Pregelatinized starches enriched in slowly digestible and resistant fractions

Abstract

Consumption of slowly digestible and resistant starches (SDS and RS) is known to modulate postprandial glucose levels and attain extended glucose release. In this study, pregelatinized high-amylose maize starches (50 and 70 g amylose 100 g(-1) starch) were subjected to hydrothermal treatments [40 g water 100 g(-1), heat-moisture treated (HMT) at 100 degrees C and low temperature-moisture treated (LMT) at 4 degrees C) to increase total amount of SDS and RS. Hydrothermal treatment of pregelatinized high-amylose starches produced higher amounts of SDS (27.0 and 26.4% for HMT and LMT amylomaize V, and 21.5 and 21.6% for HMT and LMT amylomaize VII) and RS (36.2 and 31.5 g/100 g, and 47.5 and 37.5 g/100 g, respectively), than pregelatinized normal or waxy starches (SDS- 2.3 and 3.2 g/100 g, and 13.7 and 15.8 g/100 g, respectively; and RS 10.2 and 7.8 g/100 g, and 12.4 and 11.0 g/100 g, respectively). Granule morphology was retained in pregelatinized high-amylose starches, apparently due to their restricted swelling. Starch debranching profiles showed a minor increase in DP 25-36 in SDS and RS, suggesting that higher intermediate fractions of the high-amylose starches may create an overall material effect resulting in slower digestion of hydrothermal treated starches. High SDS and RS in pregelatinized starches could be applied in cold-formed food products.