Modelling the kinetics of thin-layer yam (dioscorea rotundata) drying

Abstract

Thin-layer yam (varieties 9811-089 and 9811-091) drying was evaluated in a laboratory-type dish dryer at 45°C, 55°C and 70°C and 1 m/s average air speed in the Universidad de Cordoba’s Applied Engineering laboratory. The samples were 3.19 cm long, 0.5 cm thick, in 0.5x3x5 cm slices. The effects of temperature, variety and geometry on drying-time were evaluated using a completely random factorial adjustment design: temperature (45°C, 55°C and 70°C), geometry (slices and fillets) and variety (9811-089 and 9811-091). Three repetitions were made per treatment, producing a 28.15% reduction in drying time at 70°C. Drying curves were constructed from the obtained results; it was observed that drying took place during the decreasing period, proving that diffusion was the mechanism involved in Discorea rotundata drying for the studied varieties. Drying curves were adjusted to Page, diffusion, Thompson, Newton, modified Page, Henderson and Pabis mathematical models. The logarithmic model (determined by determination coefficient (R2)) estimated mean error (SE) and relative mean deviation (%P), showing that the logarithmic model better described the drying process (R2 ≥ 99.17 and SE ≤ 0.0299).