Research On Fall Damage Characteristics And Quality Deterioration Law Of Huangguan Pear Fruit

The fruit of the Huangguan pear has a unique taste and rich nutrition,and the market prospect is very broad.Because pear fruit is prone to mechanical damage during postharvest processing.Focusing on the postharvest processing loss of pear fruit,this thesis takes the fruit of Huangguan pear as the research object,studies the biomechanical characteristics of the fruit of Huangguan pear,and the factors affecting the drop damage.Effects of drop damage on physiological and biochemical indexes of the fruit of Huangguan pear during storage.The main research content and results are as follows:1)Research on the biomechanical characteristics of the fruit of the Huangguan pear.The geometric mean diameter,sphericity,surface area,and density range of the fruit were determined to be 76.436～76.960 mm,0.966%～0.985%,18355.904～18607.858 mm²and 0.898～0.909 g.cm^-3;Carried out compression and tensile mechanical tests,and determined the elastic modulus,Poisson’s ratio,failure stress and failure strain of the fruit core to be 2.75 MPa,0.296,0.40 MPa,and 0.18 respectively;the elastic modulus,Poisson’s ratio of the pulp,failure stress and failure strain were 2.48 MPa,0.297,0.39 MPa and 0.21 respectively;the elastic modulus of fruit peel was 31.97 MPa,and Poisson’s ratio was 0.297.2)Research on the influencing factors of fruit drop damage of Huangguan pear.Aiming at the influencing factors of postharvest processing on the fruit damage of Huangguan pear,an orthogonal experiment was carried out to analyze the primary and secondary relationship of the impact of drop height,fruit quality,and impact materials on fruit damage.The research results showed that the primary and secondary order of the influencing factors of fruit damage was drop height,impact material,and fruit quality,and the impact of drop height and impact material on fruit damage was extremely significant,and the impact of fruit quality on damage was significant.3)Finite element simulation of fruit drop damage of Huangguan pear.According to the measured geometric parameters and mechanical parameters of Huangguan pear fruit,the finite element model of the drop collision of Huangguan pear fruit was constructed using Abaqus software,and the drop height and collision material were used as design variables to simulate the drop collision process of Huangguan pear fruit.Regression fitting was performed on the damage volume.The simulation results show that the critical heights of drop damage for steel plates,wood plates and HDPE plates are 131.90 mm,150.56 mm,and 170.14 mm,respectively.4)Research on the regularity of quality deterioration of damaged Huangguan pear fruit during storage period.The effects of drop and collision conditions on the changes of physiological and biochemical indexes of Huangguan pear fruit during storage were studied.The results of the study found that with the increase of drop height and storage time,the fruit weight loss rate,ethylene production,respiration rate and titratable acid increased,and the hue angle,firmness and soluble solids of the fruit decreased compared with the control group.