Isolation of polysaccharide from alove vera gel by precipitation

Abstract

The study of isolation of polysaccharide from aloe vera gel by precipitation can be categorized into 2 sections. For the first section, suitable solvent for the precipitation process was studied. When 100 ml aloe vera gel was precipitated with 400 ml of 95% methanol, 95% ethanol, and 95% iso-propanol, it was found that the average product dry weight of each solvent precipitation were 0.0367, 0.0435, and 0.0517 g, respectively. Polysaccharide content with respect to the average product dry weight of methanol, ethanol, and iso-propanol precipitation were 17.84%, 28.72%, and 20.81%, respectively. Therefore, 95% ethanol was chosen as the solvent for the precipitation. In the second section, various factors affecting polysaccharide separation from the aloe vera gel were investigated. Those factors were solvent to gel ratio, system pH, temperature, and stage of precipitation. It was found that solvent to gel ratio of 6:1 yielded the maximum average product dry weight, 0.1877 g, when 100 ml aloe vera gel was precipitated. Polysaccharide and protein content with respect to the average product dry weight were 26.51% and 0.28%, respectively. Considering pH of the system, the maximum average product dry weight was obtained when pH was not adjusted (pH = 5.52). Focusing on the system temperature, the suitable temperature in the precipitation process was founded to be 32 degree celsius (room temperature). When 1 litre of aloe vera gel was precipitated, the product dry weight was 1.8571 g. Polysaccharide with respect to product dry weight was 33.74%. Elemental analysis showed that the dry product composed of carbon and nitrogen with the contents of 32.32% and 1.26 % by weight, respectively. C:N ratio was 25.74:1. As for the effect of the stage of precipitation, the single stage precipitation yielded 1.6664 g of product dry weight and 1.1969 g was obtained from 6 stages precipitation.