STRUCTURAL MODIFICATION AND BIOAVAILABILITY OF STARCH COMPONENTS AS RELATED TO THE EXTENT OF MAILLARD REACTION - AN ENZYMATIC DEGRADATION AND A SOLID-STATE C-13 CPMAS NMR-STUDY

Starch and starch components, amylose and amylopectin, from potato, ha ve been studied in order to understand the modifications, induced by d ifferent levels of the Maillard reaction occurring in the presence of amino acids (L-lysine in this study), in the macromolecular structure and digestibility. Structural characterization was performed by C-13 C PMAS NMR, and differences in the bioavailability of these polymers wer e studied by enzymatic degradation kinetics. Results obtained reveal t hat changes are induced by the Maillard reaction, whose occurrence has been verified and measured by the furosine (epsilon-N-2-furoylmethyl- L-lysine) evaluation, on the macromolecular structure of starchy mater ials and on their enzymatic susceptibility. Lysine seems to act as a d isordering agent; a loss of crystallinity is evident for starch and am ylopectin and, in particular, for amylose. Finally, within the same sa mple, as the lysine concentration increases, the polymer digestibility decreases, confirming that structural organization is not the only de terminant of starch digestibility.