Studies On The Physical And Mechanical Properties Of Mongolian Snakegourd Seeds

As everyone knows, the medical and economical value of Mongolian snakegourd (Trichosanthes kirilowii maxim.) is tremendous. The physical and mechanical properties of Mongolian snakegourd seeds, like those of other grains and seeds are needed in the design and construction of equipment and structures for handling, transportation, processing and storage of the seeds and in the assessment of the product quality. Various types of cleaning, grading, separation and conveying equipment can be designed and constructed on the basis of the physical properties of seeds. Therefore, the results of physical and mechanical properties of seeds are valuable. In the research, the basic properties, optical properties, compression properties, friction properties and electrical conductivity of seeds with respect to different moisture content were determined by using apparatus and home-made devices, variations with the moisture content were analyzed, the correlation between different physical and mechanical properties and moisture content were established, and the mechanism of variation was discussed;Meanwhile, variance analysis was carried out on the seeds, and the difference between the mean values was investigated by using the Duncan's multiple range tests. Mean values were reported with the standard deviation. Main conclusions of this research are shown in the following.1. Studies on the basic properties of Mongolian snakegourd seedsIn the moisture range of 6.67 to 38.76% (w.b.), various basic properties of Mongolian snakegourd seeds were determined by using different apparatus. The main conclusions are shown as follows. The first, the principal dimensions (the major, intermediate and minor), arithmetic mean diameter and geometric mean diameter of seeds increased with increase in moisture content to a maximum value at the moisture content of 30.71% (w. b.), and correlation coefficient (R) was 0.855, 0.822 , respectively. The second, in the above moisture range, the sphericity of seeds was similar. The third, particle density, one thousand seed weight increased linearly with increase in moisture content, and correlation coefficient (R) was 0.988, 0.999, respectively. The fourth, seed volume, surface area of seeds increased with increase in moisture content to a maximum value at the moisture content of 30.71% (w. b.), and correlation coefficient (R) was 0.92, 0.878 , respectively. The fifth, bulk density, porosity of seeds increased with increase in moisture content and it followed a second-order polynomial regression, the determination coefficient (R~2) was 0.99, 0.985, respectively.2. Mechanical properties of Mongolian snakegourd seeds under compressionloadingThe mechanical properties of Mongolian snakegourd seeds were determined in terms of average rupture force, deformation, energy absorbed and toughness (energy absorbed by the seed per unit volume). Samples at various moisture contents were compressed along the X-, Y -, and Z-axis. The X- axis is the loading axis through the length dimension, while the Y- axis is the transverse axis containing the minor dimension (width) at right angles to the X-axis, and Z-axis is the transverse axis containing the minimum dimension (thickness). Several conclusions are drawn form the investigation as follows. In the first, it was observed that the rupture force increased with increasing deformation to a maximum value at the initiate crack and thereafter decreased in magnitude with an increase in deformation. In the second, the deformation at seed rupture increased with an increase in moisture content for loading along the X-, Y -, and Z- axis, and correlation coefficient (R) was 0.965, 0.988, 0.936, respectively. In the third, the highest rupture force, energy absorbed and toughness in all moisture content levels were obtained for the seed loaded along the X-axis, while compression along the Y-axis required less compressive force, energy absorbed and toughness to extract the kernel as compared to other two compression axes. Rupture force, energy absorbed and toughness of seeds compressed along the X-, Y -, and Z- axis decreased to a minimum value at a moisture content and later increased as moisture content was increased further. The relationship between moisture content and rupture force, energy absorbed and toughness followed a second-order polynomial regression, the determination coefficient (R2) of regression equation of rupture force was 0.986, 0.958, 0.97, the determination coefficient (R2) of regression equation of energy absorbed was 0.986, 0.952, 0.95, the determination coefficient (R2) of regression equation of toughness was 0.979, 0.979, 0.954, respectively. In the fourth, according to the Duncan's multiple range tests, it wan showed that the effect of moisture content, compression axis and moisture by compression axis interaction on the rupture force, energy absorbed and toughness was found to be statistically significant for loading along X-, Y -, and Z- axis. In the fifth, it was observed that there was no kernel breakage for loading along the X- and Y-axes in this study. Especially, at higher moistures, there was always the tendency of the kernel breakage for loading along the Z-axis.3. Studies on the frictional properties of Mongolian snakegourd seedsIn the moisture range of 6.67 to 38.76% (w.b.), angles of repose, coefficient of dynamic friction, angles of static friction of Mongolian snakegourd seeds were determined by using home-made devices, such as inclined surface device, measuring device of repose angle and coefficient of dynamic friction measuring device. The main conclusions are shown in the following. In the first, on stainless steel, unpolished wood or plywood, and rubber, angles of repose, coefficient of dynamic friction, angles of static friction increased with increase in moisture content to a maximum value at the moisture content of 22.69% (w. b.), and thereafter decreased gradually. Secondly, at the same moisture content, the highest value of angles of repose, coefficient ofdynamic friction, angles of static friction was on the rubber, the second was on the wood or plywood, while the least was on the stainless steel. Thirdly, according to the Duncan's multiple range tests, difference among the materials, moisture content, and the interaction of material and moisture content was found to be statistically significant for the angles of repose, coefficient of dynamic friction, angles of static friction.4. Studies on the color properties of Mongolian snakegourd seedsInstrumental measurements of color characteristics were performed with a colorimeter (SC-80, Kangguang ) for a 10° observer, normalized light D65 and a 10° diaphragm. Color was described on the CIELab scale. The metric chroma and hue angle as well as the absolute color difference AE*ab, were calculated according to the equations for the seeds in all moisture content levels. Main conclusions are shown in the following. In the first, L* (lightness), a* (redness and greenness), b* (yellowness and blueness) and C* (metric chroma) of the seed increased with increase in moisture content and it followed a second-order polynomial regression, the determination coefficient (R2) was 0.991, 0.988, 0.986, 0.986, respectively. In the second, H* (hue angle) decreased linearly with increase in moisture content, and correlation coefficient (R) was —0.986. In the third, the values of lightness difference, yellowness and blueness difference, metric chroma difference were higher between different moisture content as compared to the values of redness and greenness difference, hue angle difference;the absolute color difference between the moisture content of 6.67% (w. b.) and 14.69% (w. b.) was found to be statistically insignificant, as well as between the moisture content of 22.69% (w. b.) and 22.69% (w. b.).5. Studies on the electrical conductivity of Mongolian snakegourd seedsInstrumental measurements of electrical conductivity characteristics were performed with a conductivity meter (DDB-6200, REX), and the absolute electrical conductivity was calculated according to the equations for the seeds in all moisture content levels. Several conclusions were drawn from the investigation. Firstly, the absolute electrical conductivity of seeds increased linearly with increase in moisture content, and correlation coefficient (R) was 0.987. Secondly, according to the Duncan's multiple range tests, difference among the moisture content was found to be statistically significant, except for the variation between the seed of the moisture content of 14.69% (w. b.) and of 22.69% (w. b.).