Modeling of cross flow ultrafiltration of stevia extract in a rectangular cell

Prediction of ultrafiltration performance during clarification of pre-treated stevia extract by cross flow ultrafiltration in a rectangular cell is presented in this work. The steady state performance is modeled by using classical film theory. The transient state behaviour is quantified by using a model available in literature. In the model, higher molecular weight solutes are clubbed in one gel-forming component and Stevioside is assumed to be other component. In the process of modeling, the gel characteristics are estimated. Both total recycle and batch concentration mode of operations are modeled. The model results are in good agreement with the experimental data.     

Enzyme recovery and effluents generated in the enzymatic elimination of clogging of pectin cake in filtration process

The ultrafiltration recycling method has the capacity to retain enzyme, thereby avoiding the supplementation of fresh enzyme in subsequent rounds of hydrolysis. The objectives of this research were to recovery and reuse the enzymes by ultrafiltration to unclog the membrane enzymatically during the enzymatic hydrolysis of the pectin cake. The recovery of the enzymes after use to unclog membranes by means of ultrafiltration was tested and reuse them to successive unclogging processes with satisfactory efficiency. The kinetic equations of the variation in the content of the effluents with time were also determined. Different unclogging experiments carried out at different temperature and times led to the activation energy value of 47.4 kJ/mol being determined.     

Modeling of permeate flux of synthetic fruit juice and mosambi juice (Citrus sinensis (L.) Osbeck) in stirred continuous ultrafiltration

Ultrafiltration studies of synthetic sucrose and pectin mixture and enzymatically treated mosambi juice have been performed in a stirred continuous cell. A model based on gel layer theory is developed to predict the flux decline during filtration for both synthetic and actual juice. From the steady state flux data, the mass transfer coefficient is observed to vary with operating pressure only and a modified Sherwood number relationship is proposed for such a system. The permeate of the filtered juice contains almost all the nutritional values of the original juice with significant improvement in clarity.     

The role of gluten in a pound cake system: A model approach based on gluten–starch blends

In order to evaluate the role of gluten in cake-making, gluten–starch (GS) blends with different ratios of gluten to starch were tested in a research pound cake formula. The viscosities of batters made from commercial GS blends in the otherwise standardised formula increased with their gluten content. High viscosities during heating provide the batters with the capacity to retain expanding air nuclei, and thereby led to desired product volumes. In line with the above, increasing gluten levels in the cake recipes led to a more extended oven spring period. Cakes with a starch content exceeding 92.5% in the GS blend suffered from substantial collapse during cooling. They had a coarse crumb with a solid gummy layer at the bottom. Image analysis showed statistical differences in numbers of cells per cm², cell to total area ratio and mean cell area (p < 0.05). Both density and mean cell area were related to gluten level. Moreover, mean cell area and cell to total area ratio were the highest for cakes with the lowest density and highest gluten levels. Relative sodium dodecyl sulfate (SDS, 2.0%) buffer (pH 6.8) extractabilities of protein from cakes baked with the different GS blends decreased with gluten content and were strongly correlated with the intensity of collapse. Taken together, the results teach that protein gives the cakes resistance to collapse, resulting in desirable volumes and an optimal grain structure with uniform cell distribution.