Moisture Ratio Data Research Articles

Mathematical modeling of drying behavior of cashew in a solar biomass hybrid dryer

The main objective of this study is to analyze the drying behavior of cashew nut experimentally in a so- lar biomass hybrid dryer using mathematical models. Suitability of fifteen different mathematical drying models available in the literature is used to describe the drying characteristics of cashew. Experimen- tal data of moisture ratio, temperature and relative humidity obtained from different dryer conditions were fitted to the various empirical drying models. The performance of the drying model was compared based on their correlation co-efficient (R 2 ), Root Mean Square Error (RMSE) and Reduced Chi-Square ( χ2 ) between the observed moisture ratios. The two terms and Midilli models showed the best fit under so- lar drying. Page model was found to be the best model for describing the thin layer drying behavior of cashew for biomass drying and hybrid drying.

Drying characteristics of zucchini and empirical modeling of its drying process

The aim of the study was to dry zucchini ( Cucurbita pepo) by two different methods (convective hot-air (CHD) and microwave-assisted drying (MWD)). The effect of air temperature (60, 70 and 80°C), microwave (MW) power (180, 360, 540 W) and sample thickness (5 and 10 mm) on some drying characteristics of zucchini were investigated. Thirteen mathematical models available in the literature were fitted to the experimental moisture ratio data. The coefficients of the models were determined by non-linear regression analysis. It was determined that the model that fits the moisture ratio data the best varies at different drying conditions. Increasing drying temperature and MW power and reducing sample thickness improved the drying rate and drying time. Drying in microwave has reduced the drying time by 52-64% for zucchini. It was found that the effective moisture diffusivities increased with increasing temperature and MW power. MWD samples had better rehydration ratios compared to ones dried only in tray drier for 5 mm thickness.

Drying characteristics of zucchini and empirical modeling of its drying process

The aim of the study was to dry zucchini (Cucurbita pepo) by two different methods (convective hot-air (CHD) and microwave-assisted drying (MWD)). The effect of air temperature (60, 70 and 80°C), microwave (MW) power (180, 360, 540 W) and sample thickness (5 and 10 mm) on some drying characteristics of zucchini were investigated. Thirteen mathematical models available in the literature were fitted to the experimental moisture ratio data. The coefficients of the models were determined by non-linear regression analysis. It was determined that the model that fits the moisture ratio data the best varies at different drying conditions. Increasing drying temperature and MW power and reducing sample thickness improved the drying rate and drying time. Drying in microwave has reduced the drying time by 52-64% for zucchini. It was found that the effective moisture diffusivities increased with increasing temperature and MW power. MWD samples had better rehydration ratios compared to ones dried only in tray drier for 5 mm thickness.

Drying characteristics of osmo-convectively dried sapota slices

Sapota is a highly productive, nutritious and tropical fruits of India contributing 1424 MT, on 160 ha area with the productivity of 8.9 MT/ha. In India, sapota is generally consumed fresh. Ripened sapota cannot be stored more than a day or two. However, it is highly perishable in nature, ripens faster and becomes unfit for consumption very soon. The post-harvest losses in sapota fruits is in the ranged from 25-30%. These losses mainly occur due to high ethylene evaluation and metabolic activity. To avoid the huge wastage, the surplus could be processed and preserved properly. Wastage of large quantities of sapota fruits before it reaches the consumer is due to poor quality transportation as well as storage facilities. One effective method of reducing this huge loss would be by converting it into various commercial sapota products like slices, powder, juice, concentrate, etc. Therefore, it is necessary to produce the final product with wholesome, soft and of acceptable quality. The products may be dehydrated, canned and refrigerated. Dehydrated fruit products have inherent advantages, such as prolong shelf-life, higher degree of resistance to bacterial attack and lower transportation, handling and storage costs. The use of faulty dehydration process causes quality defects of dehydrated fruits as tough woody texture, slow or incomplete rehydration, loss of juiciness and shrinkage. Osmotic dehydration is less energy intensive technique than air or vacuum drying process, since it can be conducted at low or ambient temperature. It is the process of water removal from a product by immersion in concentrated aqueous solution. The osmotic process prior to convective drying can be used as a pre-treatment for the dehydration of food prior to further processing such as freezing, vacuum drying, etc. Therefore, a study was proposed to investigate osmotic behaviour and drying characteristic of sapota slices under osmo-convective drying process. The optimum conditions for osmotic treatment were determined with the values of 27.72% WR and 8.25% SG for process parameters, syrup temperature of 47.36 °C, and sugar concentration of 53.53 °B for 167.85 min duration. After optimization, osmotically treated samples were dried in convective dryer at temperature 40, 50 and 60 °C. The convective drying behavior and drying characteristics was investigated for osmo-dehydrated sapota samples, at air temperature of 40, 50 and 60 °C. It was observed that the moisture content of the product was reduced exponentially with drying time and no constant rate period was observed. To determine the most suitable drying equation the the moisture ratio data of osmosed sapota dried at various air temperatures were fitted into the six thin-layer drying models. Among those two term model as best fitted for drying data. This indicated that the total mass transfer resistance was primarily due to the internal moisture diffusion within the sample.

Mathematical modeling of drying behavior of cashew in a solar biomass hybrid dryer

The main objective of this study is to analyze the drying behavior of cashew nut experimentally in a solar biomass hybrid dryer using mathematical models. Suitability of fifteen different mathematical drying models available in the literature is used to describe the drying characteristics of cashew. Experimental data of moisture ratio, temperature and relative humidity obtained from different dryer conditions were fitted to the various empirical drying models. The performance of the drying model was compared based on their correlation co-efficient (R2), Root Mean Square Error (RMSE) and Reduced Chi-Square (χ2) between the observed moisture ratios. The two terms and Midilli models showed the best fit under solar drying. Page model was found to be the best model for describing the thin layer drying behavior of cashew for biomass drying and hybrid drying.

Moisture transfer modeling during solar drying of potato cylinders considering shrinkage

ABSTRACTIn the present work, the thin layer drying kinetics of potato during natural convection solar drying was investigated experimentally. Cylindrical potato samples with length 50 mm and varying diameter of 8, 10 and 13 mm were dried in an in-house designed and fabricated laboratory scale mixed-mode solar dryer. Thirteen different thin-layer mathematical models were fitted to the experimental moisture ratio (MR) data. The obtained results indicated that the Modified Page model could satisfactorily describe the drying curve of potato cylinders with higher value of R2 and lower values of RMSE and χ2. The shrinkage parameter is incorporated in the analytical diffusion model to study the moisture transfer mechanism of potato cylinders. It was observed that the values of effective diffusion coefficient (Deff) and convective mass transfer coefficient (hm) are overestimated in the range of 85.02–90.27% and 39.11–45.11% for the range of sample diameter examined, without considering the shrinkage effect in the mass transfer analysis. A Multiphysics approach was adopted in this study to get insight into the drying behavior of potato cylinders in terms of food-moisture interactions during the solar drying process. The predicted results of MR are in close agreement with the experimental data. Moreover, the anisotropic behavior of shrinkage as well as the moisture distribution inside the potato cylinder was very well described by Multiphysics model.

EFFECT OF DRYING METHODS ON CHARACTERISTICS OF CHERRY TOMATO AND MATHEMATICAL MODELING

In this study, cherry tomatoes (Lycopersicon esculentum var. Cerasiforme) were dried with two differentmethods (tray dryer (TD) and microwave (MW)) using different temperatures (60, 70 and 80 °C)-MWpowers (140, 210 and 280 W). The effects of drying parameters on some drying characteristics of cherrytomatoes were investigated. Thirteen mathematical models available in the literature were fitted to theexperimental moisture ratio data and the coefficients of the models were determined by non-linearregression analysis. It was observed that drying in microwave oven has reduced the drying time by38%. The effective moisture diffusivities increased with increasing temperature and MW power. Thebest fit models were found as Logarithmic, Wang&Sing and Midilli. The activation energy values werefound as 25.00 ve 15.3 W/g for samples dried with TD and MW, respectively. The closest color valuesto wet sample were detected at 60 °C for TD, but there were no differences between MW powers. Colorvalues of MW samples were found be better than TD samples. Maximum rehydration rate was detectedat 60 °C for TD and 210 W for MW

Influence of temperature on vacuum drying characteristics, functional properties and micro structure of Aloe vera (Aloe barbadensis Miller) gel

Aloe vera possesses therapeutic, antioxidant and some other functional properties. These properties may be affected by processing operations. The present study investigated the influence of operating temperature on vacuum drying characteristics, functional properties and the inner solid structure of the fresh aloe vera gel. The gel was dried at a constant pressure of 720 mm Hg in the drying chamber at varying temperature of 30–60°C. The experimental data of moisture ratio of Aloe vera were used to fit different models and the effective moisture diffusion coefficients and activation energy were also calculated. The Page model was found to be the best fit to experimental data. The functional properties like water retention capacity, fat absorption capacity, and swelling of the dried product were studied and found to be decreased with increasing operating temperature. The damage to the inner solid structure was more pronounced at higher temperatures because of faster mass transfer through the pores of the solid. The best quality product was obtained when the temperature was maintained at 30°C.

Drying Kinetics of Eggplant (Solanum melongena) in a Fluidized Bed Dryer: Experimental Evaluation and Modelling

The drying kinetics of eggplant were studied experimentally in a laboratory-scale fluidized bed dryer. Experiments were conducted at drying temperatures of 60, 70, and 80°C and at constant air velocity of 3.10 ms−1. The drying rate and moisture ratio were determined as a function of time. At any given temperature, only the falling rate period was observed during the drying process. Effective moisture diffusivity was in the range 2.667–4.311 × 10−8 m2/s while activation energy of 23.5 kJ mol−1 was obtained from the Arrhenius equation. The experimental moisture ratio data was fitted to ten mathematical models. Statistical analysis showed that the by Demir et al. has the best fit quality. In terms of product quality, the dried samples had low rehydration ratio of 4.889. In addition, compared to direct sunlight drying, the dried product from the fluidized bed dryer exhibited better color quality.

Modeling the Drying Behavior of Unsalted and Salted Catfish (A rius sp.) Slabs

The effect of air temperature on the drying behavior of unsalted and salted catfish (Arius sp.) slabs (10 × 5 × 1 cm) was investigated. Drying at 30 and 40C occurred in both the constant rate and falling rate periods, while drying at 50 and 60C occurred in the falling rate period only. Drying rate constants increased from 0.0474 to 0.2352 1/h for unsalted slabs and from 0.0819 to 0.3038 1/h for salted slabs as drying temperature increased from 30 to 60C. Diffusion coefficients increased from 1.61 to 5.79 × 10–10 m2/s in unsalted slabs and from 2.31 to 8.55 × 10–10 m2/s in salted slabs. Six mathematical thin layer drying models were applied to the moisture ratio data and the two-term model gave the best prediction. The rehydration ratio averaged 1.20 and 1.22 for unsalted and salted slabs, respectively. A drying temperature of 50C for 8 h is recommended. Practical Applications Drying of both fresh and salted fish continues to be of importance in many developing countries as a preservation method. In the Caribbean region, dried, salted fish remains a very popular part of the cuisine due to the flavor, and many imported brands dominate the supermarket shelves due to the poor inferior sensory characteristics and keeping quality of locally produced salted fish. Improvement in the drying methods for local and regional fish types requires a better understanding of the drying mechanisms and how drying is affected by various controllable factors. The present work seeks to investigate the drying of locally available catfish (Arius sp.). It focuses on the interaction between process conditions, drying kinetics and product quality to arrive at clear conclusions which can facilitate the improved production of dried, salted catfish fillets and which can be beneficial to the industry.

Dehydration kinetics of onion slices in osmotic and air convective drying process

The effect of different pre-treatments (i.e. osmotic dehydration in 10, 15 and 20°Brix NaCl solution and drying air temperature of 50, 60 and 70°C) on drying behaviour of onion slices were investigated. The onion slices were dried in a laboratory model tray dryer. Drying of onion slices occurred in falling rate period. Five thin-layer drying models (Exponential, Page, Henderson and Pabis, Logarithmic and Power law) were fitted to the moisture ratio data. Among the drying models investigated, the Page model satisfactorily described the drying behaviour of onion slices. The effective moisture diffusivity of pre-treated samples was higher than that of non-treated samples

Moisture migration by magnetic resonance imaging during eggplant drying: a preliminary study

SummaryThe paper investigated the effect of hot‐air drying (50, 60 °C) on the physical properties of cylindrical eggplant samples. Drying kinetics, water profiles along longitudinal and transversal sample sections through nuclear magnetic resonance imaging (MRI) and volumetric shrinkage were determined. During the drying process at 50 °C, the volume of removed water was found lower than the reduction in sample volume, while at 60 °C it was higher. MRI showed that the water migration mainly occurs transversally than longitudinally. The curves of mass water loss obtained by both the standard weighting method and MRI showed conformity. Experimental data of moisture ratio and of shrinkage volume were fitted using empirical models available in the literature. This preliminary study showed that the nondestructive MRI technique offers the possibility to study water distribution in food during drying processes. The quantitative moisture distribution maps allow future development and verification of models for prediction of mass transport phenomena in foods during drying.

The model and mass transfer characteristics of convection drying of peach slices

The influences of drying temperature, hot air velocity and thickness of peach slice on the drying process were studied in a laboratory convective hot air dryer. The experimental data of moisture ratio of peach slices were used to fit the models and the effective moisture diffusion coefficients (Deff) were calculated. Moreover, the relative relations between the Deff and drying temperature was also related. The result showed that the Page model showed the best fit to experimental drying data for drying temperature, with the increase of temperature from 60 to 80°C, the Deff varied from 5.6083×10−10 to 1.3388×10−9m2·s−1, it fitted the Arrhenius equation, which the activation energy was 42.53kJ·mol−1; the Wang and Singh model was found to be the most satisfactory for air velocity, with velocity from 0.423 to 1.120m·s−1, the values of Deff varied from 6.6626×10−10 to 1.1350×10−9m2·s−1; the Logarithmic model was found to be the most satisfactory for the thickness of peach slice, with thickness from 0.002 to 0.004m, the values of Deff varied from 4.1543×10−10 to 1.1007×10−9m2·s−1.

Drying characteristics of paddy in an integrated dryer.

Drying characteristics of paddy (long grain variety PR-118 procured from PAU, Ludhiana) in an integrated dryer using single as well as combined heating source was studied at different air temperatures. The integrated dryer comprises three different air heating sources such as solar, biomass and electrical. Drying of paddy occurred in falling rate period. It was observed that duration of drying of paddy from 22 to 13% moisture content (w.b.) was 5-9h depending upon the source of energy used. In order to select a suitable drying curve, six thin layer-drying models (Newton, Page, Modified Page, Henderson and Pabis, Logarithmic and Wang and Singh) were fitted to the experimental moisture ratio data. Among the mathematical models investigated, Wang and Singh model best described the drying behaviour of paddy using solar, biomass and combined heating sources with highest coefficient of determination (r (2)) values and least chi-square, χ (2), mean bias error (MBE) and root mean square error (RMSE) values. However, Page model adequately described the drying behavior of paddy using electrical heating source.

Kinetics of Food Biopolymer Film Dehydration: Experimental Studies and Mathematical Modeling

The dehydration process in thin biopolymer-based films, involving the two main macromolecules in food systems, namely, proteins and polysaccharides, has been investigated. Experimental measurements of the weight loss of polymer films were carried out in an enclosed Perspex chamber under controlled conditions of temperature, relative humidity, and air flow. We found that all of the experimental moisture ratio data for films of pure biopolymers, as well as their mixtures, can be superimposed on a single scaled dehydration curve. According to theoretical calculations, this curve cannot be described by a moisture diffusion-dominated drying process, irrespective of whether film shrinkage is included or ignored. We also derived an analytical expression for evaporation-controlled drying. When film shrinkage is fully taken into account in the calculations, very good agreement between the experiments and the theoretically derived curve is obtained. However, the theoretical results can be improved even further by considering a model that includes both diffusion and evaporation processes, with diffusion being fast but nonetheless finite, so as to only play a minor secondary role in the dehydration of such films. Theoretical models have also been extended to describe systems in which film shrinkage can also arise from changes in the partial molar volume and not just loss of moisture. Using a variable “effective” partial molar volume for water provides a possible method for modeling the entire drying process over different stages of dehydration in which the solid phase adopts significantly contrasting structures.

MASS TRANSFER KINETICS OF BANANA SLICES DURING OSMO‐CONVECTIVE DRYING

ABSTRACT The mass transfer kinetics of banana slices during osmotic dehydration in terms of water loss and solid gain in sugar syrup was studied. The effect of process parameters such as thickness of banana slices (4, 8 and 12 mm), sugar syrup concentration (40, 50 and 60% w/w) and sample‐to‐sugar syrup solution ratio (1:2, 1:4 and 1:6) on water loss and solute gain were also evaluated. Water losses and solid gains were increased with increase in sugar syrup concentration and banana slice sample‐to‐sugar syrup solution ratio and it has increased with the decrease in thickness of banana slices. Two‐factor analysis of variance for all experiments indicated that osmosis time of banana and sugar syrup solution concentration, sample‐to‐sugar ratio and thickness of banana slices were highly significant, whereas combination osmosis time and sugar syrup solution concentration, sample‐to‐sugar ratio and thickness of banana slices were nonsignificant. Osmotic time of 5–6 h was required to attain maximum water loss and solid gain by banana slices. The optimum best combination of banana osmosis for water loss and solid gain were found to be: 50% sugar syrup solution + 8 mm thickness of banana slices + 1:6 sample‐to‐sugar syrup solution ratio. Drying kinetics of osmosis banana slices were studied in a laboratory model tray dryer at 55, 60 and 65C air temperature. Seven thin‐layer drying models were fitted to the experimental moisture ratio data. Among the mathematical models investigated, the Wang and Singh model satisfactorily described the drying behavior of banana with high r2 values of 0.9989. The effective moisture diffusivity ranged from 5.3 × 10−8to 9.3 × 10−8 m2/s.PRACTICAL APPLICATIONSThe process of osmotic dehydration can be used for the preparation of shelf‐stable products for the purpose of use during off‐season. The quality of pre‐osmosed banana slices are much more superior to the product dehydrated with the convectional method of convective dehydration. The osmotically dehydrated banana slices can be used as banana‐figs, fruit candy, fruit toffee, infant food and it can become part of foodstuffs like cakes, pastries and many others.

Kinetics of Thin Layer Drying of Button Mushroom

Drying kinetics of white button mushroom (Agaricus bisporus) slices in a fluidized bed dryer at three different drying air temperatures of 45, 55 and 65°C with constant drying air velocity of 2.5 m.s-1 was studied. The drying of mushroom slices occurred in the falling rate period. Seven thin-layer drying models, commonly used for perishable fruits/vegetables, were tested for the drying behaviour of mushroom slices. The logarithmic model fitted best to moisture ratio data with higher R2 and least c2 , MBE, RMSE values. The effective moisture diffusivity in white button mushroom increased from 9.21x10-8 to 1.49x10-7 m2.s-1with increasing drying air temperatures in the fluidized bed dryer. The average activation energy of 36.39 kJ.mol-1 was required for detaching the water molecules from mushroom slices during fluidized bed drying.

Modeling of Thin-Layer Drying of Apple Slices in a Semi-Industrial Continuous Band Dryer

The drying kinetics of apple slices was investigated in a semi-industrial continuous band dryer. Apple slices with a thickness of 5 mm were dried at temperatures of 50, 60 and 70 °C, air velocities of 0.5, 1.0 and 1.5 m/s and chain linear velocity of 1.85E-04, 2.22E-04 and 2.78E-04 m/s. The Weibull model was fitted to the experimental data of moisture ratio against sample position using MATLAB computer program. The low reduced chi-square and RMSE and the high regression coefficients indicated the suitability of the Weibull model for predicting moisture ratio of apple slices during drying in length of continuous band dryer. Correlations of the scale and shape parameter of the Weibull model with the variables of T, Ua and Uc were determined. The transport of water during drying was described by Fick’s second low and effective diffusivity varied from 9.24E-08 to 3.5E-07 m2/s. The energy of activation was described by the Arrhenius equation and varied from 35.37 to 45.51 kJ/mol.

Modeling of thin-layer drying of potato slices in length of continuous band dryer

The main goal of this paper is to investigate the thin-layer drying behavior of potato slices in a semi-industrial continuous band dryer. Potato slices with thickness of 5 mm were used for drying experiments. The experiments were done at air temperatures of 50, 60 and 70 °C, air velocities of 0.5, 1 and 1.5 m/s and chain linear velocities of 1.85 × 10 −4, 2.22 × 10 −4 and 2.78 × 10 −4 m/s. Three drying models were fitted to the experimental data of moisture ratio in order to assess a suitable form of the drying curve for potato drying. The Page model was selected as the best according to R 2, χ 2 and RMSE. The effective diffusivity varied from 3.17 × 10 −7 to 15.45 × 10 −7 m 2/s and the energy of activation was found in the range of 39.49–42.34 kJ/mol.

Thin layer drying kinetics of cocoa and dried product quality

Studies were carried out to investigate the cocoa drying kinetics and compare the quality of the dried beans produced from sun and artificial hot air drying. Currently, these are the methods commonly used by cocoa farmers and plantations to dry cocoa beans. Drying trials were conducted in thin layer using natural sun light and by hot air inside an air-ventilated oven at air temperatures of 60 °C, 70 °C and 80 °C. Comparison was also made against freeze-dried cocoa beans for quality assessment. The quality attributes assessed were colour (L*, a*, b* and hue angle), texture (hardness and fracturability) and polyphenol content (total polyphenols, epicatechin and catechin contents). Theoretical modelling was performed on the drying kinetics using Fick's law of diffusion and to determine the effective diffusivity values. Reasonable values were obtained for the coefficient of determination (R2) between the experimental and predicted moisture ratio data (range 0.9845–0.9976). Effective diffusivity values were found within the range reported in literatures (range 1.61 × 10−10 m2 s−1–8.01 × 10−11 m2 s−1). Quality assessment showed significant differences (p