Research Article
Maryam Ebrahimi; Morteza Khomeiri; Yahya Maghsoudlou
Abstract
Introduction:Toxigenic fungi such as A. flavus grow widely in peanut and produce aflatoxins, a group of carcinogenic metabolites. Aflatoxin produced in peanut differed from the genetic variety of plant. The high humidity and moderate temperatures in the subtropical Caspian littoral of northern Iran could ...
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Introduction:Toxigenic fungi such as A. flavus grow widely in peanut and produce aflatoxins, a group of carcinogenic metabolites. Aflatoxin produced in peanut differed from the genetic variety of plant. The high humidity and moderate temperatures in the subtropical Caspian littoral of northern Iran could increase the growth of A. flavus and the production of aflatoxin. The objectives of this study were 1) to determine the chemical composition of peanut cultivars grown in Golestan Province, Iran, 2)to select resistant variety of peanut to aflaoxigenic A. flavus growth and 3) to evaluate relationship between A. flavus growth and changes in oleic and linoleic acid content and peroxide value. Materials and method: Peanut samples were used from four important varieties of peanut, Goli, Mahalli, China and India. those have been harvested from farms in Golestan province, Iran. Fat, protein, ash, moisture, reducing sugar, AFB1 content and peroxide value in each sample were measured by the standard method of AOAC. Fatty acids of the peanut seed oil were analyzed using gas chromatography (GC, Varian CP-3800 model) with a flame ionization detector (FID) and a DB-WAX column (50 m × 0.32 mm ×0.2 µm). To study the effects of A. flavus on peanut varieties, they were sterilized with 0.5% NaClO solution and then one ml of A. flavus spore suspension was added to every 20gr disinfected peanut and was placed in the incubator for eight days at 26°C. After incubation, the number of seeds colonized by fungi, spore production, AFB1 production, the association between colonization rate of hydrolysis of fatty acids and peroxide value were determined.Results and Discussion: The results showed that there were significant differences (P
Research Article
Shohreh Nikkhah; Nasser Sedaghat
Abstract
This research was carried out in order to investigate on the effects of packaging type and storage temperature on qualitative and quantitative characteristics of dried melon. “Thashkandi” and ‘ Khatoni” melon varieties؛ osmotic solutions of 0% and 10% sucrose and cabinet dryer ...
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This research was carried out in order to investigate on the effects of packaging type and storage temperature on qualitative and quantitative characteristics of dried melon. “Thashkandi” and ‘ Khatoni” melon varieties؛ osmotic solutions of 0% and 10% sucrose and cabinet dryer were applied for dried melon production. Dried fruits were packed with modified atmosphere (PE-PA film, 85 micron thickness, two gas mixtures: (70% CO2%, 30% N2(1) and 60% CO2%, 40% N2(2)) and without modified atmosphere (polyethylene and polystyrene films). After 6 months results showed that control dried in 10% osmotic solution preserved in 25°c and 4°c treatment had the most and the least firmness respectively. Melon pretreated by 10% osmotic solution, packed in atmosphere 1 had the least water activity. Dried melon preserved in 4°c had higher L*(brightness) and b*(yellowness) indices. Khatooni cultivar produced dried melon with higher a*(redness). Dried melon pretreated by 10% osmotic solution and packed in atmosphere 2 had less a*(redness). Furthermore dried melon pretreated by 10% osmotic solution and packed in atmosphere 2 and preserved in 4°c had minimum O2% and maximum CO2% in package.
Research Article
Nasser Sedaghat; Sara Khoshnoudi
Abstract
Introduction : Pistachio (Pistaciavera L.) is a tasty nut and a good source of nutrients. Ithas a high content of numerous beneficial nutritive and bioactive compounds such as proteins, carbohydrate, moisture, vitamins, minerals, fiber and other micronutrients compounds, but the most exceptional components ...
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Introduction : Pistachio (Pistaciavera L.) is a tasty nut and a good source of nutrients. Ithas a high content of numerous beneficial nutritive and bioactive compounds such as proteins, carbohydrate, moisture, vitamins, minerals, fiber and other micronutrients compounds, but the most exceptional components are the amount of fats and especially unsaturated fatty acids. Therefore, this nut is highly susceptible to rancidity, especially after roasting. Despite the high quality, raw pistachio and pistachio processing industry at Iran, export of roasted and packaged pistachio, due to low shelf life and drastic changes intaste, is not very successfull. An effort was made to investigate the efficacy of gelatin in comparison with carboxymethyl cellulose (CMC) as edible coating to retard fat oxidation in roasted pistachio.Materials and methods:Five coating formulations were investigated in this study as follow: A) Gelatin (4% w/v) + ascorbic acid (1% w/v): TGA, B) CMC (1% w/v)+ ascorbic acid (1% w/v): “TCA”, C) ascorbic acid (1% w/v): “TA”, D) Gelatin (4% w/v) + CMC (1% w/v) + ascorbic acid (1% w/v): “TCGA” and 5) control sample (uncoated sample): “TCO”.Roasted pistachio nuts were coated by dipping the nuts in the coating solutions. For each treatment, 100 gram of pistachio nuts were packaged (BOPP/Al/CPP, 80 micron plastic bags) in triplicate. The physicochemical analysis included measurement of free fatty acid (FFA), peroxide value (meq.O2 kg-1),hardness (N), moisture (%) and the sensory evaluation (texture, rancidity, taste and overall acceptability) were performed on coated and uncoated pistachio nuts stored at 35 and 50 °C. The nuts were sampled on the 0th, 1st, 2nd and 3rd month of storage. Data was analyzed using Minitab 16. Analysis of variance (ANOVA) and general linear models (GLM) procedure wereused to compare the mean values of each treatment and Significant differences between the means of parameters were determined based on the results of the Tukey’s multiple range test (p0.05).FFA content of TCGA sample was significantly lower than other samples.The highest protection, according to these criterions, was provided by gelatin-CMC coating containing ascorbic acid.The control samples exhibited more bitterness and off flavor than the coated samples, seemingly on account of chemical reaction and second products of oxidation content. Instrumental and sensory hardness of pistachio nuts which were coated with gelatin and/ or CMC (TCA, TGA and TCGA) were significantly (p
Research Article
Ayda Saleh; Mahmoud Rezazadehbari; Mohammad Alizadeh khaled abad; Najmeh Sabahi Mohammadi
Abstract
Introduction : Yoghurt is one of the most popular dairy products in all over the world.Nowadays due to the tendency of consumers to use the products with healthy effects, probiotic and synbiotic products are considered. Yoghurt by itself is a healthy food; because of its high levels of protein and calciumcontents.Consumption ...
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Introduction : Yoghurt is one of the most popular dairy products in all over the world.Nowadays due to the tendency of consumers to use the products with healthy effects, probiotic and synbiotic products are considered. Yoghurt by itself is a healthy food; because of its high levels of protein and calciumcontents.Consumption ofprobiotic bacteria via food products is a way to reestablishthe intestinal microflora balance. Several studies have been done to improve the growth and viability of probiotic bacteria by adding supplements to milk.The objective of this study was to investigate the effect of three component mixture (Arabic gum, whey protein concentrate and milk protein concentrate) on quality indices of synbiotic yoghurt containing transglutaminaseenzyme. The content of theseprotein component, the amount of enzyme, enzyme addition time to the yoghurt samples and storage time were variableMaterials and methods:Yoghurt samples were prepared with milk which contained 2.5 percent fat.Milk was heated around 40 ̊C. WPC, MPC and Arabic gum were added to samples according to the research design and increasing the solid none-fat content of the milk up to 1.5%. Samples were pasteurized at 90 ̊C for 10 minutes in a water bath and were cooled rapidly to 43 ̊C for inoculation starter culture and probiotic bacteria. Also enzyme was added to samples before or after pasteurization (according to the research design).In this study microbial test was done to investigateviability of probiotics (BB-12) by differential culture medium (MRS-LP Agar). The titratable acidity was determined using 0.1 N NaOH until accessing the constant pink colour for 30secondes. Water holding capacity (WHC) was determined due to measure the protein quality of keeping water inside. Syneresis is expressed as the weight percentage of serum released by centrifugation. Viscosity was measured using a Brookfield viscometer.Viscosity measurementswere made using 250 mL ofyoghurt samples at 10 _CDiscussion & Results: The effect of WPC, MPC, Arabic gum, enzyme concentration and theaddition time of enzyme on viability of B. lactis (BB-12) for 21 days of cold storage at 4 ̊C were monitored. The results indicatedthat the effect of Arabic gum, WPC and MPC on viability of probiotic was significant (p
Research Article
Mohammad Reza Edalatian Dovom; Masoud Yavarmanesh; Fariba Ghiamati Yazdi; Morteza Khomeiri; Neda Nayyeri
Abstract
Introduction : Lactic acid bacteria (LAB) are a group of gram positive, catalase negative bacteria which possess unique metabolic, physiological and morphological characteristics. In addition, lactic acid bacteria are considered as a valuable source of antimicrobial agents including bacteriocins. Bacteriocins ...
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Introduction : Lactic acid bacteria (LAB) are a group of gram positive, catalase negative bacteria which possess unique metabolic, physiological and morphological characteristics. In addition, lactic acid bacteria are considered as a valuable source of antimicrobial agents including bacteriocins. Bacteriocins are defined as non-toxic peptides produced by LAB. "Maskeh" as an Iranian traditional butter carries indigenous LAB which secrete and harbor bacteriocins. Our objective in this study was to evaluate the influence of antimicrobial compoundsproduced by isolated LAB from Maskeh, a local traditional butter, against some pathogenic bacteria suchas: staphylococcus aureus, Listeria innocoa and E. coli using culture-based methods. In the following step, influence of some technological parameters including different temperatures, pHs and proteinase K were determined on stability of antimicrobial compounds in bacteriocins.Materials and methods: Three samples of milk, yoghurt and local butter known as Maskeh were collected from different regions in the south ofKhorasanRazavi, Gonabadcity.Indicator microorganisms and culture condition: In order to activate the indicators, following the cultivation in corresponding and suitable media, they were incubated for 24 hours in suitable temperatures.Survey of antimicrobial activities: In Agar Spot, Antagonistic activities of isolates were evaluated in solid media. Finally clear zone of inhibition was measured in mm. In Well- Diffusion Assay (WDA), positive isolates from previous step, were selected for this assay. In this method, cell-free supernatant (CFS) of isolates were examined for their antagonistic activities. Finally clear zone of inhibition were evaluated around the wells.Determination of antimicrobial compound nature: Effect of proteinase K on CFS: In order to evaluate the enzyme sensitivity of bacteriocin like compounds produced by LAB, CFS of isolates were subjected to proteinase K (final concentration 0.5 mg/ml). Mixture of enzyme- CFS was incubated in 37C for four hours. Finally, the remaining inhibitory activity was determined using WDA.Influence of different temperatures on CFS: Heat sensitivity of bacteriocin like compounds was evaluated with subjecting the CFS of isolates to various temperatures. Again remaining activity of isolates was evaluated with the help of WDA.Influence of different levels of pH on CFS: CFS of isolates was adjusted at different pHs and their inhibitory effects were determined using WDA.Discussion & Results: Following the sequencing, 51 isolates were identified from different steps of Maskeh production. Results showed that 44 out of 51 isolates were effective at least against one indicator. It was clear that E.coli, Staph.aureus, Listeria. innocoa, Lb.plantarum, Lb.sake, Lac.lactis ssp. lactis,Lac.lactis ssp. cremoris were inhibited by 33, 7,11,12,7,35 and 7 isolates, respectively. Among pathogenic indicator bacteria, E.coli was inhibited maximally and regarding the non-pathogenic indicators, Lac.lactis ssp. Lactis was inhibited by the most of the isolates. Among the isolates, Ent.faecium B161 and Str.thermophilus B258 presented the highest inhibitory effect against Listeria.innocoa.Interestingly both these strains had been isolated from Maskeh, implying that they originated the same source. Formation of clear inhibition zone in agar spot method is related to colony-associated antimicrobial compounds like H2O2, lactic acid and other organic acids. Also, the strongest clear zone of inhibition was against Listeria.innocoa. Lb.plantarum B120 showed inhibitory effect against 6 out of 7 indicator bacteria. This strain has been isolated from Maskeh, and only did not affect on Lac.lactis ssp. lactis.In the next step, in WDA, CFS obtained from isolates were subjected to inhibition activity evaluation. In this assay, 39 isolates showed inhibitory activity against at least one indicator and 12 isolates had no inhibition against indicators. E.coli was inhibited by the most of the isolates (11), followed by Listeria.innocoa by 8 and Staph.aureus by 2 isolates. But noticeable point is that the strongest influence was seen against Listeria. In the last step, influence of technological parameters such as : temperature, pH and enzyme were determined on antimicrobial and inhibitory activity of CFS. In this survey, only those isolates were chosen which showed inhibitory effect against Listeria innocoa. Regarding the temperature, with increasing of this factor, the diameter of clear zone had decreasing trend. This means that bacteriocin- like compounds are sensitive to heat. Among analyzed isolates, CFS of two isolates namely Aerococcusviridans M156 and M141 possess the highest sensitivity. In contrast, the highest resistance was related to Aerococcusviridans M165. Evaluation of antagonistic activity of CFS of isolates at different pHsexperienced, in pH between 3-5, growing trend of inhibitory activity which is due to produced lactic acid. Maximum of antagonistic activity was seen at pH=3 and along with pH increase toward the alkaline condition, it decreased.Aerococcusviridans M165 and M141 showed clear zone of inhibition equal to 6.5 and 6, respectively at pH=7.Proteniase K as a proteolytic enzyme, exhibited decomposing influence on antimicrobial effects of all isolates, except two of them. This phenomenon implies the proteinaceous nature of antimicrobial compound in CFS, because of decomposition as a result of proteolytic enzyme. But regarding two isolates, the clear zone did mot destroyed even after enzyme treatment.Conclusion: Some CFS or their producing isolates can be exploited as bio-preservatives; CFS of Aerococcusviridans M 165 can be applied in foods subjected to high heat treatment. In acidic and low pH food, we can use those isolates which theirCFS remain their activity at low pH.
Research Article
Sareh Boostani; Mahmoud Aminlari; Marzieh Moosavi-Nasab; Mehrdad Niakosari; Gholam Reza Mesbahi
Abstract
Introduction : Soybean is an excellent plant protein source with diverse applications in food systems. Despite numerous commercial applications and rich nutritional properties of soybeans, soy proteins are sensitive to heat and other damaging agents during food processing which can limit their applications ...
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Introduction : Soybean is an excellent plant protein source with diverse applications in food systems. Despite numerous commercial applications and rich nutritional properties of soybeans, soy proteins are sensitive to heat and other damaging agents during food processing which can limit their applications in food industries. Maillard reaction includes a series of chemical reactions between the free carbonyl groups of carbohydrates and the un-protonated amino groups of proteins under mild experimental conditions. This is one of the most desirable approaches for applying in food systems, because of the safety of the procedure and the independency of adding extra chemicals. Natural occurring Maillard reaction can be a relatively safe and inexpensive method in order to improve functionalities of food proteins. The production of conjugates haspositive influences on food proteins functionality such as solubility, water holding capacity, emulsion activity and stability, foaming properties, thermal stability, whipping ability, textural and gelation properties and also reduce allergenicity of proteins. Due to the positive characteristics and reasonable price of both soy proteins and maltodextrin in food industries, the aim of current study was to enhance the heat stability and functional properties of soy proteins through glycosylation with maltodextrin. In addition, assessment of changes in protein properties as a function of incubation time were evaluatedMaterials and methods: Preparation of purified soy proteins (Acid precipitated soy proteins) was done by a multistage process of washing, centrifugation, dialysis and freeze drying. The resulting powder contained pure soy globulins. Conjugation of acid precipitated soy proteins with maltodextrin was performed according to the method described as follows: protein-polysaccharide at a weight ratio of 1: 3 were dissolved in 0.01 M phosphate buffer, at pH values of 8, and were incubated at ambient temperature for 1 hr. Solutions were frozen at –80°C and then freeze dried. Lyophilized powders were incubated at 60 °C for 1, 3, 5 and 7 days, under 79% of relative humidity provided by saturated KBr. For each treatment an un-conjugated (control) sample was prepared under the same conditions. The formation of protein-polysaccharide conjugates was confirmed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and gel filtration chromatography (Sephadex G-100 chromatographic system was used to separate the conjugated proteins from the un conjugated samples). Determination of protein denaturation temperature changes were carried out using METTLER TA Q100-DSC thermal analyser.The emulsifying properties of the samples including emulsifying activity and emulsion stability were assessed according to the procedure established by Pearce and Kinsella. Protein solubility was measured by calculating the amount of nitrogen in the supernatant and total nitrogen content of the samples and reported as percentage of protein solubility at pH 3, 5, 7 and 9. Foaming properties of the samples including foaming capacity and foaming stabilitywere determined using calibrated measuring cylinderDiscussion & Results: When the heating duration is increased, wider and heavier molecular weight bands emerge near the top of the running gel of SDS-PAGE, and yet these were not observed in the control. As a result of conjugation, the protein-carbohydrate covalent binding occurs, producing heavier molecular weight species, and thus leading to its accumulation on top of the separating gel. Compared with un-modified soy proteins, the conjugated soy proteins eluted in the void volume of G-100 gel permeation chromatography column, suggesting increase in the size and molecular weight of soy proteins due to the covalent attachment of maltodextrin. According to differential scanning calorimetry (DSC) analysis, thermal stability of soy proteins was remarkably increased by conjugation with maltodextrin and maximum denaturation temperature was observed for the mixture incubated for 7 days. The improved thermal stability is manifested in increase in denaturation temperature of globular proteins, hence conjugation leads to significant improvement of soy proteins stability. Increase in thermal stability is the result of inclusion of the hydrophilic carbohydrate moiety to the surface of the proteins. Compared to control sample, the solubility, foaming characteristics and emulsifying properties were significantly improved by increasing incubation time. The protein solubility of conjugate remarkably increased at all pH’s compared with the un-conjugated proteins. Covalent links between hydrophilic maltodextrin and soy proteins could enhance the reaction tendency between proteins and water molecules under unfavorable conditions. Improvements in the emulsifying properties of the conjugated samples can be explained by the fact that there is a combination among the emulsifying activity of proteins and the stabilizing impacts of polysaccharides per molecule. Foaming capacity of proteins can be affected by the solubility of proteins. Furthermore, maltodextrin is a hydrophilic carbohydrate which can improve the stability of soy proteins foams by acting as a thickener, thus increasing the strength of bubbles. It should also be considered that functionality of proteins are frequently influenced by protein solubility, and this could also serve the understanding of why improvements occur in functional properties of conjugated proteins, compared to un-conjugated ones. The results indicate that physiochemical and functional properties of soy proteins were modified and improved by conjugation with maltodextrin.
Research Article
Narjes Damavandi Kamali; Amirreza Shaviklo; Ali Motamedzadegan
Abstract
Introduction: At least 60% of the estimated 300,000 metric tons of tuna that are processed in Iran areby-products which arebeingwasted and converted to non-human products as fish meal or fertilizers. Therefore, a major challenge facing the tuna canning industry is to find the new processes to utilize ...
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Introduction: At least 60% of the estimated 300,000 metric tons of tuna that are processed in Iran areby-products which arebeingwasted and converted to non-human products as fish meal or fertilizers. Therefore, a major challenge facing the tuna canning industry is to find the new processes to utilize tuna processing by-products (mainly dark muscle) into valuable foods. The characteristics of tuna dark meat (TDM) make it not acceptable for these industries. Therefore, the isolation of proteins from TDM for food application would be a more responsible way of using a nutritious and abundant rest raw material.The pH-shift technology for recovering fish proteins involves the solubilisation of chopped and homogenized fish flesh either in an aqueous acidic or alkaline solution. The protein rich solution is separated from solids (insoluble proteins, skin, bones, and scales) and neutral lipids by centrifugation. The soluble proteins are then recovered by isoelectric precipitation by adjusting the pH to 5.5 and the precipitated proteins are removed by centrifugation. This method can be potentially applied with any white/ dark muscle fish or fish by-products. No evidence can be foundon isolation of protein from TDM. Therefore, this study was carried out to investigate stability and functional properties of proteins recovered from TDM. Materials and methods: The ground TDM was homogenized for 1 min (speed 50) with 9 volumes of ice-cold distilled water. The proteins in the homogenate were solubilized by dropwise addition of 1 N HCl or 1 N NaOH until the intended pH (2.5, 3.0 and 3.5or10.5,11.0 and 11.5) was reached. The protein suspension was centrifuged. The soluble proteins were precipitated by adjusting the pHs to 5.5 using 1 N NaOH or 1 N HCl. Precipitated proteins were collected via a second centrifugation. Proximate analysis of tuna protein isolates (TPI) was carried out. TBARS, pH, viscosity, water holding capacity (WHC), gel strength, biting and folding tests, texture profile analyses (TPA), and color were measured. Qualitative protein analysis was carried out using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).Results and discussion: The protein, fat and moisture contents of the acid-aided protein isolates were found to be 28.65, 5.35 and 74.36% respectively. While alkaline-aided protein isolates contained 29.57% protein, 4.17% fat and 71.23% moisture. A significant difference was found in TBARS level between the isolated products. The lowest TBARS value was found in acid-aided isolate and isolate treated at pH 11.5. The TBARS value of isolates extracted at pH 10.5 and 11 was 0.15 mg malondialdehyde / kg, which was below the border line recommended for fish products. Lipid oxidation in fish protein isolates has been reported during pH-shift process. The lipid content of TPI samples and activating of haem proteins as prooxidants at different pH may describe lipid oxidation in TPI samples. The average viscosity of TPIs was 3.81 cP (Centipoise). The highest viscosity scores were observed for the isolates prepared at pH 11.0 followed by the isolates made at pH 3.5 and 11.5. The isolates treated at pH of 2.5, 3.0 and 10.5 had the same level of viscosity. Low viscosity might be due to low cross linking degree of protein molecules. The low viscosity of the prototypes may possibly be explained by decreasing interaction between proteins and the surrounding medium. Therefore, denaturation and modification of protein conformation in tuna protein samples may have affected the viscosity.The WHC of the samples (12-16%) was similar to the proteins isolated from the other fish by-products. The highest value of WHC among TPIs was found for the isolates prepared at pH 3.5. The rest samples had the same value of viscosity. The WHC can be defined as the ability of a protein gel to retain water against a gravitational force. The level of water retained in a gel is affected by the same factors that affect the formation of a good protein gel ‘i.e.’ moisture, pH and salt. Furthermore, the WHC usually reflects the extent of denaturation of the protein and water contents. It has been reported that WHC is closely related to fish species, amount of salt, different processing method and the interaction between these factors.The highest scores for gel strength, biting and folding tests and TPA (hardness, cohesiveness, springiness and resilience) were observed in TPIs treated at alkaline pH. The muscle proteins being particularly responsible for gelation are myosin and actomyosin. It has been reported that alkali-aided protein extraction caused less denaturation than an acid-aided process. This lower denaturation of proteins leads to products with enhanced texture. Hardness and cohesiveness were found to be maximum for samples prepared at pH of 11.5. The increase in hardness may also be due to the stronger gel network formed by the concentrated myofibrillar proteins in the protein isolates. The difference between TPA parameters of the recovered proteins andthe TDM mightbe due to the difference in lipid and collagen content.The alkali-aided process recovered proteins of higher whiteness than the acid-aided process possibly due to high removal amount of myoglobin and haemoglobin during leaching. The electrophoretic patterns revealed the stability of proteins in alkaline pH. The lowest reduction in band intensity of myosin (myosin heavy chain) and actin was found when the alkaline-aided process was applied. Accordingly the highest band intensity of myosin and actin proteins was observed at the high pH (11). The weak bands of protein among acid-aided samples have possibly been due to the hydrolysis effect of enzyme activity.
Research Article
Adeleh Mohammadi; Saeedeh Arabshahi- Delouee
Abstract
Introduction:Frankincense is a natural oleo-gum-resin which is obtained through slits made in the trunks of trees of the genus Boswellia (Family Burseraceae). The genus Boswellia is approximately represented by 43 different trees and shrubs distributed mostly in the India, Arabian peninsula, and east ...
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Introduction:Frankincense is a natural oleo-gum-resin which is obtained through slits made in the trunks of trees of the genus Boswellia (Family Burseraceae). The genus Boswellia is approximately represented by 43 different trees and shrubs distributed mostly in the India, Arabian peninsula, and east africa (mothana et al.2011). Trees from the genus Boswellia (Burseraceae) are traditionally used as a medicine, a fumigant, in various cosmetic formulations and in aromatherapy in several countries around the world.Frankincense therapeutic effect significantly depends on the amount of oleoresin. These effects include anti-inflammatory, hepatoprotective, anticancerous, anti-HIV, anti-microbial, antifungal, anti-ulcerous, gastroprotective, hypoglycemic andantihyperlipidemic properties (Aman et al. 2009; Al-Harrasi and Al-Saidi, 2008; Khadem et al. 2009 and Shah et al.2009).Lipids are susceptible to oxidation on storage and frying processes. Characteristic changes associated with oxidative deterioration include development of unpleasant tastes and odors as well as changes in color, specific gravity, viscosity and solubility.Lipid peroxidation is one of the major agents of deterioration for vegetable oils, fats and other food systems (Iqbal and Bhanger, 2007). During oxidation hydroperoxides are formed which again break down to form products like alcohols, aldehydes, ketones and hydrocarbons, which possesses offensive off flavors (Grace Roy et al.2010).In order to inhibit oxidation, synthetic antioxidants, such as BHA (Butylated hydroxyanisole), BHT (Butylated hydroxyanisole) and TBHQ Ter-butyl hydroquinone have been added to foods but there is concern about the use of these compounds due to their reported adverse effects on health. This has led to an increasing trend in the search and replace of these synthetic antioxidants with natural ones such as phenolic compounds (Mariod et al. 2006).Antioxidants affect the process of lipid oxidation at different stages due to differences in their mode of action. Because of the complexity of the oxidation process itself,the diversity of the substrates and the active species involved, the application of different test methods is necessary in the evaluation of antioxidants. The aim ofthisstudy was to evaluatethe antioxidantproperties of various solvent extractsand essential oil offrankincense(Boswellia serrata)and evaluation ofitsantioxidant activityinsoybeanoil.Materials and methods: In this study, the dried powder of B.serrata (25g) was extracted overnight in 250 ml each of methanol, ethanol and acetone respectively, in a mechanical shakerat room temperature and each extract was filtered with Whatman No. 1 filter paper. The filtrates obtained from methanol, ethanol and acetone extractions were evaporated at 40 °C in a rotary evaporator. The content of phenolic compounds was measured by Folin–Ciocalteu, Briefly 20 µl of extract solution were mixed with 1.16 ml distilled water and 100 µl of Folin–Ciocalteu reagent, followed by addition of 300 µl of Na2CO3 solution (20%) after 8 minutes. Subsequently, the mixture was incubated at oven at 40 °C for 30 minutes and its absorbance was measured at 760 nm.The ability of extracts to scavenge DPPH radicals was determined according to the method of Blois (1958). Briefly, 1 ml of a 0.1 mM methanolic solution of DPPH was mixed with 3 ml of extract solution in methanol (containing 100–1000 μg/ml). The mixture was then vortexed and left for 30 min at room temperature in the dark. The absorbance was measured at 517 nm. The percentageof the DPPH radical scavenging was calculated using the equation given below:% inhibition of DPPH radical= ( Abr - Aar ) / Aar×100where Abr is the absorbance before reaction and Aar is theabsorbance after reaction has taken place. The molecule 1, 1-diphenyl-2-picrylhydrazyl (a,a-diphenyl-bpicrylhydrazyl DPPH) is characterized as a stable free radical by virtue of the delocalisation of the spare electron over the molecule as a whole, so that the molecule does not dimerize, as would be the case with most other free radicals (Nur Alam et al., 2013).Next, oxidative stabilityand antioxidant activity of methanol extract concentrations (200, 500, 800, 1000 ppm) with the synthetic antioxidant TBHQ (100 ppm) were evaluated in soybean oil without antioxidants (63 ˚C, 12 days).Results and discussion: The extract significantly (p0.05) suppressed the formation of peroxides and thiobarbituric acid-reactive substances (TBARS) during accelerated oxidation, even at a level of 200 ppm. Based on the obtained results, the methanolic extract at 1000 ppm had the highest antioxidant activity among other extracts and inhibits the peroxide value and the index of thiobarbituric acid, but it coulden't compete with the synthetic antioxidant TBHQ. Results showed that, Boswellia Serrata was found as a potential source of natural antioxidants due to its marked antioxidant activity.
Research Article
Roya Kazemizadeh; Vajiheh Fadaei Noghani
Abstract
Introduction: Flavored milk is a healthy beverage, nutritious, delicious and thirst elimination by a large group of people, especially children consumed. Therefore, the need to find different ways to enhance the nutritional value of milk and its products is of many researchrs’ interest.Pomegranate ...
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Introduction: Flavored milk is a healthy beverage, nutritious, delicious and thirst elimination by a large group of people, especially children consumed. Therefore, the need to find different ways to enhance the nutritional value of milk and its products is of many researchrs’ interest.Pomegranate fruits peel is an inedible part obtained during processing of pomegranate juice. Pomegranate peel is a rich source of tannins, flavonoids and other phenolic compounds;which is currentlybeingwidely used in medicine and food industry. Moreover, consumers prefer to use natural antioxidants rather than synthetic ones. The datedatesyrup has unique odor and taste; it has high potential to be a new sweetener which is natural and chemical-free. Datesyrup hasa natural sweetness and is considered easy to digest. Also, it has low fat, no cholesterol and saturated fat and a good source of dietary fiber is considered. In this study, the effect ofaqueous extract of pomegranate peel adding at levels 10%, 20%, 30% and datedatesyrup adding at levels 2%, 4% and 6% on antioxidant property, total polyphenols contents andmicrobial total countof functional flavored milk was investigated during 21-day cold storage. Materials and method: Raw milk from Deniz factory (Iran), date syrup with Brix ° 83 from Dombaz company (Iran), Reagent Folin - Ciocalteau, reagent 2,2-Di Phenyl-1-Picryl Hydrazyl(DPPH) and gallic acid mono-hydrated from Sigma (America) were prepared. Other laboratory chemicals and PC-AGARCulture media from Merck (Germany) was purchased.Also, pomegranate variety of Shiraz Black Tail (Iran) was used.Preparation ofAqueous extract of pomegranate peelFresh pomegranate was washed and peeled and stored at room temperature away from sunlight for a week. 50gr of powdered pomegranate peelwas mixed with 500 ml of distilled water with temperature of 30°Cand was maintained at 30°C for 12 hours.Preparation of flavored milkThe milk used for producing functional flavored milk samples was preheated at 50ºC, then date syrup was addedat levels of 2%, 4% and 6% and aqueous extract of pomegranate peel was also added at levels of 10%, 20% and 30% to milk and the whole mixture was mixed for 5 minutes; The mixture was then heated to75ºCfor 15 minutes. After cooling at 25°C, flavored milksamples were refrigeratedat 4ºC.Determination of antioxidant activityThe antioxidant activityof flavored milk samples was measured according to Elfalleh et al. (2012) method using model CARY 50spectrophotometer,Australia, at 517 nm by a Radical Scavenging Activity (RSA) and DPPH reagent .Determination of total polyphenolsThe total polyphenolsof flavored milk samples were measured according to Elfalleh et al. (2012) method usingmodel CARY 50spectrophotometer,Australia, at 765 nm by Folin- Ciocalteu reagent. The amount of phenol content was calculated by standard curve of gallic acid .Microbial total countMicrobialtotal count was determinedin plate count agar according to Iranian National Standard no.5484. Sample plates were incubated in model zn1434incubator, Iran, at 31 ° C for 72 hours.Experimental designIn this study, A completely randomized design was employed usng SAS software (version 9.1) to determinate the antioxidant activity, total polyphenols and microbial count. The experiment was consisted of three factors including pomegranate peel extract (in three levels 10, 20 and 30%), date syrup factor (in three levels 2, 4 and 6%) and time (in four days 0, 7, 14 and 21).Results and Discussion: According to present research, with adding pomegranate peel extract percentage of free radical scavenging and total polyphenols content increased (p
Research Article
Setareh Hosseinzadeh; Mohammad Hossein Hadad Khodaparast; Aram Bostan; Mohebbat Mohebbi
Abstract
Introduction: Flavor plays a pivotal role in consumer satisfaction and further consumption of foods. Most available aroma compounds are synthetic and most of consumers tend to avoid them as they are of the idea that the chemical flavors are toxic or detrimental to their health. Recently, the market of ...
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Introduction: Flavor plays a pivotal role in consumer satisfaction and further consumption of foods. Most available aroma compounds are synthetic and most of consumers tend to avoid them as they are of the idea that the chemical flavors are toxic or detrimental to their health. Recently, the market of flavors from natural sources is shifting its focus on application rather than synthetic flavors (Badee et al, 2012). Essential oils consist of sensitive compounds against environmental effects. Microencapsulation is one of the methods which increases the stability of essential oils and flavors during storage and transportation. Different methods which may be used for microencapsulation include spray drying, spray-cooling, spray-chilling, coaservation, extrusion, fluidized bed method (KashappaGoud et al, 2003). However, spray drying method is preferred due to its high speed, high reliability, high flexibility and its being economical and the fact that it can be easily implemented in industry (KashappaGoud et al, 2003). Spray drying of essential oils requires homogenizer, spray dryer and chemical materials used for walls such as some types of emulsifiers and ingredients including maltodextrin, dried corn syrup, gum Arabic, gelatin and milk protein (Adamiec&Kalemba, 2004; Badee et al, 2012). Arabic gum (acacia gum) is a biopolymer which is derived from internal sap of acacia tree. It consists of a heteropolysaccharide complex with highly ramified structure (Phisut, 2012). It is an effective emulsifier for flavor emulsions thanks to its high water solubility, low solution viscosity, good surface activity, and ability to form a protective film around emulsion droplets (Chanamai&Mcclements, 2001). Maltodextrins are products of starch hydrolysis, consisting of D-glucose units linked mainly by α(1→4) glycosidic bonds. They are described by their dextrose equivalence (DE) which is inversely related to their average molecular weight. The greater the DE is, the shorter the glucose chains are and the more water they absorb (Phisut, 2012). Materials and method: Spearmint oil was produced by clevenger distillation from spearmint leaves (Mohal Khan et al, 2012). Malthodextrin with DE=18-20 from Xiwang Starch Co. Ltd., China, has a sweet taste and it is used in combination with emulsifiers, creates the walls and covers and causes thermal resistance and resistance to browning. Solubility in water=min 98%, moisture=4.5-6%, pH=4.5-6.5 and ash=max 0.1%. Arabic gum was prepared from Slandwide Corporation Co., Philippines, which is used as an emulsifier, stabilizer and the cover (moisture = max 10%, ash=max4% and pH =4-5).In making an emulsion, deionized double distilled water was used.A Solution of maltodextrin/arabic gum (1:1) in ratios of 10%, 20% and 30% in deionized water were prepared at 45°C and 1200 rpm for 1h (by Stirrer IKA). The solution was kept in cool room temperature at 4°C overnight (Badee et al, 2012; Baranauskiene et al, 2007). Then, 2.5% spearmint oil was added to an aqueous and homogenized (15000 rpm for 10 min) solution with an Ultra Turrax (model T25 digital, IKA Co, Germany) (Badee et al, 2012; Baranauskiene et al, 2007; Baranauskiene&Venskutonis, 2009; Frascareli et al, 2012). Then sonificasion (model ,HD3200, BANDELINE Co, Germany) for 1 minute by amplitude control 100%, frequency 20 kHz at 45 °C. The emulsion was spray dried in a BUCHI B-190 spray dryer (Badee et al, 2012; Baranauskiene et al, 2007; Baranauskiene&Venskutonis, 2009) where the inlet temperature was 180 °C, outlet temperature 60°C, pump speed 10 ml/min, air flow 600 l/h and pressure 4 bar. The powder was stored at -18°C until tested.Results and Discussion: The results of this research showed that during microencapsulation of spearmint oil at the fixed rate of 2.5%, wall concentration were effective in the stability of emulsions and in keeping menthol and d-limonene in microcapsule during drying and storage. By increasing wall material from 10% to 30% the most stability in emulsion was obtained and more half life and less release in microcapsules was achieved. Also, temperature plays an important role in protecting the volatile components, so that the microcapsules stored at 4°C had about half life which was 80 days more than the the samples stored at 25°C.
Research Article
Hamed Mahdavian Mehr; Arash Koocheki; Mohebbat Mohebbi
Abstract
Introduction:Deep fat frying is a cooking method where oil is used as the heat transfer medium, in direct contact with food at a temperature above boiling point of water. The aim of this process is to combine short cooking times with unique characteristics. It also involves heat and mass transfer simultaneously. ...
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Introduction:Deep fat frying is a cooking method where oil is used as the heat transfer medium, in direct contact with food at a temperature above boiling point of water. The aim of this process is to combine short cooking times with unique characteristics. It also involves heat and mass transfer simultaneously. During frying time, the mass transfer is characterized by the dynamics moisture loss from the food and the fat uptake into the food. There is some experimental evidence showing that water loss and oil absorption are correlated and progress with specific kinetic. In the meantime, oil uptake of product is an important issue, affecting the nutritional and organoleptic qualities of fried foods. However, one problem associated with fried foods is the considerable amount of oil absorbed during the deep frying process. It is affected by oil temperature, frying time, initial water content of food ingredients, product surface area, the ratios of product weight to frying oil volume, pretreatments and many other factors. So far, several approaches have been suggested for decreasing oil uptake during deep frying of fried foods. One way to decrease oil absorption in foods is referred to batter coating. In this regard, the ingredients and flow behavior's properties of batter are the most important parameters to determine the performance of batter coating and reduction of oil uptake in the final product. In the batter formulations, proteins and gums can be used as important and effective components, because they have great water bonding and barrier properties, which has strong impact on reduction of oil uptake during frying. Therefore, the objective of the present study was to assess the effects of replacement of Godume shahri seed gum (0.5 and 1%) or soy protein isolates (2 and 4 %), as part of the wheat flour in batter formulation, on rheology of batter, batter pickup and mass transfer kinetic parameters during deep frying of chicken nuggets.Materials and method:Raw materials including fresh chicken breasts, onion, salt, hot pepper, wheat flour, baking powder, and 100% pure sunflower oil were purchased from local markets. SPI (92% protein. w/w, db) were obtained from FSL Co. The batter formulations consisted of wheat flour, salt (1.5% w/w, db), baking powder (0.5% w/w, db), SPI (2 and 4% w/v, db) and Godume shahri seed gum (0.5 and 1%). 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. The flow behavior index (n) and consistency coefficient (k) values were computed by fitting the power law model.The chicken nuggets, containing a mixture of chicken breast meat (88%), onions (10 %), Pepper (0.5%) and salt (1.5 %) were prepared in slab shapes using a manually operated cutting device. The dimensions of the chicken nuggets were about 4.5 cm (length) × 2.6 cm (width) ×1.1 cm (thickness) (±0.2 cm). Batter pickups (%) were calculated by the weight difference between the chicken nuggets after coating to the weight of chicken nuggets before coating. Deep frying was performed in programmable deep fat fryer contained 1.5 L refined sunflower oil. Samples were placed in a wire basket and then submerged for the required times of zero, 1, 2, 3, 4 and 5 minutes at 150 ◦C, 170 ◦C, and 190 ◦C. Oil and moisture content of the chicken nuggets were determined by standard techniques. For modeling moisture and oil transfer phenomena in fried chicken nuggets, Fick’s law of diffusion and a first order kinetic model were used respectively.Results and Discussion:Results showed that Godume shahri seedgum had more effect on apparent viscosity compared with soy protein isolates. Polysaccharidic structure of Godume shahri seed gum prepares high number of hydroxyl groups. Hydrodynamic interactions between polar and hydrophobic groups trap most of the free water and consequently increase batter viscosity. All batters showed shear thinning behaviour (n≥0.529). The power law model was adequately suitable to describe the flow behavior of the batters (R2≥0.994). Coating uptake at the surface of nuggets was significantly affected by the batter consistency. The consistency index for batter containing gum was high and therefore the coating uptake was higher for these samples. The maximum moisture loss rate and the effective diffusion coefficient obtained for chicken nuggets coated with only batter. Addition of soy protein isolates and Godume shahri seed gum to batter formulation, decreased the Deff to 3.55-5.46×10-8 m2/s and 3.38-5.32×10-8m2/s, respectively. This can be attributed to the effect of different batter formulations and special functions of gum and protein. The activation energy to remove moisture and oil absorptionwere 10.79 (kJ/mol) and -7.91(kJ/mol) for the control sample, 13.37-17.64 (kJ/mol) and -5.90 to -9.18 (kJ/mol) for soy protein isolates and 11.9-14.7 (kJ/mol) and -7.56 to-10.30 (kJ/mol) for Godume shahri seed gum, respectively.
Short Article
Sareh Boostani; Mahmoud Aminlari; Marzieh Moosavi-Nasab; Mehrdad Niakosari; Gholam Reza Mesbahi
Abstract
Introduction: Engineering of food proteins with improved functional properties and higher resistance to heat is the main goal of food scientists. Food technologists are always seeking for innovative, simple and effective methods to manipulate proteins, hence natural modification has had the most attention ...
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Introduction: Engineering of food proteins with improved functional properties and higher resistance to heat is the main goal of food scientists. Food technologists are always seeking for innovative, simple and effective methods to manipulate proteins, hence natural modification has had the most attention in last decades. One of the natural ways used for protein modifications isMaillard grafting reaction. Maillard reaction as a consequence of covalentbindingbetween the available amino groups of the proteins and carbonyl containing moiety of the polysaccharides, causes a loss in free amino group content of the mixture that can be measured through different methods. Protein-polysaccharide hybrids, as a result of dry heating of two biopolymers mixture under controlled reaction conditions, cause the emergence of conjugates with novel functionalities.Selecting appropriate reaction conditions has a significant impact on the properties of the final conjugates. Among the factors affecting the degree of conjugation, temperature, pH and incubation time have considerable roles in determining the degree of conjugation. There are various methods by which conjugation degree can be assessed and factors such as accuracy, cost, accessibility and etc. must be considered when selecting a measuring method. Therefoe, in this study the effect of different Maillard reaction conditions on the conjugation degree of soy proteins-dextran heated mixtures have been investigated. In addition, the glycation degree was compared and reported by both OPA assay and UV absorbance methods.Materials and methods: Soy proteins–dextran conjugates were prepared as described later. First, soy proteins and dextran were mixed with phosphate buffer (0.1 M, pH: 8.5 and 7) and 1 to 4 ratio of protein to polysaccharide. After mixing and incubating at ambient temperature for some hours, solutions were frozen at –80 ℃ and freeze dried. Then, the lyophilized powder was incubated at 40 ℃ for 0, 4, 8, 24 hours and 2, 4, 6, 8, 12 days, at 60 ℃ for 0, 1, 2, 3, 4, 6, 8 days and at 80 ℃ for 0, 1, 2, 4, 8, 16, 24, 48 hours, under the 79 percent relative humidity in presence of saturated KBr. For each treatment a non conjugated sample was prepared in the exact same condition. Conjugation of proteins to polysaccharides was monitored by two methods (OPA assay and UV absorbance). Determining degree of glycation by OPA method was done as follows, in this procedure the level of available amino groups was estimated using the ortho- phthaldialdehyde (OPA) reagent, the absorbance was measured at 340 nm and degree of glycation was measured using a formula. To investigate the UV absorption of conjugated proteins, the samples were diluted using distilled water and the absorption was read using a UV-visible spectrophotometer.Results & Discussion: Covalent linkage between amino group of proteins and carbonyl group of polysaccharides causes depletion in the amount of available amino groups. The extent of soy proteins-dextran conjugation under various Maillard reaction conditions was evaluated by the reduction of available amino groups of proteins, the more reduction in amount of amino groups, the more conjugation between protein and polysaccharide. OPA results showed that, in the samples heated at 40 °C and 80 °C (at both pH 7 and 8.5), the amount of free amino groups slightly reduced compared to 60 °C heated samples. The disappearance of available amino groups at 60°C was faster than other temperatures and formation of conjugates in this temperature was more successful. A stepwise reduction in free amino group content observed with increasing incubation time. When soy proteins were incubated at pH 8.5 for 8 days at 60 °C, a considerable decrease in available amino group contents occurred. UV absorption results showed similar trend of changes in OPA method. Increasing UV absorption is due to the intermediate Maillard reaction products (MRP). Increasing incubation time, temperature and pH cause a significant increase in UV absorbance. Increasing UV absorption with increasing heating time indicates the fact that Maillard reaction products (MRP) formation is more favorable at alkaline pH. Data of UV absorption are a proper evidence for OPA assay results. Conclusion: As a conclusion, both OPA assay and UV absorption methods are cost effective, accurate and simple methods which can represent valuable information concerning the Maillard conjugation.
