Research Article
Mina Kargozari; Leila Bagheri; Alireza Mohammadi
Abstract
Introduction: In recent years, sugar-free or reduced-sugar foods and beverages are becoming very popular among the consumers. At the same time, consumers are increasingly concerned about the quality and safety of many products present in the diet, in particular, low-calorie synthetic or natural sweeteners. ...
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Introduction: In recent years, sugar-free or reduced-sugar foods and beverages are becoming very popular among the consumers. At the same time, consumers are increasingly concerned about the quality and safety of many products present in the diet, in particular, low-calorie synthetic or natural sweeteners. Sugar adds viscosity and provides body in drinks and semi-liquid foods like syrups and fruit juices. In order to achieve the same quality, taste and texture profile, reducing or removing sugar from a product often requires replacement with a number of alternative ingredients such as hydrocolloids. Hydrocolloids are widely used in many food formulations to improve quality attributes as thickening and gelling agents. Xanthan gum is a polysaccharide used as a food additive and rheology modifier, commonly used as a food thickening agent and a stabilizer, to prevent ingredients from separating. Stevia is an attractive natural sweetener and sugar substitute extracted from the leaves of the plant species Stevia rebaudiana. Inulin is a starchy substance found in a wide variety of fruits, vegetables, and herbs, which improves the technological properties and enhance the nutritional value of food and also has synergistic sweetening effect with sweeteners including stevia. Dietitians suggest that inulin belong to a class of water-soluble dietary fibers known as fructans, but research suggests prebiotic and bifidogenic properties of this compound that has caused it to be also regarded as a functional compound.
Materials and methods: Lemon drink with different formulations containing sugar (0, 6, 12 %), stevia (0, 0.02, 0.04 %) and xanthan (0, 0.18. 0.26 %) were prepared. To mask the bitter taste of stevia, inulin which has functional properties, was added to the formulation at the level of 0.5 %. In this study, liquid-gel method was used to suspend the solid particles of pulp and reach the desired consistency. Liquid gel structure was built by adding hot xanthan solution to the half diluted lemon drink while being stirred. Flow behavior and particle size distribution were examined. The dynamic yield stress of the samples was calculated and the stability of pulp particles in lemon drink was predicted by determination of the forces acting on the particle. Specific gravity measurement of lemon beverage was performed after removing the pulp using 50 ml pycnometer at 20°C according to the Iranian National Standard No. 2685. Mean diameter and size distribution of cloud-forming substances in pulp-free beverages were measured with a static light scattering laser diffraction-based particle size analyzer Malvern Master Sizer. Physicochemical (pH, acidity, ash, brix and density), sensory (taste and appearance) and microbial properties of lemon diet drinks were also examined.
Results and discussion: Xanthan, having considerable effect on flow behavior of lemon drink samples, created high amounts of apparent viscosity at low shear rates. In samples containing xanthan, yield stress was observed and its value was measured by extrapolation based on the Herschel-Bulkley model. The calculations of pulp suspension were conducted based on the yield stress, which were consistent with the results of stability observed. The results of the particle size distribution test showed that xanthan significantly increases the particle size of the lemon beverage. This means that the anionic hydrocolloid xanthan also react with lemon drink colloids and broader range of particle size was created. Higher xanthan concentration had led to increased particle size range. Lower sugar and stevia concentration in combination with xanthan reduced the particle size. Based on the results obtained, pH of samples ranged from 2.85 – 2.90 and acidity expressed as citric acid ranged from 0.47 – 0.52 that was in accordance with the standard related to the physicochemical properties of non-carbonated drinks and beverages (Iranian National Standard No. 2837). Other properties such as water-soluble solids value and density were not discussed due to the lack of standards for low-sugar beverages and the need for a national standard in this field was felt. The results concerned to the physical and chemical characteristics of different treatments indicated that lemon beverage acidity and pH values did not show significant differences among the samples and the samples containing higher amounts of sugar, xanthan and stevia had higher brix, ash and density values (P
Research Article
Mehran Nouri; Behzad Nasehi; Vahid Samavati; Saman Abdanan
Abstract
Introduction: Increased awareness of diet-health association has led to the growth of health food industry. Deep-fat fried foods such as donuts enjoy wide popularity owing to their taste, distinctive flavor, aroma and crunchy texture. There is, however, a great health concern over large fat content of ...
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Introduction: Increased awareness of diet-health association has led to the growth of health food industry. Deep-fat fried foods such as donuts enjoy wide popularity owing to their taste, distinctive flavor, aroma and crunchy texture. There is, however, a great health concern over large fat content of fried foods. Incorporating the dietary fiber such as hydrocolloids into the food substrate in the batter formulation is one of the most effective strategies to decrease fat uptake in fried foods. Dietary fibers act as water binders in a coating or batter formulation through which reduce fat uptake of fried foods. That is, an increase of water content of food could lead to a decrease of oil penetration during the frying process. Persian gum (PG), as a novel gum, is exudates of the wild or mountain almond trees (the main source is Amygdalus scoparia Spach). Carrot pomace is a fibre-rich by-product of carrot juice industries which contains approximately 80% of carrot carotenes. Carrot juice yield is reported to be only 60-70% and the remaining pomace is usually disposed of as feed or fertilizer. There is an increasing interest in microwaving foods for several reasons: it is faster than conventional methods, the energy consumption is often lower and foods cooked by microwaving maintain nutritional integrity. Therefore, the aim of this study was to examine the effect of microwave pre-treatment on physico-chemical properties of donut containing Persian gum and carrot pomace powder sources of dietary fiber.
Materials and methods: Donuts were prepared according to the formulation reported by Melito and Farkas (2012). Ingredients used in control donut formulation were consisted of 100 g of wheat flour (9 g/100g), 38 g of water, 9g of Shortening, 13g of Egg, 13g of water for yeast, 6.3g of sugar, 6.3g of nonfat dried milk powder, 3g of active dried yeast, 1.6g of Vanilla extract, 1.6g of baking powder, and 1.6g of Salt. For the making of donuts, the flour blends were prepared by replacing wheat flour with 1.2 g/100g PG and 645 g/100g CPP. As well, water was added at 48.16 g/100g based on flour weight. The exudate gums of mountain almond trees were collected in Lorestan province. In order to eliminate foreign matters such as dust and dirt, the PG was washed three times with its threefold weight of ethanol (96% w/v) for 15 min under constant stirring. After removing ethanol by drying in an oven (at 60º C for 6 h) the PG was ground using a coffee grinder (model 320, Spain), sieved (180 µm) and packaged in polyethylene packs and then stored in 4ºC. Fresh carrots were purchased from a local market. Carrots were washed and then pressed with a juice extractor and the resultant pomace was collected. The carrot pomace was blanched in water (80 ± 2°C for 3 min) and then cooled in cold water (4º C). The pomace water was drained with cheese-cloth prior to drying. Finally, the carrot pomace was dried in an oven (60º C for 12 h). The dried pomace was ground using a coffee grinder to fine powder. The carrot pomace powder was sieved (180 µm) and packed in polyethylene packs and then stored in 4ºC. Specific volume of donuts was determined using the rapeseed displacement AACC method. Moisture content of donuts crumb was measured using a oven at 105 ºC for 3. The fat content of dried donuts was determined by Soxhlet extraction with petroleum ether for 5 h. Firmness and springiness were measured in triplicate using a TA.XT2i Texture Analyzer equipped with a 5 kg load cell and a P/35 mm aluminum cylindrical probe. Crumb grain (total number of cells and porosity) and crumb color of donuts were evaluated using an image analysis system consisted of a digital camera, a personal computer and MATLAB R2014a software. The control and optimized donuts were evaluated for acceptance of their appearance, crust color, crumb color, aroma, texture, taste and overall acceptance based on a nine-point hedonic scale. Response Surface Methodology (RSM) and Box-Behnken design with 3 factors were applied to obtain optimal levels of independent variables including microwave power (300-900 W), microwave time (30-90 s) and frying time (70-130 s).
Results and discussion: The results indicatedthat moisture content significantly (p
Research Article
Maryam Mahfoozy; Arash Koocheki; Seyed Mohammad Ali Razavi
Abstract
Introduction: Freezing is one of the ways to extend the shelf life and improve the chemical and microbiological stability of food products. Food products are exposed to different processes and the functional properties of the products change during these processing. Hydrocolloids are used to stabilize ...
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Introduction: Freezing is one of the ways to extend the shelf life and improve the chemical and microbiological stability of food products. Food products are exposed to different processes and the functional properties of the products change during these processing. Hydrocolloids are used to stabilize the products undergoing different food processing. However the addition of hydrocolloids to food products shifts the foods characters. On the other hand, hydrocolloids decrease the growing rate of ice crystals in dispersions. Lipidium perfoliatum locally called Qodume shahri. The study on the functional properties of Lipidium perfoliatum seed gum (LPSG) proved that this gum was able to bind with a large amount of water and increase the product consistency. The main purpose of this study was to understand the effect of freezing condition on functional properties including the rheological properties (steady shear rate), emulsion particle size distribution and foaming stability at different gum concentration of LPSG.
Materials and methods: The materials were purchased from a local detailer. LPSG was extracted in optimum condition (T: 48±1 ºC, pH=8, proportion water to seed 30 to 1, t: 1.5 h) according to method previously described by koocheki et al. (2009). After the preparation of the freeze-dried gum powder, dispersions of LPSG were prepared in distilled water at different concentrations (0.5, 0.75 and 1% w/v). In order to study the effects of freezing condition on the functional properties of LPSG, the samples were freezed at slow and fast conditions. The flow behavior was described by fitting the shear stress (τ) to shear rate (γ) data with the models to determine the best model to describe the flow behavior of LPSG. For the Emulsion preparation, the aqueous phase was prepared by mixing 2 g WPC into 30 g distilled water and an appropriate amount of LPSG (0.1 and 0.2 g) into 50 g distilled water on a magnetic stirrer for 10 min at room temperature. The dispersions were then left overnight at 4 ºC prior to emulsion preparation. The emulsion was prepared by mixing 20 g sunflower oil with WPC using a magnetic stirrer for 10 min. The mixture was subsequently pre-homogenized with a laboratory homogenizer at a rate of 20,000 rpm for 2 min at room temperature. After that, the gum solution was added to the emulsion and homogenized for 4 min at the same rate. The particle size analyzer was used to measure the mean diameter. For the foaming stability, the gum dispersions were prepared at 0.5% gum concentration and left overnight in a refrigerator to ensure a complete hydration. Afterwards, they were treated with different temperatures. 2% of egg white powder was added to the solutions and mixed by a homogenizer for 2 min at 20000 rpm. The foam stability was calculated as the foam volume after 30 minutes. A completely randomized design with the factorial arrangement was used for statistical analysis. All experiments were statistically analysed by Analysis of Variance (ANOVA) in Minitab R14. The p-values of < 0.05 were considered significant. All measurements were triplicated and the average values were reported.
Results and discussion: Results showed that the LPSG apparent viscosity increased insignificantly after the fast freezing condition. All samples illustrated non-Newtonian shear thinning behavior. Herschel- bulkley model was the best model to describe the flow behavior of the LPSG solution with the high determination coefficients. Among the selected rheological models, the flow behavior indices and consistency coefficients were unchanged. However freezing condition had no significant effect on the emulsion particle size. After 30 min foam stabilized by LPSG was constant. Therefore, LPSG can be considered as an appropriate stabilizer and thickening agent during freezing condition.
Research Article
Hossein Javadi kia; Mahdi Ghasemi-Varnamkhasti; Sajad Sabzi
Abstract
Introduction: Nowadays, with the development of imaging systems and image processing algorithms, a new branch of agriculture and food industry quality control has emerged. Meat and related products have high commercial value and they are one of the most important items of household food basket (Jackman ...
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Introduction: Nowadays, with the development of imaging systems and image processing algorithms, a new branch of agriculture and food industry quality control has emerged. Meat and related products have high commercial value and they are one of the most important items of household food basket (Jackman et al., 2011). The apparent color of the meat is one of the most important ranking factors which determines the quality and marketing value (Ramirez and Cava, 2007; Shiranita et al., 2000). There is a relationship between color, appearance etc. and the shelf-life of meat, since the passing time causes the color to be darkened in meat due to chemical reactions and shrinkage occures Therefore, determining the storage time is important in terms of quality and marketing value (Jackman et al., 2011; Tan, 2004). In recent years, virtual image on a computer as a helpful suggestion for meat grading has been emerged. Various studies have been conducted in the field and results in a number of applications suggests that the color image processing method for assessing the quality of meat is important (Girolami et al., 2013; Mancini and Hunt, 2005; Lu et al., 2000). Due to the importance of detection of freshness veal in order to preserving the quality and post ponding the meat spoilage and disease accordingly, designing a device to detect the storage time of slaughter and in other words the freshness of veal using image processing and response surface method was studied. For this purpose, two common environment and standard maintenance of fresh meat: first in the refrigerator with an average temperature of 3°C and second in cool place with a temperature of 8°C were considered and then the effects of storage time on the meat quality was observed using a digital camera Some common models were developed for image processing and the response surface method was applied.
Materials and methods: First, some meat from three sections of veal meat: hands, feet and neck, were prepared from Kermanshah slaughterhouse and the slaughtered time was recorded as an initial time. From each of the six states in total, 18 samples were taken appropriate to the thickness of one centimeter. Samples were randomly selected for inclusion in the standard conditions (ISIRI 692).
Image processing:
More than 600 images were acquired at various storage times and they were then evaluated to find the appropriate separation methods for meat from image background. The best way to separating the meat image from the background in the image was using the RGB color and the B space values with 150 value as the threshold. In other words, the exact coordinates of meat pixels were obtained. Then background isolated by edge detection with Cany filter with coefficient of 0.7. Finally meat image was isolated from background. Then various parameters of meat image were extracted. The number of parameters were more than 50 parameters. Then sensitivity analysis were selected as three parameters: Contrast, Roughness, and Texture that had more influence on time change from the moment of slaughter and were selected as appropriate inputs of models.
Modeling by Response Surface Method:
In this method, selected parameters were used as inputs and the time of slaughter in minutes, was used as output of the model. Because of the more difference of the values of various parameters from each other, all data were normalized. Generally due to the three organs of veal and two different environments to maintain, six models in the Software Design Expert 7.0 were designed and optimized using response surface methods. In the next step, data samples at ambient temperature as well as refrigerated samples were modeled.
Results and discussion: The results of the models by the response surface methods were good and acceptable. In the final step the general models were good; these models were about all of data in environment and refrigerator.
Conclusion: In this study, considering the importance of using fresh meat calves by people as well as processing plants, some algorithms were designed and developed to estimate the pasted time of the calf slaughtered. For this purpose Samples were prepared from three parts of slaughtered calves: ham, shoulder and neck. The samples were stored in the environment and common standards place the first in refrigerator with a temperature of 3 ° C and another in cool environment with an average temperature of 8 ° C. Then some images were taken from samples at specified times. Then some parameters were extracted from images produced by the image processing in MATLAB. Then by response surface method was designed and optimized. Suitable models and finaly suggested device has ability to estimate the time of slaughter by taking image.
Research Article
Saman Abdanan; Mehran Nouri; Maryam Soltani Kazemi; Somaye Amraei
Abstract
Introduction: Nutritional quality of food during storage has become increasingly an important problem. The loss of some nutrients such as ascorbic acid (vitamin C) might be a critical factor for the shelf life of some products as citrus juice concentrates, since vitamin C content of citrus juices undergoes ...
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Introduction: Nutritional quality of food during storage has become increasingly an important problem. The loss of some nutrients such as ascorbic acid (vitamin C) might be a critical factor for the shelf life of some products as citrus juice concentrates, since vitamin C content of citrus juices undergoes destruction during storage (Plaza et al., 2011a). Ascorbic acid is an important component of our nutrition and used as additive in many foods because of its antioxidant capacity. Thus, it increases quality and technological properties of food as well as nutritional value (Larisch et al., 1998). However, ascorbic acid is an unstable compound and even under minor desirable conditions it decomposes easily. Degradation of ascorbic acid proceeds both aerobic and anaerobic pathways and depends upon many factors such as oxygen, heat, light, storage temperature and storage time. Oxidation of ascorbic acid occurs mainly during the processing of citrus juices, whereas, anaerobic degradation of ascorbic acid mainly appears during storage which is especially observed in thermally preserved citrus juices (Lee & Coates, 1999). It was reported that several decomposition reactive products occur via the degradation of vitamin C and these compounds may combine with amino acids, thus result in formation of brown pigments (Wibowo et al., 2015). In recent years, several nondestructive methods such as computer vision, spectroscopy, ultrasonic have been developed to objectively evaluate different agricultural materials (Abdanan Mehdizadeh et al., 2014; Wang and Paliwal, 2007). However, due to the physical properties of fruit, machine vision has not been discussed much in the literature (Fernanzed-Vazquez et al., 2011). One disadvantage of using spectroscopic methods is that these methods require expensive equipment and also carrying these instruments are difficult. On the contrary, the combining of a digital camera and its image processing software that replaces the traditional measuring instruments have been widely used to provide a cheaper and versatile form to measure some internal quality of many foods. Therefore, the goal of this research is to determine the best features of surface texture (entropy, homogeneity, contrast, correlation and prominence) in order to predict quality factors (pH, acidity, soluble solids and ascorbic acid) of citrus juice.
Materials and methods: Orange, sour lemon, sour orange and tangerine fruit were obtained from one of local marker in Ahvaz, Iran. All samples were washed and the juice was extracted using a Pars-Khazar rotary extractor. The citrus juice, (sour orange, orange, lemon and tangerine) immediately after pasteurization process, were kept at a temperature of refrigerators (4º C) for 60 days in darkness. After taking images of the citrus juice, pH, acidity, ascorbic acid and soluble solids were measured on days 0, 20, 40 and 60.
Physicochemical analysis:
The pH of samples was determined with a pH meter (Methrohm, 827 pH lab, Switzerland). The soluble solids content of concentrates was determined as o Bx using a refractometer (Atago Co, Ltd. Carnation, WA). Total titrable acidity was assessed by titration with sodium hydroxide (0.1 N) and expressed as % citric acid (Kimball, 1999). Ascorbic acid was determined using 2,6-dichlorophenolindophenol by visual titration (Kabasakalis, 2000).
Imaging and color analysis:
Samples were placed under the camera (Canon PowerShot SX60 HS, Japan) of a computer vision system at the distance of 300 mm inside a black box with the size of 100 ×100 ×100 cm3. The samples were illuminated using four fluorescent lamps at the angle of 45o in relation with the sample.
After taking images, color images were transformed to L*a*b* color space. The L* parameter (luminosity) is an attribute by which a surface emits more or less light and can take values between 0 (absolute black) to 100 (absolute white). The parameters a* and b* represent the chromaticity, where a* defines the red-green component (red for positive values and green for negative values) and the b* parameter defines the yellow-blue component (yellow for positive values and blue for negative values) (Quevedo et al., 2009a). Following color transformation, the well-known textural parameter called the Gray-Level Co-Occurrence Matrix (GLCM function) was applied to the images and six features through Eq. 1-6 were extracted (Table 1).
Results and discussion: Color changes during storage in three color channels L*,a*,b* showed that the variation of channel L* could illustrate deterioration of citrus juice better than other channels. In the Figure 1, a gallery of four selected images (taken at different times in the experiment) corresponding to one sour orange sample and their corresponding surface intensity (based on L* value) are showed.
The results of statistical analysis depicted that acidity and ascorbic acid, in four citrus juices, significantly (P
Research Article
Mohammad Dolatabadi; Zeynab Raftani Amiri; Reza Esmaeilzadeh kenari
Abstract
Introduction: In recent years, much attention has been focused on agricultural wastes especially those containing phenolic compounds with natural antioxidant properties. One of these sources is the green husks of walnuts. The contents of phenolic compounds of plants are influenced under various factors ...
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Introduction: In recent years, much attention has been focused on agricultural wastes especially those containing phenolic compounds with natural antioxidant properties. One of these sources is the green husks of walnuts. The contents of phenolic compounds of plants are influenced under various factors including genetic factors, agricultural varieties and the species, climate and extraction procedures. Extraction is the first step for researchers who work on plants. Traditional extraction techniques with solvent such as water have disadvantages such as time consuming process, solvent consumption and high labor work. So the need to develop and use new extraction techniques, including combination of ultrasound bath and microwave devices, has provided valuable results. This method increases the mass transfer rate of the cell wall and intracellular compounds more rapidly transported out of the cell. In the ultrasound method to create cavitation in the extraction process and with collapse of bubbles and mechanical effects on the cell wall and most influential into the cell solvent improves the mass transfer. Extraction process performed by ultrasound process was used to facilitate the release of the intracellular content. These two methods can increase extraction efficiency within a shorter time and using less solvent, increasing the amount of extracted compounds are less damaging to the environment. Three different weather conditions for walnut production in northern Iran and different methods for extraction and measurement of phenolic compounds were adapted to find the best area and the most efficient extraction method.
Materials and methods: Three areas were selected from north parts of Iran including Bandar Gaz with mild climate, Shahrood with semi-arid climate and Hezarjerib region with mountainous climate located in the Alborz Mountain chains in which walnut is one of their major products. Walnuts randomly were picked by hand without any damage to their husks from a few walnut trees in a random garden in each region. The selected walnut trees were almost similar and were about 35 to 40 years old. In the selected areas, it is not conventional to use pesticides or chemicals and toppings for walnut trees. Walnuts collected were transported to the lab in cold conditions (8 to 10° C) and after cleaning the walnuts, green husks were separated and kept at -18 °C. Solvent extraction of phenolic compounds was carried out by choosing ethanol - water in a ratio of (1-1) by soaking, ultrasound and microwave methods at different times. The amount of phenolic compounds was measured using a spectrophotometer device with the aid of using the Folin Ciocalteau reagent, and antioxidant properties were measured using DPPH free radical scavenging and regenerative power of Iron III.
Results and discussion: This research was carried out on a factorial design (334) with three replications with Duncan's test for comparison of averages at the 95% confidence level. Comparing the extraction methods (soaking, microwave and ultrasound) showed that the most efficient method was ultrasound method at 30 minutes and the highest phenolic compounds in walnut green husk was for Hezarjerib area. In addition to the savings in time of extraction and safety in this method, the extraction of phenolic compounds is preferred to the other two methods. The results showed that the antioxidant properties were increased with increase in the amount of phenolic compounds. The results of this study also revealed that the walnuts green husks from Hezarjerib had the highest antioxidant properties followed by temperate region (Bandargaz) and semi-arid region (Shahrood).
Research Article
Erfan Danesh; Hossein Jooyandeh; Vahid Samavati; Mostafa Goudarzi
Abstract
Introduction: Scientific evidence has demonstrated that consumption of high-fat foods has direct connection with increasing incidences of various diseases such as obesity, diabetes, hardening of the artery walls and blood pressure. Thus, demand for low-fat foods has increasingly been promoted by health-conscious ...
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Introduction: Scientific evidence has demonstrated that consumption of high-fat foods has direct connection with increasing incidences of various diseases such as obesity, diabetes, hardening of the artery walls and blood pressure. Thus, demand for low-fat foods has increasingly been promoted by health-conscious consumers. However, development of low-fat foods is challenging as fat makes a major contribution to sensory attributes of many foods. Low-fat cheeses are usually characterized as having a flat taste, more translucency and a rubbery and gummy texture. A common strategy for improving the properties of low-fat cheeses is to increase its moisture content sufficiently to provide moisture to protein ratio which is greater than or equal to its full-fat counterpart. The addition of denatured whey proteins, which are known for their high water-holding capacity, to cheese milk is one method used to achieve this objective. Likewise, transglutaminase treatment of cheeses milk has been shown to increase the moisture content of the resultant cheese. Enzyme transglutaminase (MTGase; protein-glutamine gamma glutamyl transferase, EC 2.3.2.13) catalyzes acyl transfer reactions between protein intra- or inter- chain glutamine (acyl donor) and lysine (acyl acceptor) peptide residues. UF-Feta cheese has the highest per capita consumption amongst cheese varieties in Iran. However, UF-Feta cheese is also perceived as being high in fat, discouraging some consumers from including it in their diets. The objective of this study was enzymatic incorporation of whey proteins into the formulation of UF-Feta cheese by TGase in order to obtain a low-fat product with desirable textural and sensory properties.
Materials and methods: The experiments were designed according to a 5-level-3-factor central composite design using response surface methodology (RSM). The independent variable were formulation ingredients including TGase enzyme (0-2 units/g protein), whey protein concentrate (WPC) (0-16 % w/w) and fat (0-10 % w/w) and the responses of interest were the physicochemical (moisture content and lightness (L*)), textural (hardness, adhesiveness, cohesiveness and springiness) and sensory properties (flavor and odor, color and appearance, texture and total acceptability) of UF-Feta cheese.
Results and discussion: The results indicated that fat reduction caused significant increment in the moisture content of UF-Feta cheese. The whey protein addition showed the same effect on moisture content as fat reduction whereas transglutaminase treatment decreased the moisture of UF-Feta cheese. As expected, fat reduction was accompanied by an increase in hardness and elasticity of UF-Feta cheese. Fat and moisture act as fillers in the casein matrix of cheese texture. When the fat content is decreased, the moisture does not replace the fat on an equal basis, so the total filler volume is decreased, resulting in lower moisture to protein ratio. This in turn increases possibilities of cross-linking between protein chains, resulting in a more compact cheese matrix with harder and chewier texture. Similarly, the increasing effect of TGase treatment on hardness and elasticity may be attributed to formation of a more compact protein matrix because of cross-linking action of enzyme on milk proteins. The whey proteins, however, decreased the hardness and elasticity of UF-Feta cheese. It seems that the added whey proteins increased the moisture content of cheese as sufficiently as to offset the decrease in the total filler volume caused by fat reduction, preventing the protein matrix to be more compact and elastic. Promoted protein-protein interactions of the cheese matrix resulting from fat reduction or TGase treatment might also account for our observation on decreased adhesiveness and increased cohesiveness. As the protein matrix becomes more compact, the cheese loses its adhesiveness. Conversely, as the number or strength of protein interactions increases, the structural integrity of cheese matrix called cohesiveness increases. Apart from fat, water can also create more open conformation for protein molecules, resulting in increased adhesiveness and decreased cohesiveness. This may justify our observation on higher adhesiveness and lower cohesiveness of whey protein-fortified low-fat cheeses with high moisture content. Not surprisingly, all the sensory attributes of UF-Feta cheese were adversely influenced by fat reduction. On the other hand, whey proteins improved the flavor and texture of low-fat UF-Feta cheeses. They, however, showed no effect on appearance score of cheese samples in spite of the fact that they somewhat compensated for lost lightness (L*) of low-fat cheeses. Similarly, TGase treatment did not affect the appearance acceptability of UF-Feta cheeses despite having significant effect on their L* value. The sensory panel did not appreciate the flavor of TGase-treated samples; however, they scored the samples treated with enzyme concentration lower than 1 U/g protein as having desirable texture. RSM suggested that the optimum formulation of 5.95% (w/w) fat, 0.56 unit TGase per gram protein and 8.79% (w/w) WPC could produce a low-fat cheese sample with desired textural (hardness 0.342 kg; elasticity 8.58 mm; adhesiveness -0.070 kg.s; cohesiveness 0.474) and sensory (overall sensory score 88.73 out of 100) attributes.
Research Article
Ali Mehraban Shendi; Mehran Alami; Shabnam Mokhtari
Abstract
Introduction: Cakes are usually formulated including wheat flour, sugar, egg and some liquids such as milk, water and oil. The textural properties of gluten in dough such as tensile, expansion and tolerance capability during mixing are major factors in baking industry. In fact, the structural protein ...
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Introduction: Cakes are usually formulated including wheat flour, sugar, egg and some liquids such as milk, water and oil. The textural properties of gluten in dough such as tensile, expansion and tolerance capability during mixing are major factors in baking industry. In fact, the structural protein to produce bread, cakes, muffins and biscuits is called gluten and the absence of gluten due to production of bakery products caused delicate texture, poor color, low size and porosity. The use of gluten-free flours such as corn, potatoes and rice, millet, Cassava, maize and sorghum in this category is inevitable. Therefore, the use of gluten alternatives such as hydrocolloids, enzymes and proteins, are essential in providing this products. MTG is transferase enzyme that can be made connection between glutamine and lysine. Result of this reaction improve nutritional and functional properties of the proteins. Covalent links generated by MTG has unique effects on gelation capacity, thermal stability and water holding capacities of products. Albumin and globulin do not have any effect on shaping of dough, but MTG connects the albumin and globulin to each other and then they become sedimented. This has beneficial effect on product quality. MTG has repairing ability on damaged wheat grains with binding protein. In this study, we try to contribute production of gluten-free sponge cake with guar gum, millet and rice flour, and MTG.
Materials and methods: TAROM rice flour purchase from local market and keep refrigerated until use it. Polyethylene bags with dimensions 15*25cm and thickness 40 microns were used. Guar gum (MEYPROTM GUAR, E412), vanilla (RHOVANILLA of RODYA company) and soy protein isolate (SPI) was prepared from China. Because of hygroscopic property of MTG, it was purchased in packages of 100 g, and stored at -15 ° C for further tests. For this purpose (0% millet-100% rice, 50%millet -50% rice, 100% millet-0%rice), guar gum (1, 2%) and MTG (0.25, 0.5%) were added. In order to increase the amino acid lysine as a substrate for the enzyme, soy protein isolate (SPI) was added to MTG containing samples. After baking (170 °C, 20 min) and cooling, each of the samples packed in polyethylene bags to evaluate characteristics. Moisture content Base on standard AACC, 2000, measured. For Size Measuring, a piece of cake weighed and placed into the container with the specific volume (Vt), The remaining space of container was filled with canola crops (Vs) and then volume of cakes calculated (Vt-Vs). For Evaluation of brain porous, cake was cubed in size 2*2 cm and Scanned by the scanner with a resolution of 1200 pixels (model: HP Scanjet G3010). Statistical analyze base on factorial design were prepared in triplicate. Duncan test at 5% level (P
Research Article
Samira Shakiba; Morteza Khomeiri; Zeid Ahmadi; Soheil Amiri
Abstract
Introduction: Ispharzeh is a plant from genus Plantago whose seeds are used commercially for the production of mucilage. The plant is mainly cultivated in Iran and Middle East. Psyllium is mainly used as a dietary fiber to relieve symptoms of both constipation and mild diarrhea and occasionally as a ...
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Introduction: Ispharzeh is a plant from genus Plantago whose seeds are used commercially for the production of mucilage. The plant is mainly cultivated in Iran and Middle East. Psyllium is mainly used as a dietary fiber to relieve symptoms of both constipation and mild diarrhea and occasionally as a food thickener. Research has also shown benefits in reducing cholesterol levels. Basil seed gum is a novel hydrocolloid extracted from Ocimum basilicum L. seeds. It has shown promising stabilizing and emulsifying properties, which makes it a potential functional ingredient for the food industry. Previous works pointed out that these gums can be used successfully for food industry. However, a detailed study on Ispharzeh hydrocolloids seeds and basil gum has not yet been done. Therefore, the objective of this study was to evaluate the ability of using Ispharzeh hydrocolloids seed and basil gum as replacing with imported gums as well as to evaluate physicochemical, and sensory properties of ketchup sauce contain these gum were evaluated.
Materials and methods: Mixture design was employed to investigate the variation of ketchup properties with respect to operating parameters including xanthan, Ispharzeh seeds and basil gum in the range of 0 to 0.1 % using design expert software. Experiments were randomized in order to minimize the effects of unexplained variability in the observed responses due to extraneous factors. The treatments were selected regarding combination of xanthan, Ispharzeh seeds and basil gum in the range of 0 to 0.1 % using Design expert software. After extraction of gums, ketchup formulation was prepared with the treatments contain Ispharzeh hydrocolloids seeds and basil gum. Control sample contained ketchup formulation without gums. pH, apparent viscosity, syneresis, color and sensory properties of produced ketchup were evaluated.
Results and discussion: The impact of Ispharzeh seeds and basil gum addition on the pH of ketchup showed that all the treatments were in the standard pH range (3.67-3.74) according to the Iran national standard of ketchup. In addition, the results showed that addition of these gum were not significantly effect on pH. The regression coefficients were calculated according to the multiple regression coefficients and a polynomial regression model equation was fitted as quadratic equation. Regarding syneresis, all the treatments were stable with no syneresis except K2 (1% Ispharzeh) and K4 (1% basil gum). Addition of Ispharzeh and basil alone, were not significantly effect on synersis but when they used in combination and with xanthan, prevent syneresis significantly. The highest and the lowest viscosity were related to K4 (1% basil gum) and K10 (0.5 % xanthan+ 0.5% Ispharzeh), respectively. The regression coefficients were calculated according to the multiple regression coefficients and a polynomial regression model equation was fitted as quadratic equation. Hunter Lab colorimeter analyzing L*, a* and b* showed that K2 and K5 (1% xanthan) had the lowest and highest L* index. Variance analysis showed that quadratic model was fitted for L* value and coefficient correlation (0.9943) was satisfactory. In addition of effects of single gums, interaction of gums also had significant effect on lightness of ketchup. According to the results obtained from the sensory analysis, overall acceptability of K4 (1% basil gum) gained the highest scores. K2 (1% Ispharzeh) had the highest firmness so, led to unpleasant mouth feel in panelists. In addition, the presence of impurities in Ispharzeh seeds which not removed in centrifuge may darkening the produced ketchup hence got lower scores by panelists. Optimization evaluation by RSM evaluated the effects and interactions of the Ispharzeh hydrocolloids seeds and basil gum concentration to optimize ketchup properties. Optimized treatments were 0.42% Ispharzeh hydrocolloids seeds gum and 0.58% basil gum. Therefore, the values for stability tests are very close to the experimental values demonstrating that the model are applicable, which showed determination coefficient (R2) of 0.99. The formulation optimization showed that combination of 0.58% Ispharzeh and 0.42% basil gum as stabilizing agents in ketchup sauce, was a suitable replacer for imported commercial gums. Future studies on the Ispharzeh seeds and basil gum in other foods as well as the stabilization of these systems during the digestion process may help to understand the mechanism behind the functionality of these gums in food products.
Research Article
Atefeh Rezai Zadeh; Zeynab Raftani Amiri
Abstract
Introduction: Today, the demand for low calorie food based on fruits and easy production and keeping primary features including texture and taste is increasing. Jelly is one of low calorie products which is produced from fruits and other components, and its usage is increasing for human health. Chemical ...
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Introduction: Today, the demand for low calorie food based on fruits and easy production and keeping primary features including texture and taste is increasing. Jelly is one of low calorie products which is produced from fruits and other components, and its usage is increasing for human health. Chemical ingredients and natural features of fruits decrease the cancer. In addition to nutrition and medical values, rheological and texture features affect the general quality of fruit jelly. Gelatin is a protein which is obtained by thermal hydrolysis of collagen and is the main protein of bone, cartilage and skin. The source, animal age and the type of collagen are influential factors on gelatin characteristics. Different gelatins have different thermal and rheological characteristics such as transformation temperature to jelly and melting temperature. The melting temperature of gelatin is lower than human body temperature. In food industry, gelatin is used as an alternative for fat, to improve elasticity and transparency of fruit juices and also is used in production of jelly, chocolate, edible films, and so on. Gelatin quality and its application in industry are mainly because of its rheological features. Global demand for gelatin during recent years increases due to its low cost and solubility in biologic environments.
Materials and methods: In this study, the gelatin from chicken feet was extracted by acidic method using hydrochloric acid 0.5% normal with the rate of 1: 3.22 weight / volume. pH was adjusted to 7 by the use of sodium hydroxyl 1 normal and was dried in an incubator at 450 c for 28 hours. Different tests such as pH, protein, ash, moisture, fat, viscosity, jelly strength, color and rheology were done in gelatin molecule to measure of storage modules (G') and loss modules (G''). Then, the effect of extracted jelly in concentrations of 0 to 1.5 % on the physico-chemical (Brix, humidity, acidity, color, texture) and organoleptic properties of cantaloupe jelly (odor, sweetness, color, appearance, jelly status, transparency, adhesion) were investigated using five point Hedonic scale ranked. Experiments related to cantaloupe jelly were conducted in terms of a completely random design. A one-way analysis of variance and Duncan test (P≤ 0.05), in three replications were used to establish the significance of differences in experimental data’s. The result was performed using the SPSS version 16.0 windows program, and charts were plotted with Excel 2010.
Results and Discussion: The results showed that the average yield of gelatin based on the wet weight was 4.80%, pH value before drying is 3.7, the total amount of protein is 83.95%, the total amount of ash is 0.89%, moisture is 9.66%, fat is 0%, viscosity is 216 centipoise. The strength of jelly is 487g that in compare with other alternatives such as gelatin from chicken skin is 355±48.1 gr, cow gelatin is 299±71.1 gr, fish gelatin including 181 to 263 gr for tilapia, 280 gr for horse mackerel fish, 125 and 177 gram for Sin croaker and Shortfin scad, respectively. The main reason for low level of gelatin in fish skin is the low amount of hydroxyl proline. Thus, it can be claimed that the high gel strength in chicken feet gelatin might be due to lower extraction temperature, strong hydrogen bond and more probably hydroxyl proline. Hydrocolloid solutions are usually viscoelastic; therefore, the level of storage modules (G') and loss modules (G'') is measurable for them. Gelatin from chicken feet exhibited G' greater than the G'' in a wide range of frequencies of the oscillatory test, which have indicated the gel network is high stable. By increasing the amount of gelatin in the cantaloupe juice, transparency and firmness of cantaloupe jelly increased. In the sensory analysis, jellies had not significant differences in the intensity of sweetness. In terms of overall acceptability, the sample containing 1.25 and 1.5 percent of gelatin gained maximum score.
Research Article
Safie Khalilian; Aman Mohammad Ziaiifar; Ali Asghari; Mahdi Kashani-Nejad; Mohebbat Mohebbi
Abstract
Introduction: Thermal properties of food during the frying process and mass transfer mechanisms (water and oil) can help in controlling the quality of the fried product (Fiszman et al., 2005). During the frying process, heat was transferred from the oil to the sample surface that it increases the temperature ...
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Introduction: Thermal properties of food during the frying process and mass transfer mechanisms (water and oil) can help in controlling the quality of the fried product (Fiszman et al., 2005). During the frying process, heat was transferred from the oil to the sample surface that it increases the temperature almost to 100 °C, the water evaporates and moved out. The sample surface was covered by bubble layers with various size and distribution. The formation of vapor bubbles on the samples surface have been effective on the micro-flows which is one of the important factor in the coefficient of heat transfer (Sahin et al., 1999). Therefore, knowledge of the relationship between the boundary layer and the surface heat transfer coefficient can determine the thermal behavior and kinetics of the migration of moisture and oil. Eggplant (Solanum Melongena L.) is one of the major agricultural crops of Asian and Mediterranean countries. Iran after China and India has achieved third place in eggplant production, which has made it remarkable, and economical. Eggplant absorbs high amounts of oil during the frying process due to its high moisture content (more than 90%) and high porous structure even if the residual water content is still quite high after frying.
Materials and methods: Fresh eggplants (Solanum melongena L. family Solanaceae) were obtained from the local market and stored at 4°C. Eggplant samples were washed with water tap and cut with manual mold into equal and similar cylindrical pieces (2.5×1cm). They were then washed with distilled water and surface water was removed using tissue paper. Finally, the samples were packed by poly-ethylene in order to prevent surface drying. A commercial sunflower oil was purchased from Ladan Factory, Iran.
Eggplant samples were dried at different temperature of hot air drying 40, 70, 100 and 130°C until moisture content 5 and 12 db%. Samples were drawn from the drier after drying, cooled at room temperature (25°C) and deep fat fried.
A domestic deep fat fryer with temperature control of ± 1°C (Seb, France) was used for carrying out frying operations. The fryer was filled with 2.5 l sunflower oil. The eggplant to oil ratio was kept at 1:50 w/v to reduce temperature variation in the oil bath. The frying was performed at 130, 150 and 170 °C for regular interval times 1, 2, 3, 4, 5 and 6 min. The frying oil was changed after 10 h of frying time. The samples were immediately removed from oil and were located on wired plate for draining and remove excess oil on the surface, and allowed to cool at room temperature before analyses. All experiments were performed in triplicates and the presented results are the mean of the obtained values.
Oil and moisture content were determined according to AOAC, 1995.
K type thermocouples (copper-nickel) with accuracy of ±1°C were used to measure the temperatures of samples. Temperature acquisition TC-08, Pico® (Technology Limited, England) with accuracy ±0.5°C and temperature controller PID Rex- D-100® (RKC) were used to data collection and oil temperature control, respectively.
In this study, convective heat transfer coefficient was calculated between surface sample and oil according to Farinu and Baik (2008).
In order to predict surface heat transfer coefficients and mass transfer kinetic eggplant samples during deep frying was used artificial neural networks. Then, the 4 inputs including: frying temperature (130, 150 and 170 °C), frying time (1, 2, 3, 4, 5 and 6 min), 4 pre-treatments drying temperature by hot air (40, 70, 100 and 130 °C) until the two moisture levels (5 and 12 %db) were used and output parameters including moisture and oil content, heat transfer coefficient with two replications which in total of 288 data were used to form the network structure.
Results and discussion: Results of this study showed that there is some complicated relationship between convective heat transfer and moisture and oil content. In addition, the convective heat transfer coefficient in up and down surface of the sample showed that oil absorption will be from upper surface. This phenomenon can be attributed to upper surface due to more bubbles of vapor out of the sample. This leads would slower the formation of crust on the upper sample. Finally, channels and cavities of the upper level will be more susceptible to the contact of oil. The results of predictive parameters of heat and mass transfer during deep frying eggplant samples using artificial neural network multilayer perceptron as a non-linear method showed closely relationship with experimental data. It indicates that the proper functioning of this method for modeling and studying the relationship between heat and mass transfer phenomena during deep frying of eggplant samples.
Research Article
Fahimeh Tooryan; Maryam Azizkhani
Abstract
Introduction: There have been great efforts to find safe and potent natural antioxidants from various plant sources. There is, at present, increasing interest both in the industry and scientific research for spices and aromatic herbs because of their strong antioxidant and antimicrobial properties, which ...
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Introduction: There have been great efforts to find safe and potent natural antioxidants from various plant sources. There is, at present, increasing interest both in the industry and scientific research for spices and aromatic herbs because of their strong antioxidant and antimicrobial properties, which exceed many currently used natural and synthetic antioxidants. Medicinal plants are complex natural mixtures which contain compounds at quite different concentrations, have antioxidant activities These properties are due to many substances, including some vitamins, flavonoids, terpenoids, carotenoids, phytoestrogens, minerals, etc. and render spices and some herbs or their antioxidant components as preservative agents in food and they were proposed as potential substitutes of synthetic antioxidants in food stuff. The number of contributions to isolation methods, techniques and activity testing of plant-origin antioxidants has significantly increased in recent years. Antioxidants are also widely used as additives in fats and oils and in food processing to prevent or delay spoilage of foods regarding to the harmful effects of synthetic preservatives on consumers’ health, there is an increasing attention, both in food industry and authorities, to medicinal and aromatic plants as natural preservatives in food products. Oxidation is one of the major causes of chemical spoilage, resulting in rancidity and deterioration of the nutritional quality, colour, flavour, texture and safety of foods .Oxidation occurrence in cheese especially full-fat types causes rancid odor and taste and loss of nutritional quality. The objectives of the present study were evaluation of aerial parts of basil (Ocimum basilicum) and clary sage (Salvia sclarea) essential oils (EOs), study their antioxidant effect on the lipid oxidation and sensorial acceptability when applied to Iranian white cheese.
Materials and methods: Investigations were carried out to assess the efficiency of two plant essential oils; clary sage and basil as natural food preservatives. In this study, the antioxidant effect of clary sage (Salvia sclarea) and basil (Ocimum basilicum) essential oils in Iranian white cheese shelf-life, at 26 ° C for 39 and 4 ° C for 90 days, were examined. Samples at three levels 0.5%, 0.75%, 1% (w/v) were treated, negative control cheese without antioxidant and positive control sample with synthetic antioxidant (BHT) 0.05% were selected. The Essential oils chemical composition were determined by gas chromatography equipped with mass spectroscopy (GC/MS). GC-MS analysis of the essential oil was performed using Agilent-Technologies 6890N Network gas chromatographic (GC) system, equipped with Agilent Technologies 5975 inert XL Mass selective detector and Agilent-Technologies 7683B series auto injector (Agilent- Technologies, Little Falls, CA, USA). The antioxidant capacity of the essential oils were assessed by measuring their scavenging abilities to 2,2 diphenyl-1-picrylhydrazyl stable radicals using DPPH method and anti-oxidative stability with peroxide value (PV) and thiobarbituric acid (TBARS) test were evaluated.
Results & discussion: Main components of clary sage EO included linalyl acetate, linalool, α-terpineol and α-pinene and the major aroma constituents of basil EO consisted of linalool and α-cadinol, eugenol ,α –Bergamotene and 1,8- Cineole. Linalyl acetate and linalool (oxygenated monoterpenes) showed stronger antioxidant activities than did the other components tested in the assays. Maximum free radical scavenging activity for clary sage and basil EOs at 1% concentration was 84.66% and 72.72% respectively that was weaker than (BHT) free radical scavenging activity (95%) by DPPH test. At 1% concentration, clary sage and basil EOs were most effective treatment at 4 and 26 C°, in free radical scavenging activity comparing to other concentrations. At 4 C° there is no any difference between all treatments up to 30th days in PV and TBARS number. The most effective treatment against lipid oxidation was at 0.75, 1% concentration basil and 1% saliva EOs at 90th days observed. Finally it seems that Basil EO was more effective than clary sage EO at both 0.75 and 1% concentration. At 1% concentration of basil EO according at 90th day storage time not observed significant difference in peroxide value and tio barbituric acid number comparing to first day. At 26 C° highest antioxidant activity was obtained at 1% concentration of basil EO. Final peroxide value (meq O2/Kg oil) and tio barbituric acid (m mol/gr oil MD) number using basil and saliva EOs was 1.379, 0.0680 and 1.817, 0.096 respectively. That significant deference was observed comparing to control sample (p
Research Article
Ali Shahdadi Sardoo; Nasser Sedaghat; Masoud Taghizadeh; Elnaz Milani
Abstract
Introduction: In Iran, the main problem in greenhouse cucumber production and post-harvest shelf life is short due to the application of traditional packaging and storage methods. This research was carried out in order to investigate on the effects of packaging type and chitosan edible coating on the ...
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Introduction: In Iran, the main problem in greenhouse cucumber production and post-harvest shelf life is short due to the application of traditional packaging and storage methods. This research was carried out in order to investigate on the effects of packaging type and chitosan edible coating on the physicochemical and sensory characteristics of Royal Greenhouse cucumber during storage conditions, in order to prevent of Royal greenhouse cucumber postharvest losses.
Materials and methods: Royal greenhouse cucumbers placed inside the three-layer plastic bags of PE/PA/PE and the effect of different chitosan coating (0, 0.5 & 1 %), concentration of oxygen (3,12 & 21%), storage temperatures (5, 15 & 25 ˚C) and storage time (3, 12 & 21 days) on cucumber quality and shelf life was studied. The quality of cucumber samples was evaluated by weight loss, firmness retention, surface color development (L*, a*, b*), shrinkage and sensory evaluation (taste and freshness).
Results and discussion: The obtained results showed that firmness and organoleptic properties decreased with increasing temperature and time storage, while weight loss and shrinkage was increased, that Leading to loss of cucumber samples quality during storage. Increasing of chitosan coating to 0.5% also showed a beneficial effect on physicochemical and sensory characteristics of the samples during the storage time compared to the control fruit, but by increasing it to 1%, decreased the quality of the final product. The results showed that using modified atmosphere packaging and storage at low temperatures can be in addition to the slow breathing fresh cucumbers from softening and prevent moisture loss the maintenance of cucumber. MAP packaging leads to keeping cucumber green and quality properties compared to the control samples. The optimum condition was obtained at chitosan coating 0.5 %, O2concentration 8.5 %, storage temperatures 9˚C and storage time of 14 days. At this optimum point maximum of firmness, L*, taste, freshness and minimum of shrinkage, weight loss and a* were found to be 10.4 (N), 48.9, 4.35, 4.5, 6.25 %, 2.75 % and -37.28 respectively.
Research Article
Hassan Sabbaghi; Aman Mohammad Ziaiifar; Mahdi Kashani-Nejad
Abstract
Introduction: Frying phenomena occur during the immersion of the product in oil at a temperature of 150–200 ºC, where a simultaneous heat and mass transfer take place. This is the most popular thermal processes of potato cooking. This fast drying is critical to improve the mechanical and structural ...
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Introduction: Frying phenomena occur during the immersion of the product in oil at a temperature of 150–200 ºC, where a simultaneous heat and mass transfer take place. This is the most popular thermal processes of potato cooking. This fast drying is critical to improve the mechanical and structural properties of the final product. These conditions lead to high heat transfer rates, rapid cooking, browning, texture and flavor development. The fried potato is easier to transport and provides better texture. Researchers have assumed the existence of two regions for fried product, separated by an interface: the core (unfried) and crust (fried) regions. In general, frying process is very complex for two main reasons: i) due to the simultaneous heat and mass transfer between food material and frying oil, ii) due to the progressive deterioration of the oil and structural changes in foods (crust and core regions). The moving boundary problem may be found in many areas of frying research involving heat and/or mass transfer. In this study, heat and mass transfer is entirely investigated during frying of potato strips. The transport phenomena during frying are including: i) Heat convection from the hot oil to the interface via the crust region, ii) Water evaporation at the moving interface at a temperature of 100 ºC, iii) The unsteady state heat conduction in both regions of crust and core, iv) The oil uptake into food. As a result, high temperature and low moisture conditions develop as frying proceeds. Water vapor bubbles escaping from the surface of the food cause considerable turbulence in the oil. Therefore, Heat and mass transfer are dependent on each other during frying process. In fact, heat and mass transfer during frying can be controlled by heat transfer at the product surface. Evaporation rate depends on the temperature difference between oil and boiling point of water. There is little information on modeling, both empirical and phenomenological, for moisture loss and oil uptake during frying. Knowledge of accurate heat and mass transfer parameters is important for modeling processes. Designing of frying processes is possible through the use of mathematical models. The aim of this study is to develop a more completely and realistic approach for determining of heat and mass transfer parameters and their relation to oil temperatures. The main process parameters influencing oil uptake are frying temperature and duration. Heat transfer coefficients for different oil temperatures determined using simple method. Mass transfer of water was assumed to be governed by Fick's law of diffusion. For more details, empirical models were used to describe the mass transport in forms of moisture and oil.
Materials and Methods: The frying operation of potato strips was performed in the fryer that was equipped by thermo controller system with K type thermocouple at three different oil temperature of 145, 160 and 175 ºC for 60, 120, 180 and 240 seconds. The core temperature changes of product recorded on computer during process using T type thermocouple connected to data logger. The moisture and oil content of samples measured for each process time and temperatures. The heat and mass transfer parameters such as kinetic coefficients of moisture (Km) and oil transfer (Ko), mass transfer coefficient (Kc), effective diffusivity (D) and heat transfer coefficient (h) were evaluated with dimensionless temperature and concentration ratio plots and also empirical equations. Relationship of these parameters to the temperature of the oil investigated using the Arrhenius equation. Thermal conductivity of potato strips during frying determined as a function of moisture content using the Anderson and Spell equations.
Results & Discussion: The results showed that mass transfer Biot number (Bim), mass transfer coefficient (Kc) and effective moisture diffusivity (D) increased significantly with increasing in oil temperature. In regression models, the linear correlation between kinetic constant of water loss and oil uptake was observed that is verification on effect of drying pretreatment on reducing oil uptake. In fact, with increasing of oil temperature the kinetic constant of water loss increased and caused increased in kinetic constant of oil uptake. Kinetic models could correctly confirm determination of mass transfer parameters. The heat transfer Biot number (Bih), convective heat transfer coefficient (h) and product thermal conductivity (k) decreased significantly with an increase in process temperature. With increasing in the rate of evaporation, following greater amount of input energy used for water loss. This would reduce the amount of available energy to increase internal energy of product and thus reduce the convective heat transfer coefficient at high temperatures. Frying process caused remove of water from product and increasing of porosity, thus observed gradually fell in thermal conductivity. Although the minimum thermal conductivity at various temperatures are close together, but two equations of Anderson and Spell showed significant difference for values of thermal conductivity and Spell was more close to published papers. High activation energy is achieved for lower moisture content that is normally due to the strong water-substrate interaction.
Research Article
Ahmad Ehtiati; Fakhri Shahidi; Arash Koocheki; Seyed Mohammad Ali Razavi; Mahsa Majzoobi
Abstract
Introduction: Sorghum (Sorghum bicolor) is a tropical plant and has the fifth ranking of world cereals production. One of the important aspects of sorghum is drought tolerance and little input need during growth which has made that suitable for cultivation in semiarid regions. Due to the presence of ...
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Introduction: Sorghum (Sorghum bicolor) is a tropical plant and has the fifth ranking of world cereals production. One of the important aspects of sorghum is drought tolerance and little input need during growth which has made that suitable for cultivation in semiarid regions. Due to the presence of tannin compounds in internal part of sorghum grains and low digestion of cooked protein, sorghum flour consumption is limited. Sorghum grain contains more than 70% starch which is an important tasteless ingredient in food formulas, as the main source of energy and thickening and gelling agent. Extraction of starch from sorghum in regarding to its nutritional problems is a good solution for extension of sorghum uses in food industry. Starch is a semi crystalline structure consisted on linear amylose and branched amylopectin molecules packed in granules. Ratio of these two molecules and their molecular short order and macrostructure and size and shape of granules determine functional properties of starch in the final product. Starch properties is depended on genetic residues so that starches from tubers have distinct differences with cereal starches even obvious differences exists between cereal starches and varieties. In this study we have investigated chemical, morphological, structural and thermal properties of starches four white sorghum line.
Material and methods: White sorghum grains were prepared from local farms with line numbers KDFGS1, KDFGS6, KDFGS9 and KDFGS20. Starches were extracted sorghum lines using alkaline steeping method and further purified using toluene-water-salt solution. Chemical parameters were determined including protein by Kjeldahl digestion method, lipid by soxhlet extractor, ash by burning in furnace, moisture by oven drying and amylose content by iodine binding colorimitry,. Light microscopy coupled with digital camera was used for granules shape and size determination moreover surface properties and morphology of granules was observed using scanning electron microscopy technique. Color of starches were determined with hunterlab colorimeter. To evaluate crystalline structure of sample i.e. type of crystals and degree of crystallinity, starches first were conditioned in desiccator containing saturated aqueous sodium chloride solution at 25°C for a week then X-ray diffraction of sample in diffraction angels from 4-40° was determined. Thermal properties of crystals melting or gelatinization were measured using differential scanning calorimetry of starch in deionized water in temperatures from 20-120°C with heating rate of 10°C/min .From heat flow changes over temperature, temperature of onset, peak and conclusion points of crystalline structure melting and its required enthalpy were calculated. Functional groups of starches were investigated using FTIR technique to observe.
Results & Discussion: Isolated starches had appropriate quality due to low amount of protein (
Research Article
Afsaneh Sadeghi; Ahmad Ghazanfari; Hassan Hashemipoor Rafsenjani; Hamidreza Akhavan
Abstract
Introduction: Moringa is a tree that grows in hot and humid regions and produces oil seeds that contain about 33% edible oil. The tree is native to the south-west regions of Asia and it is cultivated in Hormozgan and in Sistan and Bluchestan provinces of Iran. The oil extracted from these seeds is edible ...
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Introduction: Moringa is a tree that grows in hot and humid regions and produces oil seeds that contain about 33% edible oil. The tree is native to the south-west regions of Asia and it is cultivated in Hormozgan and in Sistan and Bluchestan provinces of Iran. The oil extracted from these seeds is edible and has some various industrial applications. The extracted oil usually contains considerable amount of dissolved impurities which must be removed prior to industrial usages. Major part of impurities is removed by settling or filtering process. The fine impurities are removed through a degumming process using water, acids or enzymes. The degumming process affects the physco-chemical characteristics of the oil. In this research, various physco-chemical and heating properties of Moringa oil was measured and the stability of the oil under elevated temperatures were investigated
Material and methods: The Moringa seeds were collected from the wild trees that grow in Hormazgan province. The seeds were manually cleaned and ground to mean diameter of less than 1 mm and then were placed in an oven at 65°C for 24 h to reduce their moisture. Samples of 50 g ground seeds were placed insoxhelt and n-hexane was used as the solvent. The oil extraction experiments were conducted at 60°C for 7 h retention time. The raw obtained oil was divided into two parts and one part was degummed. The degumming of the oil was performed by adding distilled water to it and raising the temperature to 80°C. Then, phosphoric acid was added to the mixture and stirred for 20 min at the same temperature and the mixture was centrifuged and the oil was separated from water and wax. Some characteristics of the raw and the degummed oils including: fatty acids, ion value, peroxide value, chemical, color, saponification value, ignition and clouding points, density and viscosity were measured and compared. The stabilities of the viscosity of the two oils were investigated under different temperatures ranging from 3 to 120°C. The oxidative stability of oils was determined against temperature, light and air exposure. In these experiments temperature ranged from 20 to 120°C, light and air exposure time were 10 days, each. High temperature stability of the oils was also verified using a Rancimat instrument.
Results and discussion: The results of fatty acids analysis indicated that the Moringa oil is generally unsaturated oil containing a total of 76% pulmonic and oleic acids. The major saturated oil content of Moringa oil was plasmatic acids which accounted for 14.3% of the total fatty acids. High amount of unsaturated acids indicates that this oil is good for cooking purposes. The degumming process caused a significant decrease in peroxide value, saponification number and total fatty acids but the viscosity and the pH of the oil increased which all indicates that the degummed oil should be more stable than the raw oil. All heating properties of the degummed oil such as melting, combustion, pour, and cloudy points of the degummed oil increased which indicates that the degummed oil is more suitable for heating foods. In investigating the stability of the oil, the viscosity of the Moringa oil was decreased as the temperature of the oil was increased however, the viscosity increased with the holding time. The increase of the viscosity was more significant at higher temperatures due to the oxidation and degradation of the oil. Generally, increase in the viscosity of the degummed oil occurred at with lower rates. The peroxide value of the raw and the degummed oil was increased as the temperature of them was increased. The increase had higher rates when temperature of the oil exceeded 60C. The peroxide value was also increased with the holding time. The change was not significant for the first four days but it rapidly increased after that. The peroxide value of the oil that kept away from the sunlight remained unchanged for the 10 days test period. The value of peroxide was also affected by aerating the oil. Degradation was initiated immediately as aeration was started but a steep increase was noticed after the second day. The highest peak was reached on the sixth days and after that the oil was completely degraded. A Racncimat test on the raw and degummed oil indicated that with increase in the oil temperature the stability of the oil decreased and when temperature was at 110°C the stability of the raw and the degummed oils were 19 and 31 hours. In general, all the tests indicted that the degummed Moringa oil had higher stability than the raw oil.
Research Article
Bahare Shahidi; Maryam Kalantari; Sareh Boostani
Abstract
Introduction: Grape syrup is a natural sugar source that is obtained by concentration of fruit juice up to about 70% soluble dry matter concentration. Iran is ranked in seventh place in terms of grape production in the world, so there's good potential for converting graph waste to the valuable food products. ...
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Introduction: Grape syrup is a natural sugar source that is obtained by concentration of fruit juice up to about 70% soluble dry matter concentration. Iran is ranked in seventh place in terms of grape production in the world, so there's good potential for converting graph waste to the valuable food products. Grapes with inappropriate appearance can be converted to grape syrup and used as an ingredient in formulation of many food products. Cake is one of the most popular products in bakery and confectionery industry. Cake composed of different components such as flour, oil, milk, baking powder and sugar. Sugar is the main ingredient for making cakes that besides the creating sweet taste, represents numerous functionalities in bakery products. Despite all the benefits of sucrose, because of the association with certain health problems like high blood pressure, cardiovascular disease, tooth decay, obesity and diabetes lots of research is underway to find a suitable replacement for sugar. The challenges ahead when replacing sugar with other sweeteners have forcedthe researchers to provide a sweetener with similar functional properties, taste and quality with sugar. The benefits of grape syrup compared with the sugar are having less crystallization problems, having higher water holding capacity properties and higher perceived sweetness in final product. Due to the mentioned challenges the present study aims to replace sugar with grape syrup in various amounts and to investigate the effects of the replacement on the physical properties of the resulting cakes.
Materials and methods: Grape juice with Brix 68-70 were obtained from local market. Cake flour was also purchased from the local market. In this research four different level of grape syrup (0, 20%, 40%, 60% replacing of sugar with grape juice) were used in cake formulations as a natural replacement for sugar. Preparation of cake batter was carried out using sugar dough method. Consistency and specific gravity of the batters and moisture content, volume, texture, color and sensory properties of the cakes were investigated according to the procedures described in standard methods.
Results & Discussion: The results showed that increasing grape syrup level caused an increase in batter consistency. The main component of the grape juice contains reducing sugars, monosaccharides such as glucose and fructose and there is a small amount of sucrose. Generally most sugars can cause highly concentrated solutions due to their highly water solubility and hydrophilic character. Sugars make hydrogen bonds with water molecules due to their hydroxyl groups, because of the molecular structure of the sugars like sucrose, fructose and glucose, it seems that increasing functional groups in grape sugars compared with sucrose, resulted in the formation of more hydrogen bonds, which caused the reduction in the mobility of free water and therefore make an increase in viscosity of the mixture.According to the results specific gravity of the cake batters increased as the grape syrup level increased. It can be concluded that the addition of the grape syrup to the cake formulation reduces gas storage capacity in the batter and therefore causes the increase in specific gravity of the system. Moisture content of cakes increased with grape syrup addition. Increasing the moisture content in the cake is probably due to competition between moisture- absorbing compounds in the formulation of cakes. The replacement of sugar with grape syrup in the cake formulations decreased the cake volumes. Cake volume is influenced by two main factors including consistency and the specific gravityof the batter. If the batter consistency be too low air bubbles and carbon dioxide that is produced by the decomposition of baking powder will leave the cake out quickly and cake volume will decrease. As mentioned before the saccharides with lower molecular weights tend to absorb more water and caused an increase in batter consistency of cakes prepared from grape syrup compared with the cakes prepared from sucrose. In addition specific gravity of the batter will increase with increasing grape syrup level, specific gravity represents the entry of air bubbles in the batter during mixing and the maintenance of the bubbles in the batter during storage and baking, lower specific gravity of cake batterreflects higher volume of the cakes. The results of texture analysis indicated that grape syrup-added cakes were softer than control sample, one reason for reducing the hardness is that when sucrose replace with grape syrup (that is mainly composed of glucose and fructose), the cake moisture content will increases and as a result caused the reduction of the cake hardness. Evaluation of color parameters showed that L values of cakes decreased and a value increased with addition of natural sweetener (Samples got darker). Sensory evaluation results showed that the cake formulation with 40% grape syrup obtained the highest score by panelists in terms of mouth-feel, wetness, and overall acceptability. It can be concluded that grape syrup could beused as a natural replacer for sugar in preparation of bakery products although further studies are necessary in order to gain appropriate formulation
Short Article
Javad Mahdizadeh Moghadam; Somaye Rahimi
Abstract
Introduction: Pumpkin is one of the agricultural products that despite its very low price, is known as a rich source of carotenoids with high antioxidant activity. Iran is one of the good producers of pumpkin at the world with fifth rank which is cultivated at provinces like Mazandaran, Guilan, Khorasan, ...
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Introduction: Pumpkin is one of the agricultural products that despite its very low price, is known as a rich source of carotenoids with high antioxidant activity. Iran is one of the good producers of pumpkin at the world with fifth rank which is cultivated at provinces like Mazandaran, Guilan, Khorasan, and Hamedan and so on extensively. Pumpkin is almost available for entire the year but many of them is spoiled and perished because of low storage equipments; on the other hand, unfortunately this valuable vegetable which is full of many types of carotenoids with high nutritive values, is not consumed by most of Iranian peoples, because of its low sensory properties such as no pleasant taste or odor; whereas it is used at many cuisines at other countries, especially North America. The pumpkin carotenoids contain natural pigment, beta- carotene and lycopene which can be used as natural colorant at food processed products or dietary supplements. Nowadays, the positive health effect of carotenoids such as improvement of eyesight, fetus growth, prevention from cardiovascular disease and cancer, maintenance of skin health and whole of body, anti blood hypertension and cholesterol is known, well, hence it must more be emphasized at household food basket. There are many researches about extraction of carotenoids form tomato, carrot, yeast and so on, but studying the pumpkin carotenoids was done less. Generally, due to the hydrophobic characteristic of carotenoids and their little solubility at water, organic solvents such as hexane are applied for their extraction, which some researches had been done about its solubility at different organic solvents, yet. Materials and methods: In this research the ripped pumpkins (Curcurbita moschata) were cultivated at private farm at Khorasan were rinsed and chopped to same cubes. Then, pumpkin cubes were peeled off and the seeds were removed. For extraction of carotenoids, the pumpkin specimens prepared at four states of raw (mashed pumpkin), cooked (mashed pumpkin), dried (40 C) (powder) and dry powder of cooked pieces (40 C). Carotenoids were extracted from pumpkin samples by various organic solvents such as hexane, acetone, ethanol, at different volume ratio of them like 1:1(v) and 1:1:1(v). When the pumpkins became colorless, the extract had been evaporated at a vacuumed rotating evaporator to gain a thick extract without any solvent. The extract had been gathered and stored at black bottles and refrigerator to minimize the side effects of light and heat on nutritive characteristics of carotenoids. The total carotenoids content of the pumpkin extracts was measured by spectrophotometric method at 480 nm according to beta- carotene. The antioxidant activity of the extracts was calculated on the basis of DPPH scavenging activity of the samples at 517 nm. The project was done on a complete random design and one-way ANOVA and Duncan test were used for statistical data analysis and clearance the significant difference among treatments at 95% confidence level. Results & Discussions: Statistical analysis of the results showed that various organic solvents, their volume ratio and also various state of pumpkin specimens had a significant effect on the carotenoid extraction from pumpkin samples (p
