Utilização de heat-moisture treatment com ácidos orgânicos: avaliação das propriedades térmicas, de pasta, morfológicas, estrututrais e digestabilidade in vitro em amidos de diferentes fontes botânicas

Abstract

The starches represent an important source of carbohydrates for the human food nutrition. However, in their native form, they might present some restrictions such as the insolubility in cold water, low stability against freezing and unfreezing cycles, besides showing a tendency to retrograde. Thus, as the modifications of these biopolymers are of great importance for the food industry, promoting technological improvements in their production. The hydrothermal treatments such as Heat-moisture Treatment (HMT), in addition, can increase the levels of slowly digestible starch (SDS) and resistant starch (RS), which is considered a prebiotic food. Starches from different botanical sources (potatoes, black beans and buckwheat) were evaluated during this study, combining the HMT with organic acids (citric, lactic and tartaric), capable of potentialize the modifications. The botanical sources behaved differently because of their particular native properties, however they presented significant and more expressive differences, in the increase of the relative crystallinity of 5.39 % and decrease of the variation of gelatinization enthalpy of 50.4 % for potato starch, increase in gelatinization event temperatures for bean and buckwheat starches, in addition to an increase in SDS contents by 2.6 times for buckwheat starch and RS of 20.5 % for bean starch. The tartaric acid, previously studied, proved to be efficient when combined with hydrothermal treatment, as well as citric and lactic acid, showing modifications on the granule surfaces observed by the electron microscopy. The results of this study can be considered positive for the use of these modifications in starches with food applications in order to improve technological and digestibility characteristics.