Cereal Chem 66:342-347   |  VIEW ARTICLE

Enzyme-Resistant Starch. I. Characterization and Evaluation by Enzymatic, Thermoanalytical, and Microscopic Methods.

D. Sievert and Y. Pomeranz. Copyright 1989 by the American Association of Cereal Chemists, Inc. 

Formation of enzyme-resistant starch (RS) during autoclaving and cooling was investigated in starches from wheat, maize, potatoes, peas, waxy maize, and amylomaize. Amylose content and yield of RS were positively correlated. The highest yield (21.3%) was obtained from amylomaize VII starch (70% amylose). Formation of RS in amylomaize VII starch was affected by the starch/water ratio, autoclaving temperature, and number of autoclaving-cooling cycles. The number of cycles exerted the most pronounced effect on RS; increasing the number of cycles up to 20 raised the RS level to over 40%. Differential scanning calorimetry thermograms of amylomaize VII preparations and isolated RS exhibited an endothermic transition over a similar temperature range (120-165 C), which could apparently be attributed to the melting of amylose crystallites. With increasing levels of RS in amylomaize VII starch preparations, a linear increase of melting enthalpies of amylomaize VII starch was recorded. Melting enthalpies of RS indicated changes in the quality of RS with increasing yields of RS. Furthermore, the thermoanalytical data suggested that amylose- lipid complexes were not involved in the formation of RS. Structural differences between heat-moisture and enzyme-treated amylomaize VII preparations, as illustrated by scanning electron microscopy, could be related to different melting enthalpies determined by differential scanning calorimetry.