Drying kinetics of some vegetables (original) (raw)

Determination of the Coefficient of Initial Drying Speed of Selected Vegetables

Farm Machinery and Processes Management in Sustainable Agriculture, IX International Scientific Symposium, 2017

Efficient production of safe, high quality food is an important element of sustainable agriculture. Fruits and vegetables belong to an exceptional group of materials in food processing, and one method of preservation of growing production of fruits and vegetables is drying them. The work analyses the dependence of the initial drying speed coefficient in the first stage of drying on the initial moisture content in the process of convective drying, using cruciferous (root vegetables), namely, carrot, parsley, celery and beet. Samples of three different thicknesses (3, 5 and 7 mm) were dried at three different temperatures (50, 60 and 70°C), with the constant flow speed of the drying agent. The results were presented graphically, in the form of charts. As expected, the analysis of the results showed that the drying process is faster for materials with higher initial water content. The coefficient of initial drying speed reached lower values for thicker slices, and increased together with the temperature of the drying agent.

Drying kinetics of plant products: Dependence on chemical composition

Journal of Food Engineering, 2013

Kinetics of drying and soaking of fruits and vegetables (apples, pears, grapes, apricots, carrots, tomatoes, peppers, garlic, onions, peas, spinach, pumpkins, mushrooms, oats, perennial ryegrass, and beans) were investigated. The rate constants and the activation energies of drying/soaking were calculated with the use of the initial and final portions of the corresponding kinetic curves. The dependence of the drying kinetics upon the chemical composition of the material was explained with the help of the diffusion model. Within it the plant tissue was modeled by a diffusion membrane and Fick's law was utilized.

Determination of Drying Characteristics of Some Vegetables

Global Journal of Agricultural Innovation, Research & Development, 2015

Drying is, removing the water effect of distorting structure, from the food products with the effect of heat. Direct sun drying, greenhouse drying and supported by solar panel greenhouse combinations were done for drying vegetables. Eggplant, cauliflower, leeks, broccoli were dried. Dry matter and water activity values were measured for each of products on the systems of directly in the sun drying, drying in the greenhouse, the panel + greenhouse. Improvements of the conditions in the greenhouse and then with some modifications should be established such as optimization of the air velocity is thought to be achieved by faster drying.

Study of the parameters' variation in the vegetables drying process

journal-of-agroalimentary.ro

The aim of the paper was the study of the parameters' variation of the vegetables drying process. As materials there were used vegetables with hard texture (celery, carrot, red beet) and as methods there were used the conventional drying (with air convection) and unconventional drying (with microwave and infrared radiations). It pursues the parameters variation as: mass, product's core temperature, humidity, drying time. It was used the hydration as an estimation method of the drying products' texture modification.

Experimental Study of the Effects of Convective Drying on Some Selected Vegetables

Journal of Engineering Research and Reports, 2021

Aim: This work gives the reports on experimental study of the effects of drying on some selected vegetables, namely fluted pumpkin (specimen I), spinach (specimen II), lettuce (specimen III), and waterleaf (specimen IV). Methodology: The vegetable specimens were dried at regulated drying temperatures of 323K, 333K, and 343K, and the percentage amount of water, fat, crude fibre, ash, protein, and carbohydrate, as well as the fungi and bacteria counts in the vegetable specimens was determined at these temperatures. Results: The results revealed that the amount of water in the vegetable specimens reached 0% earlier at the regulated drying temperature of 343K than at the other regulated drying temperatures. The results also indicated that the dried vegetable specimen II has highest fat content of 8.2%, the dried vegetable specimen III has highest crude fibre content of 14.5%, the dried vegetable specimen IV has highest ash content of 18.6%, the dried vegetable specimen I has highest pro...

Drying Behaviour of Some Selected Vegetables of Punjab

The experiments were conducted to study the drying behaviour of common vegetables of Punjab so that useful products could be prepared when required. Fresh brinjal, cabbage, okra and potato were dried after proper preparation in a hot air tray drier at 55°C -65°C. It took 13 -16 hrs of continuous operation for the drier to reduce the moisture content of the vegetable slices, from initial level in range of 321.96% (db) -762.2 % (db) to final value in the range of 5.86 % (db) to 11.08% (db), till equilibrium conditions were established. The drying occurred in falling rate period for all the vegetables with its moisture content reducing non-uniformly with time. The drying rate (% / hr) for these vegetables generally followed exponential decay with slope varying in 0.26 to 0.59 and drying constant in falling rate was found to vary in the range of 0.29 -0.42.

Evaluation of Drying Mass Constants for Some Selected Vegetables

This paper attempts to create data bank on drying mass constants of some selected vegetables. This is to facilitate the prediction of the mass of these materials with respect to any desired moisture content during drying; by applying, model equation developed based on basic drying principle. In this study, freshly harvested vegetables namely spear grass; Gnetum africanum and carrot were cut into three sizes: small, medium and large size. Each sample was oven dried and its mass weighed at an hourly interval until constant mass was obtained. Data were generated; and for each size range and bulk sample, graph plots of moisture content (MC) against drying time, rate of drying versus drying time were carried out coupled with plot of moisture content against the ratio of initial mass to mass at any given time (i.e., M 0 /M t) during drying. Results showed, the drying curve resembled that of an ideal drying curve; and so the generated data is reasonably valid for use in obtaining the dry mass constants. The values of drying mass constants were 0.0347 ± 0.013, 0.3098 ± 0.0138 and 0.1092 ± 0.0122, respectively for spear grass, Gnetum africanum and carrot.

Influence of Air temperature on the Drying Kinetics and Quality Of Tomato Slices

The influence of different drying temperatures on the drying kinetics and quality of tomato slices was studied. In particular, the effect of hot air temperature on the lycopene content, non-enzymatic browning, colour and flavour changes during drying at various temperatures in the range of 50-80 o C was investigated. Drying time reduced from 1140 mins to 540 mins as the air temperature increased from 50 to 80 o C. The non-enzymatic browning increased with temperature from 0.485 to 1.40. The lycopene levels of the fresh tomatoes significantly (p=0.05) increased from an initial value of 2.96 mg/100g to 61.23 mg/100g, 59.10 mg/100g, 60.88 mg/100g, and 65.28 mg/100g when dried at 50, 60, 70, and 80 o C respectively. Eleven out of the twelve sensors used in the electronic nose system indicated flavour degradation of all dried samples compared with the fresh tomatoes. The values of the hue angles recorded for the dried tomatoes ranged between 51.81 o and 61.95 o , revealing that the dried tomatoes were yellow hued, thus indicating less browning. The drying characteristics curves were evaluated against the Page, Henderson and Pabis, and the Logarithmic mathematical models but the Page model best described the drying of tomato slices. The effective moisture diffusivity coefficient increased with increasing drying temperature and was found to be 5.13×10 -10 m 2 s -1 , 6.45×10 -10 m 2 s -1 , 8.44×10 -10 m 2 s -1 , and 10.26 ×10 -10 m 2 s -1 at respective hot air temperatures of 50, 60, 70, and 80 o C with activation energy for moisture removal of 22.28 KJ/mol.

Mathematical modeling of thin layer drying kinetics of tomato influence of air dryer conditions

Thin-layer drying kinetics of Tomato was experimentally investigated in a pilot scale convective dryer. Experiments were performed at air temperatures of 40, 60, and 80ºC and at three relative humidity of 20%, 40% and 60% and constant air velocity of 2 m/s. In order to select a suitable form of the drying curve, 9 different thin layer drying models were fitted to experimental data. The high values of coefficient of determination and the low values of reduced sum square errors and root mean square error indicated that the Midilli et al. model could satisfactorily illustrate the drying curve of tomato. the Midilli et al. model had the highest value of R 2 (0.9997), the lowest SSE (0.22662) and RMSE (0.0040912) for relative humidity of 20% and air velocity of 2 m/s. the Midilli et al. model had the highest value of R 2 (0.99946), the lowest SSE (0.46702) and RMSE (0.0051192) for relative humidity of 40% and air velocity of 2 m/s. the Midilli et al. model had the highest value of R 2 (0.99952), the lowest SSE (0.438982) and RMSE (0.0050188) for relative humidity of 60% and air velocity of 2 m/s. The Midilli et al. model was found to satisfactorily describe the drying behavior of tomato.

Modelling of air drying of fresh and blanched sweet potato slices

International Journal of Food Science & Technology, 2010

Effects of blanching, drying temperatures (50-80°C) and thickness (5, 10 and 15 mm) on drying characteristics of sweet potato slices were investigated. Lewis, Henderson and Pabis, Modified Page and Page models were tested with the drying patterns. Page and Modified Page models best described the drying curves. Moisture ratio vs. drying time profiles of the models showed high correlation coefficient (R 2 = 0.9864-0.9967), and low root mean squared error (RMSE = 0.0018-0.0130) and chi-squared (v 2 = 3.446 · 10 -6 -1.03 · 10 -2 ). Drying of sweet potato was predominantly in the falling rate period. The temperature dependence of the diffusion coefficient (D eff ) was described by Arrhenius relationship. D eff increased with increasing thickness and air temperature. D eff of fresh and blanched sweet potato slices varied between 6.36 · 10 -11 -1.78 · 10 -9 and 1.25 · 10 -10 -9.75 · 10 -9 m 2 s -1 , respectively. Activation energy for moisture diffusion of the slices ranged between 11.1 and 30.4 kJ mol -1 .