Research Article
Azam Ayoubi; Nasser Sedaghat; Mahdi Kashani-Nejad; Mohebbat Mohebbi; Mehdi Nasiri mahalati
Abstract
Introduction: Raisin is a principal traditional export product of Iran and has a special position in the foreign trade of the country.During storage, the product turns sticky and hard due to exudates syrup and moisture loss. To solve this problem, the application of edible coating would be an appropriatesolution. ...
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Introduction: Raisin is a principal traditional export product of Iran and has a special position in the foreign trade of the country.During storage, the product turns sticky and hard due to exudates syrup and moisture loss. To solve this problem, the application of edible coating would be an appropriatesolution. Edible coating may enhance the boundary layer resistance resulting to the enhanced shelf life of the product. Edible coatings are thin layers of edible materials applied to the product surface in addition to or as a replacement for natural protective waxy coatings and provide a barrier to oxygen, water and solute movement. They are also applied in foods to minimize the migration of components within the food systems or between the foods and their surrounding environment. They are used directly on the food surface by spraying, dipping or brushing to create a modified atmosphere. There are different kinds of films which are used such as polysaccharide, protein, lipid and composites. Lipid based coatings are primarily used for their hydrophobic properties which make them good barriers to water loss. In addition to preventing water loss, lipid coatings have been used to improve appearance by generating a shiny coverin fruits and vegetables, and to decrease respiration, thereby extending shelf life. The moisture barrier properties of hydrophilic coatings can sometimes be improved by addition of lipid materials The purpose of this research was to study the effect of lipid based edible coating (glycerylmonoestearate and carnauba wax) on physicochemical and microbial properties of raisin. Material and methods: Raisin samples (cvAskari)were dried usingsoda oil method and treated with coating materials based on lipid with essential oil of thyme (thymus vulgaris).Glycerylmonoestearate, carnauba wax and tween 80 were purchased from Sciencelab, Sigma-Aldrich and Merck Co. respectively. Raisinswerecoated with the following coating solutions: -Aqueous solution of tween 80 (0.5% w/w) -Aqueous solution of glycerylmonoestearate (0.5% w/w), tween 80 (0.5% w/w) -Aqueous solution of glycerylmonoestearate (0.5% w/w), tween 80 (0.5% w/w), 150 ppm essential oil of thyme -Aqueous solution of carnauba wax (0.5% w/w), tween 80 (0.5% w/w) -Aqueous solution of carnauba wax (0.5% w/w), tween 80 (0.5% w/w), 150 ppm essential oil of thyme Control sample was treated with aqueous solution of tween 80 (0.5% w/w).Distilled water was used for preparing all of coating solutions. Coating solutions were stirred and heated to 75oC (melting point of coating materials) for 30 min on a hotplate with a magnetic stirred to obtain uniform solutions. Dipping technique was used for coating of raisins. The coated raisins were placed on a basket to drip off residual coating solution and were dried in 25oC. The raisin smples were packaged in a 3 laminatedlayer bags (PE/PA/PE) with thickness of 80µ by Henkelman packaging machine and were stored at20, 35 and 50oC for 12 weeks. During the storage period, moisture content, water activity, hardness, color parameters (L*(lightness), a*(redness) and b*(yellowness)), percent of pestilence and microbial properties (total count, mold and yeast) were evaluated. Hardness of raisins was determined in apuncture test using a QTS texture analyzer (CNS Farnelll, Essex, UK) equipped with a needle probe (stainless steel cylinder of 2 mm of diameter with a conical needle bit) and a test speed of 60 mm. min−1 during the test. Hardness was defined as maximum force to puncture raisin from the top to a 2mm depth (Rolleet al. 2011).For colormeasurement, raisins were placed in to a black wooden box (interior size of 0.5 (width) × 0.5 (length) × 0.8 (height) m3 and were illuminated using 3 fluorescent tube lights (10W, 6500K; 40cm in length). A digital camera (Canoon EOS 1000D, Powershot, Taiwan) was located vertically at a distance of 20cm from the raisin surface. The images were preprocessed by Adobe Photoshop software, version 5.5. The Color properties were analyzed using ImageJ software, version 1.44o. The experiments were factorial with a completely randomized design. The coating material, temperature and storage time were the independent variables. Analysis of variance (ANOVA) was conducted for data using MSTAT-C software, version 1.42 (Michigan State University). Differences among the mean values were also determined using Duncan’s Multiple Range test. A significant level was defined as a probability of 0.05. The experiments were carried out on 4, 8 and 12 weeks after storage with three replications. Results and discussion: Results showed that coating, temperature and storage time would have considerable effect on the physicochemical and microbial properties of raisin. Coating caused decreasein moisture loss, hardness, lightness and redness. Increasing temperature and storage time increasedmoisture loss and hardness. Minimum hardness values were measured for 20 oC and 4 weeks storage and maximum hardness values were related to 50 oC and 12 weeks storage. Also it seems that increasing temperature and storage time influences thehardness by increasing moisture loss. Increasing temperature and storage time significantly decreased L* (p≤0.01). Increased enzymatic browning in raisins with increasing temperature was accompanied by an increase in a* value, and a decrease in b* value and caused to presenting dull colors. Total count, mold and yeast of coated samples decreased during storage period. Carnauba wax was more effective than glycerylmonoestearate on stability of raisin. Essential oil of thyme also caused improving color and microbial properties. Least values of redness (-2), total count (2.06 log cfu/g) and mold and yeast (1.32 log cfu/g) were related to carnauba wax coating with essential oil of thyme.
Research Article
Seyed Ali Mortazavi; Zahra Sheikholeslami; Mehdi GhiafeDavoodi
Abstract
Introduction: Bread stales and unfortunately it is a certainty and causes significant product waste all over the world.Staling results in loss of important sensory parameters of bread, like flavor and texture, and it is a consequence of a group of several physical–chemical changes occurring during ...
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Introduction: Bread stales and unfortunately it is a certainty and causes significant product waste all over the world.Staling results in loss of important sensory parameters of bread, like flavor and texture, and it is a consequence of a group of several physical–chemical changes occurring during bread storage that lead mainly to an increase of crumb firmness and loss of freshness (Gray and Bemiller 2003). At 21th century freezing technology introduced to bakery industry in order to increase bread shelf life, access fresh bread with a minimum need for equipment and skilled personal at any time.The current trend in the baking industry is to use frozen dough to manufacture quality products because it can be quickly transformed into fresh baked product. However, the use of frozen dough has certain disadvantages such as its variable performance and loss of stability over long-term frozen storage (Ribotta and Le Bail 2007). Research has shown that ice crystallization and recrystallization causes physical damage to the gluten network, leading to changes in the rheological properties of the frozen dough. Water available for freezing forms ice crystals that injure yeast cells (Mazur 1968). Gums trap free water and control moisture migration.Furthermore, Ward and Andon (1993) mentioned that gums such as carboxymethyl cellulose, carrageenan, gum arabic, and locust bean gum may be used to alleviate the problems associated with frozen dough. Numerous studies report that enzymes play key roles in bread making such as increasing loaf volume, producing finer crumb cells, and extending shelf-life. Amylase improved frozen dough bread quality; the enzyme allowed us to obtain breads from frozen dough with high specific volume and low crumb firmness(Ribotta and Le Bail 2007). Therefore, the aim of this work was to study the effect of guar gum and alpha amylase on frozen dough and the influence of them on the minimization of the damage caused by frozen storage. Materials and methods: Wheat flour sample (cvs, Pishgam) with 10.52% moisture, 10.8% proteins ,79% ash, 26.7% wet gluten, was obtained from silo No.3, Mashhad, Iran. Bread recipes also contained active dry yeast (Razavi Co., Mashhad, Iran), vegetable oil( Ladan Co. Behshahr, Iran), salt and sugar (Local market). Amylase enzyme (25 klu/g) and guar gum afforded from Novozyme and Rodhia CO respectively. The bread formula used for Barbari bread consisted of flour (100 parts), compressed yeast (2 parts), salts (2 parts), sugars (1parts), vegetable oil (1 part) and water (based on water absorption at 500 BU). Guar and amylase replaced in bread formulation at two levels (0.4 and 0.8%), and (0.05. 0.07 %) respectively. Bread was part baked in an electric oven with an incorporated proofing chamber (Zuccihelli, forni, Hal, Italy) at 210˚C for 7 min to obtain texture structure before starting coloring reaction. Barbari bread sample were packaged in polyethylene bags and frozen in a blast freezer. After storage at -18°C for 15 day, PBF bread was thawed at room temperature for 10 min and rebaked at 260°C for 8 min. The fresh bread baked at 230 °C for 15 mines (Ba´rcenas and Rosell, 2007). Specific volume , porosity, texture evaluation, image analysis (L*a*b*) and sensory evaluation of bread were measured using AACC methods (2000). Results were reported as the average of three replications (all treatments were evaluated in three batches). The data obtained were statistically treated by a complete randomized design (factorial) analysis while the means were compared by the Duncan’s test at a significance level of 5%, in both cases using SPSS statistical software (version 17). Result and discussion: The results showed that frozen storage had significant effects on the specific volume, moisture content, crumb hardness, sensory properties and bread color. Addition of gum and enzyme to bread recipe improved bread quality, alone and in combination. The presence of guar and amylase removing the negative effects of process conditions. Addition of guar at 0.4% improved specific volume, textural properties, color, sensory score and decrease bread firmness. Also using of amylase in 0.07%,increased bread quality. When guar used in combination with amylase, the synergistic effect was observed. The best result, obtained with 0.4% guar and 0.07% amylase. Conclution: In summary, the result of this study has shown that textural and sensory properties of part baked frozen bread were poor. Addition of guar gum increased specific volume and sensory score of bread. Guar in 0.4% concentration in comination with amylase in 0.07%, were more effective and it could introduce as a improver for part baked frozen bread.
Research Article
Samira Feyzi; Mehdi Varidi; Fatemeh Zare; Mohammad Javad Varidi
Abstract
Introduction: Plant proteins play a significant role in the human diet, and among which legumes are excellent foods with several nutritional and functional advantages and low price. Among legumes, fenugreek (Trigonella foenum graecum) seed, belonging to the Fabaceae family, is a great source of plant ...
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Introduction: Plant proteins play a significant role in the human diet, and among which legumes are excellent foods with several nutritional and functional advantages and low price. Among legumes, fenugreek (Trigonella foenum graecum) seed, belonging to the Fabaceae family, is a great source of plant proteins, with a total protein content of about 25.00 – 38.60%. Functional properties are defined as physical and chemical properties, which could be altered due to the protein source and procedures used for flour preparation, protein concentrate and isolate extraction. Physiochemical parameters such as pH, temperature, salt and ionic strength can also highly affect proteins, functional properties.Therefore, in this study color parameters and functional properties of fenugreek protein isolate (FPI) were investigated. Also, the effect of pH changes on protein solubility, foaming capacity (FC) and stability (FS), emulsifying capacity (EC) and stability (ES) was studied. Materials and methods: Fenugreek seeds were obtained from a retail market in Isfahan, Iran. All chemicals were of analytical grade, and were purchased from Sigma Chemical Co. (St Louis, MO, USA), and Merck KGaA (Darmstadt, Germany). Protein Isolation: Protein from 10g defatted fenugreek flour (DFF) was extracted with 0.33M sodium chloride solution; the ratio of DFF to NaCl solution was set at 1:20 (w/v) and pH was adjusted to 9.25. The stirring period was 2 h, during which pH was also adjusted. Aliquots were then centrifuged and supernatants were adjusted to pH 4.5 (isoelectric pH of fenugreek protein). Again, the protein solution was centrifuged in order to precipitate the protein. Protein precipitate was washed twice with deionized water, followed by centrifugation and resolubiliztion by adjusting the pH to 7.2. The extraction process was carried out at room temperature (25°C). Color parameters: A digital colorimeter was used to measure the color of full fat and defatted fenugreek flours, and FPI samples. Color parameters were recorded in L*a*b* space. Protein solubility: Protein solubility of FPI at pH 2-10 was determined. A 1.5% (w/v) solution of sample was made in deionized water for each pH. The solutions were treated with either 0.5M HCl or 0.5M NaOH to obtain certain pH (2-10), while stirring. The slurry was centrifuged to separate the supernatant. Protein content was determined by the Biuret method using spectrophotometer at 540nm wavelength. Calibration was done using bovine serum albumin (BSA) as external standard. Viscosity: A suspension of 5% (w/v) FPI in distilled water was prepared. Viscosity of sample was determined using a programmable Brookfeildrheometer, using spindle ULA at room temperature. Coagulated protein: Percent of coagulated protein was measured by preparing 0.2g of FPI in 10mL of 0.025M citrate-phosphate buffer (pH 7.0). The solution was stirred, followed by centrifugation. The remaining supernatant was heated for 15min in a 100°C water bath, after cooling the same procedure was repeated. The absorbance of both samples, before heating (A1) and after heating (A2), was measured at 540nm according to Biuret method. The percent of coagulated protein was calculated by the following equation: Coagulated protein = (A1 – A2 / A1) × 100 (1) Foaming capacity and stability: FC and FS were determined using 2% (w/v) FPI solution in distilled water. For each sample solution, the pH was adjusted to desired level (2, 3, 4.5, 6, 8, and 10). The solution was stirred slightly for 5min and then was whipped vigorously by a disperser. The volume of solution before whipping, also the total volume of solution and foam after whipping were recorded as V0 and V1, respectively. The foam capacity percentage was calculated as: FC (%) = (V1- V0/V0) × 100 (2) Foam stability was determined as the total volume of solution and foam at 30, 60, 90 and 120 min at room temperature and it was recorded as V2. Foam stability (FS) was calculated as: FS (%) = (V2 - V0) × 100/ (V1 - V0) (3) Emulsifying capacity and stability:For EC and ES, a 1% (w/v) FPI solution in distilled water was prepared. The pH was adjusted to desirable level (2, 3, 4.5, 6, 8, and 10) followed by stirring for 5min, then sunflower oil was added. The mixture was homogenized to make emulsion, followed by centrifugation. Then the height of both emulsified layer after centrifugation (H1) and the total height of content before centrifugation (H0) were measured. Emulsion capacity was calculated as: EC (%) = (H1/H0) × 100 (4) The ES (%) was calculated at 0, 30, 60, 90 and 120 min by measuring height changes (H2). ES (%) = (H2/ H1) × 100 (5) Results and Discussion: FPI with 89.1% protein content had significantly (p < 0.05) lower L* than DFF, while its L* was higher than the full fat fenugreek flour. Also, FPI showed shear thinning behavior with viscosity equal to 1150, 922.5 and 787.5 cP at 15, 30 and 50 (1/s) shear rates, respectively. pH changes had noticeable effect (p
Research Article
Amir Pourfarzad; Mohammad Bagher Habibi Najafi; Mohammad Hossein Hadad Khodaparast; Mohammad Hassanzadeh Khayyat
Abstract
Introduction: Fructans are an important product of the industry of prebiotics. In addition to their interesting nutritional and health benefit properties, fructans are also used in food formulations for their techno-functional properties such as fat substitute, bulk agent, water retention. Serish (Eremurus ...
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Introduction: Fructans are an important product of the industry of prebiotics. In addition to their interesting nutritional and health benefit properties, fructans are also used in food formulations for their techno-functional properties such as fat substitute, bulk agent, water retention. Serish (Eremurus spectabilis) belongs to the family of Liliaceae and geographically distributed in the region of South Asia and Central Asia. Their roots accumulate high levels of fructans during their growth and are traditionally used to cure jaundice, liver disorders, stomach irritation, pimples and bone fractures and even as a glue for industrial application. Recently fructan extraction from numerous plants and fungus has drawn the attention of researchers. Also, several methods for fructan extraction have been developed such as hot-water extraction, precipitation by alcohol and ultrasound-assisted extraction. To the best of our knowledge, there are no reports on the fructan extraction from Serish. The present study is considered the first attempt aiming to determine the optimal conditions for water extraction of Serish fructans. Materials and methods: The Serish root powders were obtained from the local medical plant market, Mashhad, Iran. Moisture, ash, fat, protein, Carbohydrate and total dietary fiber were determined according to standard AOAC methods. All variables were examined in triplicate. Conventional extraction was carried out in a water bath. Total carbohydrate was assayed colorimetrically using the phenol–sulphuric acid method. The concentrations of soluble reducing sugars were measured using a 3,5-dinitrosalicylic acid (DNS) method. The fructan content was measured by the difference between total carbohydrate and reducing sugars. The percentage of fructan yield (%) was evaluated based on equation of Lingyun, Jianhua, Xiaodong & Yalin (2007). The purity was evaluated according to the method of Paseephol, Small & Sherkat (2007). As an index of degree of polymerization, the average chain length, was calculated according to Lingyun, Jianhua, Xiaodong & Yalin (2007). A Box-Behnken design was constructed using the software Design Expert Version 6.0.10 and was used for estimating the effect of independent variables on the extraction parameters. Three extraction variables considered for this research were x1 (extraction time), x2 (extraction temperature) and x3 (water: solid) for conventional extraction method. Lack of fit, coefficients of determination (R2), adj-R2, coefficient of variation (CV) and significant probabilities were calculated to check the model adequacy. Optimization was based on generation of the best results for fructan extraction. In order to determine the validity of the model, the experimental and predicted values were compared by paired t-test. Results & discussion: It has a marked amount of protein and fats. The ash value is relatively high, suggesting an important mineral content. The composition of total fiber suggests its possible use as a source of dietary fiber for enrichment of foods. In addition, results show that Serish root powder is a polysaccharide-rich material. The results indicated that extraction temperature has the most effect on the extraction yield. Increase of time, temperature and water to solid ratio led to significantly increase in extraction yield. Considering the significant quadratic term of extraction time, it becomes clear that yield rises as extraction time increase from 0 to 22.5 min but it decreases at higher times. The yield increase between 0 to 22.5 min might be due to the time requirement for contact of fructan to the release medium where the liquid penetrated into the Serish powder, dissolved the fructan and subsequently diffused out from the root. On the other hand, the yield decrease after 22.5 min may be ascribed to degradation of fructan to free sugar and enhancement of impurities extraction at higher times. When extraction time goes by certain threshold, the yield started to decrease. The yield showed a large tendency to increase when the extraction temperature was increased. This is maybe due to the enhancement of the mass transfer resulting from the increased solubility of fructan and the decreased viscosity of the solvent. Yield was increased by portion of water to solid. This might be attributed to the availability of liquid that increases the driving force of fructan out of the root. Based on the sum of squares, temperature had the most effect on degree of polymerization. The results indicated that increase of time, temperature and W/S ratio resulted in increase of the degree of polymerization which might be due to the enhancement of overall carbohydrates extraction. On the other hand, the degree of polymerization of extracted fructan was lower than 10. This is probably because the disruption of fructan branch to reducing sugars with increasing temperature that leads to chain length decrease. Thus, the produced oligosaccharides could be used as sweetener. W/S ratio had the most effect on purity. The results showed that increase of time, temperature and W/S ratio resulted in increase of the purity which might be due to the enhancement of overall carbohydrates extraction. With the increase in extraction time, the purity of extract increased gradually, but decreased after the purity reached a maximum at 22.5 min. This decrease may be ascribed to degradation of fructan to free sugar and enhancement of impurities extraction at higher times. Multiple response optimizations were performed to measure the optimum levels of independent variables to achieve the desired response goals. Extraction yield and purity were desired maximal. Conclusion: The final results for this optimization was found to be extraction time of 28.38 min, extraction temperature of 88ºC and water to solid ratio of 50:1 v⁄w. Response surface methodology was an efficient statistical tool to model the influence of extraction conditions of fructan from Serish root powder on the extraction yield. These results also suggested that by modifying the proportion of these components, a large range of variations may be obtained. There was a good agreement between the experimental data and their predicted counterparts, showing the effectiveness of the proposed conditions and reliability of Box–Behnken analysis on fructan precipitation.
Research Article
Nasser Sedaghat; Ghodsieh Moradi; Sara Khoshnoudi; Arash Koocheki
Abstract
Introduction:Pistachio (Pistaciavera L.) is a tasty nuts and a good source of nutrients. During the last decade, the worldwide trades of pistachio have increasing trend, likely reflecting on the increase in consumers demand for this nuts. The high oil and essential fatty acid contents of the pistachio ...
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Introduction:Pistachio (Pistaciavera L.) is a tasty nuts and a good source of nutrients. During the last decade, the worldwide trades of pistachio have increasing trend, likely reflecting on the increase in consumers demand for this nuts. The high oil and essential fatty acid contents of the pistachio kernel is important from a nutritional point of view. However, high unsaturated fatty acids content makes pistachio nuts susceptible to oxidation and consequently off-flavors and off-aromas during storage.Mold growth and the production of aflatoxins is another food-safety concern about pistachio nuts. Lipid oxidation and fungal growth can be controlledby using an appropriateatmosphere in packaging.Therefore, the main objectives of this study were to determine the effect of Modified Atmosphere(MA) compared with Vacuum and Air condition packaging on physicochemical, microbialandsensory properties of raw dried Pistachio nuts (ohadi variety) in an accelerated storage conditions at 30±2°C and 50°C for 12 weeks. Material and methods: The pistachio nuts were treated with 3 different system packaging, these treatment includes modified atmosphere packaging (MAP at 88% N2; 10% CO2 and 2% O2), vacuum packaging and air condition packaging. The pistachio nuts were packed in five-layerpouches (2 PE+ 2 PA+1 glue :80 microns)and stored in triplicate at 30°C and 50°C for12 weeksand they were sampled every four weeks. Oil from pistachio kernels for peroxide, and fatty acid assay were extracted by cold extraction and n-hexane was used as extraction solvent. Peroxide value (Meq.kg-1) of the extracted oil was determined by spectroscopic absorbance reading at 500 nm. Free fatty acids (%), as oleic acid percentages in oil samples, were determined using the titration method. Moisture content (%) was determined by drying 5 g of ground kernels at 103±2 °C until constant weight. The mouldcontent (log CFU/g) of pistachios were performed according to the Iran standard method. The textural analysis of the pistachio nuts were performed using cylinderprobe (diameter: 20 mm) at test speed 50 mm/min and deformation of 4 mm for samples. Fracture force (N) and hardness (N) parameters were measured to evaluate textural properties ofpistachio nuts samples.Sensory evaluation was carried out by a 20 member trained panel (10 females and 10 males). Sensory attributes evaluated included color, firmness, rancidity and overall acceptability on 5 point hedonic scale, whit 5 for excellent and 1 for very dislike. Analysis of variance (ANOVA) was carried out using the least significance difference(LSD) test (p
Research Article
Zeinab Mohammadi; Dina Morshedi; Masoud Mashhadi Akbar Boojar; Farhang Aliakbari
Abstract
Introduction: Hen egg white lysozyme (HEWL) is one of the proteins that has become increasingly important in many industrial aspects, including food and drug industries as well as high-technologies such as nanotechnology due to its specific properties. Its high thermal stability makes it a good natural ...
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Introduction: Hen egg white lysozyme (HEWL) is one of the proteins that has become increasingly important in many industrial aspects, including food and drug industries as well as high-technologies such as nanotechnology due to its specific properties. Its high thermal stability makes it a good natural food additive and sweetener. It has the antimicrobial activity against a wide variety of microorganisms such as Bacillus stearothermophilus, Micrococcus spp, Clostridium botulinum,Listeria monocytogenes as well as fungi. This activity remains inover a broad pH and ionic strength ranges. Thanks to its numerous advantages, it has been commonly used as an alternative to chemical antimicrobial agents in food industry such as sausage and dairy industries. HEWL has also high tendency to convert to protaneous well-ordered nanofibrils that is employed in nanotechnology. Furthermore, based on its well-known biochemical and biophysical features, HEWL is widely used as a model protein in the studies associated to the structure and function of proteins. Given theimportance increasing of lysozyme, development of an effective and simple as well as inexpensive method to purify this protein is required. Material and methods: All salts and organic solvents were obtained from Merck (Darmstadt, Germany).Fresh eggs were purchased from a local market. After separating the white part from the yolk of eggs, it was diluted and filtered through linen. The filtered solution was then precipitated with 30 and 50% ammonium sulfate. The pellet of 50% ammonium sulfate dissolved in tris buffer (pH:7 with 2.5 M of urea) and was dialyzed for 15 hours.Thereafter, the sample was loaded on the cation exchange chromatography on a column of SP Sepharose Fast Flow. The washing buffers include buffer A (tris 30mM, pH:7 with urea 2M) and buffer B (tris 30 mM pH:7,ammonium sulfate 0.7 M and urea 2M) which were gradiently exchanged. The structural characters of the purified protein were analyzed by Far-UV CD (AVIV 215 spectropolarimeter, USA) and intrinsic fluorescence (usingVarian Cary Eclipse fluorescence spectrophotometer, Mulgrave, Australia) methods. To estimate the percentage of secondary structure in proteins the CD data was deconvoluted by CDNN software. In the next step, the enzymatic activity of the purified protein was tested based on Shugar’s method with some modifications and by using different strain.In this regard, the turbidity of cultured Micrococcus lysodeikticus was measured at 450 nm by T80+ Double Beam UV/Vis spectrophotometer (Leicestershire, England) after threating the cultures with purified protein and the enzymatic activity compared with the activity of an equal concentration of standard HEWL obtained from Sigma-Aldrich (USA).Bradford assay was carried out to determine the concentration of proteins Results& Discussion: The subject of this study was to develop an effective, simple and inexpensive method topurify HEWL which has been able to scale up practically. In the first step, the filtered diluted white part of egg was precipitated withdifferent concentrations of ammonium sulfate. SDS-PAGE analysis indicated that the final pellet achievedby precipitation with 50% of ammonium sulfate had less impurity of the high molecular weight proteins. Salting out is an inexpensive and non-invasive purification method which can be used easily. Different proteins based on their specific chemical and physical properties precipitate at different concentrations of the salt. Ammonium sulfate is a common salt widelyusing for this purpose because of its inexpensive cost and high strength for salting out of different proteins. After ammonium sulfate precipitation step, the pellet was dissolved and consequently dialyzed in the presence of 2.5 M urea for 15 hours. After centrifugation, the sample solution was loaded on a cation exchange column chromatography. PI of HEWL is 11.35and the employ of a kind of cation exchange resin is appropriateto use for chromatography.After that, the column was washed with different proportions of buffers A and B. Each washed fraction of chromatography was collected and then analyzed with SDS-PAGE. The high purified protein (with more than 98% purity) was obtained in the fraction after washing with a solution of 4A+6B. Special activity of the final product was calculated which was considerably comparable to the activity of the standard enzyme. Furthermore, structural studies by circular dichroism (CD) spectroscopy indicated that the spectrum of the purified protein was very comparable with the standard HEWL. Deconvolution of CD data by CDNN software also showed that there were mostly same secondary structures in both proteins.Assessment of the intrinsic fluorescence intensity is also a valuable method to consider about integrity of tertiary structure of proteins based on exposing rate of hydrophobic residues especially tryptophan. The data extracted from CD and fluorescence spectroscopies confirmed that the purified HEWL had similar secondary and tertiary structure with the standard protein. Conclusion: This study has developed an experimental method to purify HEWL which is simple, fast, and low cost with high efficiency.
Research Article
Latifeh Pourakbar
Abstract
Introduction: Lipid oxidation is a major cause of food quality deterioration during storage of oils, fats and other fat-containing foods. Oxidation of lipids results in changes that may affect the nutritional quality, wholesomeness, colour, flavour and texture of food. Moreover, the products of lipid ...
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Introduction: Lipid oxidation is a major cause of food quality deterioration during storage of oils, fats and other fat-containing foods. Oxidation of lipids results in changes that may affect the nutritional quality, wholesomeness, colour, flavour and texture of food. Moreover, the products of lipid oxidation may be potentially toxic and may lead to adverse effects such as the production of carcinogens, mutagenesis and aging. Autoxidation occurs when molecular oxygen reacts with unsaturated lipids. The process involves a free radical chain reaction that is most frequently initiated by exposure of unsaturated lipids to light, heat, ionizing radiation, metal ions or metalloprotein catalysts. Free radicals are defined as any chemical species having one or more unpaired electrons. Antioxidants are a group of chemicals capable of extending the shelf life of food that contain lipids. They are used to retard the development of unpleasant flavour caused by the oxidation of unsaturated fatty acids. They retard oxidation of lipids by reacting with free radicals, chelating free catalytic metals and also by acting as oxygen scavengers. Currently the food industry uses synthetic antioxidants such as BHA, BHT and TBHQ to retard lipid oxidation. However, there is concern about the safety and toxicity of synthetic antioxidants in relation to their metabolism and accumulation in body organs and tissues. Synthetic antioxidants are known among other things to cause impairment of blood clotting, lung damage and to act as tumor promoters. As a result of this, consumers have a preference for natural ingredients and there is a growing interest in the potential use of antioxidants from natural sources. Phenolic extracts from herbs and spices, cereals and legumes have been reported to effectively retard lipid oxidation in oils and fatty foods. As a result of concern for the safety of synthetic antioxidants, there is a growing interest in the potential use of phenolic extracts from plant sources as antioxidants in lipids. The potential use of phenolic extracts from different plant sources such as sorghum, herbs and spices have been studied extensively. Extracts of spices such as rosemary and sage are now available commercially for use as natural antioxidants. Phenolic compounds are defined as substances possessing a benzene ring bearing one or more hydroxyl substituents, including their functional derivatives. There are different sources of phenols such as grapes, olive oil, sorghum, beans, spices and herbs. Phenols have many favourable effects on human health. They decrease the risk of heart diseases by inhibiting the oxidation of low-density lipoproteins (LDL). A large range of low and high molecular weight phenols exhibiting antioxidant properties have been studied and proposed to be used as antioxidants against lipid oxidation. This is particularly true for those phenolics with multiple hydroxyl groups that are generally the most efficient for preventing lipid oxidation. Phenolic compounds are also known to possess antibacterial, antiviral, antimutagenic and anticarcinogenic properties. Generally the efficacy of phenolic compounds as antioxidants depends on a number of factors such as the number of hydroxyl groups bonded to the aromatic ring, the site of bonding, mutual position of hydroxyls in the aromatic ring and their ability to act as hydrogen or electron donating agents and free radical scavengers. All polyphenols are capable of scavenging singlet oxygen and alkyl radical through electron donating properties, thus generating a relatively stable phenoxyl radical. The goals of this study were to investigate the effect of incorporation of different apple cultivars’ phenolicextracts onformation of primary oxidation products in buttercomparing tosome of thesynthetic antioxidants such as BHA and BHT Material and methods: Different apple cultivars from different places of West Azerbaijan province had been collected and their total phenol content, flavonids and antioxidant properties were measured according to Folin-Ciocalteu, Colorimetry and Diphenylpicrylhydrazyl (DPPH) methods respectively. The measurement of peroxide value and thiobarbituric acid of local butter oil samples consisting of different concentrations of extract and synthetic antioxidants was performed as well. Discussion & Results: In conclusion, this investigation demonstrates that apple is a rich source of phenolic compounds and antioxidant capacity.Fuji and Sheikh Ahmad cultivars showed the maximum and minimum content of total phenol content, flavonoids and antioxidant activity which are 2940.24 and 1350.22 microgram equivalent gallic acid/ gram of dry extract; 2530.32 and 1200.74 microgram equivalent quercetin/ gram of dry extract and 91.87 and 32%. The maximum and minimum amount of peroxide value and thiobarbituric acid was reported for control and 400 ppm apple extract samples respectively. The results of this study showed that "Fuji" cultivar contained the highest antioxidant activity.The Fuji apple extract are able to reducethe formation of hydroperoxides in butter oil during storage at 6ooC. The phenolic extracts from Fuji apple to be more effective than BHA in stabilising butter oil at 60ºC. Apple phenolic extracts inhibited oxidation of butter oil. Theextracts were able to retard oxidation because of the ability of phenolic compounds toscavenge and stabilise lipid radicals by donating hydrogen atoms.Also the concentration of the extract was an effective factor in the inhibition of oxidation; that is, as we increased the concentration, the inhibition of oxidation also increased. Conclusion:: Due to their ability to act as reducing agents, phenolic compounds in apple phenolic extracts from Fujivarieties can be used as antioxidants in butter oil toretard formation of primary oxidation products, specifically hydroperoxides.
Research Article
Abdolkhalegh Golkar; Ali Nasirpour; Javad Keramat
Abstract
Introduction: Hydrocolloids are widely used in food systems as an emulsifying or stabilizing agent. One way to improve the emulsifying properties of hydrocolloids is complexation with proteins. In general, protein and hydrocolloid components may be combined together by either A) covalent bonding (conjugates) ...
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Introduction: Hydrocolloids are widely used in food systems as an emulsifying or stabilizing agent. One way to improve the emulsifying properties of hydrocolloids is complexation with proteins. In general, protein and hydrocolloid components may be combined together by either A) covalent bonding (conjugates) or B) electrostatic complexing. Conjugates can be efficiently prepared during the storage of freeze-dried or spray-dried powders of protein- hydrocolloid mixtures if stored at appropriate temperature and relative humidity. Farsi gum (FG) is a natural gum that exudated from mountain almond trees (Amygdalus scoparia Spach). In this study, BLG (β-lactoglobulin)-FG conjugates were prepared by dry heat treatment at different BLG/FG mixing ratios (1:1, 1:2 and 2:1) and emulsifying properties of these conjugates were characterized. Materials and methods: Firstly, BLG and FG were dry mixed at BLG/FG (1:1, 1:2 and 2:1) weight mixing ratios. The BLG-FG mixtures were incubated at 60 ºC for a period of 1-14 days in desiccators containing saturated NaCl (to have 75 % relative humidity). Formation of BLG-FG conjugates was confirmed by SDS-PAGE. With the advancement of Maillard reaction, Amadori and browning compounds formation was determined by the absorbance at 304 nm and 420 nm, respectively. Creaming Index (CI) was assessed by determining the height of serum layer developed during storage (at 30 min intervals for 180 min) in emulsion (0.5 wt. % total biopolymer and 25% v/v O/W). The emulsion activity index (EAI) and emulsion stability index (ESI) were determined by turbidimetric technique at 500 nm absorbance. In addition, the effect of storage (3 days) at accelerated condition (40 ºC) and freeze-thaw treatment on droplet size distribution of emulsions (1.5 wt. % total biopolymer and 40 % v/v O/W) were evaluated by static light scattering. Finally, microstructure of BLG-FG emulsion was captured by light microscopy. Statistical analysis of the all data was carried out using SAS 9.1 with significance defined at P0.05) effect on EAI. However, ESI was significantly increased over time and ESI of 2-week incubated BLG-FG conjugate was significantly different (P
Research Article
Fatemeh Roshani; Sara Movahhed; Hossein Ahmadi Chenarbon
Abstract
Introduction: Potato is raw food stuff with high popularity worldwide when deep fried. Deep frying is a fast budget process used for preparing savory food. In this process, oil is used both as a heating intermediate and as an ingredient producing calorific products. Nutrition has become a major health ...
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Introduction: Potato is raw food stuff with high popularity worldwide when deep fried. Deep frying is a fast budget process used for preparing savory food. In this process, oil is used both as a heating intermediate and as an ingredient producing calorific products. Nutrition has become a major health concern, particularly in developmental countries where obesity has turned into an ever-increasing problem, mostly among children. Deep frying is a widely-practiced method for cooking fast foods with desirable sensory properties. Frying is a process of simultaneous heat and mass transfer where heat is transferred by a combination of convection and conduction. At high temperatures, a great amount of moisture content is also lost as vapor, compensated by oil uptake in foods. Oil uptake of foods is an important concern associated with their moisture loss. Thus, it is important to examine moisture loss during frying. Today, the interest in production and consumption of low-fat French fries is on the rise. At the same time, the frying method has a great effect on quantitative and qualitative characteristics of foods. The final moisture content in French fries is about 38% of the product’s final weight. sufficient moisture content is therefore required in French fries to achieve both a soft moist core and a crunchy tasty crust. Numerous methods or pretreatments such as ultrasound and drying may improve these properties. Moreover, finding relationships between different variables during deep frying by modelling may provide an optimal control over process conditions thereby improving the quality of the final fried product. In the present study, effects of ultrasound and drying pretreatments on moisture content, oil uptake, activation energy and effective moisture diffusion coefficient in Satina potato slices during deep frying were investigated. Material and methods: 10kg of Satina potatoes were provided and stored at room temperature. Bahar vegetable frying oil containing cotton seed, sunflower and soybean oils was used for frying. For each experiment, potatoes were washed, peeled and sliced by a household French fry cutter with 1.2×1.2×4 cm dimensions. The cut samples were placed in a plate to avoid moisture loss and were washed with distilled water to remove surface starch before frying. The excess surface water was also removed by a hygroscopic paper. Then ultrasonic pretreatments at two frequencies of 20 and 40 kHz were applied for 15min, and the drying pretreatment was also conducted at 60°C for 15min. To fry the samples the fryer was filled with 1.5 lit of oil. The deep fryer was set to adjust temperature and frying time automatically. When the temperature reached the set value, 100-120g potato samples were placed in the frying basket, which was then submerged in oil automatically. The pretreated samples were fried at 170°C and 190°C for 5, 7 and 10 min. Oil uptake and moisture loss during frying were recorded at certain time intervals. Next, the fried samples were removed from the deep fryer and were placed on a mesh tray to remove the excess oil. The oil uptake and moisture content were analyzed. Oil content was measured by the Soxhlet method. It is based on extracting fat from foods using proper solvents. Moisture content was measured by drying in a convection oven at 105°C until reaching a constant weight. Moisture content and oil uptake of potatoes slices during deep frying were also modeled versus time. The factorial experiment was laid out in a completely randomized design with three replications, and means were compared using Duncan’s multiple-range test. SPSS 14 was used for statistical analyses. Results & Discussion: According to the results, samples pretreated with 20 kHz ultrasound at the same temperature and time conditions had higher moisture content than those treated with the 40 kHz frequency. The highest moisture content was found in samples pretreated with 20 kHz at 170°C for 5min. On the other hand, samples receiving 40 kHz ultrasound pretreatment showed higher effective moisture diffusion coefficient and activation energy than those receiving the 20 kHz pretreatment. The highest diffusion coefficient was achieved using 40 kHz at 190°C for 5min, whereas the highest activation energy was observed with 40 kHz at 170°C for 10 min. It should be mentioned that the effective diffusion coefficient was within the 6.95 × 10-8 – 8.80×10-8 m2/s (R2=0.99) range. Activation energy was also in the range of 13.161 – 16.307 kJ/mol (R2=0.99). Conclution: Samples pretreated with 40 kHz ultrasound showed the lowest oil uptake as compared with those pretreated with 20 kHz frequency. The highest oil uptake was observed for samples pretreated with 20 kHz at 170°C for 10 min. Through the multivariable regression analysis, it was found that the exponential model had the best fitting in predicting changes in moisture content and oil absorption.
Research Article
Hamed Mahdavian Mehr; Arash Koocheki; Mohebbat Mohebbi
Abstract
Introduction: Batter coating is a new technology to reduce fat content of fried foods. The ingredients and flowproperties of batter are the most important parameters to determine the performance of batter coating and quality of the final product. Among batter additives, proteins can be used as an important ...
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Introduction: Batter coating is a new technology to reduce fat content of fried foods. The ingredients and flowproperties of batter are the most important parameters to determine the performance of batter coating and quality of the final product. Among batter additives, proteins can be used as an important and effective component, because of their emulsifying properties, water absorption, and barrier properties. Previous studies have shown that soya protein isolate (SPI) is a very good hydrophilic protein which could be used to control the viscosity of batter. The batter temperature has direct effect on its flow behavior's properties and has a major impact on the quality of final coated product. Therefore, the aim of the present study was to evaluate the effects of temperature (5, 25 and Cº45) and SPI content (2 and 4%), on flow properties of the batter and quality of deep-fried chicken nuggets. Materials and methods:Raw materials such as fresh chicken breasts, onion, salt, hot pepper, wheat flour, baking powder, and 100% pure sunflower oil were purchased from local markets. SPI (92% protein) were obtained from GolharKhorasanRazavi Company. The batter formulations consisted of wheat flour, salt (1.5% w/w, db), baking powder (0.5% w/w, db) and SPI (2 and 4% w/v, db). For all samples, water/dry mix proportion had always been 5:3. Rheological properties of the batters were carried out using a Bohlin rotational viscometer. For each test, shear rate increased from 0 to 300 s−1, followed by a logarithmically decrease from 300 to 0 s−1. The flow behavior index (n) and consistency coefficient (k) values were computed by fitting the power law model, and time dependency properties of the batters were obtained from the area between the upward and downward curves. Temperature dependency of consistency coefficients were assessed by fitting the Arrhenius model. The batter coating on the chicken substrate was appliedat three temperatures (5, 25 and 45 Cº), and batter pickups (%) were calculated by the weight difference between the chicken nuggets after coating to the weight of chicken nuggets before coating. Coated samples were stored at -18 Cº for two weeks. After thawing, chicken nuggets were fried at 180°C for 3 min in sunflower oil using a programmable deep fat fryer. The influence of SPI concentrations and batter temperature on color and crust adhesion of deep-fat fried chicken nuggets was measured with image processing. In brief, images were taken by a digital camera under controlled conditions, and then analyzed by Image J software. The Percentage of adhesion (CRA), obtained by calculating the ratio of the pixels corresponding to the perimeter of the substrate where coating is adhered to the pixels corresponding to the total perimeter of the substrate. The color of deep-fat fried chicken nuggets were examined in terms of L*, a* and b*values. Oil and moisture content of the chicken nuggets was determined by standard techniques. Results & Discussion: Results showed thatall samples had a shear-thinning behaviour at all batter temperatures (n≥0.539). Power law model was adequately suitable to describe the flow behavior of the batters (R2≥0. 994). The activation energy was between 5.106 to 5.630 (kj/mol).Addition of soy protein isolates into the batter, enhanced the time dependency, whereas, the increase of temperature decreased the hysteresis area. The relative increase in apparent viscosity with increasing SPI might be attributed to the high capacity of SPI to absorb free water. However, decrease in apparent viscosity and time dependency of batters with increasing the temperature could be due to the intermolecular interactions in batter system. An increase in temperature weakens the intermolecular interactions and increases the mobility of macromolecules which reduces the batter resistance to shear force. The batter temperature and formulation had significant effect on the batter pickup. This effect was mainly due to the changes occur on flow properties of batter. Using SPI increased the a* and decreased the L* of the final product. This could be due to the active participation of SPI in the Millard reaction. The data obtained for crust adhesion revealed that the increase in SPI concentration lead to a decrease in batter adhesion to the crust. In other words, the ability of soya proteins to form film during early time of frying reduces the moisture migration from the substrate to oil, which creates a positive pressure in the inner layer of crust and reduces the adhesion. Conclusion: Chicken nuggets coated with batter containing SPI had higher moisture and lower oil content than the control sample. Finally, the change in batter temperature had no significant effect on the crust adhesion and oil and water content in the final product.
Research Article
Amir abbas Omidfar; Esmaeil Atayesalehi; Zahra Sheikholeslami
Abstract
Introduction: Low quality and short shelf-life are the most important reasons for bread waste. Statistics show that each Iranian person consumes about 150 kg bread annually, but the low quality of bread and public discontent, would resultin 30 percent waste of traditional breads. Previously barley malt ...
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Introduction: Low quality and short shelf-life are the most important reasons for bread waste. Statistics show that each Iranian person consumes about 150 kg bread annually, but the low quality of bread and public discontent, would resultin 30 percent waste of traditional breads. Previously barley malt was used as an additive to improve the quality and shelf life of bread (including Barbari bread). The most common type of the malt used in the world is barley malt. This is because of the utilization of most of the malt product in the world, including to produce beverages based on malt, particularly alcoholic and non-alcoholic onesand considering that the malt made from barley grains has the best quality among the other cereals to produce these products.Therefore, discussion on other malted cereals would be find less in the literature especially corn malt (which has not a good quality to produce malted beverages). On the other hand, corn is the main cereal widely consumed in the world after wheat and rice. The purpose of this study was to produce Barbaribread usingcorn malt (powder or extract) as an additive to increase shelf-life, volume and softness, as well asimprove the sensory characteristics (staling, total appearance, softness, texture, brain color, crust color, crust appearance, flavor and odor). Materials and methods: For this purpose, bakery flour with 85% extraction rate, Dent corn (Zea mays var. Indentata), Saccharomyces cerevisiae as an active dry yeast, malt extract or powder and other additives, used in the formulation of Barbari bread. To evaluate the sensory characteristics, the bread samples were analyzed by 15 trained referee. The results were based on a factorial arrangement with two factors completely randomized design that the first factor is type of corn malt (powder or extract) and the second one is amount of corn malt (in four levels of 0, 0.5, 1.0 and 1.5 percent) was evaluated. Results & Discussion: The resultsshowed that the treatment with 1.5 percent extract corn malthas the highestspecific volume(with an average of 4.5) and thetreatment with 1.5 percent powderhas the lowestspecific volume(with an average of 3.67). And just the treatments with 1 and 1.5% malt extract in compared with the control sample showed significance differences (P
Research Article
Zahra Hashemi; Mohammad Hojjati; Mohammad Tahanejad
Abstract
Introduction: Oxidative degradation of lipids is a major factor limiting the shelf life of foods. The free radical reaction of lipid peroxidation is generally responsible for the deterioration of fatty foods. In general, use of synthetic antioxidants during the manufacturing process are applied to prevent ...
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Introduction: Oxidative degradation of lipids is a major factor limiting the shelf life of foods. The free radical reaction of lipid peroxidation is generally responsible for the deterioration of fatty foods. In general, use of synthetic antioxidants during the manufacturing process are applied to prevent fat oxidative and rancidity while their carcinogenic effects have been approved. Since the use of synthetic preservatives in food have been declined, researches on alternative natural products such as aromatic plants extract and essential oil have been extended.Aromatic plants are used traditionally in various regions of Iran for their preservation and medicinal properties, in addition to enhancing the aroma and flavor of foods. Aromatic plants components that have antiradical activities were used as natural antioxidant in food and biological products. The aim of this research was extraction and identification of the chemical compounds of Ferula gummosa Bioss essential oil and investigation of its antioxidant capacity in frying oil. Materials and methods: Aerial parts of F. gummosa were collected during fall 2013 from Khouzestan province of Iran. The collected aerial parts were then dried in the shade. The essential oil of aerial parts was extracted by hydro-distillation technique using Clevenger apparatus. Analyses of isolation, identification, and quantification of the component of the essential oil of F. gummosawere performed with a GC coupled with a mass spectrometer detector GC/MS. Analyses were carried out using helium as the carrier gas on DB-5 column (30 m×0.25 mm i.d., 0.25 μmfilmthickness). Injector and detector were hold at 240 and 300°C, respectively, and 0.5 μL of the diluted essential oil was injected. Identification of most of the compounds was made according to GC-MS retention times (authentic chemicals), Kovats indices (KI) in reference to n-alkanes (C8–C24), and mass spectra (authentic chemicals and NIST05 spectral library collection). Identification was considered tentative when it was based on mass spectral data only. Volatile compounds were quantified using percentage peak area calculations by means of a GC-FID with the same column and nitrogen as the carrier gas. The total phenol content in the F. gummosaessential oil was determined by a spectrometric method, according to the Folin–Ciocalteu phenol method by mixing of 0.2 ml of the essential oil with Folin-Ciocalteau reagent diluted and Na2CO3. The absorbance was measured at 765 nm after incubation in the dark at ambient temperature. The results of the total phenolic contents were expressed as gallic acid equivalents.The DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS [(2,2´-azino-bis 3-ethylbenzthiazoline-6-sulphonic acid)]tests were used for estimating antioxidant effects because the DPPH and ABTS radicals are the two most widely used and stable chromogen compounds to measure the antioxidant activity of biological material. In addition, the model of the DPPH radical-scavenging and ABTS radical cationdecolorization assay can be used to evaluate the antioxidant activities in a relatively short time compared with other methods. For this purpose 0.05 ml of the essential oil at different concentrations (0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10 mg/ml) were mixed with 5 ml of 0.2 mMmethanolic DPPH solution and kept in the dark for 30 min at room temperature, then absorption-decrease was measured at 517 nm. The radical scavenging activity assessed by the ABTS method was expressed as the TEAC (trolox equivalent antioxidant capacity) value based on absorbance at 734 nm. In this test, ascorbic acid was used as positive control. The antioxidant activity of essential oil was evaluated against Tertiary butylhydroquinone (TBHQ) as an synthetic antioxidant in frying oil by peroxide value and thiobarbituric acid (TBA) index under rush condition in 90° C during one week. Results & Discussion: GC-MS analysis of the volatile constituents of the F. gummosa essential oil allowed the identification of twenty-nine compounds representing 96.80% of the total volatile oil. The main components were β- pinene (37.9%), α- pinene (9.05%), terpinene-4-ol (7.78%) and ρ- cymene (6.58%). The mean amount of total phenolic of obtained essential oil was 59.7 mg gallic acid/g dry plant material.In the present study, the essential oil showed good free radical scavenging capacity at all concentrations studied, however the scavenging activity increased with increasing concentration of the essential oil. Antioxidant activity of essential oil from F. gummosa at 1 mg/ml was similar to TBHQ at 0.1 mg/ml (P ≤ 0.05%). The scavenging capacity test showed that the EC50 value of the essential oil was found to be 0.094 mg/ml. ABTS test showed that the F. gummosaessential oil was able to reduce the stable radical and 1mg/ml of essential oil had the highest antiradical activity (0.113 mg/ml ascorbic acid equivalent). Oven test revealed that 500 and 1000 ppm of essential oil had the higher activity than TBHQ in 200 ppm in frying oil. Conclusion: The results indicated that F. gummosa had high total phenolic content. Also, according to these results, there was a relationship between totalphenolic content and antioxidant activity.The findings of this study showed that F. Gummosa essential oil can exhibit strong antioxidant activity, probably due to its particular chemical composition, mainly the high amounts of monoterpenes. Therefore, this essential oil could be used for the preservation of edible oil against oxidation and for increasing its shelf life as a natural preservative ingredient.
Research Article
Masumeh Molashahi; Ebrahim Alizadeh Doughikollaee; Ghorbanali Mahghani
Abstract
Introduction: Fish salting is a traditional method of processing in most countries including Iran. There are different methods of salting which can be used for producing different salted products. There is variation in the amount of salt used in the salting process depending on the context of use.Salting ...
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Introduction: Fish salting is a traditional method of processing in most countries including Iran. There are different methods of salting which can be used for producing different salted products. There is variation in the amount of salt used in the salting process depending on the context of use.Salting was done simultaneously with salt penetration into the muscles of fish and water dripping out of the fish tissue, which lead to prevention and/or reduction of microbial and enzyme activity. Wet salting using Pickel method is one of the methods of salting in which the dry salt is used to remain together with the water dripped out of the muscle in the vessel during salting. This method results in better preservation of fish against the biological spoilage, better taste and suitable distribution of salt in the texture. The importance of this method compared with other methods of salting is its ability in protecting the texture of fish against oxidation because of high rate of salt penetration. Using different salting methods affect weight change of fish. That is, the salted fish produced using wet salting method is heavier than the fish salted through dry method. Fish breeding especially that of silver carp is one of the important activities of aquaculture in our country. This is because of high rate of silver carp production and provision of a product with a better taste to markets. To assess the effectiveness of wet salting during refrigerated storage (4˚ C), In this study physicochemical, microbiological and sensory evaluation of salted silver carp would be employed. Materials and methods: The fresh silver carps with weight of 0.5 kg were purchased from market (Bandar Torkman, North Iran) and transported in isothermal iceboxes to the fish control quality laboratory at Ashoradeh Island in 2012. The fishes were cleaned and salted with 10 and 20% concentrations and then stored in refrigerator (+4°C). Chemical parameters (Humidity, Protein, Salt, PV and TBA), pH, Microbial parameters (TVC, PTC, and Halophile) and sensory analysis were measured at 0, 3, 6, 9 and 12 days. The experiments were performed in three replicates. Results & Discussion: The present study showed that by increasing the salt concentration from 10 to 20 % at 4 ° C the salt amount of salted fish muscle changed from 10.70 to 13.60 after 12 days of refrigerated storage. This suggests that an increase in salt concentration result in higher salt absorption. The difference between the results of two treatments in different times were statistically significant (P
Research Article
Atefeh Farahmand; Fateme Mousavi Baygi; Masoud Taghizadeh; Amin Ziaforoughi
Abstract
Introduction: One of the most important aspects of food preservation is controlling the moisture of material such as fruits.Dryingis considered as important method to controlbacteriasafely using reduction of moisture. The hot air drying method has been widely adopted in manufacturing of conventional ...
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Introduction: One of the most important aspects of food preservation is controlling the moisture of material such as fruits.Dryingis considered as important method to controlbacteriasafely using reduction of moisture. The hot air drying method has been widely adopted in manufacturing of conventional dried food.Nowadays, Infrared radiation (IR) has significant advantages over conventional drying. Among these advantages,higher drying rates giving significant energy savings anduniform temperature distribution giving a better quality of product. Therefore, it can be used as an energy saving drying method. Earlier attempts forapplying infrared waves to drying of agricultural materials have been reported in the literatures, such as banana, onion, garlic, apple, corn, pomegranate seeds and peach. The persimmon (Diospyros kaki) is native to East Asia, most likely China. This fruit has very short shelf-life; it is due to thehigh soluble tannin content of the fruit during storage even at refrigerated conditions. The persimmon is mainly eaten fresh, but can be dried.Duringdrying the tannin cells coagulate, so astringency is removed and the sugars in the fruit exude to the surface where they crystallize, thus producing a sweet, candied product. The objective of this study was to examine the drying behavior of the far infrared and hot- air drying of persimmon slices by comparing the physical quality. Materials and methods: Persimmon (Diospyros kaki) used in this study was purchased from a local market (KhorasanRazavi, Mashhad). The whole samples were stored at 4°C. The initial moisture content of persimmon was found to be 78.2 kg H2O/kg moisture. The sampleswerecut into 5mm slices using a cutting machine and were dried to 10% final moisture (wet basis). - Infrared dryer setup: Infrared (IR) dryer used in this research was equipped with IR lamp (1300W). Persimmon slices were placed in a single layer on the drying tray and heated from one side. Thermocouples (Type K) were inserted at the center of persimmon slice.IR drying tests were conducted with final product temperatures controlled at 50°C, 60°C and 70°C. -Hot air dryer setup: Persimmon slices were arranged in a single layer on the trays and dried in cabinet dryer at material temperatures of 50°C, 60°C and 70°C.Air velocity in the dryer was 1.5 m/s. -Quality evaluation: Persimmon slice drying characteristics including rehydration ratio, color parameters, shrinkage, texture and sensory properties were investigated ResultsandDiscussion: It is clear that the moisture content and drying rate decrease continuously with drying time. The drying rate was rapid during the initial period but it became very slow at the last stages of dryingprocess. Persimmonslices dried with hot-air and infrared dryer at temperatures 60 and 70◦c respectively, had a maximum rehydration ratio. In general, infrared drying showed significant effect on L value (p
Research Article
Seyed Yousef Pourmir; Alireza Sadeghi Mahoonak; Javad Fattahi Moghadam; Yahya Maghsoudlou; Mohammad Ghorbani
Abstract
Introduction: Citrus fruits, which belong to the family of rutaceae are one of the main fruit tree crops grown throughout the world. Although sweet orange (Citrus sinensis) is the major fruit in this group accounting for about 70% of citrus output.Citrus fruits are well – appreciated fortheir refreshing ...
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Introduction: Citrus fruits, which belong to the family of rutaceae are one of the main fruit tree crops grown throughout the world. Although sweet orange (Citrus sinensis) is the major fruit in this group accounting for about 70% of citrus output.Citrus fruits are well – appreciated fortheir refreshing juice and health benefits.The health benefits of citrus fruits are linked to the high amounts of photochemical and bioactive compoundssuch as flavonoids, carotenoids, vitamins and minerals available in their juice.These phytonutrientsmay act as antioxidants, stimulate the immune systems; induce protective enzymes in theliver or blockthe damage of the genetic materials. The phytonutrients and vitamins may be responsible for theantioxidant, anticancer and anti-inflammatory properties of the citrus species.Citrus fruits processing accounts for approximately one third of total citrus fruitproduction, more than 80% of it is orange processing, mostly for orange juice production.The most important processed citrus fruits product isorange juice. Orange juice can be presented in different forms. The major types of orangejuice are the freshly squeezed orange juice and concentrated orange juice.Siavaraz local orange is an orange cultivar grown in north of Iran which is used mainly in orange juice production. There is no systematic study about the relation between physical characteristic of fruit at harvest time and its juice quality and quantity. Materials and methods:In this study, the physical characteristics, quantitative-qualitive properties of siavaraz local orange at harvesting times and changes in anti-oxidant components of its juice during processing and storage were investigated.The fruit were collected in eleven different harvest time (start of fruit harvesting and every two week intervals) and different parameters including fruit length, diameter, spherical coefficient, density, peel thickness, juice percentage, total soluble solid (TSS),titrable acidity(TA) were evaluated. In next stage ascorbic acid, total phenolics and anti-oxidant capacity of different fruit juice include fresh squeezed juice by hand and extractor, juice reconstituted from orange concentrate with 60° brix, juice reconstituted from orange concentrate with 65° brixwere evaluated and compared. Finally, changes in vitamin C content during refrigerated storage infresh squeezed juice by hand andjuice reconstituted from orange concentrate were measured. Results & Discussion:Results showed that siavaraz local orange was in four size with different physical characteristics. The highest amount of density was belonged to small fruits with 0.977 at the first harvest stage. Small oranges with lowest peel thickness had the highest juice percentage but the large oranges with the higher TSS showedhigher production efficiency (327.24%). The TA and pH in first stage of harvest were the highest and the lowest, respectively compared to other stage. The highest concentrate efficiency (6.42%) and juice quality (9.88° brix) were obtained at the harvest stagenumber six and seven, respectively. The lowest amount of juice percentage for concentrate production was observed at the stagenumber six (15.6 kg). By investigating the anti-oxidant compounds, results reveals that ascorbic acid and anti-oxidant capacity of juice taken by juicer extractor, were higher (p
Research Article
Omid Doosti Irani; Mahmood Reza Golzarian; Mohammad Hosein Aghkhani; Hassan Sadrnia
Abstract
Introduction: High percentage of orchard products, such as apples, is wasted due to mechanical damages that cause fruit quality loss. Damages due to static or dynamic pressure or impact are among very common mechanical damages that begin to bruise fruits. Post-harvest bruise damage is a major cause for ...
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Introduction: High percentage of orchard products, such as apples, is wasted due to mechanical damages that cause fruit quality loss. Damages due to static or dynamic pressure or impact are among very common mechanical damages that begin to bruise fruits. Post-harvest bruise damage is a major cause for the loss in fruit quality. Bruising means damaging fruit tissue and consequently physical changes resulting in fruit color and chemical changes resulting in fruit tastes (Xing and Baerdemaeker, 2005). Most research projects conducted on apple bruising have focused on the use of image processing techniques for detecting apple surface defects from images. In addition to images taken in visible spectral range, thermal images have been also used for this purpose. Having reviewed the literature and research gaps in this area, we set two hypotheses for this research project: first, the color characteristics of bruised tissue would change over time and these changes would be detectable on the images taken from the affected fruits. Second, there would be a significant difference between the surface temperature of bruised and sound tissues. The distribution of temperature on an impact-caused bruised tissue would change over time in a different manner compared with that for a sound tissue. The color and temperature variation is particularly related to the intensity of impact caused bruising and where the impact is applied on apples. Therefore, the first objective of this paper was to study the color changes on the tissues bruised from the impacts with three energy levels applied on three locations on apple surface with different curvatures: top, middle and bottom. The second objective was to investigate the temperature variation on the surface of the bruised apples and to examine the capability of visible and thermal imaging in detecting bruised tissues at different times after bruising occurred. Materials and Methods: For these purposes, the experiments were conducted on sixty apples of Golden Delicious variety. From sixty samples, five apples were used for determining apples ripeness index and five apples were used for determining emissivity factor which was used later in calibrating fruit surface temperatures on thermal images. Bruising was simulated by an impact pendulum. Bruising was conducted at three impact energy levels of 200, 700, 1200 mJ and applied at three locations on apple surfaces: top, middle and bottom. The samples affected by bruising-simulated impacting device were kept in a refrigerator at 5°C and were individually imaged in a regular basis until 624 hours after impact application. At the time of imaging, both visible and thermal images were taken from each sample. Samples visible images were taken in an imaging box with uniform controlled lighting. Thermal images were taken while samples were placed in a box that was thermally insulated from surrounding temperature. A newly defined color factor, named excessive yellow index (EYI) was extracted from visible color images. The EYI index formula is EYI = 1.5r+b-1.5g where r, g and b are red, green and blue color values, respectively. Factorial experiment was conducted for the assessment of EYI. This experimental design looked at the effects of three factors of time, impact energy and impact landing location on EYI. Result and discussion: The results showed that time passed after impact and the location of impact application had significant effect on EYI at 95% confidence interval. The apples EYI index decreased until 15 days after impact application and started increasing thereafter. Surface temperatures were extracted from the thermal images of samples. The results of processing thermal images showed that the bruised tissue was cooler than the sound tissue until 48 hours after impact application. Both tissues had the same temperature from 56 to 96 hours and then the bruised tissue started becoming warmer by 0.5-1°C after 96 hours. The color variation of bruised region was not detectable from visible images within the first 48 hours after impact application, while these regions were cooler than undamaged region and detectable from thermal images. The bruised regions started to turn dark brown at 48 hours after impact application. However, there was no temperature difference between bruised and sound regions on fruit surface for the period of 56-96 hours. The bruised brown regions paled after 360 hours. As a result, this reduced the capability of visible images for discriminating bruised apples from sound ones. Conclusion: The results of this research show that both the visible spectrum and thermal imaging systems can record the changes in color and temperature at different times after the bruising in apples. Therefore, these methods can be used as an efficient methods for grading apples.
Short Article
Seyed Mohammad Ali Razavi; Mostafa Mazaheri Tehrani; Bahareh Emadzadeh
Abstract
Introduction: Recently, consumers have directed their interest towards low fat products as they associated them with a reduced risk of well-known health problems such as obesity and coronary heart diseases. Fat is a multifunctional ingredient in ice cream system. Thus, in attempts to provide desirable ...
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Introduction: Recently, consumers have directed their interest towards low fat products as they associated them with a reduced risk of well-known health problems such as obesity and coronary heart diseases. Fat is a multifunctional ingredient in ice cream system. Thus, in attempts to provide desirable flavor and physical characteristics of full fat ice cream, manufactures looking for fat replacers (Drake et al. 1999). Hydrocolloids have functionalities such as thickening, gelling, fat replacing, which allow them to use in different industries (Roller and Jones, 1996; Williams and Phillips, 2000). Guar gum is used as a stabilizer in ice cream and provides smoothness in texture, retards ice crystal growth, and increases freeze-thaw stability (Wielinga, 2000). The rheological properties and potential of basil seed gum (Rayhan) as a novel stabilizer for structure formation and reducer for ice recrystallization in regular ice cream have been recently investigated (Hosseini-Parvar, 1388; Bahram-Parvar, 1391). In this research, the physicalproperties of light (5% fat) and low fat (2.5% fat) ice creams as a result of replacement of milk fat by guar gum (as a commercial hydrocolloid), basil seed gum (as a novel hydrocolloid) and their blend (50:50) at different concentrations were investigated and compared to those of control sample (10% fat). Materials and methods:The ice cream formulations were prepared based on the following composition: 2.5% (L), or 5% (R) or 10% (B) milk fat, 11% MSNF, 15% sugar, 0.1% vanilla, 0.15% emulsifierand 0.35%, 0.45%, 0.50% or 0.55% selected gums (guar gum, basil seed gum or blend (50:50) of them). Liquid materials including milk and cream were mixed together and warmed up to 50˚C. After that, the pre-weighed and mixed dry ingredients were dispersed into them, under agitation. The mixes were pasteurized at 80˚C for 25 s, homogenized at 23000 rpm for 2 min, cooled rapidly to 5˚C and then aged at constant temperature overnight (12 h) at 5˚C. The freezing was carried out in a batch soft ice cream maker. Apparent viscosity of ice cream mixes were evaluated using a rotational viscometer at 5˚C and 51.8 s-1. Before melting rate determination, samples were tempered at –18°C overnight, Ice cream samples (30 g) were put on a wire screen mesh and allowed to melt at ambient temperature. Melting rates were measured from the slop of linear portion of drained mass vs.time graphs. The pH values for mix samples were measured with a pH meter. After the mix was frozen in a batch freezer, Draw temperature of ice creams was obtained using a digital thermometer.Mix and ice cream samples (3 g) were diluted 1: 500 in two steps with deionized water and absorbance was measured by a spectrophotometer at 540 nm. Turbidity (%) was calculated as (absorbance in mix - absorbance in ice cream)/absorbance in mix 100%. A known volume of ice cream and mix were weight and overrun was determined as (weight of the mix - weight of the ice cream)/ weight of the mix 100%. Results & discussion: Reducing fat in any food formulation will cause a decrease in viscosity (Cody et al., 2007). Fat reduction decreased apparent viscosity (P0.05), ranging from 6.31 to 6.34. Draw temperature as a measure of freezing point of ice cream is dependent on the type and concentration of the soluble constituents and varies with the composition. Addition of some ingredients such as sweeteners, lactose and salts decrease the freezing point. Fat is immiscible with the aqueous phase and carbohydrate polymers are very large molecules, depression of the freezing point is caused indirectly by using of these materials, as a result of decreasing the water content (Marshall and Arbuckle, 1996). In this study, a reduction of fat content of full fat ice cream resulted in higher draw temperature. However, there was not a specific trend in the temperature values of samples with same fat content and different fat replacer levels. There was no significant difference between turbidity of samples with same kind of gum. Similar results were obtained by Schmidt et al. (1993), which related to sufficient amount of milk fat (2.1 and 4.8 %), milk proteins and emulsifiers in ice cream formulations. Conclution: Decreasing the fat content generally caused an increase in the value of overrun. But, very high viscosity of mix may prevent vigorous agitation and air incorporation that seems the reason of why increasing fat replacer concentration resulted in overrun reduction
Short Article
Hojatollah Bodaghi; Younes Mostofi; Abdulrasoul Oromiehie; Zabihollah Zamani; Babak Ghanbarzadeh; Ziba Ghasimi Hagh
Abstract
Introduction: Active and intelligent packaging devices and systems represent emerging technologies that may have profound implications on the quality, safety and integrity of packaged food and beverage products. It is well known that the photocatalyst titanium dioxide (TiO2), being a wide band gap (3.2 ...
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Introduction: Active and intelligent packaging devices and systems represent emerging technologies that may have profound implications on the quality, safety and integrity of packaged food and beverage products. It is well known that the photocatalyst titanium dioxide (TiO2), being a wide band gap (3.2 eV) semiconductor under UV illumination, generates energy-rich electron-hole pairs that can be transferred to the surface of TiO2, and promotes reactivity with the surface-absorbed molecules leading to the production of active radicals. These active radicals oxidize C-H bonds resulting in degradation of the organic molecules TiO2 photocatalyst has been used to degrade organic pollutants and inactivate a wide spectrum of microorganisms. To the best of our knowledge, there is no report on the photocatalytic disinfection properties of low density polyethylene (LDPE)-TiO2 nanocomposite produced by extrusion. Therefore, in this study LDPE-TiO2 nanocomposite film was prepared by a film blowing machine. The antimicrobial activity of the new packaging film against Pseudomonas spp. and Rhodotorula mucilaginosa, representing the main microorganisms on fruit and vegetable crops, was examined in vitro under UVA light. The antimicrobial property of the developed active film was also tested in a food application Materials and methods: LDPE -TiO2 nanocomposite was prepared by the melt blending method. Modified TiO2 (M-TiO2) powder obtained by mixing modified anatase and rutile phases in a weight ratio of 7:3 (total of 30 g), LDPE granules (935 g), PE-MA (30 g) and glycerol (5 g) were blended for 1 h using a mixer. The mixture was extruded by a Brabender twin-screw compounder (model DSE 20, Germany) for incorporating nanoparticles into the LDPE matrix. For LDPE and its nanocompounds, a constant temperature of 130 °C was used in all the zones of the extruder and the speed of the central screw was set to 120 rpm. The extrudate was cooled down in air at 23 ± 3 °C and pelletized. A composite LDPE-TiO2 film with a thickness of 30 ± 3 µm was finally obtained by a film-blowing machine. The resulting film had a milky whitish appearance. In vitro and in vivo antimicrobial activity test of film Each test film (6 cm diameter) was placed in sterilized petri dishes under aseptic conditions. One mL of each microorganism stock solution (containing approximately 108 and 107 CFU/mL for Pseudomonas spp. and R. mucilaginosa, respectively) was pipetted onto each test piece in its petri dish. Test samples were placed at a distance of 25 cm from six 8-WUVA black light bulbs Samples were taken in three replicates at 60 min intervals for 3 h. Then, 9 mL of sterile saline solution was added to the petri dishes containing the test and polyethylene films and shaken for 180 s on a universal small shaker (IKA MS 3 digital, Germany). One milliliter of solution was withdrawn at each sampling event and diluted to 1/10, 1/100, 1/1000, and 1/10,000 with sterile saline solution. A volume of 0.1 mL of the undiluted and diluted solutions was plated over appropriate media. Pseudomonas agar base (PAB) was incubated at 25 °C for 48 h for Pseudomonas spp. and Sabouraud dextrose agar for R. mucilaginosa and the colony-forming units (CFU) were counted. For in vivo test, every 6 days, approximately 20 g of packed apricot pieces with nanocompsite films, were collected randomly and placed into 180 mL of saline solution and agitated in a stomacher bag for 120 s. Decimal dilutions were made in sterile saline solution and 0.1 mL of the undiluted and diluted solutions were plated. Results and discussion: This work describes a TiO2 nanocomposite thin film with biocidal capacity for food packaging that was prepared by the extrusion method. The film caused inactivation of Pseudomonas spp., R. mucilaginosa and mesophilic bacteria in saline solution and on apricot when exposed to UVA light. The number of microorganisms on LDPE-TiO2 nanocomposite film plus UVA light was lower than that on LDPE-TiO2 nanocomposite film without UVA light and LDPE film exposed to UVA light. These results suggest that the TiO2 nanoparticles were responsible for the antimicrobial effect when exposed to UVA light illumination. The higher antimicrobial activity of the composite films under UV light is due to the photocatalytic reaction of the TiO2 nanoparticles in the matrix. Thus, the prepared TiO2 nanocomposite films are effective in diminishing live microorganisms and are promising as antimicrobial packages.
