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Physical and chemical characteristics of Aloe ferox leaf gel

O'Brien, C., Van Wyk, B.-E., Van Heerden, F.R.
South African journal of botany 2011 v.77 no.4 pp. 988-995
Aloe ferox, Aloe vera, activated carbon, alcohols, chemotypes, galactose, gels, glucose, hydrolysis, leaves, mannose, quality control, total dissolved solids
Aloe ferox leaf gel differs substantially from that of Aloe vera but almost no commercially relevant data is available this species. Leaf dimensions, gel yields and gel compositions were studied, based on samples from several natural populations. Glucose is the only free sugar in aloe gel (0.1 to 0.4mgml⁻¹ in A. ferox). Monosaccharides released after hydrolysis show potential for gel fingerprinting and allow for a distinction between A. ferox and A. vera. The former yields various combinations of glucose and galactose as main monosaccharides, while the latter yields only mannose. Further variation studies are recommended because A. ferox appears to have three different gel chemotypes. Conductivity shows species-specific ranges — in A. ferox below 3000μScm⁻¹ in fresh gel and above 3100μScm⁻¹ in aged gel (corresponding values for A. vera were 1670 and 1990μScm⁻¹). The level of phenolic (bitter) compounds in A. ferox gel can be reduced by treatment with activated charcoal, resulting in a small loss of total dissolved solids. Alcohol precipitable solids and insolubility are useful variables for quality control of gel powder. The methods and data presented are the first steps towards developing quality criteria for A. ferox leaf gel.