Two fractions (permeate and retentate) from fiber free Aloe vera gel were prepared using an ultra-filtration (UF) system with a tubular ceramic membrane (MWCO of 50 kDa), and their dilute solution properties were investigated. The intrinsic viscosities of fiber free Aloe vera gel and the retentate and permeate fractions that were prepared by ultra-filtration were 18.48, 37.74, and 2.01 dL/g, respectively. UF aloe retentate as a polysaccharide rich fraction exhibited polyelectrolyte behavior showing a sharp decrease of intrinsic viscosity by the addition of NaCl. However, as its NaCl concentration increasing to 1 M, its intrinsic viscosity slightly increased due to conformational change caused by the high concentration of NaCl. On the one hand, the intrinsic viscosities of the dilute UF-retentate solution were exponentially decreased with increasing temperature, and the temperature dependency of its intrinsic viscosity showed a sharp discontinuity at 30oC instead of a linear Arrhenius behaviour, indicating a variation of flow mechanism or network rearrangement of a molecular chain. The chain stiffness of polysaccharide rich fraction at bellow and above 0.5 M of NaCl addition was 0.048 and 0.515, respectively, showing different stiffenings and significant conformational change. The coil overlap parameter and critical concentration of UF-retentate were 3.0 and 0.08 g/dL, respectively.

Two fractions (permeate and retentate) from fiber-free Aloe vera gel were separated using ultra-filtration (UF) system with tubular ceramic membrane (MWCO of 50 kDa), and their molecular properties were investigated. The retentate of UF Aloe gel was a polysaccharide-rich fraction containing about 2.3-fold higher polysaccharide content than fiber-free gel. The FT-IR and 1H NMR spectra of this fraction showed the characteristic patterns of β-binding polysaccharide and a higher degree of acetylation indicating a higher level of bioactive polysaccharide content. The molecular weight and polydispersity of polysaccharide fraction from GPC (gel permeation chromatography) were determined to be 36.8-43.9 kDa and 1.24, respectively, indicating a kind of undispersed polysaccharide. From the SEM observation, the surface structure of polysaccharide fraction had a gel cluster-like structure with a convoluted rough surface. The molecular conformation by Congo red assay exhibited a property of helix structure confirming the existence of a higher-ordered structure as a biological activity conformation.