Partial removal of acetyl groups promotes the synergistic interaction of polysaccharide from leaf skin of Aloe barbadensis Miller with xanthan gum

This study was to investigate the effect of acetyl contents on the structural properties of polysaccharide (ASP-4N) extracted from leaf skin of Aloe barbadensis Miller ( Aloe vera), as well as the rheological and textural properties of mixtures of deacetylated ASP-4N with xanthan gum (XG). FTIR and 1D NMR characterization showed that the molecular backbone of deacetylated ASP-4N were not discernibly affected during the deacetylation process with sodium carbonate. ASP-4N or deacetylated ASP-4N solution was mixed with XG for further gel characterization. The results showed that natural ASP-4N or deacetylated ASP-4N could not form gel with XG when the acetyl content >= 26.6%; However, it formed a gel with XG as acetyl content was decreased to 19.3%. In addition, sol-gel transition temperatures of the gels were around 42-48 degrees C. The critical acetyl content of ASP-4N that could synergistically form a gel with XG was in the range of 26.6-19.3% (w/w). Mechanistically, the decrease of ASP- 4N acetyl contents allowed the exposure of more mannose in backbone and thus reduced steric hindrance and promoted the synergistic interaction with XG.