Extraction of pectin from agroindustrial residue with an ecofriendly solvent: use of FTIR and chemometrics to differentiate pectins according to degree of methyl esterification

Pectins are members of the more complex class of high molecular weight heteropolysaccharides. They consist mainly of (1 -> 4)-linked alpha-D-galacturonic acid residues, which may be partially methyl esterified. The quantity of methyl esterified groups throughout the chain influences the physico-chemical characteristics of the pectin, especially in terms of complexation and gel formation. There have been many studies of pectin extraction, but each experimental condition confers different characteristics to the product. This work used a green solvent (citric acid solution) and an ultrasonic bath to extract pectin from passion fruit peel, an important agroindustry waste. Response surface methodology and central composite design were used to evaluate the yield of pectin. Principal component analysis was applied to FTIR spectra in order to distinguish pectins according to their degree of methyl esterification.