From the sigmoidal to the downward concave shape behavior during the hydration of grains: Effect of the initial moisture content on Adzuki beans (Vigna angularis)

Autor(es)

Miano, Alberto Claudio ^[1] ; Duarte Augusto, Pedro Esteves ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Luiz de Queiroz Coll Agr ESALQ, Dept Agrifood Ind Food & Nutr LAN, Piracicaba, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: FOOD AND BIOPRODUCTS PROCESSING; v. 96, p. 43-51, OCT 2015.
• Citações Web of Science: 17

Resumo

This work studied the change of the hydration behavior of Adzuki beans (Vigna angularis) as a function of their initial moisture content. By studying the hydration kinetics at different initial moisture contents, it was demonstrated that the hydration behavior of this grain changes from the sigmoidal to the downward concave shape (DCS) when the initial moisture content is above similar to 20% d.b. This change happens when the moisture content passes from zone II to zone III of the grain's adsorption isotherm. This was attributed to the transition from the glassy state to the rubbery state, especially the in seed coat components. The seed coat is impermeable when the moisture content of the grain is low, so the water ingress is only by way of the hilum. However, when the seed coat is above similar to 20% d.b. the water enters not only via the hilum, but also by way of the seed coat. The hydration behavior of the grain was modeled using a sigmoidal mathematical model, whose parameters were evaluated as a function of the initial moisture content; the water absorption rate parameter demonstrated a sigmoidal increasing behavior. The time to reach the inflexion point of the curve, related to the lag phase, showed an exponential decay. The equilibrium moisture content was not affected. Finally, a general model, which was able to predict the moisture content as a function of the initial moisture content of the grain and the process time, was obtained. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 14/16998-3 - Utilização da tecnologia de ultrassom para melhoria de processos em alimentos: transferência de massa e processamento térmico
• Beneficiário: Pedro Esteves Duarte Augusto
• Modalidade de apoio: Auxílio à Pesquisa - Regular