Efeito do tratamento térmico de baixa umidade e da oxidação com ozônio nas propriedades físico-químicas, reológicas e térmicas de amido.

Abstract

The processes used to modify starch involve treatments that are safe for the consumer, as also to the environment. Modified starch by physical processes such as heat-moisture treatment (HMT) and chemical such as oxidation with ozone are able of producing a variety of starches with numerous properties that are applicable in the food industry and yet can be considered as clean technology, since both modifications do not generate large volumes of waste chemicals. Against this background the objectives were to evaluate the effect of single and dual heatmoisture treatment (HMT) at different temperatures on physico-chemical, thermal and viscographic properties of rice, cassava and pinhão starches, and study the influence of different pH and reaction temperatures on the physical, chemical, thermal and viscographic properties of cassava starch oxidized with ozone. The results shown that the temperature variation affected more the starch properties than the single or dual HMT. The starch subjected to single HMT at 120°C was the most applicable to food applications, where low swelling power, low viscosity and high thermal stability are necessary. Oxidation of cassava starch with ozone promoted changes on the properties of modified starch compared to native starch. It was found that the increase or decrease of the values of these properties are determined by temperature and pH conditions during the modification. Analyzing all of these properties after oxidation with ozone, it was found that the pH resulted in the greatest effect on the physical, chemical, rheological and thermal properties than the reaction temperature.