IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2017 | Volume:13 | Issue:60|Papers Count:23

The objective of this study was to investigate the effect of adding thyme and pennyroyal powder in the diet of quail on the microbial and sensorial characteristics, water-holding capacity and color, in fresh meat; furthermore Variations in oxidative and acidity of quail meat during storage in refrigerated condition. For this reason two experiments were undertaken. In the first, 180 quail were randomly assigned to control group (basal diet), and groups that feed with 0.5, 1 and 1.5% thyme powder (%w/w). And in the other trial, treatments were giving to eat 0.5, 1 and 1.5%.of pennyroyal powder (%w/w). The results showed that the addition of thyme or pennyroyal leave's powder in the diet of quail, decrease microbial activity and increases water-holding capacity (p<0.05). Sensory analyses of the samples did not showed significant differences in taste, smell and juicy properties of the samples; while the control had the softest texture and treated fed quail with pennyroyal leaves powders had the hardest texture. In all treatments, oxidation and pH changes during storage could not be explainable. Consequently, this medicinal herbal could be controlled activity of microorganisms and improved water-holding capacity and firmness, and since they had no effect on the color index, sensory properties and oxidation reactions, is a pleasurable alternative instead of antibiotics in feed of quail.

In the present study, the influence of various emulsifiers (Tween 80, Tween 60, Tween 20, Sodium caseinate, WPC and WPI), ratio of emulsifier (Tween 80) to oil phase (orange peel essential oil) at eight levels (1, 1.5, 1.75, 2, 2.25, 2.5, 2.75, and 3: 1), and the possibility of using complete form, soluble and insoluble fractions of the two native gums (Persian gum and gum tragacanth) individually and combined in the formulations on the formation and some properties of orange peel essential oil nanoemulsions was evaluated. Ultrasonic emulsification technique was used to produce nanoemulsions and the mean droplet diameter (Z-average), polydispersity index, viscosity, flow behavior, physical stability of selected formulations during storage (up to 90 days at 25oC), as well as the total input energy during process was evaluated. Our results showed that surfactant-to-oil ratio (SOR) had a significant effect on the mentioned properties (P<0.0001) where the lowest Z-average was observed at SOR=2. Meanwhile, none of the local gums and proteins were able to form nanoemulsions in the absence of emulsifier (Tween 80). Moreover, their soluble fractions (individually and combined at reasonably low concentration) showed significant effect (P<0.0001) on the measured properties in the presence of emulsifier. Furthermore, the flow behavior of nanoemulsions was Newtonian, and the effect of storage time on the Z-average value was significant (P<0.0001).

The use of edible coatings is a suitable method to reduce oil uptake in fried foods. In this study the effect of maltodextrin as a coating in three levels concentration (1, 3, 5%) and also immersion times of strips in coating solutions (2 and 4 minutes), temperatures (170, 180, 190oC), and time of frying (5, 6, 7 minutes) on moisture, oil uptake reduction, color, crispiness and organoleptic characteristics of french fries were determined, using Response Surface Methodology. The findings showed that the effects of experimental variables on moisture content, color parameters, hardness and oil content of french fried were Significant (p<0.01). The moisture content decreased with increasing temperature and frying time, but the amount of oil absorption and hardness increased. Results indicated that French fries coated with maltodexterin resulted better product in oil uptake, as maltodexterin reduced oil uptake of French fried up to 41.93%. Potato strips coated with maltodexterin (5% solution and 2 min immersion), and fried in 170°C for 6 min showed the lowest oil content (19.9%). Additionally, color and sensory properties in French fries that were prepared with maltodexterin coating were not significantly different than French fries without coating. According to the results of this study, maltodexterin can be considered as suitable and cheap coating material to reduce oil uptake of French fried

Edible films are thin biopolymer based materials. The objective of this work was to determine the water vapor permeability, mechanical, thermal and morphological properties of edible films based on big head crap fish skin gelatin. These films were prepared with 3 g gelatin/100ml of water, 0-10% sorbitol and 10% glycerol at natural pH. The samples were conditioned at 75±3% relative humidity and 25oC for two days before testing. As expected, elongation at break and water vapor permeability increased, but tensile strength and elastic modulus decreased with increasing of sorbitol content. Fish skin gelatin films with 10% glycerol and 5% sorbitol, had highest glass transition and melting temperature in comparison with those films free from sorbitol. SEM images showed that gelatin films with plasticizer were smooth and uniform in surface with lots of cavities and voids in them. The films plasticized by 10% glycerol had smooth glassy surface. Films plasticized with different concentrations of sorbitol and 10% glycerol showed a dense and compact structure in compared with the control unplasticized samples.

Researchers give some reasons to discover new antimicrobial substances of plant origin; they are consisted of increseaing bacterial resistance to antibiotics, and susceptibility to antimicrobial. The present study examines the effect of aqueous and ethanolic extract of Pinus elderica fruit on infection and poisoning of food microorganisms “in vitro”. Antimicrobial effect of the extracts using agar disk diffusion method and the Minimum Inhibitory Concentration (MIC) of microbial growth and Minimum Bactericidal Concentration (MBC) of bacteria was performed using serial dilution method. Comparison of antibacterial activity of ethanolic and aqueous extracts of this plant showed better effect on Gram-positive bacteria than Gram-negative bacteria. Such maximum growth of inhibition zone showed at ethanol extract from Pinus elderica fruit on strains of staphylococcus aureus, which was 17.5+0.14 mm. From two strains of Gram-negative bacteria, E. coli was the most resistant against aqueous and ethanolic extracts of this fruit. Accordingto the results, Pinus elderica have some what antibacterial effects.

In this study, the effect of substitution date concentrate and stevioside sweetener on qualitative properties of sponge cake was evaluated. The objective of this research work was preparing cake with fewer calories and minimum quality loss. In this research, the effect of compounds of date concentrate and stevioside sweetener separately and combined in 15 different formula and at levels of 25, 50, 75 and 100% (by weight sugar) on various properties cakes were tested. The results showed that stevioside cakes, compared to control samples and date concentrate cakes, had more moisture and lower color, height and sensory scores. Also, The results of the texture profile analysis indicated that increased levels stevioside causing significant changes in some parameters of texture instrumental. On the other hand, date concentrate cakes had more color, less altitude, intermediate humidity and higher sensory scores. Texture profile analysis also revealed that compared with stevioside samples, cakes containing date concentrate showed more favorable texture parameters. Furthermore, using of combined formulas of stevioside and date concentrate improved physical properties and sensory cake samples. Finally, after calculating the energy contents of selective and control samples revealed that the selective cakes had less energy content.

Economic value of the rice product is determined by the quality of rice after paddy conversion operation to white rice. Conversion Coefficient and crack percent are two important indices for determining the quality of rice after conversion operation that type of dryer used is effective on level of these indices. In this study effect of air temperature was studied in four levels (40, 45, 50 and 55oC); final moisture in three levels (8-10, 10-12, and 12-14%) and rice variety in three levels (Tarom-domsiah, Hashemy, Shirudy) on crack percent and conversion coefficient during the drying in a fluidized bed dryer. Experiments were conducted in the factorial design with three replications and three factors 3×3×4. Results showed that conversion coefficient of Tarom-domsiah, Hashemi and Shiroodi varieties reduced with increasing of moisture at all four temperature levels. In order to dry rice, temperatures 40oC and 50oC for Tarom-domsiah variety and temperature 55oC for Shiroodi variety lead to the best conversion coefficient. Crack percent of Hashemi variety increases with rising of drying temperature but crack percent of Shiroodi variety is reduced. Minimal crack percent of Tarom-domsiah, Hashemi and Shiroodi varieties is gained at temperatures (45oC and 50oC), 45oC and 55oC respectively. Hence, it is recommended to use temperatures mentioned for drying of these varieties in order to obtain minimal crack content.

Doogh is a fermented beverage that is prepared by mixing yoghurt with water and some salt. There are resembling beverage basis of yogurt in neighboring countries around Iran. For example, dilution ratio, fat content, rheological characteristics and taste like doogh, however, they all contain aggregated casein Serum separation is one of the main problems of this product during storage period. In this study, the effect of the additional of guar gums (0.3%), and xanthan (0.3%) and a mixture of two gums (0.15%-0.15%) on the rheological properties and serum separation of low fat doogh was examined. Rheological behavior of doogh samples was fitted with Ostwald-de Waele model. Mathematical calculations of data based Ostwald-de Waele model, showed that the low-fat doogh is non-Newtonian and shear thinning (Pseudo plastic) fluid type. Also, using the Arrhenius equation dependence of the apparent viscosity to temperature is determined and the activation energy between 11.09 to 19.07 kJ/mol is calculated.

Lysozyme- maltodextrin conjugates were prepared by microwave heating of the mixtures at different times. The formation of the protein- polysaccharide conjugates was confirmed by SDS-polyacrylamide gel electrophoresis, free amino group content, browning intensity and UV absorbance measurement and determination enzyme activity. SDS-PAGE profile showed that lysozyme-maltodextrin conjugates were formed. The results of free amino group content indicated that increasing microwave heating time caused an increased in glycation degree. Browning and intermediate maillard products, as monitored by absorbance at 420 nm and absorbance at 294 nm, sharply increased compared to control sample. Enzymatic activity of glycosylated lysozymes were reduced compared with unmodified lysozyme. Significant changes in browning intensity, free amino group content and SDS-PAGE profile indicated that lysozyme-maltodextrin conjugates were successfully formed using microwave heating treatment. Moreover, higher microwave heating intensity enhanced the extent of glycosylation. All data showed that microwave heating treatment could be an effective and promising method for linking polysaccharides to proteins.

Sourdough fermentation by lactic acid bacteria and baker's yeast with acidification of dough and producing lactic acid and acetic acid has significant effects on quality characteristics of bread. Application of liquid sourdough in bakery industry has attracted much attention due to higher dough yield, ease of transition and one-step process in order to achieve desired texture and flavor characteristics in final product. In the research, Response surface liquid methodology was used to optimize sourdough fermentation for increased acidification. Fermentation time (5.3-18.7 hrs.), temperature (21.6-38.4oC), and dough yield (249.6-350.4) were considered as independent factors according to central composite design and their effects were studied in liquid sourdoughs fermented with Lactobacillus casei subsp casei, Lactobacillus fermentum and Saccharomyces cerevisiae. Lactic acid and acetic acid contents and total titrable acidity (TTA) were considered as the main responses. The second order polynomial models satisfactory predicted the effects of variables on acidification properties (R2adj> 0.80). Statistical analysis showed that all the responses were significantly (P<0.01) correlated to fermentation time and temperature. Increase in fermentation time and temperature was associated with an increase in lactic acid, acetic acid and TTA and fermentation time was the most affecting factor on acidification. Lactic acid was not affected by dough yield but the lower dough yield caused in high acetic acid content and acidity. Based on response surface and contour plots, the optimum conditions for maximum acidification were: fermentation time (21 hrs.), temperature (38oC) and dough yield (DY: 325).

Microbial oil has lots of similarity to the plant’s oil; the only difference between them is that microbial oil is rich in unsaturated fatty acids. This oil can be used in pharmaceutical industry for technical purposes or as edible oil in food industry. The purpose of this study was to increase lipid production and the amount of unsaturated fatty acids in oleaginous yeasts by mutagenesis. In this study, optimization of lipid production in the yeast, Yarrowia lipolytica, was done using ultraviolet random mutation and screening was done with the inhibitory effect of cerulenin on lipid synthesis. Mutants that had normal growth in the presence of cerulenin were selected as superior strains for further investigations. Lipid production in mutants and wild strains were compared after incubation period. Then, the mutant with significant increase in lipid production was selected. The best mutant had increasing of 50% and 30% in lipid production and growth yield, respectively. Also, Linoleic acid was increased after mutation. The composition of fatty acids in the lipid profile of the evaluated yeast did not change a lot after mutation. Of course, unsaturated fatty acids were increased, so this technique was very effective to improve lipid production. Cerulenin used as an effective screening technique in this study and paved the way for the isolation of superior mutants.

b-galactosidase, is one of the most important and widely used enzymes in three areas of health, Food Industry and environment, so kinetic modeling of this enzyme could be playing an important role in the optimization of its industrial production process. First, in this study kinetic of b -galactosidase production by Bacillus licheniformis bacteria in batch fermentation was evaluated during 22 hours, in the range of 20-50 g/l of initial lactose concentration as a limiting substrate, at 30oC. Then, with the observation of inhibition at the highest concentration of this range, logistic and Haldane kinetic models were selected to model and determine the kinetic parameters of fermentation. These models were obtained a good approximation of the experimental results of substrate utilization in all phases and microbial growth data in the exponential growth phase and the stationary phase, but minor deviations of the experimental data were observed in the decelerating growth phase. In addition, b -galactosidase activity results were in good agreement with experimental data, and the maximum deviation in this data was observed in initial concentrations 30 and 40 g/l of substrate simultaneously with the end of the exponential phase and beginning of decelerating phase of microbial growth (The fourth hours of starting inoculum). The linear regressions between experimental data and results obtained from the models, in all initial concentration of lactose and for each variable biomass concentration, substrate concentration and enzyme activity, was more than 0.95.

Malting is one of the biotechnological processes that includes steeping, germination and killing of cereal in controlled environment in which hydrolytic enzymes are synthesized and cell wall, protein and starch of endosperm are largely digested. Purpose of this study was evaluation of malting quality and identification of suitable line for production of malt products. In this study, effect of malting processing on physicochemical properties including of kernel density, bulk density, thousand weight kernel, protein and cold water extract yield of EBYT and Yusuf varieties evaluated in complete randomized design plan. Experiments were made in triplicate. The results of ANOVA showed that sample type had significant effect on all physicochemical properties (p<0.01). Maximum amount of kernel density (1332.33 kg/m3) and minimum amount of that (832.33 kg/m3) were related to barley seed of yusuf variety and obtained malt of yusuf variety, respectively. Malting process results in decrease of thousand weight kernel, kernel density and bulk density and increase of protein content and cold water extract yield. Cold water extract yield in obtained malt of EBYT line was higher than obtained malt of yusuf variety, and consequently, those utilities in enzymatic extracts preparation and also in confectionary, cake and cookie industries.

synthetic antioxidants has led to an increased interest in exploration of effective and economical natural antioxidants. The objective of this study was to evaluate the effects of rosemary (Rosmarinus officinalis) essential oil (REO) on oxidative stability of virgin olive oil under accelerated conditions. The REO composition was analyzed by gas chromatography/mass spectrometry. REO and BHT were added to virgin olive oil at 1000 and 100ppm, respectively and their oxidative stability was investigated by using active oxygen method (AOM). Gas chromatography/mass spectrometry analyses of the REO revealed that α-pinene (17.07%), camphor (9.62%), and bornyl acetate (9.42%) were the major components of REO. REO was significantly effective on oxidation retarding of virgin olive oil. Effect of REO on delaying hydroperoxides formation of virgin olive oil was similar to that of BHT. REO significantly increased induction period, protection factor, and antioxidant power of virgin olive oil. The induction period, protection factor, and antioxidant power of virgin olive oil containing REO (40.01±1.35 h, 1.67±0.05, and 39.96±1.76, respectively) was similar to those of sample containing BHT (44.44 ± 0.23 h, 1.85±0.01, and 45.96±0.05, respectively). Generally, REO is a good natural antioxidant for extending the shelf-life of virgin olive oil.

Fast foods such as beefburgers has attracted much attention in recent years due to the industrialization of societies. One kind of beefburgers is beefburgers with low meat content, that decrease of meat and replace some of the meat with vegetable proteincauses some problemssuch as dry and brittle texture, dark color and bad taste. Because using gums is one way to reduce some of these bad effects, in this research effect of adding xanthan gum (0.2% and 0.4%) and guar gum (0.2% and 0.4%) and mixture of them on cooking loss, water holding capacity, texture, color and sensory properties of beefburgers were investigated. The results showed that adding gums had no significant effect on the color of final products, but significantly increased water holding capacity in comparison with control sample. Also, cooking loss significantly decreased due to the adding of gums. By addition of gums, except in the case of Adhesiveness, other texture parameters such as hardness, cohesiveness, elasticity and chewiness were significantly decreased. According to sensory analysis results, adding gums, just in the cases of texture and overall acceptability were significantely preferred in comparison with control sample and had no significant effect on beefburgers color, aroma and taste. Finally, samples containing mixture of 0.2% xanthan and 0.4% guar were choosed as the best.

Nowadays the nanoparticles have been extensively developed in food industry, particularly food packaging systems. The incorporation of nanoparticles in the packaging material can improve the mechanical, thermal and barrier properties of the packaging material. In this study, polyethylene terephthalate (PET) /TiO2 nanocomposites were prepared by melt blending of PET and TiO2 nanoparticles. The morphology of the prepared nanocomposite films was investigated by scanning electron microscopy (SEM). UV-Visible spectroscopy was used to study the transparency of prepared films. Gravimetric method was employed for measuring water vapor permeability of films. Thermal and mechanical properties were performed using differential scanning calorimetry (DSC) and tension test, respectively. The transmittance decreased considerably in TiO2 nanocomposites compared to neat polymer in both UV and visible range. The incorporation of nanofillers especially at 3% wt. loading level increased the crystallinity of PET. The results of mechanical test showed that the ductility of nanocomposites was enhanced compared to neat polymer. The parameters elongation at break and dissipated energy are measures of polymer ductility. Incorporation of nanoparticles into packaging material matrix noticeably decreased the water vapor permeability of PET. In general, TiO2 nanoparticles improved the mechanical and thermal properties of PET packages. Gas permeability of prepared nanocomposite films decreased due to increased diffusion path. Improvement of packaging material characteristics could have an interactive role in extending the shelf life of foods.

Pasta is a combination of ingredients is produced by drying a mixture of semolina, durum wheat, hard wheat flour with water or other allowed mixture. Used Wheat for pasta should be provided from hard or durum wheat containing more than 12/5% protein and 30% wet gluten ratios, this product should keep it' s physical appearance while cooking and must not be waned, hard and elastic while chewing, stick to tooth and lose less dry material while cooking in boiled water. In pasta or other corny product, milling is one of the main procedures. Inappropriate wheat milling causes damaged starch. The damaged starch absorbs much more water, plays an important role in cooking procedure and has important effects on paste rheological features. In this research for considering the effects of the damaged starch on pasta quality, five flours with different starch ratios were selected. The content of moisture, ash, protein, dry, wet gluten and gluten index was determined on every flour, pasta rheological properties evaluation was performed using farinograph. Other tests such as; cooking value, cooking loss value, adherence, color and sensational assessment on products have been carried out. Results indicated that difference in the rate of damaged starch has no effect on the flour chemical features. The higher starch damage caused higher water absorption, lower development, stability time and lower quality score. Data indicated higher damaged starch caused higher cooking value, cooking loss value, higher adherence and increase the product darkness. Results showed lower quality assessment score by increasing damaged starch.