New Method for a Two-Step Hydrolysis and Chromatographic Analysis of Pectin Neutral Sugar Chains

Abstract

A new method for the determination of the main neutral sugars in pectin has been developed. The sample preparation involves a mild chemical attack followed by an enzymatic hydrolysis. The completeness and nondestructive character of the method are demonstrated by comparison of the results obtained with different acids such as H2SO4, HCl, and trifluoroacetic acid (TFA) at different concentrations (2, 1, or 0.2 M) at two temperatures (80 or 100 degrees C). The chemical hydrolysis of pectin neutral sugar chains with strong acid (1 or 2 M) and high temperature (100 degrees C) shows that the liberation of the pectin sugars is not realized at the same rate for each sugar. Different optimum conditions are thus obtained. However, the chemical pectin hydrolysis with 0.2 M TFA at 80 degrees C is characterized by the liberation of pectin neutral sugar side chains without any degradation within 72 h of hydrolysis. Under these conditions, the liberation of some pectin sugars, essentially galactose, glucose, and rhamnose, was not complete. An enzymatic hydrolysis is necessary to obtain a complete release of all the sugars. The combination of the two treatments, a chemical hydrolysis realized with diluted acid (0.2 M) for 72 h at low temperature (80 degrees C) on one hand and an enzymatic hydrolysis on the other hand, allow a total liberation of pectin sugars. The quantitative analysis of the carbohydrates is realized with accuracy, high selectivity, and sensitivity with high-performance anion-exchange chromatography with pulsed-amperometric detection. The sugars can be analyzed without any derivatization with a limit of quantification of 0.1 mM.

Pectin Extraction from Lemon By-Product with Acidified Date Juice: Effect of Extraction Conditions on Chemical Composition of Pectins

“…Pectin was probably partially degraded into smaller molecules by the extreme extraction conditions. Similar elution patterns were observed by Garna et al (2004Garna et al ( , 2007 who found that, under severe extraction conditions, the Mw of pectin decreased and attributed this to degradation of the side sugars chains and the hydrolysis of galacturonic acid chains.…”

“…The galacturonic acid (Gal A) content of the pectin mixture samples ranged from 41.5% to 74.5% (on a dry-weight (Masmoudi et al 2008) with higher purity probably by release of neutral sugar side chains as a product of partial acid hydrolysis of pectin (Garna et al 2004). The same effect was found by Robert et al (2006) who extracted pectin from chicory roots.…”

Identification of Novel Poly-Acylated Anthocyanins from Gynura bicolor Leaves and Their Antioxidative Activity

“…These three compounds were isolated and purified from crude extract using HP-20 chromatography, ODS chromatography, HW-40F chromatography and preparative HPLC to give three pure compounds. Each compound was was adjusted to a neutral pH with 2 M NaOH, and then sugar moieties were analyzed by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) analysis (Saito et al, 2008;Garna et al, 2004) using a Dionex DX-500 (Antec Leyden, Zoeterwoude, Netherlands) with a CarboPac PA1 column (4.0 mm i.d. × 250 mm; Antec Leyden).…”

Evaluation the Organic Acids Ability for Extraction of Anthocyanins and Phenolic Compounds from different sources and Their Degradation Kinetics during Cold Storage

“…Acidic hydrolysis rates for polypectate (<5% DM) declined as the pH value was raised from 2 to 6. Pectin (35% and 70% dm) hydrolyzed more slowly than polypectate below pH 3.5, but then degradation rates increased because β-elimination became the dominant reaction above pH 3.8 [Garna et al, 2004]. The results indicate that carboxylic acids could not catalyze the degradation of cell wall polysaccharides as well as mineral acid since acid-catalyzed hydrolysis is proportional to H+ concentration [Mosier et al, 2002].…”