Research Article
Shadi Basiri; Fakhri Shahidi
Abstract
Introduction: Morus Alba, known as white mulberry, is a short-lived, fast-growing and small to medium sized mulberry tree, which grows to 10–20 meters tall. The species is native to northern China, and is widely cultivated and naturalized elsewhere. The fruit is 1–2.5 cm long in the species in the ...
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Introduction: Morus Alba, known as white mulberry, is a short-lived, fast-growing and small to medium sized mulberry tree, which grows to 10–20 meters tall. The species is native to northern China, and is widely cultivated and naturalized elsewhere. The fruit is 1–2.5 cm long in the species in the wild, it is deep purple, but in many cultivated plants it varies from white to pink, being sweet and bland. The fruits are also eaten, often dried or made into wine or vinegar. In traditional Chinese medicine, the fruit is used to treat prematurely grey hair, to tonify the blood, and treat constipation and diabetes. White mulberry is a fruit with high nutritional quality. The shelf life of mulberry is short due to its high moisture content. Dried mulberry and its molasses are popular products from mulberry fruit. Hydrocolloids are used in fruit snacks formulations to create novel texture, increase stability for their water-holding capacity, improve texture and have an impact on flavor release and other structural and sensory properties in the respective products. Hydrocolloids are also widely used in the food industry as thickeners, stabilizers and gelling agents in various products including ice cream, sauces, jellies and pastille products. Guar gam is kind of long-chain galacto-mannan with high molecular weight, obtained from endosperm of guar plant. This type of synergistic behavior among polysaccharides is commercially valuable, because it creates a novel texture and a more desirable structure. The aim of this research is to produce mulberry pastille as a novel and value added product with long shelf life. Beside it can be introduced as a healthy snack replacing sugar. Materials and methods: The materials include mulberry puree, hydrocolloids (Gelatin and guar) and citric acid. Berries were collected from the gardens around Mashhad (Iran). Guar was purchased from Sigma Chemical Company, citric acid was purchased from Merk Chemical Company, Germany. Gelatin (0, 1, and 2 %) and Guar (0, 0.5, and 1 %) were used for pastille formulations. To produce fruit pastille based on mulberry puree, the prepared puree was mixed into hydrocolloids. After measure pH and moderating to PH = 4.3 by adding acid citric in 40 % concentration and controlling the Brix degree to constant Brix of 45, the mixture was prepared. Then the prepared mixture was poured into a network framework of steel origin in the cavities with 1.2×1/2 and the molds were hold in the refrigerator for 2 hours with 4°C to fasten the gel. The obtained gel was taken out of the mold cavities and placed in a glass plate. The samples were then dried at 70° C in a hot air drier with airflow rate of 1.5 m/s for 6 hours. The samples were evicted every 30 minutes. Parameters such as color, sensory and textural characteristics of samples were investigated. Statistical design was 2 factors factorial with three replicates adopted completely randomized design. Results and Discussion: The results of texture evaluation showed that increasing guar gum improves the cohesion, elasticity and chewiness of the samples, while their adhesion were decreases. Conclusion: Mulberry pastille including 1% Guar and 1% Gelatin having the lowest amount of firmness, adhesion, chewiness and suitable color characteristics, was determined as the best formulation among the other investigated samples.
Research Article
Elham Nourmohammadi; Alireza Sadeghi Mahoonak; Mohammad Ghorbani; Mehran Alami; Masoumeh Sadeghi
Abstract
Introduction: Proteins are vital substances for health since they provide nitrogen, amino acids and the energy required for normal body performance. However, the applications of proteins are limited due to their certain properties, such as their low solubility. The enzymatic hydrolysis of proteins is ...
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Introduction: Proteins are vital substances for health since they provide nitrogen, amino acids and the energy required for normal body performance. However, the applications of proteins are limited due to their certain properties, such as their low solubility. The enzymatic hydrolysis of proteins is an extensively used approach to produce bioactive peptides and promote the chemical, functional and nutritional properties of proteins. These compounds have interesting biological properties such as anti-oxidative, anti-hypertensive, anti-bacterial, anti-cancer and anti-thrombotic activities. Lipid peroxidation is one of the main reasons behind the deterioration of foodstuffs during processing and storage. In this case, the addition of anti-oxidative compounds is considered as an effective way to improve the shelf-life of lipid containing foods. Due to carcinogenic effect of synthetic anti-oxidative compounds, extensive efforts have been done to find natural anti-oxidative compounds with plant origin during recent years. Pumpkin (Cucurbitapepo) seeds are rich of proteins, unsaturated fatty acids, phytosterols and essential minerals like Zn, K, Ca, Mg, Fe, Cu and P. Oil content of pumpkin seeds is about 40-60%, and mostly consisted of oleic, palmitic and stearic acids. On the other hand, its protein content is about 45-46%, and this amount will reach to 55-56% after defatting. To date, pumpkin seeds have been mainly used for pumpkin oil production. After the oil extraction, a protein-rich by-product (pumpkin oil cake) remains, which is often used for animal feeding. In this study, the enzymatic hydrolysis of pumpkin oil cake protein isolate by a food-grade protease named trypsin was attempted and the optimum treatment was selected based on the DPPH radical scavenging and ferrous ion chelating activities Materials and Methods: In this study, the optimization of the hydrolysis of pumpkin (Cucurbitapepo) oil cake protein was investigated using response surface methodology (RSM) and central composite design (CCD) in order to achieve the maximum DPPH radicals scavenging and metal ion chelating activities. For this purpose, trypsin concentrations of 1-2% and hydrolysis temperatures and times of 35-45 ċ and 2-5 hours were examinedas independent variables. Preparations of pumpkin oil cake protein isolate (POCPI) Defatted pumpkin oil cake was dispersed in distilled water (1:10 w/v). The pH was adjusted to 10 with 1N NaOH, mixed for 1 hour at room temperature and centrifuged at 5000g for 20 minutes (Combi514R, South Korea). The supernatant was collected, pH was adjusted to 5 with 1N HCl and centrifugation was performed at the same condition. Supernatant was discarded and precipitate was collected as pumpkin oil cake protein isolate. Enzymatic hydrolysis Pumpkin oil cake protein isolate was dispersed in tris-HCl at pH= 8 for trypsin enzymatic treatment (5% w/v). After that, trypsin was added at 1%, 1.5% and 2% and hydrolysis was carried out for 2, 3.5 and 5h at 200 rpm in shaker incubator (8480-VS, South Korea). Hydrolysis temperatures were 35, 40 and 45˚C. At the end of hydrolysis, the enzyme was inactivated for 15 minutes at 85˚C; dispersion was centrifuged at 4000g for 30 minutes, the supernatant was collected and freeze dried. DPPH radical scavenging activity An aliquot of 1000 microliterpumpkin oil cake proteinhydrolysate was mixed with 1000 microliter of 0.1mM DPPH solution prepared in 96% ethanol. The mixture was allowed to stand for 60 minutes in the dark and the absorbance was read at 517 nm. The blank was prepared with the same manner except that 1000 microliter water was used instead of 1000 microliter pumpkin oil cake proteinhydrolysate. Ferrous ion chelating activity Pumpkin oil cake protein hydrolysate(4.7 ml) was mixed with 0.1 ml 2mM FeCl2 and 0.2 ml 5 mM ferrozine and was kept at room temperature for 20 min. The absorbance was read at 562 nm and the blank sample was prepared with the same manner except that 4.7 ml distilled water was used instead of sample. Results & Discussions: The results of this study, showed that the optimum conditions to reach the maximum DPPH radicals scavenging and metal ion chelating activities were 35 ċ, 5h, 1.1% enzyme concentration and 45 ċ, 2.05h and 2% enzyme concentration that showed DPPH radicals scavenging and metal ion chelating activities of 76.28% and 49.61% respectively. These results were to large extent similar to those suggested by Design Expert software (75.89% and 50.84%). The R2 was 0.9184% and 0.9761% for DPPH radicals scavenging and metal ion chelating activities respectively. Moreover the adjusted R2 was estimated to be 0.1333 and 0.1827 for DPPH radicals scavenging and metal ion chelating activities respectively, which suggested the suitability and fitness of proposed model for the considered responses. Conclusions: Based on the results, pumpkin oil cake protein hydrolysate demonstrated appropriate anti-oxidative and metal ion chelating abilities. The results of this study indicated that pumpkin oil cake protein hydrolysate had the ability to be used as an effective and natural anti-oxidative compound in lipid containing foods.
Research Article
Hamid Bakhshabadi; Mohammad Rostami; Masoumeh Moghimi; Abolfazl Bojmehrani; Anehbibi Bahelkeh; Negar Toorani
Abstract
Introduction: Using oilseeds in the human food stuffs, employing their meal for animal feed and also their usage in pharmaceuticals, soap making and fuel has prompted great interest for farmers to plant them and for the government to promote their cultivation. Among them, sunflower is one of the main ...
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Introduction: Using oilseeds in the human food stuffs, employing their meal for animal feed and also their usage in pharmaceuticals, soap making and fuel has prompted great interest for farmers to plant them and for the government to promote their cultivation. Among them, sunflower is one of the main oilseeds in the world which its cultivated area has expanded due to fair cultivation requirements, high yield of the oil, high nutritional value and also lack of anti nutritional factors. Sunflower (Helianthus annuus) is an annual plant belonging to Asteraceae family. This is a dicotyledonous, cross-pollinated monoecious plant that is fertilized by wind and insects. Sunflower seed oil has an excellent nutritional quality, as in recent years, cultivars with high oil (especially oleic acid) content have been substantially nurtured. The most different methods of extracting oil from oilseeds are the press and solvent methods. Similar to the other seeds with high oil content such as canola, the most effective way of extracting oil from sunflower is mechanical pressing followed by solvent extracting. In this method, the mechanical press extracts about 60 percent of the oil and the solvent method extracts the remaining oil. For the first time, the present study was aimed to improve temperature of cooker and moisture of output seeds for producing sunflower oil with lowest degree of insoluble fine partial in oil, moisture and acidity and meal with lowest levels of moisture and oil. Materials and Methods: Sunflower seeds used in this research were supplied from one of Iran's provinces and were transferred to the company of Khorasan cotton and oilseeds to produce oil and meal. After receiving the sunflower seeds in the factory, they were entered into silos in dark and ambient temperature; impurities such as dust, sands, stones, spoiled seeds, small weed seeds and other extraneous materials were separated by mechanical sieves. After cleaning, the seeds were entered into the cracker and they were broken into smaller particles and then were moved into the cooker; at this stage, the temperature of cooker and moisture content of the exiting seeds were set to 70, 80 and 900 C, and 7, 7.5 and 8%, respectively. Then, conditioned seeds were entered into the Buhler flicker device for flaking. Afterwards, the flakes were moved into the Desmet extractor (heating condition of 500C for 7 hours) to extract the oil from the seeds by hexane solvent. Then, the tests were performed on the oil and meal. Severalphysic-chemical properties of sunflower oil including insoluble fine partial, acidity values as well as moisture, protein and oil contents of the obtained meals were determined. Statistical analysis and process optimization were carried out using response surface methodology (RSM). Results and discussion: The achieved results expressed that with an increase in cooking temperature, insoluble fine partial and oil acidity values of the extracted oil were boosted while moisture content of oil and meal values alongside oil content of the obtained meal showed reduction. With increasing of the moisture content of cooker’s seeds, the insoluble fine partial value of the extracted oil was reduced while oil acidity value was increased. Increasing the moisture of cooker’sseeds led to the oil reduction in the meal. The highest oil content in the meal was achieved in the condition that the cooker temperature was 70oC and the moisture of output seeds from the cooker was 7%. The analysis of resulted data showed that two parameters of the cooker’s temperature and cooker’s seeds moisture content had significant effects on the moisture content of the meal. Increasing the cooker temperature from 70 to 90oC caused a decrease in the meal moisture. As result shown, increasing the moisture content of output seeds from the cooker increased the moisture content of the meal. Increasing the cooker temperature from 70 to 90oC reduced the protein amount of the meals. Results of different studies showed that increasing the temperature will decrease the protein amount of the meals. Increasing the moisture was also resulted in the decrease of residual protein in the meal. The obtained results of the optimization procedure revealed that the application of the cooking temperature of 70 °C and moisture content of the output seeds equal 7.73 and 7.65 % led to achieving products with the least values of acidity and insoluble fine partial in the obtained oil as well as meals with the minimum remaining oil.
Research Article
Masoud Taghizadeh; Behdad Shokrollahi; Fatemeh Hamedi
Abstract
Due to the need to find new protein sources with considering the fact that the bitter vetch seed has high levels of protein content, physicochemical and mechanical properties of bitter vetch seed and functional properties of its flour were evaluated in this study. The effects of altering the pH on protein ...
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Due to the need to find new protein sources with considering the fact that the bitter vetch seed has high levels of protein content, physicochemical and mechanical properties of bitter vetch seed and functional properties of its flour were evaluated in this study. The effects of altering the pH on protein solubility, foaming capacity, foaming stability, emulsion capacity and emulsion stability were studied. The average length, width and height of the grains were 3.5638 mm, 3.6197 mm and 3.8365 mm. the arithmetic and the geometric mean diameter, sphericity and the area were 3.6733mm, 3.6701mm, 1. 0318 and 42.405mm2 respectively. The average true density, bulk density and porosity were 1326.6 kg/m3, 0.7962 kg/m3 and 40.2753% respectively. also the average coefficients of static friction of the plywood, glass, rubber, fiberglass and galvanized iron surface layer were 0.4348, 0.1943, 0.4244, 0.3249 and 0.3739 respectively. Flour produced from this seed contains 24% protein and 9% fat. water and oil absorbing capacity were obtained 2.01 ±0.01 and 1.77±0.03 respectively (grams of water or oil per grams of sample). The results also showed that changes in pH, affected the solubility, foaming capacity, foaming stability, emulsion capacity and emulsion stability of bitter vetch flour.
Research Article
Saman Abdanan; Somaye Amraei
Abstract
Introduction:.Color is the first quality attribute of food evaluated by consumers, and is therefore an important quality component of food which influences consumer’s choice and preferences (Maguire, 1994). Color measurement of food products has been used as an indirect measure of other quality attributes ...
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Introduction:.Color is the first quality attribute of food evaluated by consumers, and is therefore an important quality component of food which influences consumer’s choice and preferences (Maguire, 1994). Color measurement of food products has been used as an indirect measure of other quality attributes such as flavor and contents of pigments because it is simpler, faster and correlates well with other physicochemical properties. Therefore, rapid and objective measurement of food color is required in quality control for the commercial grading of products (Trusell et al., 2005). Among different color spaces, L*a*b* color space is the most practical system used for measuring of color in food due to the uniform distribution of colors in this system as well its high similarity to human perception of color. All of the commercial L*a*b* colorimeters generally measure small, non- representative areas (Pathare et al., 2013) while the RGB digital cameras obtain information in pixels. Therefore, this research establishes a computational solution which allows acquiring of digital images in L*a*b* color units for each pixel from the digital RGB image (Fernandez-Vazquez et al., 2011). In recent years, computer vision has been used to objectively measure the color of different foods since they provide some obvious advantages over a conventional colorimeter, namely, the possibility of analyzing of each pixel of the entire surface of the food, and quantifying surface characteristics and defects (Mendoza & Aguilera, 2004). The color of many foods has been measured using computer vision techniques (Pedreschi et al., 2011; Lang et al., 2012). A computational technique with a combination of a digital camera, image processing software has been used to provide a less expensive and more versatile way to measure the color of many foods than traditional color-measuring instruments. This study used four models to carry out the RGB to L*a*b* transformation: linear, quadratic, support vector regression and neural network. This article presents the details of each model, their performance, and their advantages and disadvantages. The purpose of this work was to find a model (and estimate its parameters) for obtaining L*a*b* color measurements from RGB measurements. Materials and Methods: The images used in this work were taken with the following image acquisition system (Samsung, SM-N9005 color digital camera with 13 Mega pixels of resolution ,Fig.1). The camera was placed vertically at a distance of 60 cm from the samples and the angle between the axis of the lens and the sources of illumination was approximately °45. Illumination was achieved with 4 natural daylight 150 W lights. Fig. 1. Schematic diagram of image acquisition system. In order to calibrate the digital color system, the color values of 42 color charts were measured. Each color chart was divided into 24 regions. In each region, the L*a*b* color values were measured using a Minolta colorimeter. Additionally, a RGB digital image was taken of each chart, and the R, G and B color values of the corresponding regions were measured using a Matlab program which computes the mean values for each color value in each region according to the 24 masks. In this study four models for the RGB to L*a*b* transformation namely: linear, quadratic, artificial neural network (ANN), support vector regression (SVR) have been used. Results and discussion: In the evaluation of the performance of the models, the support vector regression and neural network model stands out with an error of only 0.88 and 2.37, respectively. Leon et al. (2004) investigated some models for the RGB to L*a*b* conversion. In the evaluation of the performance of the models, the neural network model showed an error of only 0.93%. In another research Yagzi et al. (2009) measured the L*a*b* values of atlantic salmon fillets subjected to different electron beam doses (0, 1, 1.5, 2 and 3 kGy) using a Minolta CR-200 Chroma Meter and a machine vision system. For both Minolta and machine vision the L* value increased and the a* and b* values decreased with increasing irradiation dose. However, the machine vision system showed significantly higher readings for L*, a*, b* values than the Minolta colorimeter. According to the construction of these models, the correlation between measured and predicted color is well established; therefore, based on the promising obtained results from Computer vision, it is possible to find a L*a*b* color measuring system that is appropriate for an accurate, exacting and detailed characterization of a food item based on a color digital camera. In order to show the capability of the proposed method, the color of an orange was measured using both a Minolta colorimeter and the studied approach. The colorimeter measurement was obtained by averaging 6 measurements in 6 different places of the surface of the orange, whereas the measurement using the digital color image was estimated by averaging all pixels of the surface image. The results are summarized in Fig. 2. b* a* L* Measurement Method 35.49 28.32 58.98 Minolta colorimeter 37.35 27.30 61.20 Machine Vision (SVR) 30.60 30.19 60.18 Machine Vision (ANN) Fig. 2. Estimate of L*a*b* values of an orange
Research Article
Sima Shamsaei; Seyed Mohammad Ali Razavi; Bahareh Emadzadeh; Esmaeil Atayesalehi
Abstract
Introduction: An emulsion is made of dispersed particles through the continuous phase, while not dissolving happens between two phases. Mayonnaise is oil-in- water emulsion (James and Dakin, 1962), as one of the most sauces used in the world. It has a mild odor and taste, creamy to pale yellow color ...
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Introduction: An emulsion is made of dispersed particles through the continuous phase, while not dissolving happens between two phases. Mayonnaise is oil-in- water emulsion (James and Dakin, 1962), as one of the most sauces used in the world. It has a mild odor and taste, creamy to pale yellow color and a pH in the range of 3.6- 4.0, which does not exceed 4.1 (Iranian National Standard, No 2454). Emulsion products are naturally instable. Different factors such as temperature, particles size, stirring, mechanical movements, constituents’ concentration, presence or absence of stabilizers and thickeners may affect the emulsion stability (David, 1999). Ocimum basilicum L., known as basil (or ‘‘Reyhan” in Iran), is a common herb plant grown in Iran. Soaking in water, basil seeds become gelatinous. The high mucilage content of basil seeds can make it a novel source of edible gum (Razavi et al., 2008). The objective of this paper was to investigate the effect of basil seed gum as well as xanthan as fat replacers on some physical and rheological properties of low fat mayonnaise. Materials and methods: Emulsion stability determination: Mayonnaise samples were centrifuged at 5000 rpm for 30 minutes. Emulsion stability (ES) was then determined using the following relation (Worrasinchai S et al., 2006): Stability index= (Total volume/ Volume of emulsion remaining)100. Particle size measurement: Particle size distribution of low-fat mayonnaise samples was determined using laser light diffraction technique (Fritsch Analysette 22, Germany). Rheological measurements: A rotational viscometer (Visco 88, Malvern, UK) equipped with a thermal circulator was used to measure the steady shear rheological properties of samples at the shear range of 14-300 s-1 and constant temperature of 25 oC. Power law, Bingham, Casson, and Herschel-Bulkley models were fitted on the experimental data and the rheological parameters of these models were determined using Slidewrite plus-bar Graph software (1983, Advanced Graphics Software, Inc, USA). Image processing: A scanner was used to capture the samples’ image and the scanner resolution was set to 300 dpi. 7g sample was placed onto a plate and then 152×210 Pixel parts was cut from the obtained image. All images were stored in JPEG format for further analysis. The Clemex image processing software (Clemex Vision Professional, PE4, Canada) was used to determine the color parameters (L*, a* and b*). Results and Discussion: Steady shear flow behavior: The results showed that all samples are classified rheologically as non-Newtonian shear thinning fluids. According to R2 values, Power law was considered as the best rheological model to describe the flow behavior of samples. The maximum and the minimum consistency coefficients of Power law model were observed for the formulation containing 0.75% xanthan gum and 0.45% basil seed gum, respectively. In this study, the apparent viscosity of mayonnaise (in shear rate 42 s-1) raised with increasing gum concentration that this increase in samples 4 and 5 were not significant (P>0.01). The highest apparent viscosity was observed in sample 3 that was prepared with a concentration 0.75% of xanthan gum, while the lowest viscosity was related to sample 4 that was contained of 0.45% basil seed gum. With increasing gum concentration, Bingham viscosity of the samples increased, but this increase in the samples (1, 7, 8) and (2, 6, 9) was not significant (P> 0.01). Yield stress values of Herschel-Bulkley (τH), Bingham (τB) and Casson (τC) models raised with the increasing of gum concentration. Highest yield stress value was related to mayonnaise containing 0.45% xanthan gum and the lowest yield stress value related to mayonnaise prepared with 0.45% basil seed gum. Particle size distribution: Particle size distribution of mayonnaise at concentration of 0.6 % xanthan gum, basil seed gum and mixture of xanthan- basil seed gum had mono-modal particle size distribution. Emulsion stability: Among samples, formulations of 1, 2, 3, 8, and 9 were quite stable and there was no instability (two-phase state). Higher stability in emulsions containing xanthan gum was probably due to higher viscosity of this gum compared to basil seed gum. Color: The best color was observed in sample 6. In this study, with increasing concentration of gum in three samples (1, 2, 3), the amount of L* decreased, it means that the brightness of the product was reduced while in samples containing a mixture of gums (xanthan- basil seed gum), increasing the gum concentration resulted in an increase in L* parameter.
Research Article
Fatemeh Rahmati; Arash Koocheki; Mehdi Varidi; Rassoul Kadkhodaee
Abstract
Introduction: Proteins are food ingredients with critical functional properties and participation in developing food products. So far, functional properties of several plant proteins such as pea, chickpea and lentil, groundnut, beach pea and bayberry have been investigated. Nowadays, there is an increasing ...
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Introduction: Proteins are food ingredients with critical functional properties and participation in developing food products. So far, functional properties of several plant proteins such as pea, chickpea and lentil, groundnut, beach pea and bayberry have been investigated. Nowadays, there is an increasing demand for plant proteins because they are available and inexpensive. Legume proteins are important plant protein sources. However, except for soy, due to the inadequate information about their structural and functional properties, they do not have appropriate application as functional ingredients in food products. Beans are a great source of nutrients such as protein, carbohydrate, dietary fiber, minerals and vitamins. Based on the several research reports, different dry beans have 15-25% protein and they are the second group of legume seeds, after soy, cultivated throughout the world. As mentioned earlier, insufficient information about structure of legume proteins is the main reason why they are unexploited in food industry. Therefore, the goal of this research was to evaluate the functional properties of proteins from three types of common bean (Speckled Sugar, Red Mexican and Great Northern bean). We also have attempted to evaluate the structure-function relation of these three sources of bean proteins because it is known that there is a direct relation between chemical conformation and the function of a protein which must be considered in food processing. Materials and methods: Protein of three types of common bean (Speckled Sugar, Red Mexican, and Great Northern) was extracted (pH 9, water flour 10:1). Afterwards, their physicochemical (including protein electrophoresis pattern, solubility, hydrophobicity), and functional properties (including emulsifying capacity, heat stability, gelation and foaming capacity) were evaluated to understand how bean protein structure influences its structure. Electrophoresis pattern was obtained based on 2 dimensions (pH and molecular weight). Protein solubility was evaluated by biuret method at pH range 3-9. ANS (8-anilino-1-naphthalenesulfonic acid) was used to measure surface hydrophobicity (pH 3-7).Emulsion samples (1% protein, 25% sunflower oil, pH 3-7) were produced, then emulsion capacity and emulsion heat stability (80°C for 30 min) were evaluated. Gelation of proteins was evaluated at protein concentration of 4-12% at different pH values (3-7). Foaming capacity (%) was measured as the difference between volume after and before whipping. Foam stability (%) was recorded during 90 minutes. Results and Discussion: Results showed that all proteins were rich in Phaseolin. In fact, this fraction was the major building fraction of all three bean proteins. Evaluation of solubility indicated that isoelectric point of three proteins was located at acidic pH range (pH 4.5). Results confirmed an indirect relation between protein solubility and hydrophobicity. All three protein isolates, similar to the other legumes protein, were more soluble at alkaline pH, while the highest surface hydrophobicity was observed at pH 3. Generally, Speckled Sugar bean protein had the most solubility, while Great Northern bean protein showed the highest surface hydrophobicity. Among three bean protein isolates, Speckled Sugar bean protein performed better as an emulsifier, whereas Great Northern bean protein formed gel at the lowest concentration (6% at pHs 3 and 7). In addition, foaming was higher at acidic pH (pH 3). Therefore, it was concluded that emulsifying capacity is mostly influenced by protein solubility, while gelation and foaming properties are affected by protein hydrophobicity. As the main consequence, the results achieved in this research confirmed that there is a direct relation between structure and the function of a protein. In fact, special structural properties are responsible for special functions.
Research Article
Hassan Sabbaghi; Aman Mohammad Ziaiifar; Mahdi Kashani-Nejad
Abstract
Introduction: Texture is one of the most important attribute in foods and is always issues for the manufacturing of fried products, because texture plays a crucial role in consumer acceptance and the perceived quality of foods. Prediction of changes in texture during frying can be helpful in process ...
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Introduction: Texture is one of the most important attribute in foods and is always issues for the manufacturing of fried products, because texture plays a crucial role in consumer acceptance and the perceived quality of foods. Prediction of changes in texture during frying can be helpful in process control. Structurally, this quality parameter in fried potato strip made from the formation of a composite structure with two layers as: dry and oily outer layer (crust), and a moist or soft interior layer (core). So, the explanation of texture development during frying is difficult because of the innate heterogeneity of the fried potato tissue. Moreover, both thermal degradation and texture development are functions of variables such as processing time, oil temperature and vaporized moisture of product. Textural changes during frying described as the result of various physical, chemical, and structural changes involved in the frying process. One solution to reduce the complexity of real bio systems in engineering is using various empirical correlations. Application of these relations for prediction of textural changes during frying can help us for understand the proper conditions to achieve desired texture. The purpose of the present investigation was to study the influence of the frying temperatures on texture of potato strips. In fact, textural changes during various stages of frying potatoes including initial heating, surface boiling and falling rate period were investigated. Texture evaluation is done by mechanical measurements, because the stimulus in texture perception is mainly mechanical. Also, textural studies are not clearly performed up to now with focus on cook value as a main factor in potato frying. According to the definition of cook value, this parameter indicates total time of baking in 100 °C. Fractional conversion applied as a technique for analyzing texture degradation kinetics and softening of vegetables upon prolonged heating. A few assumptions were made during study: i) Potato shrinkage is neglected ii) Product is not completely dried iii) The stages of frying were considered separable only based on surface and center temperature iv) Texture of potato strips affected by cook values of each frying stages. Materials and methods: The potato strips with specified size fried at a constant temperature of 145, 160 and 175 °C for 30, 60, 90, 120, 150, 180, 210 and 240 seconds. Then, various stages of the process were separated using surface and center temperature profiles of product that were recorded by data logger and T-type thermocouple in computer. Heating extremity of each stage was determined using cook value parameter. Mechanical properties such as apparent modulus of elasticity (Secant modulus) and toughness were used to show which occurred during frying. The secant modulus (S) variations described using fractional conversion model. The degree of cooking for each sample was expressed in term of cook value and its relationship with the overall acceptance of product was examined. Finally, the suitable temperature was determined by sensory evaluation to achieve the desired texture to determine the proper cook value and to prevent over cooking of product. Results and Discussion: The stages of frying by immersion for experimental conditions can be divided as: I. Initial heating (The first 30 seconds for all oil temperature) II. Surface boiling (30-60 s). III. Falling rate (up to end, longest period). IV. Bubble end point (not considered). Generally, higher oil temperature showed larger center and surface cook values because of the fast temperature increase inside product. During initial heating period (I) because of temperature increase without boiling, the changes in cook values versus time are negligible. Surface cook value increased slowly compared with core during surface boiling. Maximum cook value for core temperature was higher, because of the vapor pressure at the center of the product and thus water evaporation at temperatures above 100 °C (cook value above 1 second). During falling rate period due to gradual reduction of evaporation rates, and thus the vapor pressure drop within product, boiling temperature reduced to 100 ° C. The major part of texture destruction occurred during initial heating period and the changes of textural characteristic were going to be constant at the end of surface boiling. The slope of the regression line for fractional conversion model decreased as temperature increased and therefore product was harder, but equivalent value of secant modulus was independent of process temperature. The consumer texture desired was found for temperature of 160 °C with medium cook value. The kinetics of potato softening followed an exponential decay equation with good correlation on empirical data. The temperature dependence of the degradation rate was reliably modeled by the Arrhenius equation. Activation energy (Ea) for model parameters Se and Ks was 13047.12 and -24949.74 J/mol, respectively. Negative Ea for kinetic constant (Ks) indicated an inverse relationship with oil temperature. In addition, elevated oil temperatures caused less softening of French fries because of higher cook value and thus higher evaporation rate.
Research Article
Safieh Rajabzadeh; Masoumeh Bahreini; Mirza Mohammadreza Sharifmoghadam
Abstract
Introduction: Foodborne pathogens are a major public health problem. Despite the increase in management and consumer interest in food safety, the number of food poisoning cases has been continuously increased in recent years. For example in 2010, human salmonellosis cases were reported in Europe and ...
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Introduction: Foodborne pathogens are a major public health problem. Despite the increase in management and consumer interest in food safety, the number of food poisoning cases has been continuously increased in recent years. For example in 2010, human salmonellosis cases were reported in Europe and in 2011, a multistate foodborne E.coli O157:H7 outbreak affected 8 people and also a larger multistate Listeria monocytogenes outbreak caused 146 infections and 29 deaths. Traditional culture methods for detection of microorganisms in food are laborious and time consuming. Due to Economic impact of foodborne contamination and diseases, there are great efforts to develop more sensitive methods for rapid and accurate pathogen detection and identification in foodstuffs. Recently, molecular techniques such as PCR based DNA amplification have been employed that offer several advantages over the classical microbiological methods, such as shortening time of analysis, lowering detection limits, increasing specificity and having potential for automation. In this study we used multiplex PCR system, for the simultaneous detection of the three pathogens (salmonella spp., L. monocytogenes and E. coli O157:H7) in artificially inoculated lettuce. Materials and methods: Bacterial strains used in this study, Salmonella entrica serovar Typhimurium PTCC1709, Listeria monocytogenes PTCC1298 and E. coli O157:H7 NCTC12900, were grown in Trypticase Soy Broth at 37°C and then serial dilutions of strains from 100 to 106 cfu/ml (1 to 1000000 cfu/ml) were prepared using normal saline (0.85 g/l). Lettuce samples were cut into pieces of 5 ± 0.2 grams. To sterilize, the pieces overwhelm in 3% sodium hypochlorite solution for 15 min and in order to eliminate extra chlorine ions, the samples moved to sterile distilled water containing some drops of 1% sodium thiosulfate for 2 min. Bacterial strains were inoculated on lettuce as pure and mixed cultures separately. For the mixed cultures 100 µl of each bacterial strain inoculated on lettuce (in total 300 µl). The eluted bacteria were re-suspended in 100 µl of sterile normal saline and used for DNA extraction. DNA extraction was performed on each bacterial strain before and after inoculation to lettuce. The target genes were the rfb gene (antigen O157 producer) for E. coli O157:H7, the invA gene (invasion protein A) for salmonella spp., and the prfA gene (transcriptional activator of the virulence factor) for L. monocytogenes. The genes described here have been used as the most specific and reliable genetic targets for the above microorganisms. As an internal control gene, the 16S rRNA gene was targeted in the presence of bacterial DNA. Monoplex PCR reactions were performed in a final volume of 25 µl. Master mix composition was as follows: PCR buffer 10X, 2.5 µl; MgCl2 25mM, 2.5 µl; Taq DNA Polymerase 5 U/µl, 0.2 µl; dNTPs 10 mM, 0.4 µl; F/R primers 10 pmol, 1µl; extracted DNA as template, 2 µl and distilled water, 15.4 µl. Thermal cycler conditions were as follows: predenaturation at 94°C for 5min; 35 cycles consisting of denaturation at 94°C for 30s, annealing at 55°C for 30s and extension at 72°C for 60s; and final elongation at 72°C for 7 min. Multiplex PCR reactions were performed in a final volume of 25µl using 4 µl of total extracted DNA from three pathogens as template (mixture of three bacteria). Master mix composition was as follows: PCR buffer 10X, 2.5 µl; MgCl2 25 mM, 2.5 µl; Taq DNA Polymerase 5U/µl, 0.5 µl; dNTPs 10mM, 1 µl; EC-F/R, 1 µl; SAL-F/R, 0.8 µl and LIS-F/R, 1 µl (concentration of each primer was 10 pmol) and distilled water 8.9 µl. Thermal cycler conditions were as follows: pre-denaturation at 94°C for 3 min; 35 cycles consisting of denaturation at 94°C for 30s, annealing at 57°C for 30s and extension at 72°C for 90s; and final elongation at 72°C for 10 min. PCR products were visualized via gel electrophoresis, with 1% agarose gels. Results and Discussion: The main focus of this work was on the use of rapid method instead of culturing stages for detection of foodborne pathogens from ready-to-eat vegetables. Lettuce was used as a model for ready-to-eat vegetables and inoculated with E. coli O157:H7, salmonella spp. and L. monocytogenes. Multiplex PCR was performed after elution of bacteria from lettuce and the test provided a detection limit of 1 cfu/1g for three foodborne pathogenic bacteria The primer selection and multiplex PCR optimization allowed the setting of a robust method with performances comparable to a duplex PCR system, when tested on a complex food system. The sensitivity and robustness of the method proposed, together with its ability to perform well on a complex food matrix, make it a suitable method to be implemented in control laboratories for the detection of the target pathogens in food samples.
Research Article
Nazila Dardmeh; Asghar Khosrowshahi; Hadi Almasi; Mohsen Zandi
Abstract
Introduction: Nanocomposites are prepared by introduction of dispersed nanoscale particles into the polymer matrix based on four methods: template synthesis (sol-gel preparation); intercalation of polymer; and in situ intercalative polymerization and last one is melt blending, the most favorable and ...
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Introduction: Nanocomposites are prepared by introduction of dispersed nanoscale particles into the polymer matrix based on four methods: template synthesis (sol-gel preparation); intercalation of polymer; and in situ intercalative polymerization and last one is melt blending, the most favorable and practical method due to its simplest, economical and environmentally friendly technic. This method involves annealing, statically or under shear, a mixture of the polymer and organically modified clay at the softening point of the polymer based on usual compounding devices, such as, extruders or mixers (Papaspyridesb 2008). PET is a semicrystalline thermoplastic polyester which has been extensively used in all sizes as a packaging material in direct contact with food, beverages and as an alternative packaging to polyvinyl chloride for edible oils (Kirwan et al. 2011). As polymeric nanocomposites are mainly used as structural materials, the layered silicate clay are preferred. The crystal lattice of 2:1 layered silicates, consists of two-dimensional layers where a central octahedral sheet of alumina is fused to two external silica tetrahedral by the tip. Montmorillonite (MMT) belongs to type 2:1 layered smectite clay which in the basic structure, the trivalent Al-cation in the octahedral layer is partially substituted by the divalent Mg-cation (Pavlidoua and Papaspyridesb 2008). As evident, MMT is greatly hydrophilic in the interlayer and incompatible with organic polymer such as PET, thus to increase compatibility of clay with polymer, inorganic inter-layer cations (Na+, K+ or Ca2+) exchanged by the cationic surfactants (e.g., quaternary ammonium salt). Modified MMT or organoclay interacts better with polymer due to its increased gallery space (Utracki et al. 2007; Parvinzadeh et al.2010). Three different types polymer/clay nanocomposites can be obtained depending on the preparation method and the nature of the components used, including polymer matrix, layered silicate and organic cation. Tactoid nanocomposites formed when stacks of modified layered silicates are retained after introduction into the polymer. Subsequently, interaction between the nanolayers and polymer is not only unsuccessful but reduces mechanical properties of composite as well. Our main objective of this research was to study the effect of the nanoclay addition on mechanical, colorimetric and transparency properties of poly (ethylene terephthalate) (PET) nanocmposite films. Materials and methods: Bottle-grade poly (ethylene terephthalate) granules with intrinsic viscosity of (IV) = 0.82 dl g-1 were provided by the Iranian Tondgooyan Petrochemical company. The organically modified montmorillonite, Cloisite 15A, was supplied by Southern Clay Products Inc. Standard of TPA was supplied from Fluka Chemical, trademarked Sigma-Aldrich Corp., Switzerland. High-pressure liquid chromatography (HPLC) grade water, aceto-nitrile, acetic acid and methanol (HPLC grade) were purchased from Merck (Darmstadt, Germany). TPA was dissolved into methanol with a slight increase in temperature. Working standard solutions were prepared on the day of use at concentrations of 0.4, 40, 100 and 1,000 ppb and calibration graphs were plotted using these concentrations of standard solutions. The PET granules and nanoclay particles were dried in an oven for 24 h at 110 and 80C before extrusion, respectively. Melt blending technique was used for preparing nanocomposite films in a co-rotating twin screw extruder ZSK 25 .The temperature profile (throat to die) was as follows: 250, 270, 275, 270, 270 and 265C with a screw speed of 250 rpm. PET granules were dry mixed with 1, 3, and 5% wt of Cloisite 15A. The total weight of material per batch was 300 g. The resulting nano-composite strand was cooled in a water bath, granulated and dried overnight in oven at 110C. A laboratory press with a temperature plates of 280C under a pressure of 5 MPa for 10 min was applied to compress specimens. Then cooled them in water and ice bath to achieve transparent films. The influence of different amount of nanoclay addition on resultant nanocmposites was studied by Fourier transform infrared spectroscopy (FT-IR) and mechanical test. Also, influence of nanoclay presence on water vapor permeability (WVP), color and transparency of the nanocomposites were investigated. Results & Discussion: The results showed that nanoclay addition improved the mechanical properties (Young’s modulus, elongation at break and tensile strength) and WVP up to 3% (wt). However, nanoclay addition reduced the transparency of resultant nanocomposites films but it prevented wave transmission at three UV region which leads to better protective effect of film as a food packaging materials. It seems that introduction of Cloisite 15A into the PET matrix reinforced the mechanical properties of resultant nanocomposites. The Young’s modulus of the nanocompo-sites significantly increased compared with the neat PET, indicating that PET/Cloisite 15A nanocomposites were stiffer than PET. The maximum Young’s modulus was observed for PET/C15A containing 3% wt with an increment about 8 MPa. This increase in modulus may be attributed to uniform dispersion and alignment of nanoclay along with compatibil-ity with PET matrix as confirmed by XRD, DSC and SEM. The Young’s modulus enhancement is consistent with that of other research (KIMet al. 2007; Scaffaroet al. 2011; Ghanbari et al. 2013a,b]. Tensile strength like elongation at break shows same trend, increases on increasing nanoclay content except for nanocomposite containing 5% which indicates brittle behavior compared to PET. This can be explained consider-ing that higher aspect ratio of nanoclay tends to aggregate and forms tactoids (as shown in SEM and XRD) and conse-quently indicates poor mechanical properties.
Research Article
Azadeh Ranjbar Nedamani; Aman Mohammad Ziaiifar; Mahdi Parvini; Mahdi Kashani-Nejad; Yahya Maghsoudlou
Abstract
Introduction: Canning is the most effective way to food preservation. Starch- based foods include the major food materials such as porridges. These foods due to sensitivity to high shear rates used in rotary retorts and thus texture decomposition, usually sterilized in static retorts. Broken heating ...
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Introduction: Canning is the most effective way to food preservation. Starch- based foods include the major food materials such as porridges. These foods due to sensitivity to high shear rates used in rotary retorts and thus texture decomposition, usually sterilized in static retorts. Broken heating behavior, can headspace and initial temperature have important role on heat transfer rate and the position of cold area in these products. Heat breaking phenomena in the thermal curve, which can be seen in foods containing starch, is essentially related to gelatinization and destroying of starchgelstructure. Starchmaybe naturally exist in foods ormay be added to food formulations as an additive to create the consistency, filler, volumeproviders, emulsionstabilizer and etc. However, during thermal processing of foodscontaining high amounts of starch, complexstructural changes occur which leads to viscosity increases. These changes aredue to structural changes of starch during gelatinization; such as irreversible swelling of the starch granules, melting of starchcrystals, leaking of starch granule compound. Depending on thetype of starch and its concentration, the final product can bean aqueous solution or agel structure. Increasing in starch viscosity after gelatinization leads to decrease in heating rate, but with the advancement of heating time, when most granule swelling occurs, and the granules are being disrupted and the viscosity is reduced. This leads to increase the heating rate. This dual behavior of starch dispersion viscosity, leads to break in heating curve. Such solutions are named broken heating curve foods.The aim of this study was numerical simulation of the effect of starch concentration and initial temperature on heat transfer rate of starch dispersion during static sterilization with COMSOL software. Materials and methods:To prepare 100ml of 3.5 and 5% starch dispersion, 3.5 and 5 g starch was dissolved in 96.5 and 95 ml distilled water at 24.7C, respectively. The solution was then heated at 50C for 10 min to avoid sedimentation during the heat process. Samples were filled at 50 and 75C initial temperatures. In each can (9.9×10.1cm), T- type thermocouple was placedin one-third length from the bottom. All measurements were performed in triplicates. The 8-port data logger (Pico-TC08, England) and related software (PicoLog) were used to record the temperature data with 10s intervals.The full filled cans (without headspace) were statically heated in vertical position with no rotation. Numerical solutions of the governing equations were performed by COMSOL Multiphasics 4.2b software. A BDF method for time stepping and Backward Euler to time discretization were used. The system used to run the test and solve the equation was Intel VR CoreTM i5CPU M 460 @ 1.70 GHz and 6GB RAM. Numerical simulation of COMSOL software include spairing two physical phenomena: heat transfer and fluidflow. Since the system was cylindrical shaped can contain food with natural convection, non-isothermal laminar flow equationswere used. For this problem, one geometry and two domains were defined. The governing equations for non-isothermal laminar flow for domains were defined. Since in thermal diffusion analysis, the formula methods are more correct than empirical methods, formula methods were used in this study for calculating j and f. The accuracy of these calculations was evaluated using CFD. Parameter - f is the slope of heating curve. Jhindex, as a dimensionless correction factor. Results and discussion: The results showed that thecold area is near theone-tenth ofcans bottom. Inboth product initial temperatures, varying the concentration of the starch in product from 3.5 to 5% leads to longer heating time. The increase in the thermal process time at one-tenth of can bottom is more than one-third of can bottom. The time which the dispersion reaches to static temperature also changes with starch concentration in dispersion. The temperature difference in 5% starch dispersion at static temperature at the end of heating process is more considerable than 3.5% starch dispersion. Higher starch concentration induces a decrease in f (The fh coefficient represents thetime required to move heating process one cycle in heating curve and it can be calculated from the slope of the linear part of heat curve) at one-third of can bottom while an increase in f at one-tenth of can bottom. This behavior can be related to the fact that the starch gelatinization takes place earlier in one-third of can bottom than one- tenth due to the faster increase in temperature.
Research Article
Abbas Abedfar; Alireza Sadeghi; Mahdi Kashani-Nejad; Morteza Khomeiri; Mehran Alami
Abstract
Introduction: Sourdough is a very complex biological system and an important modern fermentation method of cereal flours and water. Sourdough fermentation is based on lactic acid and alcoholic fermentation depending on the composition of micro flora and fermentation conditions. Commercial sourdough processes ...
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Introduction: Sourdough is a very complex biological system and an important modern fermentation method of cereal flours and water. Sourdough fermentation is based on lactic acid and alcoholic fermentation depending on the composition of micro flora and fermentation conditions. Commercial sourdough processes do not rely on fortuitous flora but on the use of specific starter cultures. There has also been much progress in the development of tools that allow for the selection of key sourdough microorganisms for particular activities such as those concerned with enzymatic, antimicrobial, nutritional and additive replacement aspects. Most of the beneficial properties attributed to sourdough are determined by the acidification activity of dominant Lactobacillus starters. Sourdough fermentation can improve texture and palatability of whole grain fiber-rich, stabilize or increase levels of various bioactive compounds, retard starch retro-gradation and improve mineral bioavailability. The acidification of the sourdough and the partial acidification of the bread dough will impact on structure-forming components like gluten, starch and arabinoxylans. The swelling of gluten in acid is a well-known effect and mild acid hydrolysis of starch in sourdough systems has also been hypothesized for delay bread staling. The objectives of this research were to apply the dominant Lactobacillus starter isolated from traditional sourdough for cup bread production with whole wheat flour and delay it's staling. Materials and methods: In this study, following isolation of dominant Lactobacillus starter from traditional sourdough produced with whole wheat flour, the starter was identified by specific PCR. The single colonies obtained from streak plate of the sourdough culture, were subjected to species specific PCR. Afterwards, the mentioned starter was used for sourdough preparation. For this purpose, the effect of flour components (extraction rate, moisture, protein, ash and falling number), fermentation times (8, 16, 24 h) and sugar contents (0.5, 1, 1.5%) on starter activity were evaluated. pH and total titratable acidity (TTA) of sourdough treatments were measured. After processing of cup breads with sourdough treatments, the staling of these breads were also examined 2, 48 and 96 h after baking, based on crumb firmness (texture analysis) and amount of porosity (Image j method). Finally for statistical analysis a completely randomized design with factorial arrangement and 3 replications was used. To study the relationship between bread hardness and porosity with fermentation conditions, multiple linear regression was used and regression models were exhibited. Results and Discussion: By sequencing of the PCR products (obtained from sourdough culture), dominant Lactobacillus starter was identified as Lactobacillus plantarum. The TTA profile for the sourdoughs was also quite similar (starters interestingly continue to produce acid) and by increasing of TTA, the pH values were decreased. The acid production depends on factors such as fermentation temperature, time and dough yield. In general, a higher temperature, a higher water content of sourdough and the utilization of whole meal flour enhances the production of acids in wheat sourdoughs. The effect of sourdough on softness improvement was partly due to a higher porosity. Among the bread samples, 96 h after baking, lowest crumb firmness was observed in sample produced with sourdough with 24 h fermentation and 0.5%. sugar content. The maximum amount of crumb firmness was observed in sample produced with sourdough after 8 h fermentation and 1.5% sugar content. Furthermore, the maximum amount of porosity was obtained after 24 h sourdough fermentation and 1.5% sugar content, while the lowest amount was obtained after 8 h sourdough fermentation and 0.5% sugar content. After evaluation the results of texture analysis and porosity tests, significant correlation coefficients were established between porosity and softness, and it is reported that volume improvement is the main reason for a better shelf life in sourdough breads. The relationship between factors affecting on sourdough fermentation including fermentation time, sugar content and flour components, were also exhibited as regression models for examination texture characteristics of sourdough breads based on those viscoelastic behavior. By increasing the fermentation time in all of the sourdoughs, crumb hardness was decreased. Acids strongly influence the mixing behavior of doughs. Doughs with lower pH values require a slightly shorter mixing time and have less stability than normal doughs. Fundamental rheological evaluation of acid effect on gluten systems model indicated that both softness and elasticity of gluten were increased. Further to the direct impact of low pH on dough characteristics, secondary effects of acidification and fermentation time including changes in the activity of cereal or bacterial enzymes associated. Wheat flour proteases have optimal activity around pH=4. In addition, proteolytic enzymes with acidic pH optima in vital wheat gluten have been detected. Process requirements for optimum quality were strain-specific and different for textural improvement which should be taken in to account in designing future sourdough baking processes. According to results of this research, the influence of sourdough on bread softness during storage was depended on fermentation conditions and significant effect of sourdough process conditions on bread staling was clarified in comparison to control sample.
Research Article
Mohammad Reza Asghari; Raheleh Jami; Alireza Farokhzad
Abstract
Introduction: Nowadays, due to mechanization of life, consumers need of food which they spent little time for preparation, So Fresh cut industry is growing rapidly in the world. These products had strong growth since 1940, and in 2013, most sales of fresh cut fruit related to apples, against 21.8 percent. ...
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Introduction: Nowadays, due to mechanization of life, consumers need of food which they spent little time for preparation, So Fresh cut industry is growing rapidly in the world. These products had strong growth since 1940, and in 2013, most sales of fresh cut fruit related to apples, against 21.8 percent. Minimal processing operations include grading, washing, sorting, slicing, chopping and then packaging of fruit or vegetables. Since these operations result in quality loss, due to water loss, softening, microbial contamination, increased respiration, ethylene and tissue browning. To extend the shelf life of fresh cut fruit, some effective techniques including, low temperature, modified atmosphere packaging, nanotechnology and coating have been applied. Nowadays, edible coatings are used for fresh cut fruits to reduce respiration and control physiological changes. Nano-scale ingredients lead to increase surface to volume ratio so increases the activity of the particles and their impact, the other hand use of calcium compounds in the fruit can be caused strength of the cell wall and bridges between pectin polymers in cell wall and cell membrane so the activity of digestive enzymes decreases. Materials and methods: Golden delicious apples were selected for uniform size and appearance in a commercial orchard in Urmia. Fruit disinfected with disinfectant solutions for 10 min. half of the apples in the laboratory before cutting were immersed in nano calcium carbonate solution at concentrations of 0, 0.1, 0.2, and 0.4 % for 4 min and the other half of the fruit after cutting treated with the same concentrations of nano calcium carbonate for 2 minutes. Control fruit were treated with distilled water. Fresh cut were dried at 20 ᵒC for 15 minutes and placed in plastic containers (8 slices per a dish), In Refrigerator equipment at 1±0.5ᵒC and relative humidity 90-95% for 20 days. Results and discussion: Fresh cut apples coated with nano calcium carbonate reduced the enzyme activities. So that in treated samples compared to control samples polyphenol oxidase activity was reduced. Also, antioxidant activity and catalase levels were higher than the treated fruit during storage. As a result, fresh cut apples coated with nano calcium carbonate can be used as an easy way to increase the shelf life of apples in cold storage.
Research Article
Hossein Jooyandeh; Vahid Samavati
Abstract
Introduction: Accumulation of free radicals could lead to permanent oxidative destruction of organisms by attacking macromolecules and organelles of the body, thus causing organism aging, fatigue and degenerative diseases. Therefore, discovering and developing safe and non-toxic natural antioxidants ...
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Introduction: Accumulation of free radicals could lead to permanent oxidative destruction of organisms by attacking macromolecules and organelles of the body, thus causing organism aging, fatigue and degenerative diseases. Therefore, discovering and developing safe and non-toxic natural antioxidants has been an interesting topic in recent decades. Compared to synthetic antioxidants, extracts from plant resources usually have quite stable constructions and great antioxidant activities, and can easily be absorbed without dangerous immunoreactions. Many antioxidant compounds, naturally occurring from plant sources, have been identified as free radicals or active oxygen scavengers. Malva neglecta (MN), which is known as Panirak/Tooleh in Iran is an annual and herbaceous plant. The leaves and flowers of MN are used in traditional phytotheraphy and in treatment of cough, respiratory system and digestive system problems. The objective of this study was to optimize process conditions of extraction in order to obtain the highest yield from crude extract of MN leaves and identify its antioxidant properties. Materials and methods: Three-variable-three-level Box-Behnken design-response surface methodology (BBD-RSM) with five replications at central point was used to optimize the extracting parameters of crude extract from the MN leaves including extraction time (1-8 h), extraction temperature (50-100°C), and the water/solid ratio (3-30). The ability of extracted materials to scavenge the free radicals of DPPH, OH and super oxide was also evaluated by chemical analysis. Results and Discussion: All three independent variables effected the yield of crude extract of MN leaves. The extraction yield of MN crude extract significantly increased from 5.90% to 8.01% with extraction time varying from 1 h to 6 h. However, the yield was not altered meaningfully, as the extraction time was increased from 6 h up to 8 h. This may be due to degradation of the polysaccharides because of the extended extraction time. The extraction process was performed with temperatures from 50 °C to 100 °C, with the other extraction variables such as ratio of water to raw material and extraction time fixed at 13 ml/g and 3.5 h, respectively. The extraction yield of crude extract increased with increasing extraction temperature and peaked at 7.89 at 100 °C. Different ratios of water to raw material have considerable effect on extraction yield. In this study, we used ratios of water to raw material from 3 to 30 ml/g, with fixed parameters (extraction time and extraction temperature at 3.5 h and 75 °C, respectively). Extraction yield increased noticeably from 6.10 to 8.10 with ratio of water to material varying from 3 ml/g to 24 ml/g. As extraction time, at the higher experimental levels, as the ratio of water to raw material was increased (from 24 up to 30 ml/g) the yield of crude extract was not changed considerably. Under the appropriate condition of ratio of water to raw material, the crude extract molecules can swell thoroughly, and more compounds could dissolve in water to improve extraction yield. The determination coefficient (R2 = 0.9897) suggested that the model was valid, implying that 98.97% of the variation could be explained by the fitted model. The adjusted determination coefficient was used to evaluate the correlation between the experimental values and predicted values, and the outcome (R2Adj= 0.9794) suggested that the correlation was significant. The f-value (1.49) for “the lack of fit” indicated that the “lack of fit” was not significant relative to the pure error (p > 0.05). The CV for yield of MN leaves was 0.64%, which defined a good reliability of the experimental values. The adequate precision value 21.61 and PRESS 0.42 for our model indicated an appropriate model could be designed. On multiple regression analysis, the quadratic polynomial equation for the independent variables and response variable expressed as follows: Y =7.82 + 1.025X1 + 3.241667X2 + 2.031X3 + 0.525X1X2 - 0.7X1X3 + 0.675X2X3 – 0.206X12 – 0.21833X22 Where, Y is extraction yield (%); X1, extraction time (h); X2, extraction temperature; and X3, ratio of water to raw material (ml/g) Statistical analysis of the results showed that the optimal conditions for higher extraction yield were extraction time: 6 h, extraction temperature: 90oC, and the ratio of water to raw material: 19. Under these conditions, the experimental yield was 9.22% ± 0.47%, which well matched the predicted value (9.18%), under these conditions; the experimental yield was 9.18%. Furthermore, results obtained from chemical analysis showed that DPPH, OH and super oxide scavenging of MN crude extract increased rapidly with increasing of its concentration. DPPH scavenging rate of the crude extract was more than BHT standard (89% vs. 78%) at their maximum equivalent concentration (300 ppm). Furthermore, OH and super oxide scavenging ability of MN crude extract (87% and 91%, respectively) were significantly more than ascorbic acid standard solutions (74% and 81%, respectively) at their highest experimental concentrations (150 ppm). Based on our results, components extracted from Malva neglecta leaves may introduce as an antioxidant and free radical scavenger. This study could help food industries to add a new source of hydrocolloid with certain functionality as an alternative additive in different foods, cosmetic and pharmaceutical products.
Research Article
Sareh Boostani; Marzieh Moosavi-Nasab; Mahmoud Aminlari; Mehrdad Niakosari; Gholam Reza Mesbahi
Abstract
Introduction: Proteins play a fundamental role in biological systems and are often sensitive against organic solvents, heat and other damaging factors. Proteins are the basic component of food formulations and enhancement the functional characteristics and stability of the proteins has always been the ...
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Introduction: Proteins play a fundamental role in biological systems and are often sensitive against organic solvents, heat and other damaging factors. Proteins are the basic component of food formulations and enhancement the functional characteristics and stability of the proteins has always been the main goal of food industry engineers. One of the natural ways used for protein modifications is Maillard reaction. Maillard reaction as a result of covalent binding between 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. 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. Much research has shown that conjugation can increase thermal stability and functional characteristics of food proteins and also reduce the allergenicity of suspected proteins. Although many studies have been conducted on the effects of conjugation on functional properties of proteins, the impacts of conjugation on proteins behavior after food processing have been less investigated. So, in this paper the influences of Maillard reaction on functional properties of soy proteins have been investigated. In addition, characteristics of conjugated proteins after pasteurization treatment was also studied. Materials and methods: Construction of protein- polysaccharide conjugates was done in several steps. First, soy proteins and dextran were mixed with phosphate buffer (0.1 M, pH: 8.5) 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 different times, at 60℃, 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 SDS-PAGE electrophoresis, browning intensity measurement and UV absorbance analysis. SDS-PAGE was conducted according to Laemmli procedure using a discontinuous buffer system. A vertical gel electrophoresis unit was used with 3% acrylamide stacking gel and 10% acrylamide running gel. Evaluation of the color changes as an indicator of grafting intensity was investigated by monitoring absorption at a wavelength of 420 nm. To investigate the UV absorption of conjugated proteins, the samples were diluted with SDS (Sodium dodecyl sulfate) solution and the absorption was read by a UV-visible spectrophotometer at 294 nm. The impact of modification on characteristics of soy proteins was monitored by examining the functional properties changes of protein samples. In the last stage soy drinks were prepared from conjugated and non conjugated proteins then the prepared beverages were subjected to thermal processing conditions and the influences of Maillard conjugation on the stability of soy drinks was monitored over time. Results and Discussion: SDS-PAGE electrophoresis profile showed that proteins-polysaccharide conjugates were formed. As a result of conjugation, the protein-dextran covalent binding occurs, leads to the formation of higher molecular weight components, resulting in its accumulation on the top of the separating gel. When heating time increased a wider and higher molecular weight bands appeared near the top of the running gel however they were not observed in the native soy pattern. Covalent linkage between amino group of proteins and carbonyl group of polysaccharides causes a color changes from light yellow to brown, browning intensity results showed that the even during early incubation time, a significant absorption was observed at 420 nm compared to the control samples. UV absorption results showed similar trend of changes in browning intensity measurement. Increasing UV absorption is due to the intermediate Maillard reaction products (MRP). Increasing UV absorption with increasing heating time indicates the fact that Maillard reaction products (MRP) formation are more favorable in the long incubation time. Data of UV absorption are a good evidence for SDS-PAGE and browning intensity results. Functional properties results indicated that grafted proteins had better functional properties. The storage stability of soy drinks prepared from conjugated proteins was significantly higher than the samples prepared from non conjugated proteins. Stability of beverages after thermal processing and during storage is one of the most important features of protein drinks and many efforts have been made to develop mentioned characteristics. Stability of soy drinks produced from the conjugated proteins was significantly higher than those prepared from non conjugated soy proteins. Functional characterization of proteins is dependent on several factors, the majority of soy drink composed of proteins that could be denaturated by heating applied during thermal processing, as the results showed conjugation with dextran caused an increase in denaturation temperature of soy proteins which enhance the resistance of proteins during thermal processing treatment. In addition, the solubility and emulsifying properties of soy proteins increased with conjugation which can be a good reason for improvement the relation between protein and surrounding water molecules and therefore increases the protein storage stability. It can be concluded that Maillard reaction could be applied as a means to prepare soy proteins–dextran conjugates with better functional properties and more stable during processing and storage.
Research Article
Maryam Naghipouzade Mahani; Mohammad Hosein Aghkhani; Khalil Behzad; Abbas Rohani
Abstract
Introduction: Conventional technology of sugar production from sugar beet roots consists of the next subsequent steps: sugar beet slicing, thermal denaturation of the sliced beet roots followed by diffusion in hot water at 70–75 _C, purification of extracted juice by lime, concentration of purified ...
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Introduction: Conventional technology of sugar production from sugar beet roots consists of the next subsequent steps: sugar beet slicing, thermal denaturation of the sliced beet roots followed by diffusion in hot water at 70–75 _C, purification of extracted juice by lime, concentration of purified juice and crystallization. The diffusion process is one of the most important steps that effect on product yield. The quality of cossettes is too important that increase extraction yield. Therefore the main function of the beet-slicing operation is to improve the diffusion operation. The most important factors in producing quality cossettes are the type of knives. Most knives have a V shape that cause increase of the surface area of the beets. At slicing operation, Amount of the sucrose of beet extract directly. Considering the blade edge causes the rupture of beet cell so it effects on quality of juice and yield of extraction. Also the different blades edge causes different surface areas that effect on osmotic operation. In this work, the effect of two kinds of blades (serrate and flat edge) is studied on extraction process and the juice quality. Material and method: Fresh sugar beets (Beta vulgaris) were obtained from Ferdowsi university farm and storage at 5C°. For each test run, 300gr of cossette 4mm thickness and 8cm in length were cut by cutting device with ability of blade change. The sucrose content of cossetttes was measured in ICUMSA method. These tests were organized as follows 4 steps. The first step was washing. Considering amount of sucrose of sugar beet extract directly at slicing operation, the decrease of sucrose content of cossettes and the sucrose of washing juice should be measured. For this stage, 120gr of cossettes were washed with 320gr of distilled water. After washing the cossettes, the sucrose content of cossettes was measured again and the decrease of suocrose content of cossettes was calculated and sucrose of washing juice was measured. For the thermal-pretreatment step, 130gr of sugar beet cossettes were treated with 260gr of distilled water 70C° at 7min and the sucrose of thermal-pretreatment juice was measured. In the diffusion step, 130gr of these cossettes were immersed in 260gr of distilled water 73C°. The solute concentration (Brix, g solubles 100 g_1 juice) was measured by digital refractometre (PR-101, Atago, 50 Kyo, Japan) every 5 to 10 min up to equilibrium conditions. The final step was pulp pressing. The pulps were compressed by laboratory press (2 bar) at 15min. following by the pressed pulp was weight then the sucrose content of them was measured. In the following, purity and nonsucrose of juice were determined for washing, thermal-pretreatment and diffusion steps. These parameters were measure in ICUMSA unit which is based on polarimeter method. Also extraction yield of diffusion, mass of extraction sucrose and extraction sucrose at diffusion, pressed pulp yield, extraction degree and energy were calculated. The data were analyzed in 2-sample t-test at minitab17 and the graphs were drew in excel. Results and discussion The results showed that the edge of the baled had significant effect on the juice purity (washing and thermal-pretreatment steps), non-sucrose content and sucrose of juice, extracted sucrose at cutting operation, extracted sucrose at diffusion, degree of extraction, yield of pulp, time and energy (P<0.05). The most juice purity was obtained from flat blade with 78.33%, 84.86% and 85.52% at washing, pretreatment and diffusion steps respectively. Also the least of non-sucrose content was obtained from this blade with 0.1%, 0.55% and 0.51% at washing, pretreatment and diffusion steps respectively. The serrate blade increase the tearing (rupturing) of the beet cells at slicing operation. Torn cells allow more impurities (nonsugars) to be diffused into the surrounding juice, causing an increase in nonsugars and, consequently, a reduction in juice purity. For the serrated blade, The most extracted sucrose at cutting operation and diffusion step, mass of sucrose of diffusion juice and degree of extraction were obtained 14.5%, 94.4%, 7.22 gr and 0.19 respectively that compare to another blade is more. The edge of serrate blade increases the surface aria of cossettes compare to use of flat blade. The surface area is one of the most important parameter to improve osmotic operation. The more contact area between the beet cells and the water in the diffuser cause the more movement of sugar from the cells to the diffusion juice. Therefore the use of the serrate blade improves the osmotic operation and enhances the extracted sucrose. The least of pulp yield, extraction time and energy were obtained 27.97%, 40 min and 1.7 Kw/h respectively for this blade. The increase of sucrose extraction reduces the pulp yield. As regards osmotic operation improve whit the increase of surface area cossettes, therefor the sucrose extract at lees time and the total energy decrease. Regarding to the results, both of blades improve some of the extraction parameters.
Short Article
Bahareh Shabanpour; Mansoureh Neirizi; Zeinab Noori Hashemabad
Abstract
Introduction: Surimi is one of the procedures that nowadays it is suggested to increase the consumption of fish such as silver carp (Shabanpour et al., 2008). Surimi is washed and minced fish meat myofibrillar concentration of proteins, this would wash out most of the soluble material in surimi (Sultanbawa ...
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Introduction: Surimi is one of the procedures that nowadays it is suggested to increase the consumption of fish such as silver carp (Shabanpour et al., 2008). Surimi is washed and minced fish meat myofibrillar concentration of proteins, this would wash out most of the soluble material in surimi (Sultanbawa & Li- chan, 1998). Raw fish freshness and quality of the most important factors affecting the quality surimi (Phatcharat et al., 2006). Low-temperature storage, especially storage in ice, one of the most suitable criteria for refrigeration methods and maintain the quality of fish (Benjakul et al., 2002), although changes in chemical, biological and physical on the ice completely stopped when maintenance is not are (Benjakul et al., 2003; Riebroy et al., 2007). The aim of this study was to evaluate the maximum duration of storage of silver carp in ice for surimi production with high quality and efficacy during storage on the quality of surimi made from these fish when kept in ice. Materials and methods: Silver carp ((Hypophthalmichthys molitrix fish at intervals of 0, 4, 8, 12 and 16 days after initial preparations into surimi process and the assessments of microbial (bacterial load and total bacterial load of cool), chemical and sensory respectively. Chemical experiments: Thiobarbituric acid method Siripatrawa and Noipha (2012), volatile nitrogen bases by Goulas and Kontominas (2005), protein solubility and humidity values of pressure Rawdkuen et al (2009), pH Suvanich method and colleagues (2000). White index by Kristinsson et al (2005) using a colorimeter Lovibond CAMsystem500 model model was calculated and determined. Measuring the properties of gel production: Preparation Gel by (Jafarpour & Gorczyca, 2008) and evaluation gel by (Lanier, 1992) were done. Microbial testing of samples was done according to (Sallam, 2007) Sensory analysis of samples: To assess quality parameters include color, odor, taste and overall acceptance of samples of hedonic scale (slightly modified) was used. In order to test a panel group consisted of 10 people consisted of very good quality Grdydstvh use with a score of 7, well with a score of 5, acceptable with a score of 3, bad and very bad rating with a score of 0 is 1 (Shabanpour and et al., 1386). Data analysis: The results of ANOVA using SPSS 16 software analysis and comparison of data using Duncan's multiple range test was 0/05 Sensory evaluation and analysis of non-parametric Mann-Whitney U test was used to test. Results and Discussion: The research results showed that the solubility of proteins soluble salt (because ice crystals formed during cold storage the concentration of mineral salts in muscle cells increases), protein solubility, chemical indicators, microbial and sensory surimi (Due to raw materials oxidation (hydroperoxides) secondary unstable and prone to decomposition products such as aldehydes), White indicator, the ability to get qualitative rating factors evaluated (taste, odor, color and overall acceptability) negative trend and Percent moisture (Because denaturation of proteins myofibrils), microbial changes, changes in pH (Due to volatile nitrogen bases), changes in the volatile nitrogen bases ( Due to microbial growth) and TBA (Because tissue damages) has increased. Sensory and microbiological analysis results showed that the shelf life of silver carp in ice for surimi production is suitable for 8 days.
