A mathematical model based on Fick's diffusion equation with a concentration-dependent diffusion coefficient was proposed to describe the absorption of water by legumes. The equation was solved by using a numerical scheme. Parameter study was performed. The model is capable of predicting sigmoidal-shaped water uptake curves common to many legumes. Differences are discussed between the surface resistance boundary condition used in this study and the radiation boundary condition widely used for dehydration calculations. The validity of using the proposed model to described the water uptake of legumes was verified by the good fit between the experimental and theoretical curves.

Influence of temperature on the concentrationdependent diffusivity of water into soybean was investigated. At a constant water content, Arrhenius relation existed between the water diffusivity and temperature. The activation energy for diffusion was found to be between 9 and 13 Kcal/mole. The activation energy also was found to vary linearly with the water content.

SummaryA modified dynamic method is introduced to determine the oxygen transfer coefficient, KLU, in aerobic fermentation systems which are not mechanically agitated. The dissolved oxygen concentration is measured continuously following a step down or a step up in aeration rate. The response curve is analyzed to obtain the value of KLU.Experiments were carried out a t several different air flow rates using a mixed culture in cocurrent tower fermentors with motionless mixers. The effect of sieve trays and Koch motionless mixers on oxygen transfer was investigated using a 3 in. diameter column. The values of KLU obtained at the bottom of each column were found to be higher than those obtained at the top. Comparison of the results showed that the values of KLa were higher when the Koch mixers were used than when the sieve trays were employed.The oxygen uptake rate by the organisms, r X , is also calculated by using the KLa values obtained. They compare favorably with the experimentally measured values.

Solutions of ethylenediamine tetraacetic acid and sodium bicarbonate were used to soak faba beans before canning. Soaking in ethylenediamine tetraacetic acid solutions only caused a slightly lighter bean color. Soaking in bicarbonate solutions Increased both the drained weight and the softness of the cooked beans, and it also made the bean color darker. The profiles of loss of both thiamin and riboflavin during the canning process were determined. Riboflavin was lost primarily during retorting while thiamin was lost in several processes including heat pretreatment and soaking. Mechanism of loss for the two vitamins was mainly leaching; very little thermal destruction was observed. None of the soaking treatments affected the retention of these vitamins.

SummaryPressure drop, gas hold-up, and oxygen transfer were investigated in a sieve tray column, a column with Koch motionless mixers, and a bubble column. The oxygen transfer experiments were conducted using cocurrent flow of gas and liquid under steady-state conditions with oxygen transfer from the gas to the liquid phase. The oxygen transfer rates and efficiencies of the sieve tray column and the column with Koch mixers were found to be superior to those of the conventional bubble column. Gas hold-up was also greater when sieve trays or Koch mixers were inserted in the tower. The pressure drop was found to be primarily due to the liquid head in all three columns.