Influence of Infrared Dry Heat Treatment on the Structure and Properties of Potato Starch

The current study presents a novel approach to starch modification using infrared dry heat treatment (IR-DHT). IR-heating at 200 degrees C allows one to reduce the processing time to 15 min and does not lead to irreversible amorphization of starch structure. Upon IR-DHT, an increase in density of starch granules from 1.4888 +/- 0.0005 to 1.5038 +/- 0.0005 g cm-3 is observed. The crystallinity degree of the starch exposed in water at 20 degrees C after IR-DHT does not change compared to the crystallinity of native starch hydrated at the same temperature. However, the exposure in excess of water of native potato starch at 45 degrees C induces an increase of crystallinity up to 81% (along with a significant increase in the intensity of the d100 reflection), while heat-treated starch exposed in water at the same temperature has reduced crystallinity (RC = 39%). In addition, the concentration of soluble carbohydrates released during the exposure process (45 degrees C, excess of water) increases by an order of magnitude for heat-treated starch compared to the native sample. Hence, IR-DHT may become a promising way to influence the processes of acid and enzymatic hydrolysis and control starch properties, such as pasting, solubility, and digestibility. The increase in the density of potato starch as a result of dry heat treatment (DHT) exceeds the differences in the density of native corn and potato starches of the same moisture content (1% - increase in density after DHT, 0.4% - difference in densities of potato and maize starch) and are irreversible. Also, DHT leads to a change in the thermal behavior of potato starch. image