Damage Mechanism Of Korla Fragrant Pear Under Impact Extrusion Synergistic Load And Its Effect On Storage Quality

Korla pear is known as the holy fruit of the Western regions,because of its sweet and smooth,thin skin,thin meat,juice and less slag,popular among consumers.Pear need to go through picking,grading,transportation,storage and other links to be sold to the market,because of the thin skin is vulnerable to mechanical damage,extrusion,impact and two kinds of load interaction caused by the most serious damage,the damage after the pear quality decline speed up,microbial infection makes the pear rot,affect the value of goods,resulting in huge economic losses in the pear industry,therefore,It is of great significance to clarify the law of pear damage under different loads and reveal the mechanism of pear damage to reduce pear waste and improve industrial economic benefits.In this paper,Korla fragrant pear is taken as the research object to study the impact law of impact,extrusion and synergic load on the aromatic pear damage,establish the mathematical model between load and damage volume,combine the appearance characteristics and microstructure of the aromatic pear damage classification grade,establish the aromatic pear damage volume prediction model based on hardness and absorbed energy.The interaction of impact and extrusion load on aromatic pear was studied by using the material wear theory to reveal the damage mechanism of aromatic pear.The storage quality prediction model of pear with different damage forms was established based on adaptive fuzzy neural network(ANFIS).The main research conclusions are as follows:(1)Revealed the impact of single impact and extrusion load on the damage of fragrant pear.The damage volume of fragrant pear increased with the increase of impact height or compression amount in the same picking period,and the damage volume of fragrant pear increased with the delay of picking period under the same loading.Combined with the appearance characteristics and microstructure of fragrant pear,the damage grade was classified as:first-level damage with small cell tissue damage,second-level damage with large area of fragrant pear cells destroyed and shallow marks formed,third-level damage with large area of fragrant pear flesh damage and obvious tissue structure deformation.(2)Revealed the impact of impact and extrusion synergistic load on the damage of fragrant pear.Under the synergistic load,the impact height and compression volume were positively correlated with the damage volume of fragrant pear.Under the same load,the damage volume of fragrant pear gradually increased with the delay of picking date.The mathematical model of synergistic load size and damage volume of fragrant pear was in line with the linear relationship,and the coefficient of determination of the mathematical model R~2 was greater than 0.93176.According to the material wear theory,the synergistic load interaction of sweet pear was studied,and the ANFIS prediction model of damage volume was established based on the hardness and absorbed energy of sweet pear.Finally,the trimf model of membership function was determined to be optimal(R~2=0.9773).Under the impact-extrusion synergistic load,the impact height gradually increased at the same picking period and the same compression amount,and the interaction rate M showed a decreasing trend.The impact-extrusion synergistic load gradually changed from promoting effect to inhibiting effect on the damage of fragrant pear.At the same impact height,M value gradually decreases with the increase of compression amount.In the same picking period,the interaction rate M was all less than 1 under the compression-impact synergistic load,and the compression-impact synergistic load inhibited the damage of fragrant pear.At the same impact height,the interaction rate M gradually decreases with the increase of compression amount.With the same compression amount,the interaction rate M decreases gradually with the increase of impact height.The interaction rate M of the two kinds of collaborative loading modes gradually decreases as the picking period is postponed.Combined with the appearance characteristics and microstructure of fragrant pear,the synergistic load damage of fragrant pear was classified into grades.First-order damage:a small amount of damage was found in the flesh of fragrant pear,but no damage was found in the outer skin.Secondary damage:large damage appeared inside the pear,the skin appeared slight deformation.Tertiary injury:severe internal damage and obvious epidermal damage.Scanning electron microscopy is used to confirm that whatever the type of loads,the damage mechanism of fragrant pear is characterized by collapse and folding of microscopic tissue cell structure,and the relationship between the damage degree and collapse and folding of the cells microstructure is direct proportion.(3)Established prediction models for storage quality of fragrant pears with different forms of damage.Studying the changes in storage quality of fragrant pears with different forms of damage,it was found that as the storage period extended,the weight loss rate and yellow blue value b*of fragrant pears continued to increase,while brightness L,red green value a*,hardness,and soluble solid content(SSC)continued to decrease.The ANFIS model was applied to predict the quality of fragrant pears during storage.Through validation,it was found that using ANFIS to predict the quality indicators of damaged fragrant pears during storage is feasible.The membership function trimf can better predict the weight loss rate of fragrant pears,the membership function pimf can better predict the L value of fragrant pears,the membership function trimf can better predict the a*value of fragrant pears,and the membership function psigmf can better predict the b*value of fragrant pears,The membership function gasuss2mf can better predict the hardness of fragrant pears,and the membership function trimf can better predict the SSC of fragrant pears.