Properties of Popcorn Starch Expanded in a Microwave, with and without the Presence of Vegetable Oil

Abstract

The aim of this study was to evaluate the physical, chemical, pasting, thermal, crystallinity and morphological properties of starches from popcorn expanded in a microwave, with and without the presence of vegetable oil, and compared with the starch from nonexpanded grains. The popcorn grains were expanded in a microwave without the addition of vegetable oil and with addition of 4% soybean oil, using different expansion times. The increase of the expansion time of the popcorn changed the starch properties, demonstrated by the increase of the pasting temperature and the reduction of peak viscosity, breakdown, final viscosity and retrogradation, besides affecting the thermal and crystallinity properties of the starches. These changes were more intense in the starches of expanded grains with the presence of oil. Therefore, the use of vegetable oil in the expansion process accelerated the gelatinization process of starch, resulting in more intense changes of properties of the starch. Practical Application Considering the great importance and application of starch in foods, the use of popcorn starch, according to the properties presented in this study, may be an alternative to add value to these grains especially when the grain expansion properties are limited due to inadequate postharvest handling, provided that the starch is not completely gelatinized.