sedigheh amiri

Recently, due to the known antioxidant activity of plant compounds and their derivatives, great attention is attracted by using such compounds in food and biological systems. This study aimed to explore the possibility of adding the aqueous extract of pomegranate peel as an antioxidant in sunflower oil using microemulsion system. For this purpose, the effect of two solvents (water and 96% ethanol) on the extraction efficiency of phenolic compounds and DPPH radical scavenging property was investigated. Therefore, nano-capsulated aqueous extract (at 200 and 400 ppm), ethanolic extract and BHT (at 200 ppm) were added into an antioxidant free sunflower oil and the peroxide value, p-anisidine value and free fatty acid contents of treated oils were determined. Results showed that the phenolic content of aqueous extract was higher and, the lower radical-scavenging ability in DPPH test was related to ethanolic extract. The peroxide value , p-anisidine value and free fatty acid contents of sunflower oil containing 400 ppm aqueous extract at 50 were lower than other samples. It can be concluded that the usage of microemulsified aqueous pomegranate peel extract may improve the quality storage of sunflower oil when compared to the free extract.

In recent years, the demand for fried products with lower oil content has increased. Therefore, in this study, the effect of different hydrocolloid coatings including sodium alginate (0.50 and 1.00%), calcium alginate (0.50 and 1.00%), and soy protein isolate (4.00 and 5.00%) on oil absorption and quality properties of eggplant slices during different frying times [0, 90, 180, 270, and 360 seconds] were evaluated. The results showed that the samples pretreated with hydrocolloids had lower moisture loss and oil absorption than that of the control sample. In this regard, among the treatments, calcium alginate (1.00%, with a moisture content of 16.66% based on dry weight and the oil absorption of 0.11 g/g food) and soy protein isolate (5.00%, with the moisture content of 33.66% based on dry weight and the of oil absorption of 0.26 g/g food) had the highest and lowest function, respectively. The moisture content of the fried samples decreased with the frying time increase from 90 to 270 s. Meanwhile, the frying efficiency of calcium alginate coated samples, in all four examined times, was higher than the other treatments, which showed the highest value in 90 s (93.12%). The lowest efficiency was observed in the control sample at 360 s (49.51%). The L* values in the samples coated with soy protein isolate were lower than those of the other samples, which could be due to the increase in Millard reaction. Coating the eggplant samples with calcium and sodium alginate resulted in good sensory parameters for 90 s. Overall, the results of this study showed that the use of calcium alginate coating (1%) can lead to the production of low-fat fried eggplant without adversely affecting the sensory and qualitative properties of the product.

The NLCs are potent carriers for lipophilic bioactive compounds. The NLC:maltodextrin (6:10) solution at the inlet temperatures of 110 or 180 °C, and the feed flow rate of 5 or 15 mL/min was spray-dried and the powders characteristics were evaluated. The SEM micrographs showed the particle morphologies of hollow spheroids with smooth surfaces. The powder production yields as high as 66% was achieved. The sizes of NLC particles after the redispersion of the spray-dried powders shifted to higher amounts, but were below the acceptable size of NLC systems. The measurement of flowability indices such as Carr’s compressibility index, Hausner ratio, and angle of repose showed that the samples were categorized as the powders with good flowability. The results of this study revealed that NLC systems can be successfully spray-dried by using maltodextrin as the excipient without any drastic changes in the particle size.

Concerns about the environmental issues have increased the tendency to package the food stuffs with natural biopolymers. However, the use of these compounds has limitations such as the weakness in mechanical, barrier and optical properties. Alginate, as a biopolymer, has a good film forming potential; meanwhile it has poor moisture barrier properties. In order to overcome this problem, in this study, the calcium alginate film was coated with two types of lipids including sunflower oil (as a liquid oil) and tallow (as a solid fat) at two concentrations (0.5 and 5%, with and without 0.1% lecithin). Afterward, the physicochemical, barrier, and mechanical properties of the produced films were investigated. The results showed that the lamination of the alginate films with tallow fat increased the film thickness, which increased with the fat concentration. In addition, sunflower oil significantly reduced the permeability of the films to water vapor, that was more evident in 0.5% sunflower oil coated film. The results also showed that the use of these hydrophobic materials for the coating of alginate films changed the color properties and the turbidity of the films. The mechanical properties of the film, including tensile strength and elongation at the breaking point, improved by coating the alginate film with 0.5% tallow fat. Thickness, water vapor permeability, and the mechanical properties were not affected by the addition of lecithin. The SEM images proved the formation of small holes or cracks on the films surfaces. In general, this study showed that sunflower oil or tallow fat can be used as natural compounds to improve the properties of calcium alginate-based edible films, depending on the goals of packaging.

Wheat bran as a by-product of milling contain various compounds such as pentosans which have health promoting effects and functinal properties in industrial applications. In this study the extraction yield of pentosans by hot water 80oC, 0.01 mM sodium hydroxide and 2% alkaline hydrogen peroxide solutions as the conventional methods for pentosan extraction was evaluated. Then, the effects of pretreatments such as cellulase, ultrasound, autoclave and microwave in the presence of sodium hydroxide and water to increase the pentosan extraction yield were studied. Finally, in order to increase the extraction yield of the pentosans, pretreatments with the highest extraction yield (sonication, cellulase enzyme, hot water, sodium hydroxide, hydrogen peroxide) were evaluated as combined treatments. The results showed that the purity of pentosans extracted with sodium hydroxide was significantly higher than the hot water and hydrogen peroxide solution (p<0.05). Also, among the pretreatments of cellulase enzyme, ultrasound, autoclave and microwave in presence of water or sodium hydroxide, the combination of cellulase-sodium hydroxide and ultrasound-sodium hydroxide treatments resulted in the higher yields. The combined treatment of hot water (80oC)+cellulase enzyme+(0.1%)+ultrasound power (560 w, 2 minutes) and the combined treatment of hot water (80oC)+hydrogen peroxide (4%, pH=11.5) were identified respectively as the best combination factors to maximize extraction yield and pentosans purity from wheat bran.

In this study, microemulsification of orange peel oil (OPO) using Tween 60:propanol with the ratio of 1:1 was studied under different conditions of pH, ionic strength, and sugar concentration.. Results showed that critical temperature (the temperature in which one- phase microemulsion system was still stable) for the microemulsions with higher sucrose concentrations (in the range between 0 to 30%) was lower while by decreasing in sugar concentration, critical temperature shifted to higher temperatures, as it reached to 90°C for the samples without sugar. The prepared microemulsions were stable at 5 and 25°C for seven days, but samples with higher concentrations of sugar (25 and 30%) became turbid at 45°C, whereas all other samples exhibited a one-phase microemulsion system at this temperature. Microemulsions were not stable at -3°C (freezing temperatures). In sensory evaluation, it was observed that the microemulsified OPO was dissolved in water as soon as it was added into the medium, in contrast to free essential oil as it was spreading on the surface of the solution. Encapsulation of OPO caused lower release of aroma, resulting a milder odor and taste (lower intensity) in samples which were preferred by the panelists. The overall acceptability of all samples containing OPO microemulsion was significantly higher than samples with free essential oil.

Most of the food packaging materials are produced from nondegradable polymers which has become a serious environmental problem. Natural ingredients based on polysaccharides, offer an alternative for synthetic packagings that minimize the environmental pollution with a relatively low cost. The aim of this study was to evaluate the effect of solid lipid nanoparticles (SLN) on morphology, mechanical and barrier properties of sodium alginate film. For this purpose, the nanoparticles were added at concentrations of 0.025%, 0.5% and 0.1% into the alginate films and optical properties, tensile strength, elongation at break (%), Young’s modulus, water vapor permeability (WVP) and the nano-structured of films were evaluated. As SLN concentration increased,  elongation at break and WVP increased significantly (p<0.05), while no significant differences were found in the tensile strength and Young’s modulus (p>0.05). Films containing a high concentration of SLN (0.1%), were slightly yellowish in color and their opacity value increased significantly (p<0.05). The scaning electron micrographs showed that addition of SLN resulted in a hole-like structure in the film texture, which increased with nano-particles, concentration. Results obtained in the present work exhibited that the incorporation of SLN in alginate film was suitable for increasing the film flexibility but it had no positive effect on the film barrier properties.

As chemical methods are commonly used to modify the starch properties, in this study, the influence of chemical modification using POCl3 on the rice starch function was evaluated. Rice starch was isolated by alkaline extraction of the proteins and cross-linked rice starches were prepared from reactions between native rice starch (low and high amylose) and varied concentrations of POCl3 (0.1, 0.2 and 0.3 % w/w). The physicochemical, rheological and morphological properties of rice starches (water absorption and solubility, pasting viscosity parameters, light transmittance, freeze-thaw stability, and scanning electron microscopy) were evaluated. According to SEM micrographs, cross-linking did not affect granule size or shape. The cross-linked starches showed lower solubility than that of the native starches and solubility decreased with increasing the concentration of cross-linking agent. Cross-linking decreased the capability of starches to absorb water at high concentration of cross-linking agent (0.3%). The paste clarity and pasting viscosity parameters of cross-linked samples were lower than their native starches and decreased with POCl3 concentration. The freeze-thaw stability of rice starches improved by cross-linking and increased with an increase in cross-linking agent concentration. Regarding amylose content, low amylose rice starches showed lower water solubility, water absorption and freeze-thaw stability and higher pasting viscosity parameters than those of high amylose ones. The results of this study suggest that high amylose cross-linked rice starch can be used in food systems in which higher stability, or controlled increase of viscosity is desired during their processing.

Lysozyme is a natural enzyme with positive antimicrobial activity against Gram Positive bacteria، but its action is limited on Gram Negative bacteria، which is assumed a restriction for its uses in industry. The purpose of this research was to glycosylate lysozyme with dextran through Maillard-based reaction and to study the antimicrobial characteristics of lysozyme-dextran conjugate. Glycosylation of lysozyme with dextran was performed using a 1:5 weight ratio of protein to dextran، incubated at 60 MC for one week under the relative humidity of 79%. For evaluating conjugation of dextran to lysozyme، SDS-PAGE electrophoresis was conducted. Gel filtration chromatography with sephadox G-100 was used for separation of conjugated enzyme. Lytic activity، free amino group and antimicrobial activity of the modified enzyme were evaluated. SDS-PAGE electrophoresis was used to follow the glycosylation process. Results indicated that 3. 7 moles of dextran were coupled to one mole of lysozyme. The lytic activity of the conjugate was about 62% of that of the native lysozyme. Evaluation of antimicrobial activity of the lysozymedextran conjugate، indicated the effectiveness of modified enzyme against E. coli and a progressive increase in antimicrobial activity with an increase in enzyme-conjugate concentration. The antimicrobial action of lysozyme on S. aureus was not improved by conjugation with dextran as compared with that of E. coli. These results might increase the application of lysozyme as a natural antimicrobial ingredient in different food systems.