ANALYSIS OF THE METHANOL-EXTRACTABLE NONVOLATILE MAILLARD REACTION-PRODUCTS OF A MODEL EXTRUSION-COOKED CEREAL PRODUCT

Methanol extracts were prepared from starch-glucose-lysine model food systems prepared by extrusion cooking (pH before cooking 3.4, 5.0, 7.7 ). Components of the methanol extracts were separated by isoelectric f ocusing (IEF), capillary zone electrophoresis (CZE), ion-exchange HPLC (IE-HPLC), and reverse-phase HPLC (RP-HPLC). IEF was useful for givin g an initial separation of the complex mixtures and for indicating whi ch other separation techniques might be appropriate. CZE gave separati ons superior to those achieved by both types of HPLC. Both RP-HPLC (wi th diode array detection) and CZE (with scanning wavelength detection) established differences between the profiles of components of the ext racts prepared from extrudates of different initial pH. Semipreparativ e RP-HPLC was used to isolate selected reaction products of each extru date. 5-(Hydroxymethyl)furfural (HMF) was identified in each sample at levels that decreased with increasing feedstock pH. Using mainly NMR, -hydroxy-2-(hydroxymethyl)-5-methyl-3(2H)-furanone was conclusively i dentified as a component of the methyl extract prepared from the pH 7. 7 extrudate. Preliminary spectral data were obtained for three additio nal Maillard reaction products.