Variable diffusivity and volume of the grains are taken into account in the diffusion model that describes mass transfer in soybean hydration. The variable space grid method (VSGM) was used to consider the increase in grain size, and the diffusivity was considered an exponential function of the moisture content. An equation for the behavior of the grain radius as a function of time was obtained by global mass balance over the soybean grain and the differential equation considered that the increase in radius happens due to the influence of the convective and diffusive fluxes at the surface of the grains. The model was solved by an explicit numerical scheme which presented satisfactory results. The results showed the behavior of moisture profiles obtained as a function of time and radial position and also showed how the grain radius increased with time and changed the solution domain of the diffusion equation.

RESUMONeste estudo, investigamos o potencial hipolipemiante do extrato seco do fruto de berinjela (Solanum melongena), o qual tem sido comercializado no Brasil para o tratamento da hiperlipidemia humana. Assim, um estudo duplo-cego randomizado, objetivando avaliar a eficácia da Solanum melongena (SM) administrada oralmente, foi realizado. Este estudo consistiu de 41 voluntários hiperlipidêmicos alocados para tratamento com SM (n= 21) ou placebo (n= 20). Cada voluntário recebeu duas cápsulas contendo SM (450mg) ou placebo (450mg) duas vezes ao dia, sendo acompanhados mensalmente. A dose de SM utilizada corresponde ao empregado para tratar hiperlipidemia no Brasil. Após 3 meses de tratamento, os valores séricos de colesterol total, LDL-c e LDL-c/HDL-c diminuíram (p<0,05) no grupo tratado com SM. Todavia, efeito similar foi observado no grupo placebo. Os demais parâmetros, incluindo valores séricos de triglicérides, HDL-c, VLDL-c, AST, ALT, γGT, glicose e índice de massa corpórea não apresentaram modificações significativas. Assim, podemos concluir que a SM, pelo menos na forma comercializada no Brasil (extrato seco do fruto), requer um maior volume de estudos clínicos antes de ser recomendada para tratar hiperlipidemia. In this study we investigated the hypolipidemic potential of dried powdered fruits of eggplant (Solanum melongena), which has been commercialized in Brazil to treat human hyperlipidemia. Thus, a doubleblind placebo-controlled study of the effectiveness of oral Solanum melongena (SM) was conducted. The study consisted of 41 hyperlipidemic volunteers allocated to active treatment (n= 21) or placebo (n= 20). Each volunteer received two capsules containing SM (450mg) or placebo (450mg) twice daily and were followed monthly. The dose of SM used corresponds to that given to treat hyperlipidemia in Brazil. After 3 months, serum total cholesterol, LDL-c and LDL-c/HDL-c decreased (p<0.05) in the group treated with SM. However similar effect was also observed in the placebo group. The other parameters, including serum triglycerides, HDL-c, VLDL-c, AST, ALT, γGT, glucose and body mass index, showed no significant changes. We conclude that SM, at least in the form commercialized in the Brazil (dried powdered fruits), require further clinical trials before being recommended to treat hyperlipidemia.

In the present work, the mathematical modeling of the soybean hydration process is presented, considering the increase in the grain radius by Stefan problem approach. The boundary immobilization method was used in the model to take into account the spatial mesh variation caused by the diffusion of moisture in the grains. The results provided by the model show its quality when compared with experimental data, both for the adequacy of the predictions for moisture data over time and for the adequacy of grain radius increase predictions over time, for five different temperatures. The presented methodology showed improvements on results already reported in the literature. Practical applications The approach presented in this article allows one to fit diffusivity values for soybean hydration by taking into account a phenomenon commonly observed in this process: the increase of the grains during water absorption. Thus, it is expected the diffusivities to be more realistic and precise, improving the project of equipment. Since the model proposed provide the increase of the grains along the hydration process, an estimation of the increase of a higher amount of the grains could be obtained as well. Such estimation is relevant due to the considerable increase that grains suffer after absorbing water.