Notes a ARF'91A, 91D, 92A2, 92Cj and 92C2 were prepared from leaves at the Aloecrop Lyford Plantation. ARF'92B, and all of the samples from 1993 were prepared from leaves from the Aloecorp de Mexico, Gonzales Plantation. These materials do not appear to differ significantly from each other. ARF'92^ consisted of leaves from young plants while '92C2 was prepared from older plants. ARF'93C: and ARF'93E: were filleted by hand while ARF'93C2 and ARF'93E2 were filleted by machine. Aside from a slight difference in alcohol precipitable solids, there does not appear to be a difference between the materials. b Solution at 0.62 g/dl (actual 62 mg in 10 ml).
c This method is adapted from Method 988.12 0f the AOAC (AOAC, 2000a). For the purposes of determining crude polysaccharide in aloe, the second precipitation (alkaline Cu(II) reagent can be omitted. 500 mg of lyophilized powder was dissolved and precipitated with 80% EtOH. The solids content (Alcohol Precipitable Solids) of the resolublized pellet was determined by lyophilization. The total hexose content was determined by phenol sulfuric acid assay which yields the values for Total Polysaccharide hexose. d Determined by the IASC method for analysis of malic acid.
These requirements mean that Process A gel approximates the closest possibly to the freshest possible gel. Unfortunately native gel can never be a commercially viable product because it is extremely pseudoplastic and has a low solids content. Since this system was established in 1995, the ARF has maintained a much lower profile.
The consensus composition of matter of A. barbadensis gel
If we combine the IASC Texas A&M database and the ARF Process A Standard Sample program, the following composition of matter for aloe gel was obtained (Figure 8.1).
The categories used to classify the composition of matter are arbitrarily chosen, based upon the physical properties of the chemical components, which influences their behaviour during processing, the physico-chemical classes revealed by fractionation, and the biological properties found during the ARF Inter University Collaborative Study. The scheme, though arbitrary, does neatly separate the various biological activities and the overall values are in agreement with the semi-quantitative results of Waller etal.
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