Study On Physical Characteristics And Damage Of Potato Tubers At Harvesting Stage

Potato tuber damage during mechanized harvesting seriously reduces the quality of seed potatoes,the appearance and inherent quality of commodity potatoes,and affects the quality of potato primary processed products and the potato convenience food industry,as well as the economic and social benefits of the entire potato processing industry.The potato industry has caused huge economic losses,and it has also severely restricted the healthy development of the potato industry.Therefore,it is very important to study the potato tuber damage and improve the potato harvesting equipment to ensure the sustainable,efficient and healthy development of the potato industry.In this study,based on the physical characteristics of potato tubers,combined with factors such as the harvesting process of potato harvesters,the structure and materials of key components of the separation and transportation of potato,the mechanism of mechanical damage of potato tubers was systematically studied to reduce the mechanical damage during potato harvesting..The main conclusions are as follows:?1?Taking Gansu 7 and Xindaping potato tubers as the research object,physical properties such as the triaxial dimensions,density,static friction coefficient,and dynamic friction coefficient of tubers were measured.The triaxial dimensions of tubers basically obey the normal distribution.The potato shape index distribution of Gansu 7 potato is in the range of 1.09¹.84,its shape is close to the sphere,and the average density is 1.207g/cm³;the potato shape index distribution range of Xindaping It is 0.92 to 2.65,and its shape is flat and close to a long ellipsoid,with an average density of 1.048g/cm³.The estimated volume of potato tubers is very close to the measured volume.The overall estimation model can accurately estimate the potato tuber volume and can be used for parameter statistics in the selection process of germplasm resources.The coefficient of dynamic and static friction of potato tubers is slightly different from that of different friction objects.According to the selected friction object,the friction material is rubber plate,tuber,and 65Mn.The static friction coefficient value of Gansu 7 is generally greater than Xindaping.?2?The recovery coefficient of potato tubers at the harvesting stage was tested and analyzed on a self-made measuring device.The results showed that the impact of factors on the recovery coefficient of potato tuber collision was:collision material,tuber drop height,tuber quality,tuber moisture content,drop direction and potato varieties.The recovery coefficient of tuber collision between potato and 65Mn steel,rubber,potato and soil blocks decreased in turn.The recovery coefficient of potato tuber collision decreased with increasing height of drop,tuber mass and moisture content,and the coefficient of determination of regression equation was greater than 0.9.The research results can provide reference for the optimization design of key parts of potato harvester.For the part that needs to reduce the potato collision recovery factor,rubber buffer materials should be used as far as possible to reduce potato damage.?3?The evaluation system of potato tuber mechanical damage was constructed.A large number of statistics and analysis of the sample damage form classify the damage of potato tubers in the mechanical harvest process according to different forms,and determine the corresponding indicators and detection methods according to the type of damage,which is the potato tuber extrusion,drop collision and The objective evaluation of vibration damage provides the basis and standard.?4?The vibration test of potato tubers at the harvesting stage was carried out using an independently designed swinging test stand.The effects of experimental factors and interactions between factors on vibration damage and storage quality of potato tubers were analyzed,and a corresponding regression model was established.The results showed that the influence of the dip angle on the surface damage index of potato tubers was extremely significant.Vibration frequency and vibration time had significant effects on potato tuber respiratory intensity and cell permeability;vibration frequency and vibration time had a significant effect on potato tuber surface damage index;sieve plane inclination had no significant effect on potato tuber respiratory intensity cell permeability.The experimental factors affecting the damage index of potato tuber were order of inclination,vibration time and vibration frequency.The experimental factors affecting the respiration rate and cell permeability of potato tuber were in order of vibration frequency,vibration time and dip angle of screen surface.When the vibration time was 20s,the vibration frequency was 6Hz,and the inclination angle of the screen was 17.5°,the surface damage index,respiratory intensity and cell permeability of potato tuber were 12.13%and 11.14mg?CO₂?·kg^-1·h^-1?13.11%,respectively.the harvested potatoes had the smallest vibration damage and the longest storage time.?5?The relationship between potato static load characteristics and crush injury during harvest and experimental factors was studied by single-factor test and orthogonal test,and the correlation between potato tuber static load characteristics and injury was analyzed.The results showed that the hardness,breakage strength,deformation,contact stiffness,elastic modulus and damage volume of potato tubers were significantly related to the direction of pressure,variety and indenter type.There is a certain degree of correlation between the static load characteristics of potato tuber and the damage volume.The correlation degree of potato tuber damage volume from the largest to the smallest is deformation,breakage strength,hardness and contact stiffness,and the correlation values are 0.7463,0.6285,0.5763,0.4794 respectively.0.3278,the relationship between the deformation of potato tuber and the damage volume is the closest.The extent of tuber damage can be indirectly evaluated by the deformation of potato tuber.?6?The potato tubers of“Gansu 7”were used as test objects,and drop crash tests under different factors were conducted to study the influence of experimental factors on the impact characteristics of potato tubers and tuber damage.The results showed that the impact material,potato drop height and moisture content had a significant effect on the impact characteristics,but the drop direction was not significant.The interaction of impact material and drop height has a significant effect on the damage index,and the interaction term of collision material and potato moisture content has a significant effect on the damage index.There was a significant positive correlation between the maximum deformation and the damage index?r=0.729,P<0.05?.There was a significant negative correlation between the recovery coefficient and the damage index?r=-0.573,P<0.05?.The recovery coefficient was obtained.The linear regression models for the maximum deformation and damage index are R²=0.9907 and R²=0.9923.There is no correlation between peak acceleration and damage index?|r|<0.5,P>0.05?.When the potato collided with the 65Mn steel,potato tubers,rubber plates,and soil blocks,the critical heights for serious epidermal abrasions were350 mm,420 mm,500 mm,and 550 mm,respectively.Therefore,potato tubers do not collide with the control of the falling height of potatoes and the rational use of buffering properties of the collision material.