Identification and Quantification of Monosaccharides in Aloe vera Gel by Acid and Enzymatic Hydrolysis and Wet Heat Treatment

Abstract

Aloe vera (Aloe barbadensis Miller) possesses curative and therapeutic properties attributed to the polysaccharides found in its tissue. This work aimed to study hydrolyzed (chemical and enzymatical) Aloe vera gel extracts using ultrafiltration membranes with a pore size of 0.22 micron (μm). Nine chemical treatments were achieved with H2SO4 and three wet heat treatments were carried out at a pressure of 1.2 lbf/in2 for 15 minutes; in both cases, three different concentrations of Aloe vera gel juice (AGJ) were used: 1.5%, 2.5% and 3.5% w/w. The concentrations of H2SO4 were 0.10%, 0.25% and 0.40% w/w. Chemical experiments are performed over a factorial 32 design and results were analyzed using SPSS software (version 17, SPSS Inc.), finding the one labeled T7 (15 ml of AGJ 3.5% with 15 ml of H2SO4 0.10% added) the best of them, as it leaded to 0.0446 mg/ml of liberated glucose. Among the three wet heat treatments, the one labeled TC3 (15 ml of AGJ 3.5% with 15 ml of H2O added) was the best-performing one, as it leaded to 0.292 mg/ml of liberated glucose. Furthermore, an enzymatic hydrolysis was carried out using Novozymes’ Pectinex® AR and Viscozyme®. Hydrolisis with both enzymes yield to better results than acid hydrolysis: in the treatment with Pectinex® AR, 3.282 mg/ml of liberated glucose were obtained and 3.302 mg/ml in the treatment with Viscozyme®. The hydrolyzed substances obtained by acid and enzymatic hydrolysis, as well as by wet heat treatment, were subsequently analyzed by thin layer chromatography (TLC), using glucose, galactose and arabinose 1000 ppm solutions as reference patterns. Among the treatments by H2SO4, the one labeled T4 obtained an Rf value of 50, the same as on the galactose reference pattern.