فهرست مطالب masoud najaf najafi

In this study, the effect of different amounts of konjac gum (KG) (0 to 0.2%) and sage seed gum (SSG) (0 to 0.2%) as experimental variables of the mixture design and fat content (0 to 3%) and homogenization rate (0 to 24000 rpm) as experimental variables of the process design on the viscoelastic characteristics of low-fat stirred yogurt were investigated. Based on the results of stress sweep test for different samples, the storage modulus (G') had a value more than the loss modulus (G''), explaining a solid-like behavior of the samples. Also, according to the stress sweep test, G' LVE (G' at linear viscoelastic region), G'' LVE (G'' at linear viscoelastic region), γc (critical strain), τy (yield stress), τf (yield stress at flowing point), and Gf (elastic modulus at flowing point) of the samples were significantly increased, especially for samples containing higher sage seed gum, with increasing fat content and homogenization rate. To optimize the properties in this study, G" LVE were considered to be minimum and G' LVE, γc, τy and τf were considered to be maximum. According to the mentioned properties, the optimized amount of KG was 0.19%, the amount of SSG was 0.01%, the fat content was 0.59% and the homogenization rate was 12075 rpm.

In this study, the effect of different amounts of flaxseed extract (0, 2.5, 5, 7.5, 10, 12.5 and 15%) on the physicochemical and rheological properties of kashk was investigated Then, in order to better understand the effect of flaxseed extract on the evaluated properties, Sensitivity Analysis (SA) of selected regression models was performed. The results of analysis of variance showed that the effect of flaxseed extract concentration on moisture, fat, protein, pH and solubility of kashk samples was significant so that according to the results of sensitivity analysis for each one percent increase in flaxseed extract about 4.38% moisture, 11.82% fat and 0.78% pH of the samples increased. Also, for each increase of one percent of flaxseed extract, about 7.01% of protein and 2.72% of solubility of samples were reduced. Therefore, according to the results of sensitivity analysis, fat had the highest sensitivity and pH the lowest sensitivity compared to physicochemical properties to changes in flaxseed extract. Also, the results of analysis of variance of the samples showed that the effect of flaxseed extract concentration on all parameters of Herschel model (flow behavior index, consistency coefficient and yield stress) was significant So for each one percent increase in flaxseed extract about 9% consistency coefficient and 11.82% fat and 9.03% the yield stress of the samples increased.

The aim of this study was to add flaxseed extract powder to Kashk and increase its usefulness and health. In this research, fresh yogurt was used to produce Kashk. Yogurt was drained to a solid of 16.5% and then mixed with 2.5, 5, 7, 10, 12.5 and 15% flaxseed extract powder. Then the produced Kashk was dried with a spray dryer. The tests carried out on the product (Kashk powder) include chemical tests (moisture, fat, protein, pH and acidity), sensory tests (taste, color, odor, taste and general acceptance) and physical tests (solubility and viscosity). The results of this study indicated that with the increase in extract content, pH, moisture and fat content increased and acidity and protein content decreased significantly (p ≤ 0.05). Regarding the physical properties, the results showed that increasing the amount of flaxseed extract in the Kashk powder caused a decrease in solubility and a significant increase (p ≤ 0.05) of viscosity. Sensory evaluation of Kashk powder samples showed that the addition of flaxseed extract reduced the product color scores. Also, the highest amount of consistency score was belonging to the sample with 15% flaxseed extract, which had a significant difference (p≥0.05) with other samples. Addition of flaxseed extract did not have any significant effect on odor scores of different samples. On the other hand, the results showed that the addition of flaxseed extract up to 7.5% did not have a significant effect on the taste scores of the samples, but in higher amounts, significantly decreased (p ≤ p ≤ 0.05) taste scores which were mainly due to the bitter taste. Similarly, the overall acceptance score in samples with a maximum of 7.5% of the flaxseed extract was similar to the control sample, and after that, with the increase of the flaxseed extract, the overall acceptance score decreased significantly (p≥0.05).

In recent years, with increasing public awareness about the harmful effect of fat consumption, demand for low-fat dairy products has increased significantly. On the other hand, fat reduction reduces the rheological and sensory properties of food, such as taste, flavor, texture and mouth feel. Therefore, it is difficult to produce a low-fat product with the same characteristics of high-fat product. In order to imitate different functions of fat in low-fat foods, such as consistency of the product, mouth feel, color, flavor and rheological properties should be considered. Fat substitutes are macromolecules that are used to provide all or part of the fat functions in a food product and produce less calorie intake than fat. Konjac is a neutral and polysaccharide hydrocolloid that is used as a gelling agent in traditional Asian foods due to its high ability in absorbing water. In addition, it is one of the most viscous dietary fiber. The use of konjac in western countries is expanding as a component in functional foods. Konjac can therefore be used as an appropriate substitute for fat in dairy products such as cream, which in addition to reducing the amount of fat can maintain and even improve the physical and other properties of the product. The purpose of this study was to produce low-fat cream with good nutritional value, variety in formulation, as well as lower prices.

Fresh cream of 30% fat and pasteurized milk were purchased from Razavi Dairy Company and konjac gum was provided from Food Chem (China). First, the gum was mixed with the pasteurized milk at 45°C. Then the mixture was added to the cream of 30% fat to reach the fat content of 18– 25%. The final mixture, after homogenization in the different specified values of pressure, was pasteurized at 85°c for 15 min, and then packed in polyethylene bottles and kept in the refrigerator (4ºC) until theday of experiment. The effect of amounts of Kanjac gum (0.2- 0.6), the amount of fat (18- 25%) and homogenization pressure (100- 200 bar) on the sensory, color, and rheological characteristics of low-fat cream were investigated

The results of evaluating the characteristics measured using the response surface methodology indicated that the hardness, consistency, adhesiveness, b*, sensory score of texture, sensory score of aroma and overall acceptance of samples significantly increased with an increasing homogenization pressure. Also increasing fat content caused an increasing the adhesiveness, L*, b*, sensory score of taste, sensory score of aroma and total acceptance of samples. Increasing the konjac gum content also increased hardness, consistency, adhesiveness, and sensory score of texture. The distribution of responses in the principal component also showed that the instrumental measures like hardness and consistency were close to the sensory score of texture of the samples. This proximity of these attributes indicated that the properties measured by the panelists were approximately equivalent to the parameters which were measured by instrumental methods. Also, the results of the correlation coefficient between sensory and instrumental measurements showed that the highest correlation between hardness and sensory score of texture (a strong positive linear relationship (0.774), and between the consistency and sensory score of texture (a strong positive linear relationship (0.760)). Rheological and sensory properties in products such as cream, play an important role in the processing and marketability of the product. In cream, these characteristics are mainly influenced by the method of production, the amount of fat, and potential additives used. The results of this study showed that konjac gum as a hydrocolloid can be used as a proper substitute for fat in the cream, and with suitable sensory, color and rheological properties. The results of this study about the correlation between sensory properties and instrumental specification showed that the properties measured by the panelists are approximately equivalent to the parameters measured by the instrumental methods. Therefore, the results of instrumental methods in most cases can well predict the sensory properties of the cream and then can be replaced it.

It can be seen that in most studies published on low fat yogurt, the effects of fat substitutes or process changes, including the homogenization process, have been considered separately. However, process changes, especially changes in homogenization pressure, in addition to the effect on yogurt, has also an effective role on fat substitutes such as hydrocolloids and can affect their functional characteristics. Therefore, in order to understand the proper conditions of industrial production, it is necessary to study these changes simultaneously. Due to the importance of low fat yogurt production, the effect of konjac gum, sage seed gum, homogenization rate and fat content on pH, texture, and color of low-fat yogurt was investigated using mixture-process variable experiments and modeling the properties obtained from this experimental method.
 
To prepare low-fat yogurt, firstly, the cream of 40% fat was added to the milk with 0.05% fat, sage seed gum, and konjac gum were added according to the design treatments and calculated by Pearson square method. The preparation was then heated to 90 °C and cooled down to 45 °C. The starter was then added and incubated in oven until reaching pH = 4.6. The yogurt was cooled down and dispersed in a 100 g cups of polyethylene. Texture analyzer was used for combination of back extrusion and texture profile analysis (TPA) test. The evaluated parameters were: hardness (N), cohesiveness, springiness, gumminess (N), chewiness (N), adhesiveness and adhesiveness force. pH was measured according to AOAC official method NO. 981.12.
 
The results showed that only the effect of fat content on the 99% level was significant on the pH of the samples, while konjac, sage seed gum, and homogenization rate had no significant effect. By increasing the fat content, the pH of the samples also significantly increased. It is likely that the increase in fat content will reduce the metabolic activity of the starter bacteria and thus increase the pH of the samples. Also, when the fat content of the samples was kept constant (1.75%), increasing the konjac gum and reducing the sage seed gum when the homogeneity of the samples was between 0 and 1200 rpm, the hardness of the samples initially increased and then decreased. When both gums were added at the same level, the hardness decreased indicating the high synergistic effect of these gums at low homogeneity rates. The results of this study showed that only linear effect of fat in 99% level on the adhesiveness force of samples was significant so that by increasing the fat content, the adhesiveness force of the samples increased. Also, the results showed that with increasing the konjac gum and reducing the sage seed gum, the gumminess of the samples first increased and then decreased. The most gumminess sample was in the conditions that both gums were used at the same level, indicating the high synergistic effect of these gums on the gumminess of the samples. The results of color measurement showed that only the linear effect of sage seed gum and the interaction effects of konjac gum-sage seed gum, konjac-gum on homogenization rates of L* samples were significant, and with increasing the level of konjac gum and reducing sage seed gum, L* samples decreased, but with increasing homogenization rates, L* samples increased. In this research, minimization of the fat content and adhesiveness force and maximization of the hardness and cohesiveness was considered as optimization aims. The optimum point calculated as 0.146% konjac gum, 0.053% sage seed gum, 2.42% fat content and 12300 rpm homogenization rate. In this conditio, the responses were: pH=4.5, hardness=3.25 N, adhesiveness force=0.815 N, cohesiveness 0.258 mm and L* 85/18. As a conclusion of this investigation, it could be said that these types of models could be utilized in industries to optimizing the formulation of such product, reducing the cost and increasing the acceptance.

In this research, the effects of quince seed mucilage (0.75 to 1.75%) and fat (15-25%) on physicochemical properties (pH, acidity and colorimetric components), rheological (synersis and viscosity), and also sensory characteristics (taste, texture and overall acceptance) of light (single) cream were investigated. The results were investigated by Central Composite Designs (CCD) and modeled by Response Surface Methodology (RSM). The lack of fit factor for all traits was not statistically significant at 95% level; therefore, the accuracy of the lack of fit model was confirmed. According to the obtained results, the optimum point of production variables for obtaining light cream, which has the lowest amount of synersis and acidity and the highest viscosity, as well as the highest total score of taste, texture and overall acceptance, seed mucilage is 1.75% and fat is 21.12%. Such a product has a viscosity of 1355.04 Pascal S, synersis 14.14%, acidity of 0.158, flavor score of 4.86, texture score of 83.4, overall acceptance score 4.18, and desirability of 91.3%. Therefore, based on the results of this study, it can be concluded that the use of quince seed mucilage in the production of low-fat cream can simultaneously reduce the amount of fat while maintaining the rheological, physicochemical and sensory properties of the product.

Due to its distinct color, flavor and beneficial compound, the Saffron plant is extensively used in pharmaceutical and food industries, but because of its sensitive nature, its active compounds are lost in adverse environmental conditions. In this research, the preparation of water-in-oil nanoemulsion containing saffron extract was studied as an effective method for maintaining active compounds of saffron. For this purpose, nanoemulsions were synthesized by using span 80 and tween 80 as emulsifiers in three levels of 10, 12.5 and 15 percent, using ultrasound. The amount of aqueous phase (saffron extract with 12% dry matter) was 15% (wt) in all formulations and n-decan used on three levels: 70, 72.5 and 75% as oil phase. Particle size, polydispersity index and stability of each formulation at light conditions during 28 days after production were evaluated. The results showed the particle size and polydispersity index in the emulsion containing 15% emulsifier was less than the other emulsions and did not change in terms of physical stability.

In this study, a double emulsion system was developed based on an optimized initial simple emulsion with the view to increase the stability of effective saffron compounds (crocin, picrocrocin and safranal). To this end the effect of various concentrations of surfactant (10, 12.5 and 15%) and different types of carbohysrates (sucrose, sorbitol, and dextran) on the stability of simple emulsion was investigated. The principal component analysis method was used to identify the relationships between the quantitative changes of the active components and quality attributes of the emulsion. Based on the results, day 7 was recognized as a critical point on which dramatic changes in the quality attributes of the emulsion coincided with the loss of saffron active compounds. In other words, physical changes in the stability of emulshion correlated well with the destruction trend of active compounds, although picrocrocin changes were found to be of independents. Also, it was revealed that the incorporation of 1% w/w sorbitol into the aqueous extract of saffron significantly decreased the loss rate of saffron active compounds in the emulsion. In addition, the double emulsion increased the half-life of saffron active compounds during a 14 day storage period. The results showed that double emulsion system was a suitable method for saffron extract, but the qualitative properties of initial emulsion also had a great influence on their stability. Multivariate analysis methods can also be used to clarify the relationships between the qualitative properties of the emulsion and the active compounds entrapped within it.

Natural substances with plant sources are rich in bioactive and useful compounds that promote health and improve the physicochemical properties of food products. Compounds such as antioxidants, polyphenols, pigments, flavors and etc. are among the most important bioactive plant-based compounds. Red beetroot is one of the unique plants that are rich in antioxidants, anthocyanins, and red pigmentation. The red pigment of the red beetroot is known as betacyanin, and betanin is the major betacyanin compound in red beetroot. Therefore, due to the red beetroot rich in natural pigments, especially betalains, this plant product has a high potential for use as a natural colorant in food, pharmaceutical, and cosmetic products. However, the restrictions on the use of natural and edible pigments are unstable during processing and preservation. The encapsulation process is one of the effective strategies in the food industry to resolve this problem and to protect bioactive compounds during production and storage. Different methods have been used for encapsulation of bioactive compounds, among which the most prominent ones are freeze-drying, emulsion, spray drying, liposomal, niosome, coacervation, and so on. Freeze drying and spray drying are two of the most widely used and industrial methods for the encapsulation of bioactive compounds, pigments, extracts, pharmaceuticals, and microorganisms. So, the aim of this study was to produce red beetroot pulp powder as a source of bioactive and colorant compounds using spray and freeze-drying processes.

Whey protein isolate (WPI) and maltodextrin with a DE 18-20 in different ratios (100: 0, 75:25, 50:50, 25:70 and 0: 100) as wall materials were used to the beetroot extract encapsulation. The spray drying process of the extracts was carried out at an inlet air temperature of 140 °C and outlet air temperature of 65-70 °C with a pump power of 75%, a compressed air flow of 3.5 m3/h, and a feed flow rate of 5 mL/min. To dry the freeze-dried extracts, each sample was first kept at a temperature of -18°C for 3 h, and then the drying operation was performed in a freeze dryer for 24 h. In all treatments, the Brix feed solution was kept constant at 10%. The produced powders were evaluated in terms of encapsulation efficiency, moisture content, water solubility, and total phenol content.

The results showed that by increasing the amount of WPI to 50% (50:50 ratio), encapsulation efficiency significantly increased (p<0.05). In the spray and freeze-dried samples, the lowest moisture content was observed in the sample treated with 100% maltodextrin. Increasing the maltodextrin ratio significantly (p<0.05) increased the solubility of the powders in water. The evaluation of total phenol content showed that the red beetroot extract powders prepared with freeze dryer had the total phenol content. Also, the powder samples obtained from the ratio of 50:50 maltodextrin to WPI had the highest total phenolic content. Based on the results obtained in this study, it was found that the use of the 50:50 ratio for maltodextrin and WPI resulted in desirable physicochemical properties in the powders obtained by both drying methods. Therefore, due to the high costs of freeze-drying and the results of the present study, it can be concluded that the spray drying method with the conditions applied during this study can be used as an effective and promising method for the production of natural pigments based on red beetroot extract for use in food, pharmaceutical, and cosmetic industries. Hence, using a 50:50 ratio for maltodextrin and WPI as wall materials and drying aid is recommended for the production of red beetroot pulp powder.

Gum tragacanth (GT) is one of the natural secreted hydrocolloids which have many applications in food and pharmaceutical industries. Unfortunately, there is limited scientific information about the electrostatic interactions of gum tragacanth with proteins, especially the proteins that have been unfolded by physical approaches. In this regard, the main objective of this study is investigation the effect of thermal processing on the whey protein isolate (WPI) properties and their complexation with gum tragacanth. The influence ofheating time (0, 5, 10, 15, 20, 25, 30 and 35 min at 80C) on the turbidity of WPI, alone and in the mixture with GT (r = 0.1, pH 4.0 and Cp 0.1 w/w) was surveyed. Then the flow behaviour and viscosity of gum tragacanth-WPI mixture solution in the shear rate of 0-100 S-1 (pH 4.0) was compared with the individual solutions of gum and protein. Since the maximum turbidity was observed in the range of 15-35°C, the impact of heating time at three levels (15, 25 and 35 min) and biopolymer mixing ratio at six levels (2:1, 1:1, 1:2, 1:5, 1:10 and 1:20) on the protein and carbohydrate compositions of precipitation and supernatant were investigated by lowry and phenol-sulphuric acid experiments, repectively. Turbidity of protein solutions were significantly changed with rising the heating time such that the maximum turbidity achieved after 25 min thermal processing. While these solutions were unstable due to protein-protein interaction and formation of protein aggregates, GT addition leads to meaningful changes in the stability of protein solutions which was as a result of protein-polysaccharied interactions. Similar to protein solutions, the maximum turbidity of the complexes was achieved after 25min thermal processing. The rheological measurements showed that the mixture solution has pseudoplastic behavior with a large hysteresis loop as well as the higher viscosity rather than the blank solutions, all of which indicate the formation of electrostatic interactions between protein and polysaccharide and formation of complexes.By calculation of protein and polysaccharide in the supernatant and precipitation, the least ratio of Pr:PS was observed for the 25-min-treated WPI. Furthermore, the ratio of Pr:PS in the precipitation was increased significantly as Pr:PSratio was increased in the mixture. Addition ofgum tragacanth to the whey protein isolate will leads to a significant stability in the solution. Due to unfolding of WPI, using thermal processing on the whey protein isloate solution results in the meaningful increasing in the turbidity of protein solution and the efficiency of GT-WPI complex formation.

Labane or concentrated yoghurt is a semi-solid product which is being producedd by dehydration of yoghurt or separation of water and some water-soluble solids from yoghurt. High nutritional value, long shelf life, more desirable taste and texture and feasibility to produce other product are the reasons for high acceptance among customers. There are wide ranges of production methods from traditional methods which are tedious, such as separation of whey by fabric bags, to complicated time-consuming methods which also contaminate product and reduce its nutritional value. These cause demand to establish more suitable methods such as “wheyless process” by dried milk, concentrated milk protein or concentrated whey protein. On the other hand, one of the methods for enhancing firmness and textural properties of yoghurts, similar to other dairy products is utilization of hydrocolloids. These components are used for enhancing rheological an textural properties of food and commonly used as additives for increasing viscosity, gel forming ability, enhancing physical stability, film forming ability, controlling crystallization, postponing syneresis and textural improvement. Konjac gum (KG) is a neutral polysaccharide that derived from Amorphophallus konjac C. Koch tuber, which is well known in east countries during centuries. Ability to hold water and reduction of cholesterol and glucose are the reasons for grossing demand of this gum. So due to the importance of labane produced through wheyless process, the effect of different ingredients of formulation such as milk protein concentrate, cheese whey powder and konjac gum on physicochemical, rheological and sensory properties of labane was investigated and compared these properties by using Principal component analysis (PCA) and Partial least squares regression (PLS regression).

Cow milk was purchased from local market (Mashhad, Iran). Dried skim milk, milk protein concentrate, cheese whey powder   and commercial starter provided from Khorasan Razavi Pegah Company (ABY1, Christian Hansen, Horsholm, Denmark) and KG purchased from Food Chem. (China). In order to concentrate the milk, 3% dried skim milk was added to1 Kg milk. Then, according to the experimental design (table 2), MPC and CWP added to milk at 0, 4, 6 and 8% levels which reached the total solid of milk to 21.5%. KG with percentage of 0, 0.05, 0.1, 0.15, and 0.2% was added to the mixture at 40˚C. The mixtures were homogenized at 50˚C and pasteurized at 90˚C for 1 min. and then cooled to 43-45˚C. The mixtures were incubated at 43-45˚C for 3-4 hours after addition of starter. Then the samples were slowly stirred and packed in polyethylene bags after reaching to suitable pH. The samples were transfered to refrigerator for 24 hours then the tests were conducted. PH was measured according to AOAC 2005 official method NO. 935.42.25 gr of samples were centrifuged at 4˚C for 10 min. at 4500 rpm. Syneresis was evaluated as parentage of separated serum. Texture analyzer was used for combination of back extrusion and texture profile analysis (TPA) test. 50 mm in diameter cylinder with 10 mm in height and probe with 4 mm diameter and 100 mm height with the speed of 1 mm/s were used to conduct the test. Dynamic rheological parameters were evaluated by rheometer (Parphysica). The devise was equipped by 50mm diameter parallel plate with 2 mm gap. Eheo plus/32 version V3.40 software was used to measure elastic modulus (G’), loss modulus (G”) and η*.

Results showed that none of the linear, quadratic and interaction effect of MPC, CWP and KG was significant on pH of the samples at the first day. Results represented that the pH of the samples was varied from 0.36 to 0.94 after 5 days and only linear effect of MPC and CWP (at 99% level of confidence) and interaction effect of CWP-KG (at 95% level of confidence) were significant on that. The effect of MPC and CWP and interaction effect of MPC-KG, CWP-KG and CWP-MPC-KG were significant on syneresis at 99% of confidence. Results showed that hardness of the samples varied between 3.25-9.58 N and the interaction effects of MPC-KG, CWP-KG and CWP-MPC-KG were significant at 99% of confidence. None of the linear, quadratic and interaction effect of CWP, MPC and KG was not significant on springiness of the samples (p>0.05). In strain sweep test, two separated regions were distinguishable: linear viscoelastic (LVE) region that elastic and viscous modulus (G’ and G”) were constant and G’ was higher than G” which showed the solid like behavior, and non-LVE region that G’ and G” decreased by increasing strain and led to a crossover point (flowing point) which G” goes over the G’ and liquid-like behavior shows itself. In this test, strain corresponding to start of the non-LVE region and sharp reduction of G’ define as critical strain (γc) and the corresponding stress of this point defined as critical stress (τc).Results represented that G’LVE and G” LVE of the samples varied from 22.54 to 750.1 and 11.01 to 242.1 Pa, respectively and the selected model (cubic x quadratic) showed that the interaction effect of MPC-KG, CWP-KG and CWP-MPC-KG on G’LVE and G” LVE was significant at 99% of confidence while the interaction effect of CWP-MPC was only meaningful on G” LVE. Results also showed that the variation trend of G’LVE and G” LVE was the same by alteration MPC, CWP and KG in a way that both of these parameters were increased by increasing KG. The effect of MPC-KG and CWP-KG was significant on γc and τc at 95% confidence and also, in addition to mentioned effect, the interaction effect of CWP-MPC was significant only on γc. Increasing KG increased γc at higher amount of CWP and lower amount MPC which can be concluded that increasing KG amplified the gel strength. Also, the results of the correlation study between sensory and instrumental measures showed that there was a close relationship between the score of sour taste and the overall acceptance of samples, which showed that among the measured characteristics, sour taste score is more important than other parameters.

The aim of this study was to encapsulate the Barije(Ferula gummosa)essential oil (EO) in liposomal system and evaluate its physical and microbial properties.  Accordingly, nanoliposomes were produced by using specific ratios of lecithin-cholesterol by thin-film hydration-sonication method. Constitutive compounds of essential oil were identified using GC-Mass.  The physical properties of the liposomes, such as particle size, polydispersity index, zeta potential, and the efficiency of encapsulating system, were studied. Evaluation of antimicrobial properties was performed by the two methods of minimum inhibitory concentration (MIC) and disc diffusion test on E. coli O157:H7. Also, the effect of sub-inhibitory concentration of EO (sub-MIC) was evaluated before and after encapsulation against the growth of bacteria over 24 h. The most important constituents of EO were β-pinene (60.84%) and α-pinin (9.14%). The average particle size of EO loaded liposomes was in the range of 74.27 to 99.93 nm, which had a significant difference with the empty nanoliposome (138.76 nm) (p<0.05). Adding cholesterol to lecithin in a double-layered membrane of liposomes increases particle size and reduces the effectiveness of encapsulation (p<0.05). Electrostatic stability of empty liposomes was improved by adding a certain amount of cholesterol, but the zeta potential did not change significantly in cholesterol-based samples when essential oil was replaced in the liposomes (p<0.05). MIC of EO in encapsulating mode was lower in the liposomal system without cholesterol than in free mode.  This was confirmed by measuring the diameter of the bacteria's lack of growth. Nanoliposome specimens containing essential oil (60 mg lecithin) with concentration of 50 and 75% MIC significantly decreased the growth of E. coli O157:H7 compared to free essential oil (p<0.05). This research showed that nano-liposomal essential oil was successfully produced by thin layer and ultrasonic hydration method and the cholesterol-free sample in the liposomal membrane had an antimicrobial effect on E. coli O157:H7 relative to its free essential oil.

IntroductionEscherichia coli is an important bacterial pathogen transmitted through contaminated water and food. The aim of this study was to evaluate the physical characteristics of nanoliposome essential oil (EO) and its antibacterial effect on E. coli.Materials and MethodsNanoliposomes were prepared by thin-film hydration and sonication. Particle size, polydispersity index, and encapsulation efficiency were assessed. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of free EO and nanoliposome barije EO were determined by broth macrodilution against E. coli. Also, effect of different concentrations of the MIC of EO was evaluated before and after encapsulation against the growth of bacteria over 24 h.ResultsThe average particle sizes of the empty and EO loaded nanoliposome were 138.76 and 81.47 nm, respectively. Also, EO loaded nanoliposome had lower polydispersity. Moreover, the encapsulation efficiency of nanoliposomes was determined about 73.26%. MIC and MBC levels for EO loaded nanoliposomes decreased in comparison with free EO. Using 75% MIC of free EO in comparison with control, the bacterial count decreased by 3.528 and 1.12 log (CFU/mL) after 12 and 24 h, respectively. This reduction in the EO loaded nanoliposomes was 3.40 and 2.33 (CFU/mL) log (p <0.05).ConclusionNanoliposomes encapsulated barije EO were prepared successfully using the thin-film hydration and sonication method and showed enhancing antimicrobial activity against E. coli O157:H7 in comparison with the non-encapsulated one.

Plant seed mucilage is one of the most important hydrocolloids used in food industry due to the ability to create structure and texture, properties of emulsifying, thickness and dietary aspects. The aim of this study was to investigate the effect of quince seed mucilage replacement on physicochemical (pH, specific gravity, melting resistance and overrun), textural and sensory properties of vanilla ice cream. For this purpose, mucilage was used as a substitute for carboxy methyl ellulose in ice cream formulation at 5 levels (0, 25, 50, 75 and 100%). The results showed that with increasing replacement ratio, the amount of melting resistance, specific gravity and overrun significantly increased (p<0.05). Addition of mucilage did not have a significant effect on the pH of the ice cream mixture (p>0.05). Adding mucilage reduced hardness (p<0.05). Based on sensory evaluation results, adding mucilage increased the total acceptance of ice cream. In general, and considering all the characteristics, it can be concluded that the sample with 100% mucilage substitution had a higher quality than other treatments.

In this research, the effects of Konjac gum (0.2-0.6%), Fat content (18-25%) and Homogenization pressure (100-200 bar) on rheological properties of low fat cream were investigated. The results of the back extrusion test indicated that increasing konjac gum, fat content and homogenization pressure, significantly increased hardness, consistency and adhesiveness. The simultaneous increasing of homogenization pressure and fat content also led to increasing adhesiveness of the samples, which showed their synergistic effect of them on the adhesiveness. The results of the steady shear test showed that the flow behavior index (n) of all samples was less than one which indicates a shear thinning behavior (pseudoplastic) of all samples. Also increasing fat content, significantly decreased the flow behavior index of the samples and increased the consistency. konjac gum and homogenization pressure had no significant effect on the flow behavior. The optimum processing conditions for producing low fat cream with the high hardness, consistency, consistency coefficient and low flow behavior index for response variables were 146/51 bar homogenization pressure،18/01% Fat content and 0.59% konjac gum.

Production methods of concentrated yoghurt (labane) varied from traditional methods, which are tedious, such as separation of whey by fabric bags, to complicated methods. These raise demand to establish more suitable methods such as “wheyless process” by dried milk, concentrated milk protein or concentrated whey protein. So the influence of different ingredients such as milk protein concentrate (MPC), whey protein concentrates (WPC) and konjac gum (KG) on rheological properties of labane was investigated through mixture-process design methodology and optimized these properties by firefly algorithm. The results of the combination of back extrusion and texture profile analysis (TPA) indicated that increasing KG significantly increased hardness, adhesiveness and adhesiveness force especially for samples with high amount of CWP but increasing MPC and decreasing CWP decreased cohesiveness in samples with high amount of KG. Strain sweep test of the labane indicated that all sample had gel-like structure (weak gel) at 1 Hz and 20˚C. Rheological results also showed that increasing KG significantly increased G’LVE, G” LVE, γc, τy, τf and Gf especially for samples with high amount of CWP. The optimal results of different gum percentages to achieve maximum Hardness, Cohesiveness, G΄LVE, γc, τy, tan δ LVE, Gf and minimum Adhesiveness, Adhesiveness force, G˝LVE using the firefly algorithm in PC space, it has been shown that the optimum amounts of KG and MPC were close to each other and had more variance of the data which shows the similarity of the effect of these two component on the rheological parameters.

The purpose of this study was to investigate the effect of maltodextrin (MD)-whey protein concentrate (WPC) mixture on physical properties of thyme essential oil nanoemulsion. For this purpose, ultrasonically-prepared emulsions (containing 5% (w/w) thyme essential oil) were prepared using mixture of MD and WPC at different concentrations (10, 20 and 30% w/w) and different ratios (25:75, 50:50 and 75:25). Emulsion properties such as droplet size, viscosity, flow properties and physical stability were studied. Results indicated that MD-WPC ratio and concentration of suspension had significant effect on emulsion properties. Mean diameter of droplets were between 128.5621-232.6310 nm, while droplet size of emulsions with maltodextrin was smaller than those for proteins. Same results observed for viscosity. On contrary, emulsion stability decreased with increasing WPC concentration. For all emulsions, increasing the concentration of MD-WPC from 10 to 30% w/w increased the particle size, viscosity and decreased their stability.

In this study the ability of Saccharomyces cerevisiae PTCC 5052 to adsorption of aflatoxin M1 was assessed. In order to improve operational efficiency, Alumina ceramic was analyzed as a potential support for immobilization of yeast cells. In immobilization process, results indicated that the binding abilities of AFM1 by live cells of Saccharomyces cerevisiae were higher than non-live immobilized cells on alumina ceramic within 48 hours (P

Saffron which has traditionally been used in different industries as well as in folk medicine¡ is considered one of the valuable resources of antioxidant. However¡ there is little information about extraction of antioxidant compound from different parts of this plant especially its petal. Solvent-assisted extraction is considered one of the most important methods for extraction of the most valuable compounds from plant sources and is applicable in both laboratory and industrial scales. In this study¡ box-behnken design was used in order to investigate the effect of time (60-200 min)¡ temperature (25-85 ºC) and ethanol percentage (20–60%) on the yield of polyphenol¡ flavonoid and anthocyanin¡ and also the antioxidant activity and optimization of extraction process. Results showed that maximum yield of antioxidant compounds is achieved with extraction time of 104.29 min¡ extraction temperature of 66.31 ºC and ethanol percentage of 58.96%. Under these conditions¡ the values were 1134 (mg gallic acid/100 g) for polyphenol¡ 85.44 (mg quercetin/100 g) for flavonoid¡ 3584.13 (mg/100 g) for anthocyanin¡ 60.60% for DPPH free radical scavenging activity and 3.24 (mM) for ferric ion reducing antioxidant power.

Doughnut is a special fermented and fried snack. There are a few studies about wheat flour fortification with soy protein isolate to produce doughnut. The present research was done to study the effect on quality features of doughnut during preservation. Partial substitution of wheat flour with soy protein isolate at the levels of 0, 1, 2 and 5 g/100 g was carried out to determine its influence on quality characteristics of doughnuts. The water absorption and protein content of the samples were measured by Farinograph and kjeldahl method respectively. Quality characteristics of doughnut such as porosity and color were determined with Image J software. Sensory evaluation of doughnuts was carried out on 9-point hedonic scale by a panel of 12 judges.The protein content and water absorption of the fortified samples were higher, but their Volume, porosity and lightness were lower than the control. Control sample had the highest overall acceptability rating although the difference between samples were not significant (P>0.05). So it is possible to produce a doughnut fortified with 1-5% soy protein isolate with higher protein content without having significant negative effect on its acceptability.

The purpose of this study was to investigate the effect of Lallemantia royleana seed gum on the properties of oil-in-water emulsions stabilized by whey protein using “Response Surface Methodology (RSM)”. For this purpose، emulsions with different whey protein concentrates (0. 5_ 3%)، seed gum (0 - 0. 3%)، and oil volume fraction (20 - 50%) were prepared. Several properties of emulsions including mean diameter of droplets، zeta potential، surface tension and interfacial properties were studied. Selecting an appropriate model، the response-surface graph was drawn. For each response، a second-order polynomial model was developed using “Multiple Linear Regression Analysis”. Results indicated that increasing the gum concentration from 0 to 0. 15% the mean diameter of the droplets will be diminished but its further increase would enlarge the size of particles. Zeta potential analysis showed that the more concentration of resin emulsions the more negative zeta potential of emulsion will be. The optimum formulation was suggested to be: 0. 12% Lallemantia royleana seed gum، 4. 69% whey protein and 21. 59% oil.

Whey proteins are of wide application in the formation and stabilization of food emulsions. However، due to their high sensitivity to environmental conditions they quickly lose their functional properties. Glycolation of whey protein fractions is one of the methods used to modify their structure and improve their functional characteristics. The present work was carried out with the aim to prepare whey protein- starch conjugates and investigate the effect of protein to polysaccharide ratio on the quality attributes of oil-in-water emulsion. The results indicated that surface electrical charge decreased by increasing starch to protein ratio. On the other hand، changes in the surface and interfacial tension did not follow a clear trend in response to altering the mass ratio of protein. The drop size distribution curves were monomodal and nearly normal for all samples and became noticeably sharp with minimum width at protein to starch ratio 1:1. The finest and largest droplets were observed in the aforementioned sample and the one stabilized by modified starch، respectively. Studying the flow behavior of emulsions also revealed that starch containing sample exhibited the characteristics of near-Newtonian fluid، whilst the others were shown to have shear thinning pseudoplastic properties which became more distinct by increasing protein ratio leading to highest consistency index and lowest flow behavior index at %100 whey protein.