Kertészeti termények minőségbecslése dielektromos eljárással = Quality assessment of fruits and vegetables by dielectrical method

Alma, burgonya, repa elektromos impedancia spektrumat es reologiai jellemzőit megmertuk. A mert impedancia spektrumokat kulonboző elektromos modellekkel kozelitettuk, es meghataroztuk az impedancia parametereket (ellenallasok, kapacitasok, relaxacios idők, elektromos permittivitas es vezetőkepesseg). A mechanikai hiszterezis gorbekből es az allando deformacio soran az erő(idő) fuggvenyekből az altalanositott Maxwell modell alapjan kiszamitottuk a reologiai parametereket (rugalmassagi modulusok, viszkozitasok). Korrelacios vizsgalatokat vegeztunk a dielektromos es reologiai parameterek kozott. Megallapitottuk, hogy az impedancia parameterek alkalmasak lehetnek a kerteszeti termenyek minősegbecslesere. Ennek alkalmazasakent pl. az impedancia parameterek valtozasat felhasznalhatjuk az alma szeletek szaritasa soran az egyes szaritasi szakaszok kovetesere. Az impedancia parameterek valtozasa tukrozheti a szerkezeti valtozasokat is: 1. az impedancia nagysaga az almahejtol a maghaz fele csokken; 2. az impedancia erteke fokozatosan kisebb lesz, ha fokozatosan noveljuk a merő elektrodara (s ezaltal a mintara) hato erőt, ez a valtozas reverzibilis, ha az erő kisebb a folyashatarhoz tartozo erőnel. | Electrical impedance spectrum and rheological characteristics of apples, potatoes and carrots were measured. The measured impedance spectra were approached with various electrical models, and the impedance parameters (resistances, capacitances, relaxation times, electrical permittivity and conductivity) were evaluated. From rheological measurements modulus of elasticity and viscosities were calculated under generalized Maxwell-model. Impedance parameters, on the basis of correlation analysis between the dielectric and rheological parameters, can be used for quality assessment of horticultural products. As an application of quality assessment, impedance parameters were determined in apple slices during drying, in various places in apple flesh and in apple under stress. During drying of apple slices the changes of impedance parameters can be used for following the drying process. The magnitude of impedance in apple flesh gradually decreases from skin to core. Similarly, a decrease of impedance can be observed, if sample is under stress during impedance measurements. This change of impedance is reversible, if force is below the bioyield.