Atosa Assarzadegan; Mohammad Fazel
Abstract
Introduction: The fruit, with the scientific name of Cydonia oblonga comes from apple family, has a dry and fluffy flesh that, due to high vitamin C, Potassium and fiber has commercial and nutritional value. However, this fruit is as corruptible as other fruits and destructive microbial, chemical and ...
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Introduction: The fruit, with the scientific name of Cydonia oblonga comes from apple family, has a dry and fluffy flesh that, due to high vitamin C, Potassium and fiber has commercial and nutritional value. However, this fruit is as corruptible as other fruits and destructive microbial, chemical and mechanical factors that reduce its effective longevity. Enzymatic browning is a major problem for reducing the shelf life of freshly chopped fruits and vegetables. This reaction often occurs due to the activity of polyphenol oxidase (PPO) and peroxidase (POD) enzymes. Blanching is used to deactivate the relevant enzymes. Blanching is done before such processes as drying, canning, and freezing and somewhat determines the quality of the product. Sulfites are multi-functional compounds that inhibit enzymatic and non-enzymatic browning. Dehydration is one of the oldest techniques for keeping food products. Osmotic dehydration process has been emphasized in recent years due to the negative effects of conventional drying procedures, this process is done to partially remove the water from the plant tissue by immersion in a salt or salt solution. Chitosan is non-toxic, biodegradable substance that can be used as an edible coating to maintain the quality and increase the life after the fruits and vegetables harvest. This protective performance improves by adding antimicrobial, antioxidant. The lemongrass extract was added to the chitosan coating as antimicrobial. The purpose of this study is to investigate the effect of chitosan coating containing lemongrass extract on the shelf life of dehydrated quince fruit slices.
Materials and methods: Metabisulfite was used in order to prevent the browning reactions of slices prepared from blanching, water vapor and chemical solution of sodium. Then, quince slices are dehydrated with osmotic solutions of sorbitol, sucrose by immersion with chitosan containing (0, 0/5, 1 and 2 % lemongrass extract) coated and kept in sterile plates at refrigeration temperature (4±1˚C) for 4 weeks. The experiment was carried out in factorial method based on a completely randomized design with three iterations. Variables include the type of osmotic solution (sucrose, sorbitol) and coating treatments (chitosan coating containing 0, 0/5, 1 and 2% lemongrass extract). The studied characteristics included weight loss (%), acidity, pH, ascorbic acid concentration, total phenol, inhibitory activity of free radical (RSA), color properties (components L*, a*, b*, BI) of tissue that was investigated in the first, second, third and fourth week.
Results & discussion: Fruits coated with chitosan containing 2% lemongrass extract had less weight loss changes than other treatments. This can be due to the role of the extract in preventing decay, its antimicrobial properties and the formation of the semipermeable membrane by coating, which prevents weight loss. Edible coatings containing extract, by changing the internal atmosphere and reducing the respiration rate of the fruit, help to maintain better organic acids .Lemongrasses extract causes the delay in the consumption of organic acids in metabolic reactions, including respiration, due to its antioxidant properties. It seems increasing the pH of the fruit is the result of biochemical changes in the fruit during storage time, such as the decomposition of organic acids into sugars and participating the respiratory cycle in which the coating of chitosan containing extract can reduce the breakdown of organic acids by reducing respiration rate. The decrease in the drop of Vitamin C and phenolic compounds of the coated sample is due to oxygen permeation reduction and the creation of adapted atmosphere by coating. The high level of antioxidant activity of lemongrass extract is because of high phenolic compounds of which the highest amount was observed in treatment coated with chitosan containing 2% lemongrass extract. By increasing the concentration of the extract, its phenolic compounds increases which preserve more vitamin C and phenolic compounds and consequently antioxidant properties. Free radical inhibition activity was preserved due to better preservation of phenolic compounds, ascorbic acid and increasing the antioxidant capacity of fruit by chitosan coating containing lemongrass extract. The product brightness decreases during storage. Before the hot-water blanching coating process, sodium metabisulfite and osmotic dehydration have inactivated browning enzymes. Therefore, in quince coated with chitosan, the amount of color changes was not tangible due to the less respiration and as a result, less enzymatic activity of fruit. Coating containing lemongrass extract has created due to the color of coating extract with the green-tinted color. The increase in the extract concentration reduces the redness and increases the greenness of fruit, which is because of the extract color and as the effect increases, the concentration increases. By decreasing the brightness, increasing the greenness and yellowness during storage time and the browning increased. In quince coated with chitosan, the amount of softening wasn’t tangible due to less respiration and as a result, less enzymatic activity of fruit. As the concentration of lemongrass increases the stiffness of the tissue is reduced due to the effect of lemongrass on the fruit tissue cells that cause structural changes. Based on the results, the edible coating containing 2% lemongrass extract is suggested as the best formulation.
Mina Kargozari; Morteza Jamshid EIni
Abstract
Introduction: The osmotically dehydrated carrots can be added directly into soups, stews or can be used in a broad range of food formulations including instant soups, snack seasoning and etc. Osmotic dehydration is a suitable way to produce the shelf-stable products or partially dehydrated foods ready ...
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Introduction: The osmotically dehydrated carrots can be added directly into soups, stews or can be used in a broad range of food formulations including instant soups, snack seasoning and etc. Osmotic dehydration is a suitable way to produce the shelf-stable products or partially dehydrated foods ready to place in other complementary processes such as air-drying, freezing and others. Modeling can certainly make differences in the food industry, leading to reduced costs and increased profitability. In food technology, at the simplest level, there are equations that determine the relationship between two or more variable. Simulation models in operation units and food preservation systems have attracted much attention in the past four decades. The mathematical equations describing mass transfer during osmotic dehydration, allow a better understanding of the composition of the material and operating parameters during dewatering. In this regard, many experimental and theoretical models have been reported in the literature but experimental models have more popularity because of easier applications. Regarding the classification of modeling in food processes, kinetic models are classified among theoretical models. It was ideal if we could use kinetic models based on fundamental scientific theories for the purposes of prediction and controlling the changes that occur in real food systems. But the complexity of the food makes the direct application of basic models impossible. The alternative is the direct study of kinetics on real food. As a result, the obtained models would be experimental or semi-experimental. Kinetics has developed as a powerful tool in modeling food quality features and in other words the modeling of food quality estimation is almost equivalent to the modeling of reaction kinetics in foods. The present study aimed to evaluate kinetics of osmotic dehydration of carrot cubes in terms of solid gain and water loss, which was studied at three glucose syrup concentration levels (30, 40 and 50% w/w), three salt concentration levels (5, 10 and 15% w/w) and three temperature levels of osmotic solution (30, 40 and 50°C) for 240 min. The experimental data were fitted to different semi-empirical kinetic models including Magee, Peleg and Page.
Materials and methods: Fresh well graded carrots were washed and peeled manually. A vegetable dicer was used to prepare carrot cubes of dimensions 1 cm× 1cm× 1 cm. The cubes were washed with fresh water to remove the carrot fines adhered to the surface of the fruit. The initial moisture content of the fresh carrot cubes varied from 86% to 90% (wet basis). Considering the greater effectiveness of a mixture of solutes over a single solute, a binary solution of salt and glucose syrup was used as the osmotic solution. The samples were excluded from the osmotic solution after 15, 30, 60, 120, 180 and 240 minutes. Carrot cubes were then washed with deionized distilled water, and were dried using a paper towel. Evaluation of mass exchange between the solution and sample during osmotic dehydration were made by using water loss and solid gain parameters. The experimental data were then fitted to different semi-empirical kinetic models including Magee, Peleg and Page which are widely used in biologic fields and the parameters of the models were determined. Data fitting was conducted using Microsoft Excel spreadsheet (Microsoft Office, 2010) using SOLVER add-in. Coefficient of determination (R2), chi-squared (χ2) and root mean square error (RMSE) were used to determine the best suitable model. An analysis of variance was conducted to determine the significant effects of process variables on solid gain and water loss.
Results and Discussion: At the beginning of the osmotic dehydration process, because of the high osmotic driving force between the concentrated solution and the fresh sample, the rate of water removal and solid gain was relatively high. Although water loss reached nearly the equilibrium conditions towards the late processing times, solid gain kept increasing. This increase in solid gain blocks the surface layers of the product, which reduces the concentration gradient between the product and osmotic solution, posing an additional resistance to mass exchange and lowering the rates of water loss at further processing times. It was also observed that while increasing the salt concentration, the solid gain in most of the samples significantly (p
Zeynab FarhaniNejad; Milad Fathi; Mohammad Shahedi
Abstract
Introduction: Banana is one of the most popular tropical fruits in all over the world with notable post-harvest losses. Due to its high moisture content preventing long preservation period. So, it needs a proper preservation method to prevent product lost especially in main produceing countries. Since ...
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Introduction: Banana is one of the most popular tropical fruits in all over the world with notable post-harvest losses. Due to its high moisture content preventing long preservation period. So, it needs a proper preservation method to prevent product lost especially in main produceing countries. Since banana is an un-freezable fruit, thermal processing such as drying or canning could be more appropriate for prolonging its shelf life. On the other hand, high energy consumption and being cost intensive are two most important disadvantages of thermal processing. In order to decrease the side effects of thermal process on quality parameters, pretreatment of samples could be applied to reduce time of main process.Osmotic dehydration is a non-thermal pretreatment which provides partial removal of water by immersing sample in an osmotic solution.But this process also takes a long immersion time to enough reduction of moisture. So this leads to undesirable effect on texture and colors.This study was performed to eliminate some side effects of osmotic dehydration on quality and finally introduce an optimized condition resulting best performance of process.A novel all-knowing method for optimization of process is genetic algorithm (GA) which is a search heuristic that mimics process of natural selection. It generates solutions for the optimization of problems using techniques inspired by natural evolution, such as inheritance, mutation, selection, and crossover. In this research, genetic algorithm was applied to predict optimum condition of osmotic dehydration.Material and methods: Osmotic dehydration was performed using aqueous solution of sucrose in concentration of 45% (w/w) for immersion time of 3 hr. The first challenge was improving mechanical properties of banana slices by adding calcium lactate to sucrose solution in concentrationsof 0, 2, 3 and 4%.For the next step in order to protect samples from enzymatic browning mixture of ascorbic acid (0.25 %) and citric acid (0, 0.5, 1, and 1.5%) were used.The pH of solution was measured for each level of adding citric acids. The efficiency of operation was estimated by computingwater loss and solid gain. Firmness of dehydrated samples wasmeasured using a texture analyzer (INSTRON, 1140, Singapore) and penetration test. Image acquisition technique was applied to measure L*, a* and b* indices.The coefficient of efficiency was defined as the ratio of water loss to solid gain and calculated to estimate performance of treatment in new condition. Finally, optimized conditionsfor maintaining the lowest solid gain and color changes, the highest water loss and firmness waterlosswere predicted by genetic algorithms method. The accuracy of model was investigated using statistical parameters such as mean absolute error (AME), normalized mean square error (NMSE),mean square error (MSE).Results and discussion: The results of experiments showed a significant increase of firmness by adding lactate calcium. This observation was due to complex formation between calcium and cell wall ingredients. Thesecomplexes have a decreasing effect on solid gain.Because complexes preventedmacromoleculesentering such as sucrose to the cells.On the other hand,calcium lactate and citric acid had interaction on mentioned parameters.Firmness showed less firmness when citric acid was added to the solution. Because citric acid as a chelating agents can blockdivalent cations and prevent from effective reaction with plant cells.Also citric acid can disconnect methoxyl groups from protopectinproducing softer texture.However, treated samples still showed firmer texture than control sample. It could be due to the additional effect of citric acid which makes carboxyl groups available for divalent calcium cations during conversion of protopectin to the pectin.For color parameters,only use of citric acid could not decrease the total change of color because yellow index increased due to the hydration of citric acids. But for the use of two factors, a significant decrease of total change of color was observed.For water loss, increase of solvents in each treatment led to raise of water loss due to the increase of osmotic pressure.In this circumstance determination of suitable concentration for each factorresulting best performance is complex, so it is necessary to apply a system canpredict optimized conditions. Genetic algorithms estimated optimum condition formaximum firmness and water loss, minimum solid gain and total change of color.In this condition the concentrations of lactate calcium and citric acid were %3.99 and %0.86, respectively. Also predicted values for water loss, solid gain, firmness and total change of color were earned %18.01, %5.07, 1.47 N and 11.37.MAE, NMSE and AME parameters (2.062, 0.021, and 1.099 respectively) were used for investigation of difference between estimated and experimental data which showed high efficiency of genetic algorithm for optimization of osmotic dehydration of banana.Investigating the efficiency ofcoefficient of treatments showed that application of both factors (calcium lactate and citric acid) significantly had more efficiency in comparison to the control samples regarding quality factors.
Mahdi Irani; Masoud Shafafi; Hasan Irani
Abstract
This paper presents a novel approach to monitor food process based on Modular Neural Networks (MNNs) and fuzzy inference system. The proposed MNN consists of three separate modules, each using different image features as input including: edge detection, wavelet transform, and Hough transform. The sugeno ...
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This paper presents a novel approach to monitor food process based on Modular Neural Networks (MNNs) and fuzzy inference system. The proposed MNN consists of three separate modules, each using different image features as input including: edge detection, wavelet transform, and Hough transform. The sugeno fuzzy inference system was used to combine the outputs from each of these modules to classify the images of quince during osmotic dehydration process. To test the method, for classification, database was made of 108 quince samples’ images (12 classes). In experiments, the developed architecture achieved 91.6% recognition accuracy. Next step, solid gain, water loss and moisture content of quince samples were considered as MNNs outputs, whereas osmotic dehydration time and classified images were MNNs inputs. The minimum %MRE (18.153) with 89% prediction ability for water loss (WL) was obtained when applying two hidden layers with 6 neurons per each two layers. The lowest %MRE (35.5335) with 93% prediction ability for solid gain (SG) was obtained when using 6 and 8 neurons per first and second layer, respectively. And finally %MRE was at least (7.4759) with 96% prediction ability for moisture content (MC) by 6 and 5 neurons per first and second layer, respectively. The results show that this model could be commendably implemented for quantitative modeling and monitoring of food quality changes during osmotic dehydration process.
Mahdi Barmour; Jalal Dehghan nia; Babak Ghanbarzadeh
Abstract
The objective of this study was to evaluate the effect of process conditions and different pretreatments including ultrasound, microwave and osmotic dehydration on mass transfer and oil uptake during deep fat frying of potato slices. Ultrasound pretreatment was performed at frequency of 40 KHz for 10 ...
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The objective of this study was to evaluate the effect of process conditions and different pretreatments including ultrasound, microwave and osmotic dehydration on mass transfer and oil uptake during deep fat frying of potato slices. Ultrasound pretreatment was performed at frequency of 40 KHz for 10 and 30 minutes, microwave pretreatment was conducted at 5 W/g power and osmotic dehydration pretreatment was done in NaCl solutions with concentrations of 1 and 3 percent. Potato slices were then fried at 150, 170 and 190°C for 90, 180, 270 and 360 seconds. The results showed that ultrasound pretreatment for 10 minutes increases oil uptake of samples as compared with control sample, but when samples were exposed to ultrasound for 30 minutes, oil uptake was decreased. In addition, microwave pretreatment reduced oil uptake of potato slices insignificantly. Furthermore, osmotic dehydration pretreatment reduced oil uptake. In order to model oil uptake, experimental data were fitted with 6 models. The aforementioned models had the highest R2 and a minimum value of RMSE.
Hamed Fatemian; Shadi Giahchi; Seyed Ebrahim Hosseini; Abbas Gerami
Abstract
Food dehydration process in several reasons, causes deteriorate qualitative characteristics in final products. It is necessary to use some pretreatments such as osmotic dehydration. In this research, during osmotic dehydration of pear rings, the effects of concentration of sucrose solutions of 50 and ...
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Food dehydration process in several reasons, causes deteriorate qualitative characteristics in final products. It is necessary to use some pretreatments such as osmotic dehydration. In this research, during osmotic dehydration of pear rings, the effects of concentration of sucrose solutions of 50 and 60 percent (w/w), in constant temperature of 30ºC, and reconstitution of osmotic solutions (until 5 times), were investigated on quantitative and qualitative characteristics of osmotic samples, such as pH, hardness, color of texture, total sugar and moisture content of osmotic samples and pH, turbidity, viscosity of solution osmotic. The result showed that with increase concentration osmotic solution and reconstitution of osmotic solutions pH of sample and solution is increase and decrease respectively. It’s because of increase the moisture content and extraction acids from texture of osmotic sample. Also reconstitutions of osmotic solutions will cause increase the turbidity in solution, that reason is increase the production of pigment in solution. Also increases the density of osmotic solutions may cause increase the color of osmotic samples and we can say that the reason is extraction of colorful compound from texture of sample. The most reason of hardness of texture is related to a sample that it processed in a solution that is 5 times concentrated. Finally the coated sample that was osmotic dehydrated and fifth reconstituted solution was known as the superior sample.
Emad Aydani; Mahdi Kashani-Nejad; Mohsen Mokhtarian; Hamid Bakhshabadi
Abstract
In this study, Response Surface Methodology (RSM) was used to optimize osmo-dehydration of orange slice. Effect of osmotic solution temperature in the range of 30 to 60 °C, immersion time from 0 to 300 min and sucrose concentration from 35 to 65 brix degree on water loss, solid gain, moisture content, ...
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In this study, Response Surface Methodology (RSM) was used to optimize osmo-dehydration of orange slice. Effect of osmotic solution temperature in the range of 30 to 60 °C, immersion time from 0 to 300 min and sucrose concentration from 35 to 65 brix degree on water loss, solid gain, moisture content, water loss to solid gain ratio and brix change were investigated by Central Composite Design (CCD). Applying response surface and contour plots optimum for osmotic dehydration were found to be at temperature of 30 °C, immersion time of 229.2 minute and sucrose concentration of 65%. At this optimum point, water loss, solid gain, WL/SG ratio, moisture content (dry base) and brix difference were found to be 30.316 (g/100 g initial sample), 13.51 (g/100 g initial sample), 2.45, 2.77 % and 15.79, respectively. The result of artificial neural network indicated that the perceptron neural network with one hidden layer is able to anticipate the dehydration characteristics. This network predicted solid gain and moisture content with 5 neuron per hidden layers with R2 values of 0.937 and 0.959, respectively and brix difference and water loss with 30 neuron per hidden layer with R2 values of 0.961 and 0.942, respectively.
Mina Akbarian; Babak Ghanbarzadeh; Jalal Dehghan nia; Mahood Sowti Khiabani
Abstract
In this study, the optimization of osmotic solutions (containing fructose, calcium chloride and citric acid) were investigated based on maximum water loss (WL) in the osmotic dehydration of quince. The response surface methodology (RSM) and central composite design, with 18 treatment and 3 replicate, ...
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In this study, the optimization of osmotic solutions (containing fructose, calcium chloride and citric acid) were investigated based on maximum water loss (WL) in the osmotic dehydration of quince. The response surface methodology (RSM) and central composite design, with 18 treatment and 3 replicate, was used for optimizing. The results showed that fructose and calcium chloride had linear and quadratic significant effects (p
