Quantitative Characterization Of Impact Damages Of Korla Fragrant Pears And Influences On Storage Quality

As a special fruit in southern Xinjiang,Korla fragrant pears have become a pillar industry in local economic development.Due to the thin skin and crisp taste,Korla fragrant pears are easy to suffer mechanical damages during harvest,transportation and storage.Impact damage is one of major forms of mechanical damages.Korla fragrant pears with hidden impact damages are difficult to be recognized by eyes and they are easy to be mixed with good ones.In the storage period,Korla fragrant pears with hidden impact damages are easy to rot from the damage position and expand quickly,thus influencing the storage quality.Therefore,identifying damaged Korla fragrant pears and disclosing influences of impact damages on quality of Korla fragrant pears are problems that have to be solved urgently at present.It can provide guidance to post-harvest damages and storage technological control,and facilitate sustainable sound development of Korla fragrant pear industry.In this study,a mathematical model of impact height and damage area of Korla fragrant pears was constructed to realize quantitative characterization of impact damages and disclose influences of impact damages on storage quality.Moreover,a mathematical model of the relationship between impact height and deformation energy of Korla fragrant pears was constructed based on the law of conservation of mechanical energies.The threshold of hidden impact damage height of Korla fragrant pears was determined.The mathematical model of impact damage area and electrical parameters of Korla fragrant pears was constructed,which disclosed the variation laws of electrical parameters of Korla fragrant pears with different damage degrees in the storage period.Moreover,the variation laws of storage quality of Korla fragrant pears with impact damages were disclosed and a storage quality prediction model of Korla fragrant pears based on the adaptive network-based fuzzy inference system(ANFIS)was built.Some major conclusions could be drawn:(1)The impact damage threshold of Korla fragrant pears was explored.The impact damage prediction models of Korla fragrant pears caused by wooden plates and corrugated boards all conform to the quadratic function.When the contacting material is fixed,the damage degree of Korla fragrant pears is related with fruit quality and impact height.The impact height-rebounding height relation curve of Korla fragrant pears conforms to the Sigmoidal model.The critical hidden impact damage heights of A-level(130g±5),B-level(110g±5)and C-level(110g±5)for Korla fragrant pears are 37.21 cm,37.77 cm and 38.06 cm,respectively.Results provide theoretical references to implementation of damage-reduced harvest and transportation technologies in the Korla fragrant pear industry.(2)The impact damage characterization method of Korla fragrant pears based on electrical properties is proposed.In the chosen range of test frequency,the quantitative models of electrical parameters and impact damage area conform to the quadratic function models,with coefficient of determination(R2)>0.9371.The equivalent parallel capacitance(Cp)increases gradually with the extension of storage time,while complex impedance(Z)decreases gradually.The equivalent parallel resistance(Rp)has a weak correlation with storage time.Given the same storage time,Cp,Rp and Z decrease continuously the increase of test frequency.Moreover,Cp,Rp and Z decrease gradually with the increase of impact height.In the storage period,the optimal test frequency of impact damages of Korla fragrant pears is 1MHz and the Cp is the optimal electrical parameter.Results provide theoretical references to post-harvest damage identification and quantization of Korla fragrant pears during transportation and storage.(3)The storage quality prediction method of Korla fragrant pears is proposed.Weight loss ratio of Korla fragrant pears increases as the storage time prolongs,while hardness and soluble solid content decrease.The adaptive network-based fuzzy inference system is feasible to predict storage quality of the damaged Korla fragrant pears.The adaptive network-based fuzzy inference system model which uses the membership function trimf can be used to predict weight loss ratio of Korla fragrant pears with impact damages,with R2 of 0.9876.The adaptive network-based fuzzy inference system model which uses the membership function gaussmf can be used to predict hardness of Korla fragrant pears with impact damages,with R2 of 0.9923.The adaptive network-based fuzzy inference system model which uses the membership function gbellmf can be used to predict soluble solid content of Korla fragrant pears with impact damages,with R2 of 0.9930.Results provide references to predict storage quality of damaged Korla fragrant pears.Research conclusions can provide theoretical and practical guidance to post-harvest damage reduction and storage technological control of Korla fragrant pears.