Comparative study of hot air and vacuum drying on the drying kinetics and physicochemical properties of chicory roots

Abstract

The effect of the drying conditions on the retention quality for dried chicory roots () was investigated. Cubes of chicory roots were dried using hot air and vacuum dryers at 60 and 80 °C. Two different air velocities (0.2 and 0.7 m/s) were used in the hot air dryer, and two vacuum pressures (25 and 50 mmHg absolute) were set in the vacuum chamber. An exhaustive three dimensional mathematical model to describe mass transfer during drying of chicory roots of 1 cm of side was presented considering a polynomial functionality for the contraction kinetics. Experimental data obtained at laboratory scale were used to validate the proposed model showing good agreement between the experimental and estimated moisture profiles for both drying procedures. Moisture diffusivity was found to increase with the air drying temperature, velocity and vacuum pressure depending on the drying method. However, higher moisture diffusivity coefficients and lower activation energy values were obtained for the vacuum drying method. Samples dried using the vacuum drier at 60 °C and 25 mmHg presented better retention quality attributes, i.e., better rehydration, lower shrinkage and higher total phenolic content. The proposed mathematical model was able to satisfactorily predict the described behavior.

Comparison of Drying Methods and Their Effect on the Stability of Graševina Grape Pomace Biologically Active Compounds

“…The vacuum drying method was found to be an effective method for drying in industries due to the conservation of energy, i.e., less energy is needed for drying. On the other hand, this method requires additional equipment, which includes higher operational costs and control of the process is complicated due to maintaining the lower pressure [ 44 ]. Considering the lower operational costs, another method for grape pomace drying was conventional drying at 70 °C because this temperature was the most effective for vacuum drying.…”

Influence of microwave vacuum drying on the effective moisture diffusivity of seedless white grapes

“…In addition, even when the rate of moisture loss was constant, a higher vacuum degree was found to lead to a higher drying rate of seedless white grapes. The phenomenon was due to the fact that the higher vacuum degree accelerated the evaporation of water (Balzarini et al, 2018). When the vacuum degree was relatively low, the boiling point of water became relatively high.…”

Influence of Ultrasound-Assisted Osmotic Dehydration Pre-Treatment on Total Phenolic Content, Antioxidant Capacity and P-Cymene Content of Eucalyptus Deglupta

“…The increase in antioxidant activity may be attributed to the formation of melanoidins. Melanoidin is a compound that forms under the presence of low water and high sugar activity (Balzarini et al 2018). The presence of sugar in the sucrose solution facilitates the formation of melanoidin which is known to exhibit antioxidant activities (Langner & Rzeski 2013).…”