Lyophilized royal jelly preparation in nanoscale and evaluation of its physicochemical properties and bactericidal activity.

Royal jelly, due to its unique bioactive components, has special biological activities, but a great extent of its nutritional value is lost during processing and storage. Lyophilization, an effective preservation technique, can feasibly preserve the main bioactive compounds present in royal jelly. In this study, fresh royal jelly was subjected to the freeze-drying process at a pressure and temperature of 100 Pa and - 70°C, respectively, for 40 h. The results obtained indicated that the pH, turbidity, total phenol content, and antioxidant activity of the royal jelly powder (RJP), during 3 months of storage at ambient temperature (30°C), were constant with values of 4.30, 1.634 (%A.U.), 0.617 (g/L), and 28.7 (%), respectively. Moisture content of the prepared RJP was less than 1%, while that of the fresh royal jelly was 70%. Furthermore, for the fresh royal jelly, the mentioned parameters were significantly (p < .05) decreased after 2 months of storage at freezer temperature (-20°C). GC-MS analysis indicated that the amount of 10-hydroxy-2-decanoic acid (10H2DA) in RJP was 3.85 times more than that of fresh royal jelly. The obtained results also indicated that prepared RJP had a high bactericidal effect toward Escherichia coli and Staphylococcus aureus, with clear zone diameters of 12 and 15 mm, respectively. The present study provides a foundation for research on the potential application of prepared RJP and the development of dietary supplements and functional foods.

Onion Essential Oil-in-Water Emulsion as a Food Flavoring Agent: Effect of Environmental Stress on Physical Properties and Antibacterial Activity.

Plant essential oils (EOs), which are acknowledged as generally recognized as safe (GRAS) by the Food and Drug Administration (FDA), have the potential to be used as a flavoring agent. However, there are limitations to some EOs, such as low water solubility and high volatility, which limit their application in food technology. This study was conducted to develop onion (Allium cepa) EO as a flavoring agent and determine its stability against environmental stress via an emulsification technique, with different concentrations of sodium caseinate, as a delivery system. Emulsions containing onion EO were prepared using different concentrations of sodium caseinate (3, 5, and 7% w/w) via the solvent-displacement technique. The physical properties (average droplet size, color, turbidity, and stability measurement) and antibacterial activity (agar disk diffusion method) of emulsions were then determined. Results show that emulsion with 7% (w/w) sodium caseinate was the most desirable sample in terms of physical properties and antibacterial activity. Hence, it was selected for environmental stress studies (i.e., thermal processing, freeze-thaw cycles, and ultraviolet (UV) exposure). Results revealed that all types of environmental stresses had significant (p < 0.05) effects on droplet size, color, turbidity, and stability. Generally, the environmental stresses increased the droplet size except in the freeze-thaw cycle case, while all stresses decreased the stability and lightness. All types of environmental stress treatment did not show a significant (p < 0.05) effect on antibacterial activity enhancement against Salmonella Typhimurium and Listeria monocytogenes except in the case of UV treatment against L. monocytogenes. Therefore, the present work has demonstrated the potential use of emulsion as an encapsulation and delivery system of EO flavors for food applications.

Biogenic synthesis of gold nanoparticles using Artemia urumiana extract and five different thermal accelerated techniques: fabrication and characterization.

Artemia urumiana is bisexual population of the Lake Urmia of Iran. Its biomass was freeze dried and using its lyophilized powder, hydro-alcoholic extract was prepared and utilized in gold nanoparticles (Au NPs) synthesis. Six different Au NPs fabrication methods namely: microwave heating, hydrothermal, ultraviolet (UV) irradiation, ultrasonication, common heating using conventional heating, and self-assembling were utilized for Au NPs synthesis using A. urumiana extract. Gas chromatography analysis indicated that the prepared extract were contained numerous fatty acid methyl esters such as Hexadecanoic acid methyl ester. Results indicated that the formed NPs using heater and stirrer, and UV irradiation had minimum particle size of 25 and 94 nm, respectively. However, as compared to the formed Au NPs using heater and stirrer technique, UV irradiation fabricated Au NPs with high zeta potential value of -32.5 mV and small polydispersity value of 0.310. Results also demonstrated that the synthesized Au NPs using heater and stirrers, and UV irradiation had highest antioxidant activities of 13.7 and 11.9%, and bactericidal effects against Escherichia coli and Staphylococcus aurous bacteria strains, as compared to other fabricated Au NPs using other methods. There were insignificant (p > 0.05) differences between these two attributes of the formed Au NPs.

Nanoliposomal thyme (Thymus vulgaris) essential oil: Effects of formulation parameters.

Essential oils with antimicrobial or antioxidant activities have received extensive attention among customers, manufacturers, and food scientists, especially with rising worries about the safety of synthetic food preservatives. However, like other functional lipid compounds their incorporation into aqueous systems is challenging, due to their less water solubility. Furthermore, their susceptibility to light, moisture, heat, and oxygen origins their less chemical and structural stabilities. Consequently, the present research was aimed to encapsulate the thyme essential oil into nanoliposomes, using a thin layer hydration-sonication technique, which can be a proficient solution for revealed problems. The effects of phospholipid and stabilizing agents' concentrations, namely, lecithin, cholesterol, and glycerol, as main formulation parameters were investigated on characteristics of gained nanoliposomes, using a response surface method. Various empirical models were also developed to predict product characteristics by changing the formulation parameters. According to the numerical multiple optimizations, the best thyme oil nanoliposomes can be gained using equal concentrations of all three components as 1% with a mean particle size of 189.6 nm, PDI of 0.3487, the net zeta-potential of 42.48 mV, and DPPH radical scavenging of 12.72%. The prepared nanoliposomes had acceptable physical but limited chemical stabilities. The antibacterial action of manufactured essential oil nanoliposomes against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus has made them efficient candidates as natural food preservatives.

Developing three-component ginger-cinnamon-cardamom composite essential oil nanoemulsion as natural food preservatives.

Plant-based functional lipid ingredients, such as essential oils, with antioxidant and antibacterial activities, have gained substantial attention in food, cosmetic, and pharmaceutical formulations due to the increasing disquiet about the risks of artificial preservatives. However, similar to other lipid-based bioactives, their application in water-based products is challenging owing to their low water solubility and high chemical instability, especially during exposure to light, heat, moisture, and oxygen. Hence, the incorporation of essential oils into water-dispersible nanoemulsion systems can effectively address these issues. Moreover, combining various essential oils can synergistically enhance their chemical and biological properties. Consequently, the objective of this study was to develop different composite nanoemulsion systems using ginger, cinnamon, and cardamom essential oils, which were considered individually and in binary and ternary combinations. Empirical models to predict the response characteristics based on the proportions of oil phase components were also derived. The numerical multi-goal optimisation analysis suggested that 10 % ginger, 68 % cinnamon, and 22 % cardamom essential oil is the ideal oil phase combination to achieve nanoemulsions with the smallest average particle size and size distribution and the highest zeta potential and antioxidant and antibacterial activity.

Effects of rotation speed and time, as solvent removal parameters, on the physico-chemical properties of prepared α-tocopherol nanoemulsions using solvent-displacement technique.

A bottom-up approach based on solvent-displacement technique was used to prepare α-tocopherol nanoemulsions. Effects of two main evaporation parameters namely, rotation speed (1 × 10-9 × 10 rpm) and rotation time (5-15 min) of utilized vacuum rotary evaporator, on the mean particle size, polydispersity index (PDI) and α-tocopherol degradation of the formed nanodroplets were evaluated using response surface methodology. Obtained results suggested three polynomial regression models for predicting the studied response variables' affected by selected evaporation parameters. Relatively high coefficients of determination for suggested models (> 0.7839) confirmed the suitability of the generated models. Multiple-optimization procedure revealed that the optimum amounts of evaporation speed and time were 30 rpm and 10 min, respectively, which in that, prepared spherical α-tocopherol nanoemulsions had mean particle size, PDI and concentration values of 48.9 nm, 0.232 and 358.7 mg/L, respectively.

Optimization the formulation parameters in preparation of α-tocopherol nanodispersions using low-energy solvent displacement technique.

α-Tocopherol is the main compound of vitamin E with great antioxidant activity. However, like other functional lipid bioactive compounds, it suffers from low bioavailability due to its low water solubility and liable chemical structure. A bottom-up procedure based on a solvent-displacement method was constructed for fabrication of α-tocopherol nanodispersions using response surface methodology (RSM). The effects of main formulation parameters, namely, weight ratio of emulsifier to α-tocopherol and volumetric percent of acetone to water on the average particle size (nm), polydispersity index, concentration of α-tocopherol loss (% w/w) and turbidity of the nanodispersions were evaluated and optimized to gain the most desirable nanodispersions (least particle size, polydispersity index, turbidity and highest α-tocopherol concentrations). Second order regression equations, holding quite high coefficients of determination (R2 and adjusted R2 > 0.882), were significantly (p-value < 0.05) fitted for predicting the α-tocopherol nanodispersion characteristics variations as functions of studied formulation parameters. A multiple optimization analysis offered 6.5 and 10% for weight ratio of Tween 20 to α-tocopherol and volume percent of acetone, respectively, as overall optimum values for studied parameters. Statistically insignificant differences between experimental and predicted values of studied responses, verified the satisfactoriness of presented models for explaining the response characteristics as a function of formulation parameters. Thus, the employed solvent-displacement technique may provide the most desired water dispersible α-tocopherol nanoparticles for several water-based foods, cosmetic nutraceutical formulations.

Preparation and characterization of α-tocopherol nanocapsules based on gum Arabic-stabilized nanoemulsions.

The preparation of water dispersed α-tocopherol nanocapsules through solvent-displacement technique using gum Arabic (GA) as natural stabilizing and emulsifying biopolymer, for a first time was aimed in current research. The effects of GA concentrations on physicochemical and biological characteristics of prepared nanocapsules, namely, mean particle size, size distribution, zeta potential, rheological properties, turbidity, in vitro antioxidant activity and cellular uptake were evaluated, subsequently. The result indicated that the mono modal size distributed water dispersible α-tocopherol nanocapsules could be successfully attained using selected technique in sizes ranged from 10.01 to 171.2 nm and zeta potential of - 13.5 to - 47.8 mv. The prepared nanocapsules showed the dilatant rheological properties and acceptable radical scavenging (antioxidant activity). The cellular uptake of samples were increased up to 12 times more than microsized α-tocopherol. Consequently, the prepared water dispersed nanosized α-tocopherol can effectively be used in water based food and beverage formulations as nutrition enhancer or natural preservatives.

Preparation of maltodextrin stabilized α-tocopherol nanoemulsions using solvent-displacement technique.

α-Tocopherol nanoemulsions were prepared in current research using various proportions of Polysorbate 20 and maltodextrin as binary stabilizer mixtures through solvent-displacement technique. The effects of maltodextrin proportion in stabilizer mixture, on physicochemical characteristics of gained nanoemulsions, namely average particle size, polydispersity index (PDI), zeta potential, conductivity, in vitro antioxidant activity, in vitro cellular uptake and their rheological parameters were studied. The results show that using maltodextrin, as surface active biopolymer, together with Polysorbate 20, as small molecular stabilizer, could improve the characteristics of nanoemulsions considerably. The studied characteristics of all prepared shear-thinning (pseudo-plastic) nanoemulsions were well fitted to maltodextrin proportions via various polynomial models using regression statistical analysis. Thus, applying the surface active polysaccharides as stabilizer, in nanoemulsion formulations, and tuning its proportions to general used small molecular emulsifiers, can develop more desired functional lipid such as α-tocopherol nanoemulsions for various water-based food and pharmaceutical uses.

Preparation and characterization of nanoemulsion based ß-carotene hydrogels.

The aim of this study was to develop ß-carotene hydrogels using nanoemulsions, with increased ß-carotene aqueous solubility, bioavailability and improved physical and chemical stabilities. The nanoemulsion of ß-carotene was prepared using a solvent-displacement technique and converted into hydrogels using sodium alginate as stabilizer and calcium chloride as cross-linker. The effects of formulation parameters, mainly, the effects sodium alginate and calcium chloride concentrations on the physicochemical properties of hydrogels were evaluated using a surface response methodology. The second order polynomial equations, subsequently, were suggested to predict the changes of studied physicochemical characteristics of hydrogels, with relatively high regression of coefficients values. Based on numerical multiple optimization, it was concluded that using 4.1 g/l sodium alginate and 5.7 g/l calcium chloride, resulted in a hydrogel with the most desired physicochemical characteristics. No significant differences between the measured and predicted data, reconfirmed the accuracy of the models.

ß-Carotene nanodispersions synthesis by three-component stabilizer system using mixture design.

In current research, simple centroid mixture design was applied to evaluate the interaction effects between three selected food grade stabilizers, namely, Tween 80, gelatine and pectin as stabilizing system in the formation of carotenoid nanoparticles through solvent displacement process. Both, particle size and ß-carotene loss of produced nanodispersions, as selected response factors, special cubic regression models with acceptable determination coefficient (>90%) was obtained. The multiple response optimization analysis showed that the overall optimum concentration for stabilizers will be 35% w/w Tween 80, 46% w/w gelatine and 19% w/w pectin, which led to the production of ß-carotene nanoparticles of spherical shape with minimum particle size of 155.8 nm and carotenoids loss of 25.3% w/w.

Oxygen mass transfer and shear stress effects on Pseudomonas putida BCRC 14365 growth to improve bioreactor design and performance.

In this work, the experimental evidence is presented for two basic issues including oxygen mass transfer and shear analysis on the microorganism containing medium on the most prominent sections of the bioreactor. Computational fluid dynamics (CFD) methodology reproduces shear rate values for specific impeller designs using the commercial code (Fluent 6.2). CFD calculates volumetric mass transfer coefficient based on the Higbie's penetration theory. Four types of impeller are used. The spherical probe is used to measure flow hydrodynamic parameters to obtain shear rate by electro-diffusion (ED) method. The obtained results are validated experimentally and it is shown that a fully axial pattern impeller represents more enhanced results than partially axial and radial. In this regard, experimental results for volumetric oxygen mass transfer coefficient (k l a) confirm CFD predictions by acceptable deviations of 2.65, 8.90, and 9.20 for 0.15, 0.2, and 0.3 VVM, respectively. These results collaboratively indicate that LIGHTNIN-C 200 type operates more efficiently by reflecting the flow to the bottom corner stagnation areas with the minimum tolerable shear and the most velocity distribution uniformity. Furthermore, the values of k l a improve by aeration rate. Conversely, increasing the rotational speed of impeller creates difficulties for cell growth due to the generated harsh shear condition. CFD provide a better understanding of how operational and geometrical variables may be manipulated to achieve a moderate shear rate and acceptable level of mass transfer.

Experimental and CFD-PBM Study of Oxygen Mass Transfer Coefficient in Different Impeller Configurations and Operational Conditions of a Two-Phase Partitioning Bioreactor.

In this work, gas dispersion in a two-phase partitioning bioreactor is analyzed by calculating volumetric oxygen mass transfer coefficient which is modeled using a commercial computational fluid dynamics (CFD), code FLUENT 6.2. Dispersed oxygen bubbles dynamics is based on standard "k-ε" Reynolds-averaged Navier-Stokes (RANS) model. This paper describes a three-dimensional CFD model coupled with population balance equations (PBE) in order to get more confirming results of experimental measurements. Values of k L a are obtained using dynamic gassing-out method. Using the CFD simulation, the volumetric mass transfer coefficient is calculated based on Higbie's penetration theory. Characteristics of mass transfer coefficient are investigated for five configurations of impeller and three different aeration flow rates. The pitched six blade type, due to the creation of downward flow direction, leads to higher dissolved oxygen (DO) concentrations, thereby, higher values of k L a compared with other impeller compositions. The magnitude of dissolved oxygen percentage in the aqueous phase has direct correlation with impeller speed and any increase of the aeration magnitude leads to faster saturation in shorter periods of time. Agitation speeds of 300 to 800 rpm are found to be the most effective rotational speeds for the mass transfer of oxygen in two-phase partitioning bioreactors (TPPB).

Chitosan magnetic nanoparticles for drug delivery systems.

The potential of magnetic nanoparticles (MNPs) in drug delivery systems (DDSs) is mainly related to its magnetic core and surface coating. These coatings can eliminate or minimize their aggregation under physiological conditions. Also, they can provide functional groups for bioconjugation to anticancer drugs and/or targeted ligands. Chitosan, as a derivative of chitin, is an attractive natural biopolymer from renewable resources with the presence of reactive amino and hydroxyl functional groups in its structure. Chitosan nanoparticles (NPs), due to their huge surface to volume ratio as compared to the chitosan in its bulk form, have outstanding physico-chemical, antimicrobial and biological properties. These unique properties make chitosan NPs a promising biopolymer for the application of DDSs. In this review, the current state and challenges for the application magnetic chitosan NPs in drug delivery systems were investigated. The present review also revisits the limitations and commercial impediments to provide insight for future works.

Application of magnetic nanoparticles in smart enzyme immobilization.

Immobilization of enzymes enhances their properties for efficient utilization in industrial processes. Magnetic nanoparticles, due to their high surface area, large surface-to-volume ratio and easy separation under external magnetic fields, are highly valued. Significant progress has been made to develop new catalytic systems that are immobilized onto magnetic nanocarriers. This review provides an overview of recent developments in enzyme immobilization and stabilization protocols using this technology. The current applications of immobilized enzymes based on magnetic nanoparticles are summarized and future growth prospects are discussed. Recommendations are also given for areas of future research.

Effects of homogenization process parameters on physicochemical properties of astaxanthin nanodispersions prepared using a solvent-diffusion technique.

Nanodispersion systems allow incorporation of lipophilic bioactives, such as astaxanthin (a fat soluble carotenoid) into aqueous systems, which can improve their solubility, bioavailability, and stability, and widen their uses in water-based pharmaceutical and food products. In this study, response surface methodology was used to investigate the influences of homogenization time (0.5-20 minutes) and speed (1,000-9,000 rpm) in the formation of astaxanthin nanodispersions via the solvent-diffusion process. The product was characterized for particle size and astaxanthin concentration using laser diffraction particle size analysis and high performance liquid chromatography, respectively. Relatively high determination coefficients (ranging from 0.896 to 0.969) were obtained for all suggested polynomial regression models. The overall optimal homogenization conditions were determined by multiple response optimization analysis to be 6,000 rpm for 7 minutes. In vitro cellular uptake of astaxanthin from the suggested individual and multiple optimized astaxanthin nanodispersions was also evaluated. The cellular uptake of astaxanthin was found to be considerably increased (by more than five times) as it became incorporated into optimum nanodispersion systems. The lack of a significant difference between predicted and experimental values confirms the suitability of the regression equations connecting the response variables studied to the independent parameters.

Application of chitosan-based nanocarriers in tumor-targeted drug delivery.

Cancer is one of the major malignant diseases in the world. Current anti tumor agents are restricted during the chemotherapy due to their poor solubility in aqueous media, multidrug resistance problems, cytotoxicity, and serious side effects to healthy tissues. Development of targeted drug nanocarriers would enhance the undesirable effects of anticancer drugs and also selectively deliver them to cancerous tissues. Variety of nanocarriers such as micelles, polymeric nanoparticles, liposomes nanogels, dendrimers, and carbon nanotubes have been used for targeted delivery of anticancer agents. These nanocarriers transfer loaded drugs to desired sites through passive or active efficacy mechanisms. Chitosan and its derivatives, due to their unique properties such as hydrophilicity, biocompatibility, and biodegradability, have attracted attention to be used in nanocarriers. Grafting cancer-specific ligands onto the Chitosan nanoparticles, which leads to ligand-receptor interactions, has been successfully developed as active targeting. Chitosan-conjugated components also respond to external or internal physical and chemical stimulus in targeted tumors that is called environment triggers. In this study, mechanisms of targeted tumor deliveries via nanocarriers were explained; specifically, chitosan-based nanocarriers in tumor-targeting drug delivery were also discussed.

Preparation of astaxanthin nanodispersions using gelatin-based stabilizer systems.

The incorporation of lipophilic nutrients, such as astaxanthin (a fat soluble carotenoid) in nanodispersion systems can either increase the water solubility, stability and bioavailability or widen their applications in aqueous food and pharmaceutical formulations. In this research, gelatin and its combinations with sucrose oleate as a small molecular emulsifier, sodium caseinate (SC) as a protein and gum Arabic as a polysaccharide were used as stabilizer systems in the formation of astaxanthin nanodispersions via an emulsification-evaporation process. The results indicated that the addition of SC to gelatin in the stabilizer system could increase the chemical stability of astaxanthin nanodispersions significantly, while using a mixture of gelatin and sucrose oleate as a stabilizer led to production of nanodispersions with the smallest particle size (121.4±8.6 nm). It was also shown that a combination of gelatin and gum Arabic could produce optimal astaxanthin nanodispersions in terms of physical stability (minimum polydispersity index (PDI) and maximum zeta-potential). This study demonstrated that the mixture of surface active compounds showed higher emulsifying and stabilizing functionality compared to using them individually in the preparation of astaxanthin nanodispersions.

Influence of astaxanthin, emulsifier and organic phase concentration on physicochemical properties of astaxanthin nanodispersions.

BACKGROUND: The emulsification-evaporation method was used to prepare astaxanthin nanodispersions using a three-component emulsifier system composed of Tween 20, sodium caseinate and gum Arabic. Using Response-surface methodology (RSM), we studied the main and interaction effects of the major emulsion components, namely, astaxanthin concentration (0.02-0.38 wt %, x1), emulsifier concentration (0.2-3.8 wt %, x2) and organic phase (dichloromethane) concentration (2-38 wt %, x3) on nanodispersion characteristics. The physicochemical properties considered as response variables were: average particle size (Y1), PDI (Y2) and astaxanthin loss (Y3). RESULTS: The results indicated that the response-surface models were significantly (p < 0.05) fitted for all studied response variables. The fitted polynomial regression models for the prediction of variations in the response variables showed high coefficients of determination (R2 > 0.930) for all responses. The overall optimum region resulted in a desirable astaxanthin nanodispersions obtained with the concentrations of 0.08 wt % astaxanthin, 2.5 wt % emulsifier and 11.5 wt % organic phase. CONCLUSION: No significant differences were found between the experimental and predicted values, thus certifying the adequacy of the Response-surface models developed for describing the changes in physicochemical properties as a function of main emulsion component concentrations.

Protection of astaxanthin in astaxanthin nanodispersions using additional antioxidants.

The protective effects of α-tocopherol and ascorbic acid on astaxanthin in astaxanthin nanodispersions produced via a solvent-diffusion technique and stabilized by a three-component stabilizer system, were studied either individually or in combination by using response surface methodology. Generally, both α-tocopherol and ascorbic acid could retard the astaxanthin degradation in astaxanthin nanodispersions. The results showed that the using α-tocopherol and ascorbic acid can be more efficient in increasing the chemical stability of nanodispersions in comparison to using them individually. Using a response surface methodology (RSM) response optimizer, it was seen that addition of ascorbic acid (ascorbic acid/astaxanthin w/w) and α-tocopherol (α-tocopherol/astaxanthin w/w) in proportions of 0.4 and 0.6, respectively, would give the maximum chemical stability to the studied astaxanthin nanodispersions.