Dehydration kinetics of red pepper (Capsicum annuum L var Jaranda)

Shredded and whole red pepper samples were dehydrated in a laboratory drier with a through-flow air velocity of 0.5ms(-1) at 50, 55, 60 and 70degreesC. 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 58kJmol(-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 x 10(-11) and 10.99 x 10(-11)m(2)s(-1) for whole peppers and between 37.23 x 10(-11) and 99.61 x 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 44kJmol(-1) for whole peppers and 56kJmol(-1) for shredded peppers. (C) 2003 Society of Chemical Industry.