Modelling of mass transfer kinetic in osmotic dehydration of kiwifruit

Osmotic dehydration characteristics of kiwifruit were predicted by different activation functions of an artificial neural network. Osmotic solution concentration (y(1)), osmotic solution temperature (y(2)), and immersion time (y(3)) were considered as the input parameters and solid gain value (x(1)) and water loss value (x(2)) were selected as the outlet parameters of the network. The result showed that logarithm sigmoid activation function has greater performance than tangent hyperbolic activation function for the prediction of osmotic dehydration parameters of kiwifruit. The minimum mean relative error for the solid gain and water loss parameters with one hidden layer and 19 nods were 0.00574 and 0.0062% for logarithm sigmoid activation function, respectively, which introduced logarithm sigmoid function as a more appropriate tool in the prediction of the osmotic dehydration of kiwifruit slices. As a result, it is concluded that this network is capable in the prediction of solid gain and water loss parameters (responses) with the correlation coefficient values of 0.986 and 0.989, respectively

Development and evaluation on a wireless multi-gas-sensors system for improving traceability and transparency of table grape cold chain

There is increasing requirement to improve traceability and transparency of table grapes cold chain. Key traceability indicators including temperature, humidity and gas microenvironments (e.g., CO2, O2, and SO2) based on table grape cold chain management need to be monitored and controlled. This paper presents a Wireless Multi-Gas-Sensors System (WGS2) as an effective real-time cold chain monitoring system, which consists of three units: (1) the WMN which applies the 433 MHz as the radio frequency to increase the transmission performance and forms a wireless sensor network; (2) the WAN which serves as the intermediary to connect the users and the sensor nodes to keep the sensor data without delay by the GPRS remote transmission module; (3) the signal processing unit which contains embedded software to drive the hardware to normal operation and shelf life prediction for table grapes. Then the study evaluates the WGS2 in a cold chain scenario and analyses the monitoring data. The results show that the WGS2 is effective in monitoring quality, and improving transparency and traceability of table grape cold chains. Its deploy ability and efficiency in implantation can enable the establishment of a more efficient, transparent and traceable table grape supply chain.N/

Mathematical modeling of airflow, heat and mass transfer during forced convection cooling of produce in ventilated packages

Forced convection cooling process is the most widely used method of cooling to extend shelf life of horticultural produce after harvest. However, heterogeneous cooling of produce inside different parts of ventilated packages is a serious problem. Therefore, it is essential to design packages that facilitate air circulation throughout the entire package to provide uniform cooling. Selection of appropriate combinations of air temperature and velocity for a given vent design is currently done largely by experimental trial and error approach. A more logical approach in designing new packages, to provide uniform cooling, is to develop mathematical models that would be able to predict package performance without requiring costly experiments.In this study, mathematical models of simultaneous airflow, heat and mass transfer during forced convection cooling process were developed and validated with experimental data. The study showed that produce cooling is strongly influenced by different ventilated package designs. Generally, cooling uniformity was increased by increasing number of vents from 1 (2.4% vent area) to 5 (12.1% vent area). More uniform produce cooling was obtained at less cooling time when vents were uniformly distributed on package walls with at least 4.8% opening areas. Aerodynamic studies showed that heterogeneity of airflow distribution during the process is strongly influenced by different package vent configurations. The highest cooling heterogeneity index (108%) was recorded at 2.4% vent area whereas lowest heterogeneity index (0%) was detected in a package with 12.1% vent area.The magnitudes of produce evaporative cooling (EC) and heat generation by respiration (HG) as well as the interactive effects of EC, HG and package vent design on produce cooling time were also investigated. Considerable differences in cooling times were obtained with regard to independent and simultaneous effects of EC and HG in different package vent configurations. Cooling time was increased to about 47% in a package with 1 vent compared to packages with 3 and 5 vents considering simultaneous effects of EC and HG. Therefore, the effects of EC and HG can be influential in designing the forced-air precooling system and consequently, in the accurate determination of cooling time and the corresponding refrigeration load

International Journal of Farming and Allied Sciences Spray dryers: Applications, performance, essential parts and classifications

ABSTRACT: Spry dryers are one of the most functional types of dryers in chemical, pharmaceutical and food industries. In recent years, various studies have been conducted on the development of essential parts used in spray dryers in order to improve quality of the processed products. Of among unique properties of spray dryers, automatic continuous operation, rapid drying and manufactured products with desired size and density can be referred. The aim of this study was to investigate the dryers' applications and performance, various essential parts including heating systems, atomizer, drying tower and recovery system as well as to classify the dryers based on the flow type, the stage number(s) and the cycle types

Influence of β-cyclodextrin and Sodium Chloride Addition to Oil on Shrinkage Kinetics during Frying of Potato Strips

The aim of this study was to investigate the effect of process conditions and β-cyclodextrin and sodium chloride addition to oil on shrinkage kinetics during deep-fat frying of potato strips. β-cyclodextrin was added to oil at 0.3 and 0.6 g/l and sodium chloride was added at 1 and 3%. Then, potato strips were cut into 1.2×1.2×4 cm3 pieces and fried at 150, 170 and 190˚C for 90, 180, 270 and 360 seconds. The results showed that by increasing process temperature from 150 to 190˚C, shrinkage of fried potato strips is increased. Moreover, increasing process time during deep-fat frying led to increasing of this parameter. Also, by increasing process temperature and time, shrinkage was increased. In additioin, sodium chloride and β-cyclodextrin treatments in both concentrations, separately and simultaneously, decreased the shrinkage, compared to the control samples, from 0.314 to 0.278 (11.46%) on average. Due to the lack of suitable experimental models in the literature for shrinkage modeling during deep-fat frying, a number of experimental models were proposed to model the parameter. The average correlation coefficient between the experimental results with the results of the models was high. Application of additives that affect the surface tension such as β-cyclodextrin and sodium chloride can be considered as a promising strategy to improve the qualitative and quantitative properties of fried products, including reducing the samples shrinkage rate

Modeling Water Vapor Sorption and Permeability in Starch-Montmorillonite Nanocomposite Films

The aim of this study was to investigate the rate of water vapor permeability (WVP) and moisture sorption of starch-montmorillonite (MMT) nanocomposite films. The nanocomposite films were prepared using the casting method andglycerol was used as a plasticizer. The effect of glycerol concentration on WVP of the films was determined at 25°C with a relative humidity of 0-99% (inside and outside of the vials). The results showed that WVP is increased with higher glycerol content in the nanocomposite samples and there is an exponential relationship between the plasticizer concentration and WVP of the nanocomposite films. Additionally, moisture sorption kinetics of nanocomposite samples was studied by placing the films in humid environments conditioned at 25°C and 75% relative humidity. In addition, the Fick's second law and four empirical equations were used to predict the films moisture sorption and the results of the modeling demonstrated that the initial stages of moisture sorption were fully supported by Fick's law. However, by the gradual relaxation of the polymer, its behavior deviated from the law. This result indicated that the concentration gradient was not the only dominant mechanism of mass transfer. The effective moisture diffusion coefficient (D) was increased with increasing MMT concentration. This was attributed to the penetration of clay layers into polymer matrix in the amorphous regions and creation of free spaces in polymer structure. The existence of free spaces in the nanocomposite structure increased the effective moisture diffusion coefficient. Additionally, plasticizer presence facilitated mobility of polymer chains and increased the effective moisture diffusion coefficient

Effect of Surface Modification by Oleic Acid on Physical Properties of Cellulose Nanofibers

Oleic acid was used as a hydrophobic agent to modify cellulose nanofiber (CNF) and the reaction time and fatty acid content were tested in relation to the hydrophilic properties of the products as well as the physicochemical properties of CNF. It was found that the degree of substitution (DS) increased by extending the reaction time though the fatty acid content had no effect on hydrophobicity of CNF. The success of the esterification reaction was confirmed by Fourier transform infrared spectroscopy. Higher degree of substitution led to increased contact angle of CNF surfaces with water, which indicated the increased surface hydrophobicity of modified CNF. The X-ray diffraction analyses showed a lowering trend in crystallinity index and crystallite size with increases in DS value. Surface modification changed the thermal stability of CNF by lowering the degradation temperature from 290.8°C for unmodified cellulose to 195.4°C for highly esterified cellulose. Scanning electron microscopy micrographs revealed that after esterification of CNF with oleic acid, its filamentous shape was preserved. As a result, although the surface modification of CNF by fatty acid increased its hydrophobicity and its ability to mix with non-polar polymers, but it changed CNF physicochemical characteristics and weakened its functional properties