Dehydration and Separation of Grape Pomace in a Fluidized Bed System

Abstract

Grape pomace components (seed and skin) were separated in a fluidized bed system based on their aerodynamic behavior. The Weibull equation was used to explain the elutriation history. Seed dehydration was characterized by a first period of constant drying rate and a second period in which drying rate decreased following Fick's liquid molecular diffusion model. The order of magnitude of heat and mass transfer parameters, both internal and external, was similar to those reported in the literature.

Optimal experimental design for estimating the kinetic parameters of processes described by the Weibull probability distribution function

“…The results of Box and Lucas (1959) for the first-order reaction model and those of Cunha et al (1997) for the isothermal Thermal Death Time model, showed that when analysing a given system over a range of temperatures, an experiment should Chhinnan (1984); q , Heinz and Knorr (1996); o, Ilincanu et al (1995); A, Li and Morey (1984); l , Machado et al (1997); o, Misra and Brooker (1980); +, Peraza et al (1986); l , Shepherd and Bhardwaj (1988); and w, White et al (1981).…”

“…To model the simultaneous effect of drying and separation of grape pomace in a fluidised bed, Peraza et al (1986) have used the Weibull model, as mentioned in the introduction. In this work, they have measured as a response function the grape skin fraction in the bed at any time (q) and modelled grape pomace elutriation as a function of fluidisation velocity (ur) and length/diameter ratio (L/D) of the fluidised bed.…”

“…From an experimental point of view, these sampling times are perfectly feasible. The heuristic experimental design used by Peraza et al (1986) was based on six sampling points equally spaced in time, with a time lag of 5 min (t = 5, 10, 15, 20, 25 and 30 min); comparing this design with the corresponding optimal sampling procedure (three replicates taken at t = 21.0 min and three at t = 29.2 min), its efficiency (eqn (8)) would be approximately 52%. This means that the heuristic design used by Peraza et al (1986) would require twice as many points as the optimum design to have roughly the same precision of the parameters estimated.…”

“…Chhinnan (1984) evaluated four mathematical models, i.e., the exponential model, the diffusion model, an approximation of the diffusion model and the Page (Weibull) model, for describing thin-layer drying of in-shell pecans, recommending the Page (Weibull) equation for future modelling studies. Moreover, the Weibull distribution has been used to model failure of apple tissue under cyclic loading (McLaughlin & Pitt, 1984) grape pomace elutriation (Peraza et al, 1986) and water uptake and soluble solids losses during rehydration of dried apple pieces (Ilincanu et al, 1995). Machado et al (1997) adequately described moisture uptake and soluble solid losses by breakfast cereals immersed in water or milk using the Weibull model, after unsuccessful attempts to use the Peleg (1988) the diffusion and the first order models.…”

Consideration on superior capitalization of wine by-products

“…The trend of superior capitalization of wine by-products has led to the development of various separation methods that use complex equipment, which includes in their components systems for prepreparation of the seed mixture before the actual separation [5][6][7][8].…”