Starch molecular structure and phosphorylation investigated by a combined chromatographic and chemometric approach

Abstract

Structural features of starch were studied with special emphasis on the relationship between starch phosphorylation and starch chain length distribution comparing a chemometric approach with classic statistics. Starches prepared from 44 plant species were analysed with respect to the degree of phosphorylation and chain length distribution of the neutral unit chains, prepared by enzymic isoamylase debranching, using high performance anion exchange chromatography with pulsed amperometric detection (HPAEC/PAD). Chemometric algorithms such as Principle Component Analysis (PCA), Non-Negative Alternating Least Squares Regression (NNALSR) and Partial Least Squares regression (PLS) were used to analyse the systematic variation in the chromatograms and compared to Gauss decomposition. Detailed relations between chain length data and structural elements of the current cluster/bocklet model of native starch granules were revealed. By using PCA, both crystal polymorphs and botanical origin of the starch were accurately predicted. Using PLS, a strong correlation (0.93) was obtained between the chain length distribution and the degree of phosphorylation in the potato starch group. The use of chemometrics as an efficient tool to classify and predict starch functionality is documented.