Digestibility of starch systems containing amylose-glycerol monopalmitin complexes

Digestibility of gelatinized starches was investigated, with and without am ylose-glycerol monopalmitin (GMP) complexes, using potato starch and high-a mylose maize starch (HAMS). Complexes exist in two forms, the amounts forme d of each being dependent on the temperatures and durations of the thermal treatments. The competition of amylose between formation of retrograded amy lose and amylose-lipid complexes in these systems was also investigated. Differential scanning calorimetry (DSC) was used to analyse transition temp eratures and melting enthalpies, and thereby to determine the amount and ty pe of the complexes in the samples. Complex form I showed peak temperatures between 93.0 degreesC and 97.9 degrees C, and form II between 115.8 degree sC and 120.7 degreesC. The starch systems were enzymatically hydrolyzed using specific in vitro pr ocedures to determine the digestion rate and the amount of enzyme-resistant starch (XS). The rate of hydrolysis of potato starch was decreased by addi tion of GMP, and by heat treatment. Compared to potato starch, HAMS samples had about half the hydrolysis rate. In case of autoclaved HAMS samples, GM P 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 be tween 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: betwee n 0.1% and 1.2% in case of potato starch, and between 16.9% and 25.5% in th e HAMS, suggesting that complex formation was achieved at the expense of re trogradation. (C) 2001 Academic Press.