جستجوی مقالات مرتبط با کلیدواژه « electrical conductivity » در نشریات گروه « صنایع غذایی »

In this study, using thyme medicinal plant without using heat by osmotic method, sugar solution with maximum active ingredients was produced. Effects of temperature (25, 35 and 45 degrees Celsius), sucrose osmotic solution concentration (40, 50 and 60%) and sampling time (15, 30, 60, 90, 120, 180, 240 and 360 minutes) on the amount The removal of active ingredients from the plant and the change in pH values and electrical conductivity (EC) were evaluated. Then the effect of blanching with hot water in (30, 60, 120 and 180 seconds) and ultrasound (0, 15 and 30 minutes) on the osmotic processing were investigated separately. The highest EC was in the solution with 40% sucrose concentration and 45°C and the lowest was in osmotic solution with 60% concentration and 45°C. Blanching before osmosis resulted in increased pH and EC. Blanching for 30 seconds caused the greatest increase in EC. Treatment with 30 minutes ultrasound increased the pH and EC in samples compared to 15 minutes of ultrasound. The chromatographic results of the control samples and the sample containing thyme extract in sucrose solution showed the release of polar and non-polar active compounds in the osmotic solution. The release of different compounds showed a difference in their release rate during the osmosis process. Finally the results showed that the extraction of active ingredients of medicinal plants was possible by osmosis process, so that the pH and EC changed over time. The product of this research can be used in the production of beverage syrups and food. In this method, the damages of other methods of extraction of effective substances such as solvent extraction, use of heat in extraction and drying of medicinal plants such as distillation and essential oil extraction methods are minimized.

Milk is the only known substance in nature that can provide the body with complete and balanced nutrition. Recombined milk is a milk replacement product. Recombined milk components are more easily adjustable than milk components. Using electrical conductivity, valuable information is available about the quality of different materials, including food. In addition, by this method, as a simple and practical tool, the quality of many foods can be controlled. In this study, Response Surface Methodology (RSM) was used for modeling and optimization of the electrical conductivity of recombined milk. The effects of protein (1, 2, 3, 4 and 5%), Lactose (4, 6, 8, 10 and 12%), fat (3 and 6%) and temperature (50, 55, 60, 65 and 70ºC) independent variables on electrical conductivity of recombined milk as dependent variables (response) were evaluated. Process variables were statistically significant (p<0.01) as quadratic regression model for this response. The R2 factor for the modeling of the electrical conductivity of Recombined milk was 0.92 by the response surface method. Optimum conditions for the electrical conductivity of the Recombined milk in the usual range (4 to 5.5 mS/cm) contained protein 3.4%, lactose 7.7%, fat 3% and temperature of 63.9 °C.

Among the foods consumed on a daily basis, milk has the most appropriate and balanced ingredients, that is the reason milk called whole food. Milk is the only known substance in nature that can provide the human body with complete and balanced nutrition. Recombined milk is a milk replacement product. Recombined milk components are more easily adjustable than milk components. The electrical conductivity is referred to as conductivity of specific material against the electric current, which is expressed in micro Siemens units per cm (mS/cm). Using electrical conductivity, valuable information is available about the quality of different materials, including food. In addition, by this method, as a simple and practical tool, the quality of many foods can be controlled. The aim of this study was to investigate the electrical conductivity of recombined milk affected by temperature, protein percentage, and lactose content.

In order to investigate the effect of protein percentage (1, 2 and 3%) and percentage of lactose or sugar content (4, 6 and 8%) on the electrical conductivity of milk, pure dry milk powder without dietary supplementation was used. Lactose powder was used to increase the lactose content of dry milk powder. Sodium caseinate was used to increase the protein content of dry milk powder. Distilled water was used to increase the volume of samples. Total experiments were carried out at three temperature levels (50, 55 and 60 ºC). Data analysis was also done using SPSS 16 software.

The results showed that temperature, protein percentage, and lactose percentage had a significant effect on the electrical conductivity of recombined milk. The electrical conductivity of the recombined milk ranged from 2.31 to 5.7 mS/cm at 50°C, 8% lactose, 1% protein, and 60°C, 4% lactose, 3% protein, respectively. The greatest and least effect on the electrical conductivity of recombined milk was related to the effect of protein percentage and lactose percentage, respectively. By increasing the temperature, the electrical conductivity of the reconstituted milk has increased significantly. The greatest changes in electrical conductivity (16%) of recombined milk occurred by the influence of temperature factor in protein 1% and lactose 4% and its value ranged from 2.44 to 2.83 mS/cm. In addition, the lowest changes in electrical conductivity (6%) of recombined milk were obtained by the temperature factor of 3% protein and 8% lactose, and it was increased from 4.68 to 4.95 mS/cm. By increasing protein content, the electrical conductivity of recombined milk has increased significantly. The most changes in electrical conductivity (107%) of recombined milk occurred by the influence of protein percentage at 55 °C and 6% lactose and its value ranged from 2.42 to 5.6 mS/cm. In addition, the lowest changes in the electrical conductivity (100%) of reconstituted milk occurred by the influence of protein percentage at 55 °C and 4% lactose, and its content increased from 2.5 to 5 mS/cm 5. These results indicate that the protein percentage factor has the most effect on the electrical conductivity of recombined milk (compared to two temperature factors and lactose percentage). By increasing lactose content, the electrical conductivity of recombined milk has decreased significantly. The greatest changes in electrical conductivity (13%) of recombined milk occurred by the influence of lactose percentage at 60 °C and protein 3% and its content decreased from 5.7 to 4.95 mS/cm. Also, the smallest changes in electrical conductivity (1.5%) of reconstituted milk occurred by the influence of lactose percentage at 55 °C and 2% protein, and its content decreased from 5.55 to 4.48 mS/cm. The maximum and minimum amount of electrical conductivity of reconstituted milk was 5.7 mS/cm at 60°C, 4% lactose and 3% protein, and 2.31 mS/cm at 50°C, 8% lactose and 1% protein, respectively.

In this study, the moisture content of kiwifruit in vacuum dryer was predicted using artificial neural networks (ANN) method. The protein (1, 2, 3 and 4%), lactose (4, 6, 8 and 10%), fat (3 and 6%) and temperature (50, 55, 60 and 65ºC) were considered as the independent input parameters and electrical conductivity of recombined milk as the dependent parameter. Experimental data obtained from electrical conductivity meter, were used for training and testing the network. In order to develop neural network firstly experimental data were randomly divided into three sets of training (70%), validating (15%) and testing model (15%).  In order to develop ANN models, we used multilayer perceptron with back propagation with momentum algorithm. MLP models trained as two, three and four layers. The total number of hidden layers and the number of neurons in each hidden layer were chosen by trial and error. The best training algorithm was LM with the least MSE value. The highest coefficient of determination (R2) and lowest mean squared error (MSE) were considered as the criterion for selecting the best network. The network having three layers with a topology of 4-4-1 had the best results in predicting the electrical conductivity of recombined milk. This network has two hidden layers with 8 neurons in the first hidden layer and 5 neurons in the second hidden layer.  For this network, R2 and MSE were 0.992 and 0.011, respectively. These results can be used in milk processing factories. The correlation between the predicted and experimental values in the optimal topologies was higher than 99%.

In the present study, Azivash leaf gum (Corchorus olitorius L.) was used for the first time with the help of an electroporation technique in the presence of poly-vinyl alcohol as a natural nanofibre. At first, the effect of different concentrations of Azivash gum aqueous solution (2, 2.5 and 3 g / l) with polyvinyl alcohol (P70: G30, P60: G40, P50: G50 and P0: G100) on viscosity and electrical conductivity as the main soluble parameters was studied. The results showed a significant increase in viscosity concentration with gum concentration and volume ratio of polyvinyl alcohol (p <0.01). Regardless of the concentration of Azivash gum, by increasing the ratio of gum to polyvinyl alcohol, the electrical conductivity increased significantly (p <0.05). In the study of shear stress-shear rate of Azivash gum and polyvinyl alcohol solutions, pseudoplastic behavior was confirmed. Investigating the fitting of rheological data with Herschel-Balkly models, power law and casson showed that the Herschel-Balkly model with the highest R2 / RMSE is desirable to describe the flow behavior. The values ​​of the flow index and consistency coefficient were determined by the model. After the electrospining of azivash leaf gum-polyvinyl alcohol in a constant condition (voltages of 18 kV, volumetric flow rate of 0.7 ml/hr and needle distance to a collector plate of 12 cm), by microstructure analysis and based on the morphology of bead-free fibres, the Azivash gum formulation at 2 g / L concentration and the mixing ratio of 70:30 with polyvinyl alcohol was selected as the most suitable formulation with a mean nanofiber diameter of 90 nm. Based on FTIR resulrs, addition of gum to polyvinyl alcohol caused an increase in peak intensity due to carbonyl and hydroxyl groups glycosidic vibrations. Also, the thermal stability of the gum nanofibers of Azivash improved in the presence of polyvinyl alcohol.

The soaking stage is the most important steps of the parboiling process. Hot soaking requires precise control, because starch granules are gelatinized during soaking. Degree of starch gelatinization (DSG) of rice was measured using differential scanning calorimetry (DSC). This method has high costs and can not be utilized to obtain online data. Thus, in this study a mathematical relationship correlating the DSG of rice to the paddy physical (paddy moisture) -electrical (electrical conductivity (EC) and capacitance sensor output voltage of paddy water) during the soaking portion of the parboiling process was formulated. For measuring of electrical properties of paddy water was designed and manufactured an experimental system of ohmic heater and capacitance sensor for measuring electrical conductivity and voltage, respectively. For doing experiment, paddy (Shiroudi variety) was parboiled by soaking at 60, 65 and 70 oC. At each temperature, samples of paddy and paddy water were selected at five different soaking times. The experimnet results showed that paddy moisture content (21.18-35.1%w.b.), electrical conductivity (0.63-1.6 mS.cm-1) and output voltage of capacitance sensor (216 – 595 mV) of paddy water and rice DSG (5.5 to 31.7%) increased significantly (p<0.05) and exponentially (R2>0.98), exponentially (R2>0.93), quadraticly (R2>0.95) and exponentially (R2>0.96) during soaking, respectively. Linear relationships were fitted between DSG of parboiled rice and physical-electrical properties of paddy water. The results revealed that EC of paddy water be able to predict the DSG of rice during soaking with the lowest regression error.

Sugar with low price in compare to the amount of calories, producing is as one of the important nutrients in the daily diet especially for poor communities. On the other hand in the sugar industry due to consumer demand for high quality and variety in products ion exchange technigues are used wich affect the chemical properties of sample. So the aim of this study was to investigate the physicochemical properties (Brix, pH, color and electrical conductivity) of raw and white sugar by a cationic resin, heating for two hours in 70 ◦C and the anionic resin. The results showed that the brix of samples was decreased by using resin. The results also showed that cationic resin were effetive in decreasing the pH value and increasing the parameter by using anionic resin. In addition reduction in color of both sugar solution was observed by resin. In the case of white sugar color reduction was in direct contact with pH and white sugar slight increase in color was observed after using anionic resin. On the other hand the results indicated the electrical conductivity was increased by cationic resin. So the treatment by cationic resin and heating in 70 ◦C had the highest electrical conductivity.

Microemulsions are optically transparent and thermodynamically stable systems showing selective and safe extraction capability of nutraceuticals from different plant matrices. Moreover, investigation of their nanostructure (normal micelle, reverse micelle, bicontinuous) provides noteworthy information with regard to application purposes. Therefore, in the present study the extraction of lycopene from the industrial waste of tomato paste plants was done using microemulsion technique (prepared with natural surfactant of saponin and cosurfactant of propylene glycol), and the divergent nanostructures of the single phase microemulsion were investigated by electrical conductivity and rheological measurements. These measurements along dilution lines in the pseudo-ternary phase diagram and water titration method showed good ability in simple and fast determination of different nanostructures and their boundaries in microemulsion region. Moreover, Herschel–Bulkley model fitted best with upward mode (shear rate–shear stress) of all tested samples.

The present work was undertaken with an objective to study the design، development and construction and performance evaluation of a batch ohmic heating system. Direct ohmic heating (Joule’s heating) is a technology to warm up the food using an electric energy where electric current is passed through a material which gets heated by virtue of its electrical resistance. In this study، firstly new batch ohmic heating containing a static cell (200-mm-long Teflon cylinder with 94 mm diameter at a constant voltage gradient of 15 V/cm) was developed and constructed. To evaluate the performance of this heating unit various food systems was used، i. e. sodium chloride solutions (concentrations: 0. 2 and 0. 6% w/v)، starch solutions (2 and 5% w/v) and 0. 5% w/v NaCl، a two-phase food systems (5% starch، 0. 5% w/v NaCl and oil (1% and 10% w/v). Heating rates for previously named food systems were determined by tracking and recording the temperature profiles for a given time intervals. The data indicates the heating up rate increases with increasing concentrations of starch and salt but decreases with increasing oil in food.

Electrical conductivity (EC) is the ability to conduct electricity which is expressed as micro Siemens per centimeter (µs/cm). The conductance of the milk is attributed mainly to its salts content especially Na، K and Cl ions. Since measuring the milk’s EC is a rapid and inexpensive method for determining of the milk quality، therefore correlation between EC with pH، acidity، and total microbial count (TC) in raw milk was studied in order to assess the freshness of milk in this research. In a pilot study، using skim milk، pH، acidity، and TC were changed and EC measured at 25ºc. Then a total of 200 samples of whole milk were obtained from the receiving platform of a dairy plant in Tehran. In one trial 100 samples of whole milk were examined for pH، acidity and TC. Also EC was measured in different temperatures of milk samples at the time of the analysis. In the second 100 samples of whole milk، pH، acidity and TC determined and EC measured at 25ºC. According to the results obtained from the pilot study (with 10 repetition)، increasing the pH caused a decrease in EC and vice versa (P0/05). No significant correlation was found between EC with pH، acidity and TC in other trials (P>0. 05). It seems many factors may affect the EC in raw whole milk. Therefore measuring EC solely can not determine the milk quality.