Esref Isik

Geometric and Mechanical Properties of Mung Bean (Vigna Radiata L.) Grain: Effect of Moisture

In this research, selected geometric and mechanical properties of mung bean grain were evaluated as a function of moisture content. Five levels of moisture content ranging from 7.28 to 17.77% d.b. (dry basis) were used. The average length, width, thickness, arithmetic and geometric mean diameters, sphericity, thousand grain mass and angle of repose ranged from 5.145 to 6.199 mm, 3.760 to 4.474 mm, 3.537 to 4.223 mm, 4.147 to 4.965 mm, 4.090 to 4.893 mm, 0.795 to 0.789, 52.3 to 64.6 g, and 25.87 to 29.38° as the moisture content increased from 7.28 to 17.77% d.b., respectively. The bulk density was found to be decreased from 821.3 to 745.2 kg/m3, whereas the grain volume, true density, porosity, terminal velocity, and projected area were found to be increased from 27.88 to 47.33 mm3, 1230.0 to 1456.7 kg/m3, 30.43 to 46.57%, 4.86 to 5.29 m/s, and 17.48 to 19.26 mm2, respectively. There is a 43% increase in surface area from grain moisture content of 7.28 to 17.77% d.b. The static coefficient of friction on various surfaces increased linearly with the increase in moisture content. The rubber as a surface for sliding offered the maximum friction followed by galvanised iron, medium density fibreboard, stainless steel, aluminium and glass sheet. As moisture content increased from 7.28 to 17.77%, the rupture forces values ranged from 67.39 to 39.44 N; 63.86 to 42.18 N, and 53.96 to 41.79 N for thickness (Z axis), length (Y-axis) and width (X-axis), respectively.

Color and Microstructure Properties of Tomatoes Dried by Microwave, Convective, and Microwave-Convective Methods

In this study, color and microstructure changes of tomato samples were investigated after microwave (90, 160, 350, and 500W), convective (50 and 75°C), and microwave-convective (90W-50°C, 90W-75°C, 160W-50°C, and 160W-75°C) drying treatments using a laboratory microwave-convective oven. The combined microwave-convective drying decreased the drying time required when compared to drying with either convective or microwave drying alone. The color of the samples dried at 50°C was closest to the fresh samples compared to other drying conditions. All color values of fresh tomato were affected by drying. Scanning electron microscopy images showed that disruption of the tomato samples significantly elevated with increasing drying temperature or microwave power level.

Some engineering properties of white kidney beans ( Phaseolus vulgaris L.)

Some engineering (physical and mechanical) properties of white kidney bean grains ( Phaseolus vulgaris L.) were determined as a function of moisture content in the range of 10.01 to 25.00% dry basis (d.b.). The average length, width and thickness were 8.638, 16.747 and 4.958 mm, at a moisture content of 10.01% d.b., respectively. Nonetheless, the thousand grain mass increased from 472.5 to 696.2 g, the projected area from 128.13 to 198.83 mm 2 , the true density from 1128.05 to 1290.85 kgm -3 , the porosity from 39.79 to 56.38% and the terminal velocity from 5.51 to 8.50 ms -1 in the moisture range from 10.01 to 25.01% d.b. The static coefficient of friction of white kidney bean grains increased linearly against surfaces of six structural materials, namely, rubber (0.501 to 0.727), stainless steel (0.384 to 0.468), aluminium (0.345 to 0.499), galvanized iron (0.346 to 0.489), medium density fibreboard (MDF) (0.325 to 0.426) and glass (0.287 to 0.345) as the moisture content increased from 10.01 to 25.00% d.b. The shelling resistance of white kidney bean grains decreased as the moisture content increased from 105.18 to 71.44 N. Key words: Engineering (physical and mechanical) properties, white kidney beans, moisture content, thousand grain mass, static coefficient of friction.

Microwave heat treatment of dent corn (Zea mays var. indentata sturt.): Drying kinetic and physical properties

This study is on the determination of drying kinetics of corn and selecting proper model in microwave drying method. For this purpose, semi-mathematical models earlier specified were run with test results; the coefficients in the equations as well as X 2 , root mean square error (RMSE) and R 2 values were found and they were compared with the developed model. Also, the corn’s physical and mechanical features at initial and final-drying moisture values and post-drying color parameters were specified. It was concluded according to these values that the recommended model is the best model, which can define the drying curves at the practices at 400, 550, 700 and 800 W, but Page 2 is the best model at 300 W in drying corn by microwave. It was determined according to initial and final moisture values that the reduction in moisture value causes decrease in other physical properties measured with the exception of porosity. Key words: Microwave, dent corn, physical properties, color parameters, drying.