Lyophilization was used as a process for preparation of dried Aloe vera gel. The Lyophilization process significantly decreased (p<0.05) the pH, viscosity and polysaccharide glucose and mannose content of Aloe vera gel but had no effect on the content of amino acids. The carrier found to improve the physical properties of the lyophilized Aloe vera gel were 1.0% w/v acacia, 0.6% w/v methylcellulose (15 cps), and 2.0% w/v polyvinylpyrrolidone (K30). Those formulations and the one containing 0.2% v/v Bronidox-L®,0.1% w/v sodium metabisulfite and 0.05% w/v EDTA showed good physical stabilities at ambient temperature for six months. They also passed various microbiological tests based on Thai Industrial Standard for Cosmetics. The initial concentrations of glucose and mannose in polysaccharide and amino acids of all preparations were comparable except the one containing Bronidox-L®, sodium metabisulfiteand EDTA which had lower content of amino acids than the others (p<0.05). All preparations were also kept at 45ºC and 75% relative humidity for four months to study accelerated chemical stability tests. The preparation containing Bronidox-L®, sodium metabisulfiteand EDTA had the lowest chemical stability. The chemical stability of the preparation containing methylcellulose was similar to that of the pure lyophilized Aloe vera gel. On the other hand, the preparations containing acacia and polyvinylpyrrolidone were more chemically stable than the pure lyophilized (p>0.05) at both the refrigerated and ambient temperature for four months.
