New approaches to rapid spectroscopic evaluation of properties in pectic polymers

Abstract

Pectins are highly desired carbohydrate polymers in the food industry due to their capabilities as gelling agents. As pectin molecules are very complex macromolecules extracted from plant cell walls, a 100% purification method for the pectin gelling principle has not yet been devised. For this reason pectins need to be carefully characterized for parameters such as degree of esterification, molecular weight, degree of polymerization, amount of plant residual materials, pH, calcium sensitivity, total amount of galacturonic acids, etc., as these factors will determine the final properties of the pectin product.

The purpose of this paper is to demonstrate the advantages of employing two different and highly complementary spectroscopic techniques, fluorescence and near infrared, for the determination of quality parameters in pectin powders. For this purpose three sample sets of pectinic powders are investigated: (I) citrus fruit raw materials, (II) standard extracted high methoxy pectins and (III) a pectin model set with large variations in the degree of esterification. The spectroscopic ensembles of these three pectin sets are subjected to chemometric analysis for the evaluation of spectroscopic correlations with reference physico-chemical measurements such as pectin yield, gel strength, simple sugar content and degree of esterification.