Digestibility of Starch Systems Containing Amylose-Glycerol monopalmitin Complexes

Abstract

Digestibility of gelatinized starches was investigated, with and without amylose-glycerol monopalmitin (GMP) complexes, using potato starch and high-amylose maize starch (HAMS). Complexes exist in two forms, the amounts formed of each being dependent on the temperatures and durations of the thermal treatments. The competition of amylose between formation of retrograded amylose and amylose-lipid complexes in these systems was also investigated. Differential scanning calorimetry (DSC) was used to analyse transition temperatures and melting enthalpies, and thereby to determine the amount and type of the complexes in the samples. Complex form I showed peak temperatures between 93.0 °C and 97.9 °C, and form II between 115.8 °C and 120.7 °C. The starch systems were enzymatically hydrolyzed using specific in vitro procedures to determine the digestion rate and the amount of enzyme-resistant starch (RS). The rate of hydrolysis of potato starch was decreased by addition of GMP, and by heat treatment. Compared to potato starch, HAMS samples had about half the hydrolysis rate. In case of autoclaved HAMS samples, GMP addition increased the hydrolysis rate, possibly because less amylose was retrograded. The amount of RS was between 2.3% and 6.6% in case of potato starch, and between 25.5% and 32.5% in the HAMS, depending on heat treatment. Autoclaving created more RS. The percentage of RS was lower when GMP was added: between 0.1% and 1.2% in case of potato starch, and between 16.9% and 25.5% in the HAMS, suggesting that complex formation was achieved at the expense of retrogradation. © 2001 Academic Press.