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Evaluation Of Relationship Between Physical Chemistry Index And Dielectric Properties Of Lettuce And Celery During Storage

Posted on:2008-02-26Degree:MasterType:Thesis
Country:ChinaCandidate:S L XinFull Text:PDF
GTID:2121360218454405Subject:Agricultural Products Processing and Storage
Abstract/Summary:PDF Full Text Request
Vegetable is one of necessary food in daily life for containing a lot of nutrition such as vitamin, mineral and fibrino. The quality of vegetable change quickly as higher inherent moisture content during the storage and transportation, and it need monitored manually in industrialization which bring great difficulties in some particular situation such as cold warehouse storage and controlled atmosphere storage. Dielectric property is a response to bound charge in molecule of organism in extra-electric field. Metabolize of vegetable is continuous during post-harvest and the charge of vegetable can be made in organism and responsed to extra-electric field in some particular condition.The result shows that the dielectric parameters have a fluctuating along with the change of space distance in use of parallel plate capacitor during the experiment. Impedance and inductance increased with space distance increasing in the distance of 1cm-7cm, however capacitance has oppositional trend. Impedance and inductance decreased with temperature increasing in reverse of capacitance in the condition of constant humidity. After measuring at voltage from 1V to 5V, every point was measured for 5 times, the suitable voltage is 3V. 17 frequency points from 100Hz to 5MHz are chosen to measure the dielectric properties and analyzed statistically using 5 times measuring. From comparing the average deviation, standard deviation and variation coefficient, the suitable measuring frequency are 100kHz, 400kHz, 5MHz.Caused by the intensive transpiration, serious moisture loss while preserved at room temperature, shrink wilting and become yellow is appeared. Compared the correlation of dielectric properties and physical chemistry index, the results show that there is a best correlation between capacitance and moisture content during storage of lettuce and celery, the coefficient R~2 are 0.9469 and 0.9488 at frequency of 100 kHz, the coefficient R~2 are0.9444 and 0.902 at frequency of 400 kHz.It is feasible to evaluate the quality of vegetable by measuring the dielectric parameters in theory, which can provide an evidence for inspecting nondestructive test system.
Keywords/Search Tags:Dielectric Property, Storage, Vegetable, Quality
PDF Full Text Request
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