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1.  Optimization of Effective Minerals on Riboflavin Production by Bacillus subtilis subsp. subtilis ATCC 6051 Using Statistical Designs 
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.
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.
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.
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.  Effect of Lactobacillus casei- casei and Lactobacillus reuteri on acrylamide formation in flat bread and Bread roll 
The aim of this study was the evaluation of fermentation by lactic acid bacteria (LAB) contains lactobacillus (L.) casei- casei and L. reuteri on acrylamide formation and physicochemical properties of the Iranian flat bread named, Sangak, and Bread roll. Sangak and Bread roll were made with whole and white wheat flour, respectively. Whole-wheat flour had upper content of protein, sugar, ash, fiber, damaged starch and the activity of amylase than the white wheat flour. After 24 h of fermentation, the pH values of the sourdoughs made from whole-wheat flour (3.00, 2.90) were lower, in compared to sourdoughs prepared from white wheat flour (3.60, 3.58). In addition, in Sangak bread, glucose, and fructose were completely utilized after fermentation, but in bread roll, the reduced sugar levels increased after fermentation and baking that represent microorganisms cannot be activated and utilized sugars. Acrylamide formation was impacted by pH of sourdough and total reducing sugar (r = 0.915, r = 0.885 respectively). Bread roll and Sangak bread were fermented by L. casei- casei contained lowest acrylamide content, in two bread types (219.1, 104.3 μg/kg respectively). As an important result, the acrylamide content of Sangak bread in all cases was lower than in the Bread roll.
PMCID: PMC4984696  PMID: 27570278
Fermentation; Sourdough; Fiber; Bread roll; Sangak bread
3.  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.
PMCID: PMC4375191  PMID: 25829629
Probiotic yogurt; Fat; Inulin; Proteolysis; ACE-inhibitory activity; IC50
4.  Recent developments on new formulations based on nutrient-dense ingredients for the production of healthy-functional bread: a review 
Journal of Food Science and Technology  2012;51(11):2896-2906.
Bread is one of the oldest functional foods which its health effects have been investigated in many studies. The current communication presents a review of published studies in recent years on the topic and looks at possible future trends in the improved nutritional and health qualities which have been applied in the bakery industry, directing it further to the formulation design and production of functional breads. The results show that many beneficial ingredients such as dietary fibers, phenolic antioxidants, marine ingredients, and n-3 fatty acids can be used in the bread industry to increase its functionality and result in healthy products, low in calories, cholesterol and celiac disease. Moreover, the use of psyllium seed, amaranth seed, chestnut flour and prebiotics in gluten-free bread (GFB) baking may be the promising frontier to improve overall appearance, quality, sensory properties, and shelf-life of GFB.
PMCID: PMC4571229  PMID: 26396285
Functional bread; Nutritional fibers; Antioxidants; Gluten free bread
5.  Stabilization of canthaxanthin produced by Dietzia natronolimnaea HS-1 with spray drying microencapsulation 
The strain bacterium Dietzia natronolimnaea has propounded as a source for biological production of canthaxanthin. Because of sensitivity of this pigment, examine on its stability is important. In this study, stability of encapsulated canthaxanthin from D. natronolimnaea HS-1 using soluble soybean polysaccharide (SSPS), gum acacia (GA), and maltodextrin (MD) as wall materials was investigated at 4, 25, and 45 °C in light and dark conditions during 4 months of storage. It was shown that the type of walls influenced the size of emulsion droplets; spray dried particles, microencapsulation efficiency (ME), and retention of canthaxanthin in microcapsules. SSPS and MD produced the smallest and the biggest emulsion droplets and spray dried particles, respectively. Microcapsules made with SSPS resulted in better ME and higher stability for canthaxanthin. Samples were degraded in all conditions, especially in light and 45 °C. Degradation of microencapsulated canthaxanthin with SSPS and GA proceeded more slowly than did with MD. Regardless of the type of wall materials, total canthaxanthin contents of the microencapsulated products decreased by an increase in time or temperature. Also, samples exposed to light indicated less stability at 4 and 25 °C when compared to the storage at dark conditions. According to the results of this study, SSPS can be considered as potential wall material for the encapsulation of carotenoids.
PMCID: PMC4152546  PMID: 25190874
Microencapsulation; Canthaxanthin; Dietzia natronolimnaea; Spray drying
6.  Canthaxanthin biosynthesis by Dietzia natronolimnaea HS-1: effects of inoculation and aeration rate 
Brazilian Journal of Microbiology  2014;45(2):447-456.
The interest in production of natural colorants by microbial fermentation has been currently increased. The effects of D-glucose concentration (3.18–36.82 g/L), inoculum size (12.5 × 109–49.5 × 109 cfu cells/mL) and air-flow rate (1.95–12.05 L/L min) on the biomass, total carotenoid and canthaxanthin (CTX) accumulation of Dietzia natronolimnaea HS-1 in a batch bioreactor was scrutinized using a response surface methodology-central composite rotatable design (RSM-CCRD). Second-order polynomial models with high R2 values ranging from 0.978 to 0.990 were developed for the studied responses using multiple linear regression analysis. The models showed the maximum cumulative amounts of biomass (7.85 g/L), total carotenoid (5.48 mg/L) and CTX (4.99 mg/L) could be achieved at 23.38 g/L of D-glucose, 31.2 × 109 cfu cells/mL of inoculation intensity and air-flow rate of 7.85 L/L min. The predicted values for optimum conditions were in good agreement with experimental data.
PMCID: PMC4166268  PMID: 25242927
Dietzia; microbial canthaxanthin; batch bioreactor; response surface methodology; modeling

Results 1-6 (6)