Effects of drying temperature, moisture content and shrinkage on the porosity development in apple convective drying
Description: Porosity development is determined by the difference between the rates of moisture removal and material shrinkage. Both extrinsic drying parameters, such as drying temperature, air velocity and humidity and intrinsic properties (moisture content and material shrinkability) influence porosity evolution in the process of drying. The purpose of this research was to investigate the effects of low (40 ºC), moderate (60 ºC) and high (80 ºC) drying temperatures on the kinetics of moisture removal and porosity development in apple convective drying. Cylindrically-shaped apple slices with diameter of 40 mm and thickness of 10 mm were dried to the equilibrium moisture content. Porosity was estimated from continuous bulk volume and weight measurements, using theoretical model (Martynenko, 2008). The results revealed that at the beginning of drying porosity development was temperature independent until moisture content reached approximately 1.5 g/g (dry basis). In the range of moisture content from 1.5 g/g to 0.55 g/g, porosity quickly increased and reached maximum. At low moisture content, drying temperature had significant influence on porosity evolution. A more porous structure was found at higher drying temperature, which is in good agreement with previous research on potato (Wang and Brennan, 1995) and eggplant drying (Russo et al., 2013). The results revealed that moisture content has dominant effect on porosity development at beginning of drying, while drying temperature determined porosity development at the final stage of drying.
Keywords: temperature; moisture content; shrinkage; porosity; convective drying
Conference name: CSBE/SCGAB 2016 Annual Conference, Halifax, 3-6 July 2016.
Session name: Poster Session (Regular)
Citation: . 2016. Effects of drying temperature, moisture content and shrinkage on the porosity development in apple convective drying. CSBE/SCGAB 2016 Annual Conference, Halifax, 3-6 July 2016.
Publisher: Canadian Society for Bioengineering
Language 1: en
Rights: Canadian Society for Bioengineering