Study on Effects of Acidic Extraction on Yield and Structure of Tobacco Pectin by CP/MAS ¹³C NMR Spectroscopy

In order to investigate the fine structure of tobacco pectin and the key factors in extraction,the effects of extraction conditions(including pH,temperature and extraction time) on the yield,purity and structure of pectin were studied by cross-polarization/magic angle spinning ¹³C nuclear magnetic resonance(CP/MAS ¹³C NMR) spectroscopy.The results showed that:1) The highest pectin yield(10.87%) achieved after extracting for 1.5 hours at pH 1.5 and 85℃;while polygalacturonic acid(PGA) reached its highest purity(78.4%) after extracting for 1.5 hours at pH 2.0 and 95℃.2) The extraction conditions influenced the structure of pectin to a certain extent,the degrees of methylation(DM) and acetylation(DA) of pectin increased as pH value increased from 1.5 to 2.5,while decreased with the rise of temperature and the prolongation of extraction time significantly.