Dehydration kinetics of red pepper (<i>Capsicum annuum</i> L var Jaranda)

Abstract

Abstract Shredded and whole red pepper samples were dehydrated in a laboratory drier with a through‐flow air velocity of 0.5 m s −1 at 50, 55, 60 and 70 °C. Shredded peppers dried faster than whole peppers. The drying behaviour of whole samples was characterised by a constant‐ and a falling‐rate drying period, whilst that of shredded samples was characterised by a falling‐rate drying period only. The mass transfer coefficient for whole samples during the constant‐rate period was computed experimentally. The effect of temperature on the mass transfer coefficient was described by the Arrhenius model. The activation energy was 58 kJ mol −1 . In the falling‐rate period the mass transfer was described by a diffusional model, and the effective diffusion coefficient at each temperature was determined. Diffusion coefficients were estimated to lie between 4.38 × 10 −11 and 10.99 × 10 −11 m 2 s −1 for whole peppers and between 37.23 × 10 −11 and 99.61 × 10 −11 m 2 s −1 for shredded peppers. The effect of temperature on the effective diffusion coefficient was described by the Arrhenius equation, with an activation energy of 44 kJ mol −1 for whole peppers and 56 kJ mol −1 for shredded peppers. © 2003 Society of Chemical Industry