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

Abstract

Shredded and whole red pepper samples were dehydrated in a laboratory drier with a through-flow air velocity of 0.5 m s À1 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 À1 . 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 Â 10 À11 and 10.99 Â 10 À11 m 2 s À1 for whole peppers and between 37.23 Â 10 À11 and 99.61 Â 10 À11 m 2 s À1 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 À1 for whole peppers and 56 kJ mol À1 for shredded peppers.

Drying kinetics and physico-chemical characteristics of Osmo- dehydrated Mango, Guava and Aonla under different drying conditions

“…This is due to higher surface area, which enhances the drying efficiency of driers and soft tissue nature, which is useful to remove water from inner tissues to outer wall, of mango and guava than aonla. Similar results have been obtained by several other workers (Akpinar and Bicer 2005;Sanjuan et al 2003;Wang and Xi 2005). The rehydration characteristics of dried products are widely used as the quality index.…”

“…The presence of the clear falling rate period confirmed that the moisture removed was driven internally by energy absorption and the internal mass resistance which controls the drying process. Under such circumstances, it was assumed that water transportation occurs via diffusion (Sanjuan et al 2003). Thin structure and large surface area of prepared fruit slices facilitate rapid loss of moisture and thus a falling rate period.…”

Effect of temperature and loading density on drying kinetics of wheat

“…The temperature dependence of the effective diffusivity may be described by an Arrhenius-type relationship (Madamba et al, 1996;Ozdemir & Devres, 1999;Sanjuan et al, 2003;Akgun & Doymaz, 2005;Wang et al, 2006) and written as:…”

Thin layer convective air drying of wild edible plant (Allium roseum) leaves: experimental kinetics, modeling and quality

“…It decreases faster in the beginning of the drying processes and gradually slowed down through the end (Ben Haj Said et al 2011). Drying curves were characterized by a constant-and a falling-rate drying period (Sanjuán et al 2003;Da silva et al 2013;Rodríguez et al 2014). Allium roseum leaves drying behaviour results of the two mechanisms that involved in the drying process: convection and diffusion (Da silva et al 2013).…”