Weakening the integrity of waxy starch granules by selective degradation of amorphous matrices using gaseous hydrogen chloride.

Waxy corn starch with 6-12 % moisture was degraded by gaseous hydrogen chloride (HCl) then characterized chromatographically and microscopically to investigate the relationship between moisture-resulting changes in unit chain properties of starch and its susceptibility to swelling. Starches with the highest degradation extents at different moisture content had recoveries of 76-83 % (w/w) and the weight-average degrees of polymerization of 66-93 anhydroglucose unit. Additionally, the HCl-degraded starches were still of birefringent granules but with internal cavity.

Degradation of corn starch with different moisture content by gaseous hydrogen chloride.

Corn starch, subjected to solid-state degradation using gaseous hydrogen chloride, was characterized to investigate the parameter effects on starch properties and further explore the thermal behavior of inter-crystalline amorphous lamellae of starch. The obtained starch granules exhibited A-type polymorph with 75-98 % recovery (w/w). Degreasing moisture content (6-12 %) with increasing duration (1-8 h) and temperature (25-45 °C) progressively decreased the weight-average degree of polymerization to 55-75 anhydroglucose unit and increased the gelatinization temperature range.

Properties of High-Swelling Native Starch Treated by Heat-Moisture Treatment with Different Holding Times and Iterations.

Tapioca and potato starches were used to investigate the effect of heat-moisture treatment (HMT; 95-96 °C, 0-60 min, 1-6 iterations) on gelatinization properties, swelling power (SP), solubility and pasting properties. Tapioca starch had similar content and degree of polymerization of amylose, but a higher amylopectin short/long chain ratio, to potato starch. After HMT, the gelatinization temperature range was narrowed for tapioca starch, but was widened for potato starch.

Progressive alterations in crystalline structure of starches during heat-moisture treatment with varying iterations and holding times.

Corn, tapioca and potato starches after heat-moisture treatment (HMT) at 95-96 °C for 0-60 min with 1-6 iterations were characterized for their gelatinization properties to elucidate the HMT-generated differences in crystalline structure of the starches. The enthalpy changes (ΔH) of all HMT starches were decreased, and the decreases in ΔH of the whole and of the fraction corresponding to well-ordered region of crystalline structure were both in the order of corn < tapioca < potato. With increasing HMT iteration and holding time, the same order was also observed for the shifting extent of pasting properties of HMT starches to that of restricted-swelling granules.

Indigestible pyrodextrins prepared from corn starch in the presence of glacial acetic acid.

This study was conducted to evaluate the feasibility of using acetic acid (0-2.5%) as the catalyst in the production of pyrodextrins from corn starch at 140-180 °C, and to elucidate the effects of catalyst concentration and pyrolytic temperature on the characteristics of indigestible pyrodextrins. In the absence of acetic acid, noticeable changes to the loss of birefringence, increased solubility, plateau of molecular weight reduction, decreased reducing sugar content and digestibility were observed at 180 °C.