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Theoretical and practical contributions regarding the cherry-drying process with the application of the microwaves


Author: Aliona Moşanu
Degree:doctor of engineering
Speciality: 05.18.12 - Food industry processes and equipment
Year:2006
Scientific adviser: Galina Dicusar
doctor, professor
Scientific consultant: Andrei Lupaşco
doctor habilitat, professor, Technical University of Moldova
Institution:
Scientific council:

Status

The thesis was presented on the 18 November, 2005
Approved by NCAA on the 26 January, 2006

Abstract

Adobe PDF document0.23 Mb / in romanian

Thesis

CZU 664.854:634.233:621.3.029.63

Adobe PDF document 3.46 Mb / in romanian
139 pages


Keywords

cherry, drying, convection, microwaves, magnetron, temperature, oscillation, quality

Summary

There are presented 42 published scientific works and 3 patents for invention.

There has been carried out research on the kinetics of the cherry-drying process by means of convection, microwaves and the combined method. There have been determined kinetic characteristics of the drying process. Experimentally, there has been determined the constant of the convective cherrydrying speed I K and the coefficients of the humidity transfer  were calculated. As a result there has been determined a supplementary diffusion resistance in the end layer. During the combined drying, the intensity of the external diffusion is much higher that the intensity of the water evaporation from the cherry surface. It is due to the modification of the fruit exterior layers’ structure, caused by the synergetic effect of the overlap between diffusion and heat streams, oriented from central layers towards exterior layers of the fruit. The application of the microwaves leads to the intensification of the humidity interior diffusion in the cherry, II K . As a result the coefficient increases in 20 times (when the maximal nominal power of the magnetron is used).

It has been deduced that cherry-drying by means of combined power-supply, represented by convection and microwaves has to be performed at the temperature of 100 ºC, 25 % of magnetron’s nominal power and the oscillation pattern of 0,2 (impulse duration – 5 s, pause between impulses – 25 s).It has been concluded that the drying process by means of combined power-supply is 1,9 times more efficient that the convection method.

The construction of the industrial cherry-drier based on the combined power-supply has been proposed.