLS concentration of manufactured yoghurts led to an increase in a, b and total colour difference (TCD) values and a decrease in L value (p < 0.05). The sensory evaluation revealed that there was no significant different in the colour scores. However, the used panelists determined the yoghurt supplemented with 6 % DLS had the highest scores for other investigated attributes.
doi:10.1007/s13197-015-1716-4
PMCID: PMC4573096  PMID: 26396404
Fruit-flavoured yoghurt; Date liquid sugar; Syneresis; Quality physicochemical properties; Sensory evaluation
5.  Bioconversion enhancement of conjugated linoleic acid by Lactobacillus plantarum using the culture media manipulation and numerical optimization 
The ability of different Lactobacillus strains to produce conjugated linoleic acid (CLA) from linoleic acid was evaluated. Preliminary experiments revealed that L. plantarum among the screened strains had the highest CLA-producing potential (95.25 μg/mL). The cell growth of this bacterium was studied in three media of MRS broth, skim milk and skim milk supplemented with yeast extract and glucose. Results showed that the use of yeast extract and glucose could significantly increase the cell growth and CLA production. Response surface methodology (RSM) was applied to investigate the effects of three independent variables; linoleic acid (LA), yeast extract concentrations and inoculum size on the CLA formation. A second-order polynomial model with high R2 value (0.981) was developed using multiple linear regression analysis. The optimum conditions to achieve the highest CLA production (240.69 μg/mL) was obtained using 3 mg/mL LA, 4 g/L yeast extract and inoculum size of 4 % v/v. CLA concentration of the optimal sample was analyzed by Gas Chromatography (GC). The cis-9, trans-11 CLA was the major CLA isomer of total CLA detected.
doi:10.1007/s13197-014-1699-6
PMCID: PMC4554656  PMID: 26344992
Probiotic lactic bacteria; Conjugated linoleic acid; Biotransformation; Response surface optimization
6.  Optimization of processing conditions to improve antioxidant activities of apple juice and whey based novel beverage fermented by kefir grains 
A central composite design (CCD) was used to evaluate the effects of fermentation temperature (20–30 ºC) and kefir grains amount (2–8%w/v) on total phenolic content and antioxidant activities of apple juice and whey based novel beverage fermented by kefir grains. The response surface methodology (RSM) showed that the significant second-order polynomial regression equation with high R2 (>0.86) was successfully fitted for all response as function of independent variable. The overall optimum region was found to be at the combined level of 7.56%w/v kefir grains and temperature of 24.82 ºC with the highest value for total phenolic content (TPC) and antioxidant activities. At this optimum point TPC, 1, 1-Diphenyl-2-picrylhydrazyl radical scavenging, metal chelating effect, reducing power, inhibition of linoleic acid autoxidation and inhibition of ascorbate autoxidation were 165.02 mgGA/l, 0.38 ml/1 ml, 0.757 (absorbance at 700 nm), 46.12 %, 65.33 % and 21 %, respectively. No significant difference (p < 0.05) was found between actual values and predicated values.
doi:10.1007/s13197-014-1397-4
PMCID: PMC4444860  PMID: 26028723
Apple juice; Whey; Kefir; Fermentation; Total phenolic content; Antioxidant activities
7.  Characterization of the new biodegradable WPI/clay nanocomposite films based on kefiran exopolysaccharide 
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.
Electronic supplementary material
The online version of this article (doi:10.1007/s13197-014-1407-6) contains supplementary material, which is available to authorized users.
doi:10.1007/s13197-014-1407-6
PMCID: PMC4444900  PMID: 26028730
Kefiran; Nanocomposite films; Whey protein isolate; Mechanical properties; X-ray diffraction
8.  Characterization of pomegranate juice and whey based novel beverage fermented by kefir grains 
Mixture of pomegranate juice and whey was evaluated as a potential substrate for production of a novel probiotic beverage by kefir grains. Different fermentation conditions were used as viz: two fermentation temperature (19 ºC and 25 ºC) and two levels of kefir grains inoculum (5 % and 8%w/v). pH, acidity, lactose consumption as well as organic acids formation were determined during 32 hours of fermentation. Results showed that kefir grains were able to utilize lactose and decrease pH, increase acidity, produce lactic acid and acetic acid, while the level of citric acid decreased. It was observed these change depended on temperature and level of kefir grains with the highest changes at the temperature of 25 ºC and kefir grains inoculum of 8%w/v. Pomegranate juice and whey mixture therefore may serve as a suitable substrate for the production of novel probiotic dairy-fruit juice beverage by kefir grains and the sensory characteristics of this beverage were shown desirable results.
doi:10.1007/s13197-014-1412-9
PMCID: PMC4444931  PMID: 26028755
Kefir; Fermentation; Pomegranate juice; Whey
9.  Proteolytic and ACE-inhibitory activities of probiotic yogurt containing non-viable bacteria as affected by different levels of fat, inulin and starter culture 
In this study, the effects of fat (0.5 %, 3.2 % and 5.0 %), inulin (0.0 and 1.0 %) and starter culture (0.0 %, 0.5 %, 1.0 % and 1.5 %) on the angiotensin converting enzyme (ACE)-inhibitory activity of probiotic yogurt containing non-viable bacteria were assessed. Proteolytic activities of bacteria were also investigated. Yogurts were prepared either using a sole yogurt commercial culture including Streptococcus thermophilus and Lactobacillus delbrueckii subs. bulgaricus or bifidobacterium animalis BB-12 and Lactobacillus acidophilus La5 in addition to yogurt culture. Relative degrees of proteolysis were found to be considerably higher in yogurt samples than UHT milk as the control. Both regular and probiotic yogurts showed considerable ACE-inhibitory activities. Results showed that degree of proteolysis was not influenced by different fat contents, while was increased by high concentration of starter culture (1.5 % w/w) and reduced by inulin (1 % w/w). ACE-inhibitory activities of yogurt were also negatively affected by the presence of inulin and high levels of fat (5 % w/w). Moreover, yogurt containing probiotic bacteria showed higher inhibitory against ACE in comparison to the yogurt prepared with non-probiotic strains.
doi:10.1007/s13197-013-1202-9
PMCID: PMC4375191  PMID: 25829629
Probiotic yogurt; Fat; Inulin; Proteolysis; ACE-inhibitory activity; IC50
10.  Effect of ultrasound assisted extraction upon the Genistin and Daidzin contents of resultant soymilk 
Journal of Food Science and Technology  2012;51(10):2857-2861.
The purpose of this study was to determine the effect of ultrasound treatment on the contents of daidzin, genistin, and their respective aglycones, daidzein and genistein, in resultant soymilk. Soybean slurry was exposed to ultrasound treatment, filtered, and placed in an ultrasound cleaning bath set with different frequencies (35and 130 KHz), treatment temperatures (20 and 40 °C), and times (20, 40, and 60 min). Concentrations for these isoflavones were determined using reverse-phase high-performance liquid chromatography. Results indicated that both frequencies significantly (p < 0.05) increased isoflavone content (IC), glycosides, and aglycones in extracted soymilk. These results were attributed to induced cavitation, which increases the permeability of plant tissues. However, the frequency of 35 kHz caused a noticeably higher increase in IC than 130 kHz. Results also revealed significant increases in IC with increased sonication time (from 20 to 60 min) and with increased temperature (from 20 to 40 °C).
doi:10.1007/s13197-012-0744-6
PMCID: PMC4190193  PMID: 25328238
Soymilk; Ultrasound; Isoflavones; Daidzin; Genistin; Daidzein; Genistein
11.  Modelling of aflatoxin G1 reduction by kefir grain using response surface methodology 
Aflatoxin G1 (AFG1) is one of the main toxic contaminants in pistachio nuts and causes potential health hazards. Hence, AFG1 reduction is one of the main concerns in food safety. Kefir-grains contain symbiotic association of microorganisms well known for their aflatoxin decontamination effects. In this study, a central composite design (CCD) using response surface methodology (RSM) was applied to develop a model in order to predict AFG1 reduction in pistachio nuts by kefir-grain (already heated at 70 and 110°C). The independent variables were: toxin concentration (X1: 5, 10, 15, 20 and 25 ng/g), kefir-grain level (X2: 5, 10, 20, 10 and 25%), contact time (X3: 0, 2, 4, 6 and 8 h), and incubation temperature (X4: 20, 30, 40, 50 and 60°C). There was a significant reduction in AFG1 (p < 0.05) when pre-heat-treated kefir-grain used. The variables including X1, X3 and the interactions between X2-X4 as well as X3-X4 have significant effects on AFG1 reduction. The model provided a good prediction of AFG1 reduction under the assay conditions. Optimization was used to enhance the efficiency of kefir-grain on AFG1 reduction. The optimum conditions for the highest AFG1 reduction (96.8%) were predicted by the model as follows: toxin concentration = 20 ng/g, kefir-grain level = 10%, contact time = 6 h, and incubation temperature = 30°C which validated practically in six replications.
doi:10.1186/s40201-015-0190-2
PMCID: PMC4445940  PMID: 26019874
Aflatoxin G1; Pistachio nut; Predictive modelling; Kefir-grain; Optimization
12.  Determination and characterization of kernel biochemical composition and functional compounds of Persian walnut oil 
Kernel chemical composition and fatty acids profile of three walnut cultivars (Toyserkan, Chaboksar and Karaj) was analyzed. Some physicochemical properties, total phenolics content (TPC), ortho-diphenols content (ODC) and total tocopherol concentration (TTC) of extracted oils from the walnuts were also determined. The antioxidant activity of oil was measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity and β-carotene bleaching assays. The analysis of chemical composition revealed that protein and dietary fiber was highest in Toyserkan cultivar. Phosphorus was the most abundant element in the walnut kernels, followed by potassium, magnesium and calcium. The linoleic acid and linolenic contents ranged from 50.15% to 51.36% and 10.48% to 12.04%, respectively. Also, the results demonstrated that acid value, saponification value and viscosity of extracted oil had significantly varied between all cultivars. The extracted oil from Chaboksar cultivar illustrated more hydro peroxides and secondary products than those obtained from other cultivars. A positive correlation was found between Rancimat values and oleic acid content (r = 0.60), but considerably negative correlation with TTC (r = −0.81) and TPC (r = −0.92). The relationship between percentage of remaining DPPH radical and β-carotene of walnut oils showed high correlation among three selected cultivars (r = −0.94 to −0.97).
doi:10.1007/s13197-011-0481-2
PMCID: PMC3857422  PMID: 24426045
Antioxidant activity; Fatty acid profile; Juglans regia L.; Mineral content; Oil analysis; Phenolic compounds; Physicochemical properties; Proximate composition

Results 1-12 (12)