Rheological behavior and modeling of an ultrafiltration process for Aloe vera

Abstract

AbstractAloe vera (Aloe barbadensis Miller) is employed as a food supplement containing mucopolysaccharides which contribute to a healthy diet. Aloe vera mucilage is usually obtained through an evaporation process. An alternative process to preserve polysaccharide properties is ultrafiltration (UF), which impedes degradation of the compound by temperature. This work analyses the effect of the UF process on the mechanical and rheological properties of Aloe vera considering the following variables: temperature (T), input feeding rate (V), and transmembrane pressure (ΔPTM). The permeate flux varies according to the operating conditions exhibiting non‐Newtonian effects. The determination of the mass transfer coefficient is based on the analogy of transport phenomena (heat transfer to mass transfer) in non‐Newtonian fluids to obtain the permeate flux. The results show that when the mucilage is fed as a diluted shear‐thinning fluid, the UF efficiency is positively affected. To describe the rheological behavior of the concentrated mucilage, the power law and the Bautista‐Manero‐Puig (BMP) models are used and compared. Results suggest that the BMP model represents better the experimental data of permeate flux as a function of filtrate concentration with respect to the experimentally measured permeate flux.Practical ApplicationsCurrently, the use of Aloe vera mucilage as encapsulating agents, thickeners, emulsifiers, and wall materials is highly appreciated by the food and pharmaceutical industry. This research shows that the concentrate obtained from Aloe vera mucilage by ultrafiltration (UF) preserves its rheological properties, unlike other thermal processes. Results represent an interesting and promising alternative to estimate the properties of Aloe vera using more realistic rheological models with promising applications in the food and pharmaceutical industry. The Aloe vera mucilage increases the health benefits using the mucilage in different concentrations in different industrial processes.