Multi-way chemometrics for mathematical separation of fluorescent colorants and colour precursors from spectrofluorimetry of beet sugar and beet sugar thick juice as validated by HPLC analysis

In previous analyses of colour impurities in processed sugar, a multi-way chemometric model, CANDECOMP-PARAFAC (CP), has been used to model fluorescence excitation-emission landscapes of sugar samples. Four fluorescent components were found, two of them tyrosine and tryptophan, correlating to important quality and process parameters. In this paper HPLC analyses are used to chemically verify and extend the CP models of sugar. Thick juice, an intermediate in the sugar production, was analysed by size exclusion HPLC. Tyrosine and tryptophan were confirmed as constituents in thick juice. Colorants were found to be high molecular weight compounds. Fluorescence landscapes on collected column fractions were modelled by the CP model and seven fluorophores were resolved. Apart from tyrosine and tryptophan, four of the fluorophores were identified as high molecular weight compounds, three of them possible Maillard reaction polymers, whereas the seventh component resembled a polyphenolic compound. It is concluded that the relevance of CP for mathematical separation of fluorescence landscapes has been justified on two levels by HPLC; firstly as a screening method of fluorophores in complex samples and secondly as a confirmation of peak purity in chromatographic separation. (C) 2000 Elsevier Science Ltd. All rights reserved.