Showing 17 results for Varidi
Volume 12, Issue 47 (7-2015)
Abstract
Fried foods are favored by consumers because of the crispy crust, desired flavor and color, but these properties are accompanied by some undesirable effects to the consumers due to the considerable amount of oil absorption during frying process. Nowadays, the main challenge is to enhance the frying process by controlling and lowering the final fat frying of the fried foods. In this study, the effect of hydrocolloids (methyl cellulose, pectin and methyl cellulose- pectin) on the quality of deep- fat fried Falafels at 150, 170 and 190 ˚C for 1, 2, 3, 4, and 5 min were evaluated. Moisture content decreased whereas oil content, hardness, volume and color of potatoes increased with increasing fried time, fried temperature. The lowest oil content values are given for samples coated with methyl cellulose- pectin. The control samples had the highest percentage of fat content in all the frying time range.
Volume 12, Issue 48 (9-2015)
Abstract
The purpose of this study was to investigate the effect of lyophilized Alyssum homolocarpum seed gum–whey protein concentrate (with the ratio of 1:1, 1:3 and 3:1) on physicochemical properties of corn oil–in–water emulsions. Interfacial tension and emulsion characteristics such as particle size distribution, zeta potential, flow behavior, viscosity and creaming were investigated. The results showed that with the increasing gum ratio in the mixture, the interfacial tension increased, but the difference was not statistically significant. In emulsions stabilized with gum–protein mixture, increasing gum content, increased the particles size, negative charge on droplets surface, consistency coefficient, yield stress and hysteresis between the forward and the backward diagrams. The particle size distribution curve was monomodal and emulsions stabilized with this mixture showed non–newtonian and psedoplastic behavior. No creaming was observed in all emulsions.
Volume 13, Issue 0 (kongore 94- 2015)
Abstract
In this research stirred yoghurt prepared by addition of three sources of omega-3s; encapsulated fish oil, flaxseed oil and mixtures of the two oils at four levels (0, 650, 1625 & 3250 mg/1000 ml) and two addition step (after heating and after incubation step). Experiments were carried out in three replicates and a completely randomized factorial design was used for statistical analysis. Oxidative stability and fatty acid profiles were determined during the first, tenth and twentieth of storage time. The peroxide values and thiobarbituric acid values of enriched yoghurt with fish oil and enriched yoghurts after heat treatment are significantly highest. Polyunsaturated fatty acids and omega3 of enriched yoghurt with flaxseed oil is significantly higher than other samples. Therefore, it could be achieve the stirred yoghurt with higher oxidative stability by enrichment with flaxseed oil after heat treatment.
Volume 13, Issue 51 (7-2016)
Abstract
Today, many studies are doing to identify the lipolytic microorganisms because of the important role of them in the production of microbial lipases. Oilseed meals are a good place to achieve these microorganisms. In this field, yeasts are more important in comparison with other microorganisms. In this study, we isolated 27 types of fungi from Yazd sesame meal. After the evaluation of macro and micro morphological features, it was identified that 16 of them were from yeast group. Lipolytic yeasts were screened using Tween 80 agar medium and were identified to genus and species by colony and cell morphology observations and evaluation of fermentation reactions and the use of carbon and nitrogen sources. 4 lipolytic screened yeasts were included Sporidiobolus pararoseus, Sporobolomyces salmonicolor, Cryptococcus albidus and Yarrowia lipolytica .The ratio of areola diameter to the well diameter was between 2.314 – 2.714. S. pararoseus showed the maximum ratio of areola to well diameter (2.714) .Lipase activity of these four types of yeasts was measured in submerged cultures with Cezepek Dox medium for 7 days at 30 °C and 200 rpm by using of photometry method and p-nitrophenyl palmitate substrate. Lipase activity range was between 0.866 – 4.333 U/ml, and Cryptococcus albidus had the highest lipase activity 4.333 U / ml, while it showed the least biomass growth among other yeasts (OD= 0.577). Yarrowia lipolytica showed lipase activity of 3.466 U/ml and also, the highest biomass growth OD =0.806.
Volume 13, Issue 56 (10-2015)
Abstract
Yarrowia lipolytica is unusual yeast that has the ability to produce important metabolites such as lipase enzymes. Lipase enzyme has many applications in different industries including manufacturing of detergents, food industry, pharmacy, fuel and etc. In this paper, we studied the lipase enzyme produced by the yeast under different treatments of nitrogen sources such as yeast extract, peptone, soybean meal, sesame meal and sesame meal extracts on the medium of Czapek Dox Broth. Selected treatments of nitrogen resources include treatment solution (100%), solution (50%) containing with sesame cake extract (3.6%), solution (50%) containing with sesame cake extract (3.6%) in distilled water, solution (50%) containing with yeast extract (3.6%) in distilled water and solution (50%) containing with peptone (3.6%) in distilled water on the medium (CDB). Fermentation time levels are considered 3, 4 and 5 days. Among examined treatments, Treatment solution (50%) containing with sesame cake extract (3.6%) on the medium (CDB) showed the highest lipase activity (91.5900±0.56241 and 67.5200 ± 0.01000 enzyme units, respectively) in the fourth day of incubation with stirring speed (120 rpm) and temperature (30 °C). The results show use of sesame cake extract increases lipase activity more than use of yeast extract and peptone at the level of 5%. Also, statistical analysis of resulted data showed use of sesame cake extract increases lipase activity significantly at 5% level in comparison with yeast extract and peptone.
Volume 13, Issue 57 (0-0)
Abstract
Volume 13, Issue 59 (0-0)
Abstract
The lipase is used broadly in different industries such as food, drug, petroleum and detergent industry due to the catalyst ability of wide range of conversion reactions such as hydrolyzed, esterification and transesterification . Yeasts are one of the main generators of lipases. In this paper, we use RSM and CCD in order to examine the effect of PH (5.5-7.5), time incubator (3-7days) and sesame meal extracts added to experimental medium (0-100%) on lipase generation and activity, generated biomass of Cryptococcus albidusand optimization of lipase generation process and generated biomass. The results showed that the percentages of sesame meal extracts added to experimental medium and time incubator are the most effective factors on lipase generation and activity and amount of generated biomass, respectively. Based on conducted experiments, optimized conditions of lipase generation and amount of generated biomass are determined PH 5.56 time incubator 7 days and percentages of sesame meal extracts added to experimental medium 100 percent in order to achieve maximum lipase activity (98.96 unit enzyme) and cell dry weight (1.14 gram per 100 mili liter medium).
Volume 15, Issue 85 (3-2019)
Abstract
The effect of edible polysaccharide coating of Aloe vera and a packaging on physicochemical and biological properties of barberries during storage was examined. Barberries were treated with edible polysaccharide coating through immersion method and packaged under 0, 6 and 21% of oxygen concentration and maintained at 20 ºC for 12 weeks. During storage, moisture content, anthocyanin, color components and microbial characteristics were evaluated. The results showed that the effect of Aloe vera coating and packaging type on physicochemical and biological characteristics of barberries could be noticeable during storage time. Coating and packaging would reduce moisture loss, anthocyanin, brightness and redness. The number of aerobic microorganisms and amounts of mold and yeast in the samples treated with edible coating and packaging showed to be less than the control group during storage. Lastly, the results showed that coating with 10% of Aloe vera and vacuum packaging would further maintain color and anthocyanin, the main components of barberries.
Volume 16, Issue 96 (February 2020)
Abstract
Fermentation is one of the oldest techniques in food preservation, this process is defined as the biological activity of microorganisms to improve sensory, organoleptic and nutritional properties and produce a range of metabolites that inhibit the growth of unwanted microbial flora. As a result, fermented products have a shelf life substantially higher than raw materials and also have very beneficial effects on health. In this research, ginger in 4 and 8 % levels and yogurt whey in 0 and 3 % levels, were added to the carrots and evaluated during of 0,4, 8, 16, 24 and 32 days of fermentation. The results showed that by adding 4% ginger, pH, mold and yeast count and L* index decreased, acidity, total count, lactic acid count, a* and b* color indexes and overall acceptance increased. In contrast, the addition of 8% ginger had a negative effect on the studied parameters and decreased the overall acceptance and enumeration of lactic acid bacteria. Addition of yogurt (3%) decreased pH, mold and yeast count and L* index, but increased acidity, total count also color indices a* and b* and overall acceptance. In the non-yogurt and non-ginger sample from the beginning to the end of the storage period, pH, total count and mold and yeast counts increased steadily, and overall acidity and acceptance decreased. Whereas in the samples containing ginger and yogurt, the pH and count of mold and yeast decreased as the fermentation time increased to the 16th day and overall count increased, lactic acid bacteria, acidity and total acceptance. According to the results of this study, using 4% ginger, 3% yogurt and 16 days fermentation time to increase shelf life and lactic acid bacteria and improve the sensory characteristics of fermented carrots.
Volume 17, Issue 105 (November 2020)
Abstract
Abstract
Snacks have become a significant part of the diet of many people, especially children. These snacks have many fans due to their attractive objects and colors, high durability and relatively low cost. Most of them are made from cereals, and the main problem with these snacks is insufficient nutrients, which have a negative effect on health and increase obesity in people, especially children. Using quinoa grain in products, it creates diversity in current products and also increases the nutritional value of snack. On the other hand, today, attention has been paid to the re-use of by-product in the food industry and the rate of agriculture inputs, and returning these products to the production cycle will increase the value added. One of these by-product is suni bug damaged wheat, which is used not used in the cooking industry due to the damage of the gluten network and is consumed by livestock feed. In this study, the effect of the independent variables included the percentage of addition of quinoa (0.25%, 50%), moisture content (12, 15, 18%), the screw speed (120,160,200 rpm) was in the form of a central composite design. The influence of the independent variables on some physical and functional properties was investigated, including expansion ratio, hardness, water absorption index, water solubility index, sensory evaluation. The results showed that with increasing quinoa up t0 50%, increased the hardness (4.72-11.57N), water solubility index (21-28.4) and overall acceptability of the extruded product, and also decreased the ratio of expansion (3.77-2.86), water absorption index (5.39-5.05) and sensory acceptability of the texture. Sensory evaluation results showed that 12% humidity conditions, 175rpm screw speed and quinoa addition levels (19%) in the suni- bug wheat were suitable for snack production and had the highest overall acceptability.
Volume 18, Issue 114 (August 2021)
Abstract
One of the problems with the processed meat products shelf life is the formation of yellow spots in sausages. The aim of this study was to isolate and identify the microbial agents causing yellow stain from sausage by molecular- and culture-based methods. For this purpose, 15 samples from yellow spot and separation areas of chicken sausages were sampled. A total of 44 colonies grown on the MRS, M17, YGC, and PDB culture medium were inoculated into pre-packaged cutting sausages to induce the yellow spot. Yellow spots appearance9 samples and they were characterized by both culture-based methods and sequencing of a 350 bp fragment from 16S rRNA V3 region and a 800bp fragment from 18S rRNA ITS4 region. The results of the culture-based and molecular assay showed that the main causes of the yellow spots in the chicken sausage packaged under vacuum were Enterococcus faecium, Enterococcus faecalis, Streptococcus faecium and Candida saitoana. In addition, one species of Enterococcus and one species of Candida were also identified at the genus level. Examination of yellow spotted samples also showed that the microorganisms that cause yellow spotting cause changes in pH, color indices L*, a* and b*, and syneresis compared to the control sample but the rate of change is only in the syneresis quantity and a* was significant.
Volume 18, Issue 115 (September 2021)
Abstract
Mechanical injuries in to the tissue of ready-to-eat fresh-cut lettuce usually cause stresses which leads to increasing respiration rate. The shelf life of this product depends on the processing and packaging steps, the type of packaging film and the environmental conditions during storage. The purpose of this study was to evaluate the effect of storage time, storage temperature, immersion pretreatment and the number of perforations of packing film on the crispness coefficient and sensory evaluation (total acceptance) of fresh-cut packaged lettuce stored under modified atmospheric condition and also development of shelf-life kinetic model of this product. For this purpose, 250 g of the lettuce strips were washed and immersed into two different concentrations (1.5/0.5 and 1.5/0.1) of CaL/Cys, then packed and sealed in low-density polyethylene packaging films (LDPE, 42 μm thickness) with no perforation (N-MAP: 21% O2, 0% CO2) and 20 and 40 perforations per m2, respectively. The study was carried out at two temperatures of 5 and 10 °C, for a storage time of 12 days. Indices of quality maintenance, i.e., crispness coefficient and sensory evaluation (total acceptance) were investigated. Furthermore, a mathematical model was developed to describe the kinetics of changes in crispness coefficient and sensory evaluation. Then, the shelf life of the samples was predicted based on sensory evaluation. The results showed that changes in selected targeted parameters could be best described by a zero-order. The prediction of shelf life of fresh-cut lettuce samples showed that samples treated with 1.5%CaL/0.1% Cys packed in 20-PM-MAP, stored at 5°C and 10 °C and samples treated with 1.5%CaL/0.5% Cys packed in 20-PM-MAP stored at 5°C, had a shelf life of 12.62, 12.59 and 11.59 days (with no significant difference at p < 0.05), respectively.
Volume 18, Issue 118 (December 2021)
Abstract
This study was aimed to investigate the effect of Maillard reaction polymerization degree (PD) on functional properties of whey protein isolate. The whey protein isolate-gellan gum conjugate was synthesized by the Maillard reaction and the intermediate-to-final products absorption ratio (A294nm/A420nm), as the index of Maillard reaction PD, was evaluated. The whey protein isolate-gellan gum conjugates were then classified into three low, medium, and high PD using K-means clustering method, and their interfacial activity (interfacial tension reduction ability, emulsifying activity, and emulsion stability) and surface activity (foaming capacity and foam stability) were investigated. Interfacial tension at oil/water interface was reduced more efficiently by the medium PD whey protein isolate-gellan conjugate, indicating its higher adsorption rate to the interface (higher emulsifying activity), ability to form a viscoelastic thick layer at interface, and consequently increase the emulsion stability through steric repulsion. Although, foaming capacity was not significantly influenced by the PD (p>0.05), the foam stability in the presence of medium PD conjugate was significantly higher than the foams stabilized by other conjugates (p<0.05). Therefore, a medium PD is needed to improve the functional properties of whey protein and increase its industrial applications.
Volume 19, Issue 123 (May 2022)
Abstract
Abstract
In recent years, the individuals' demand for consumption of healthy and useful products has increased. With regard to the specific role of breakfast cereal in today's dietary habit, the incorporation of nutrients into their formulation is considered as a way to produce functional food products. So in this research, the effect of extrusion variables containing feed formulation (whole oleaster flour to whole oat flour (10 to 90, 25 to 75 and 40 to 60%), feed moisture (14, 18 and 22%) and screw speed (120, 150 and 180 rpm) on some properties of snack was investigated. Thus, the
central composite design was used to assess the water absorption index (WAI), water activity (a
w), expansion ratio. Based on the obtained results, in a constant condition of other variables (feed moisture; 18% and screw speed; 150 rpm), an increase of the whole oleaster flour ratio from 10 to 40% decreased the WAI (from 5.64 to 5.16) and expansion ratio (from 1.72 to 1.48). While, an increase of the feed moisture from 14 to 18% led to an increase in the WAI (from 5.01 to 5.16) and water activity (from 0.33 to 0.63), when replacement level and screw speed were 25% and 150 rpm, respectively. The evaluation results of the screw speed in the moisture of 14 and 22% indicated that increasing the speed resulted in a decrease and increase in WAI, respectively. In addition, the relationship between the expansion ratio and microstructure was proved by scanning electron microscopy method. The optimum condition was found to the blends of whole oleaster flour/whole oat flour (10:90), screw rate of 180 rpm, and feed moisture content of 22% with desirable properties including

(0.64%), expansion ratio(1.85), water absorption index(6.26).
Volume 19, Issue 124 (June 2022)
Abstract
Abstract
With regard to the importance of breakfast cereal in today's eating habit, these products can serve as vehicles for the main nutrients. Therefore, the purpose of this research was to investigate the effect of extrusion variables containing replacement level of whole oat flour with whole oleaster flour (10, 25 and 40%), feed moisture (14, 18 and 22%) and screw speed (120, 150 and 180 rpm) on some physical and functional properties of breakfast cereal. These properties included moisture content, bulk density (BD), hardness (HD), water solubility index (WSI) and color parameters assessed by central composite rotatable design. Based on the obtained results, an increase of the whole oleaster flour and feed moisture increased the moisture content and hardness and decreased the yellowness of the samples. While the water solubility index was increased by increasing the whole oleaster flour and was decreased by increasing the feed moisture. The evaluation results of the screw speed indicated that increasing the speed resulted in less bulk density, hardness and water solubility index. Additionally, the lightness of samples decreased due to a higher amount of all the variables studied. On the one hand, the difference between ingredients content and structure of the whole oleaster flour and the whole oat flour was one of the most effective factors on the obtained results. On the other hand, the influence of the feed moisture and screw speed, as very important factors of the extrusion process, on the physical and functional properties of the product was completely recognized. Optimum condition was found to the blends of whole oleaster flour/whole oat flour (10:90), screw rate of 180 rpm, and feed moisture content of 22% with desirable properties including humidity(10.26%), bulk density (0.11 g/cm3), hardness (11.01 N), water solubility index (12.66 %), lightness (56.09).
Volume 19, Issue 124 (June 2022)
Abstract
This study was aimed to investigate the effect of Maillard reaction browning intensity (BI) on the interfacial properties of emulsion systems stabilized by soy protein isolate. The covalent bonding between soy protein isolate and gellan gum was confirmed by the BI and then the resulting protein-polysaccharide conjugates were classified into three low, medium, and high BI clusters using Hierarchical Agglomerative Clustering (HAC) method. Next, the emulsification properties (emulsifying capacity, emulsion stability, and the percentage of adsorbed protein), thermal stability, and rheological behavior of emulsion systems stabilized by the above clusters were evaluated. The emulsifying capacity and emulsion stability were increased more efficiently by the high BI soy protein isolate-gellan conjugate, showing its faster migration and absorption rate, and consequently higher percentage of absorbed protein to the interface, and also form a thicker, cohesive, and viscoelastic interfacial layer along with more steric repulsion at its oil/water interface. In addition, the apparent viscosity of emulsions in the presence of high BI conjugate was significantly higher than the systems stabilized by other conjugates (p<0.05). However, due to the more unmasked hydrophobic patches of the high BI conjugated protein, the thermal stability of its emulsion was lower compared to other counterparts. Therefore, the Maillard reaction under mild and controlled conditions along with minimal final compounds formation can improve the interfacial properties of soy protein to improve its application in the food industry.
Volume 19, Issue 129 (November 2022)
Abstract
Recently, the quality of powder product was considered in food industry. Foam mat drying is an economical alternative to spray, drum and freeze-drying for the production of food powders. The high porosity and surface-to-volume ratio of foams during foam-mat drying improve final product quality. In this work, foaming properties of white button mushroom(Agaricusbisporus) were analyzedby response surface methodology. For optimization,xanthan gum (XG)solution range was considered between 0.05–0.3% w/w, mushroom concentration (water: mushroom puree) range was considered 1:0.5– 1:3.5 w/w and whipping time range was considered between 2–8 min. Based on face centered central composite design (CCF),twenty tests were done. Analysis of variance showed that the quadratic modelshaveconsiderable effects on both responses.In this research, the optimized pointwasobtainedat xanthan gum solution 0.2% w/w, mushroom concentration (water:mushroom puree) = 1:2.2 and whipping time= 6.19 minand the predicted values for foam density and drainage volumewere0.56 gcm-3 and 1.8 mL, respectively.At the second step, optimized foam dried at 50, 65 and 80°C and then drying behavior of optimized foam was investigated by different mathematical models. The results indicated that theMidilli model is high accurate model for evaluating the drying behavior of mushroom foam. At the third step, the influence of the drying temperatures on some qualitative characteristics of foam-matdried mushroom powder was investigated. It was found, as the temperature increased, water activity and water binding capacity decreased. Also, Lightness parameter for the temperature of 65°Cwas higher than other temperature.So, white button mushrooms can be processed into powder and used as a functional or nutritional addition in a variety of food products.