effect of drying temperature and vacuum on mass transfer kinetics of

effect of drying temperature and vacuum on mass transfer kinetics of

EFFECT OF DRYING TEMPERATURE AND VACUUM ON MASS TRANSFER
KINETICS OF MURTA (UGNI MOLINAE TURCZ): DIFFUSION COEFFICIENT
AND MATHEMATICAL MODELLING
Kong Ah-Hen 1, Roberto Lemus-Mondaca 2, Antonio Vega-Gálvez
Puente-Díaz
1,3
, Karina Di Scala
4,5
, Luis
6
1
Instituto de Ciencia y Tecnología de los Alimentos, Universidad Austral de Chile, Av. J. Sarrazín s/n, Valdivia, Chile.
2
Department of Food Engineering, Universidad de La Serena, Av. R. Bitran s/n, 599. La Serena, Chile.
3
Center for Advanced Studies in Arid Zones, CEAZA, Universidad de La Serena, La Serena, Chile;
4
Food Engineering Research Group, Universidad Nacional de Mar del Plata, Av. J. Justo 4302, Mar del Plata, Argentina
5
CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas), Buenos Aires, Argentina
6
Department of Food Science and Chemical Technology, Universidad de Chile, Av. Mackena 7500906, Santiago, Chile.
Abstract
In this study, murta (Ugni molinae Turcz) or murtilla berries were dried in single layer at air
temperatures of 50, 60 and 70°C under vacuum and atmospheric pressure conditions. The effect of
drying air temperature and vacuum on the basic dehydration characteristics of murta was
determined. For the kinetic modelling, ten mathematical expressions were fitted to the experimental
data. Kinetic parameters and diffusion coefficients as evaluated by an Arrhenius-type equation,
showed temperature dependency. Fick’s second law was used to calculate the effective moisture
diffusivity that varied from 3.10 to 11.27x10−10 m2/s and from 5.50 to 11.30x10−10 m2/s with
activation energy values of 59.27 and 34.30 kJ/mol for atmospheric pressure and vacuum drying,
respectively. According to the statistical tests applied, the Midilli–Kucuk model obtained the best-fit
quality on experimental data, followed closely by the Weibull distribution model, the Page and the
modified Page models.