Mixing and motion of rice particles in a rotating drum

The mixing and motion of particles were analyzed in a rotary drum as part of the development of a solid-state fermentation bioreactor for spore production from the fungus Metarhizium anisopliae. Rice was chosen as the particle because it is often used as a substrate for fungal incubation. The controlled variables were the particle load, drum spin velocity and the presence of inner tubes. The dyed-tracer technique was applied to the system, and image analysis was performed using the commercial software LensEye. A detailed calibration procedure is described. The software was able to identify particle weight concentrations of up to 20% with good accuracy. The load of particles was the only variable to influence the number of revolutions necessary to obtain a uniform mixture: 5,9 and 11 rotations were required to homogenize 5, 10 and 15 kg of particles, respectively. The presence of inner tubes strongly influenced the particle velocities in the central core of the bed and changed the velocity patterns in all regions. (C) 2012 Elsevier B.V. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Hygroscopic properties of solid agro-industrial by-products used in solid-state fermentation

One of the main drawbacks in operating solid-state fermentation (SSF) bioreactors is the reduction in moisture content (MC) of the solid phase due to microbiological and physicochemical issues. Therefore, heat and mass transfer models require hygroscopic information concerning the solid substrate. This contribution addresses the study of the sorption isotherms of sugarcane bagasse (SCB) and wheat bran (WB) obtained using the static gravimetric method, with temperature and water activity as the controlled variables. The Oswin model was selected to construct the sorption isotherm for SCB, and the Halsey model, modified in the present study, for WB. The Bates and Watts curvature measurements and the Box parameter bias were used to analyze the nonlinear behavior and assess the goodness of the fitting process. Fermentative assays were carried out in glass flasks for the production of endoglucanase employing the fungus Myceliophthora thermophila I-1D3b, controlling the environmental water activity, in order to assess the influence of the loss of moisture from the solid phase on fungal metabolic activity. (C) 2014 Elsevier B.V. All rights reserved.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

HACCP plan proposal for a typical Brazilian peanut processing company

Peanuts are likely to be infested by fungi with consequent contamination by aflatoxin in post-harvest industries. A hazard analysis critical control point (HACCP) plan is proposed for a typical Brazilian post-harvest industry from raw in-shell reception to the unpeeled peanuts transportation. Codex Alimentarius Commission guidelines were followed, with four critical control points (CCP) for aflatoxin being identified. The process steps with highest probability of aflatoxin occurrence (risk) are the in-shell reception, the dried in-shell storage, and the unpeeled kernel storage. During the storage steps there is a lack of control of air moisture and temperature. Therefore, there is no option but to keep rigid monitoring and control over each CCP, and detour lots with high aflatoxin levels to either oil or seed production. Attempts to correlate the aflatoxin levels with the rainfall showed an irregular trend of the toxin level. (c) 2008 Elsevier Ltd. All rights reserved

Structural properties of beds packed with agro-industrial solid by-products applicable for solid-state fermentation: Experimental data and effects on process performance

The knowledge of structural properties of beds packed with particles from agro-industrial solid wastes is important for modeling and simulation of heat and mass transfer in solid-state fermentation (SSF) in packed-bed bioreactors. This paper addresses the experimental determination of particle and bulk densities (rho(part) and rho(bulk)) and porosities (epsilon) of beds packed with sugar cane bagasse (SCB), wheat bran (WB) and orange pulp and peel (OPP) and with mixtures of them. The effects of moisture content (MC) and packing technique on structural properties were evaluated. Microscopic analysis of cell-size was performed and the porosity along the fermentation was determined, as well as the endoglucanase yields for different proportions of a medium composed by SCB/WB. Results showed that MC affects significantly rho(part), rho(bulk) and epsilon. For OPP and WB, epsilon ranged from 0.4 to 0.7, depending on MC, and for SCB from 0.7 to 0.9, depending on MC and packing technique. For the composed media SCB:OPP:WB (1:2:2, weight) and SCB:WB (7:3), epsilon values were similar to the ones obtained for SCB. The growth of the fungi Myceliophthora thermophila I-1D3b and Trichoderma reesei QM9414 did not affect epsilon of the medium composed by SCB:WB. A comprehensive discussion on how the structural properties of solid matrices affect the performance of SSF processes was done, considering both operational aspects and bioproducts yields. (C) 2014 Elsevier B.V. All rights reserved.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

HYGROSCOPIC PROPERTIES OF ORANGE PULP AND PEEL

This contribution addresses the hygroscopic properties of orange pulp and peel (OPP), an agro-industrial by-product used for pectinase and phytase production by solid-state fermentation (SSF). Experiments were carried out using the static gravimetric method and the modified Halsey model best fitted to the experimental data. Bates and Watts curvature measurements, Box parameter bias estimation and residual analysis were performed in order to validate the model and the estimated parameters. Desorption experiments were also carried out and the results showed that drying took place even at high air relative humidity. The results presented are fundamental for water transfer modeling in SSF in fixed bed bioreactors.Practical ApplicationsThe current work addresses the hygroscopic properties of OPP, a solid waste rich in pectin, which can be used as substrate in SSF for the synthesis of pectinases and phytases. Thermal sorption isotherms (TSI) and water desorption kinetics (WDK) were investigated, both of the key information required for the fermentation process, either on simulation or in the laboratory. Usually, the moisture content of the solid phase in SSF is far above its moisture equilibrium content, and since the microbial metabolism is strongly affected by the moisture content, knowledge of TSI and WDK are mandatory. Experimental information was gathered and TSI nonlinear models were applied and special care was taken for the parameter estimation, applying specific tools to assess nonlinearity problems. The work therefore possesses significant new information, particularly interesting for engineers dealing with design and scaling-up of SSF bioreactors and with nonlinear regression estimation.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq