Extração de amido de Amaranthus caudatus orgânico por irradiação ultrassônica e incorporação de frutooligossacarídeos por ultrassom e liofilização

Abstract

The food industry invests resources for research and development in search of new formulations and technologies related to natural foods, with good sensory quality and functionality, aiming to reduce the addition of synthetic compounds. Due to its gel-forming capacity, availability, and low cost, starch has diversified use in foods, and can be explored as a vehicle for bioactive substances, such as fructooligosaccharides. Starches from non-conventional sources (such as amaranth) have also been valued for their different technological properties. The starch extraction process is relatively easy, and new techniques are being researched, with emphasis on physical processes, such as ultrasound (US), a clean technology, with lower solvent consumption, high reproducibility and efficiency. With this, the objective of this study was to perform the ultrasound-assisted extraction of Amaranthus caudatus starch from the grain and flour, evaluate the properties of the extracted starch from conditions defined by central compound rotated design. In the sequence, it was aimed to perform the incorporation of fructooligosaccharides (FOS) in flour and amaranth starch extracted by aqueous methodology and by ultrasound from ultrasound and lyophilization. In Chapter I there is a theoretical approach to starch, ultrasound-assisted extraction and enrichment of flour and starches, focusing mainly on what has already been studied involving amaranth. Chapter II encompasses the morphology of the amaranth grain, as well as the damage induced by ultrasound application to the seeds. The fractions that make up the seed were identified, with emphasis on the perisperm, which packs the starchy content. After US exposure, damage and rupture of the grain structure were intensified with time and vibration amplitude. Starch released during treatment was visualized by microscopy and gelatinization temperatures and enthalpy analysed, which were impacted by sonication. Chapter III involves the extraction of starch from amaranth flour compared to the aqueous methodology. The application of US allowed higher yield when shorter extraction time was used, especially under low vibration amplitude, which also imparted interesting paste characteristics, colour, thermal stability, gelatinization enthalpy and protein content. To conclude, the last Chapter presents the incorporation of FOS both in the flour and in the native and US-extracted starch (the best extraction point being chosen). The techniques used for incorporation were US and freeze-drying. The mixtures presented better distribution with the application of US preceding lyophilization, with higher whiteness index, low viscosity, and with the formation of a tangle. It was possible to maintain high FOS concentration in the native and US-extracted starch. Thus, the use of flour or starch enriched with prebiotics, highlighting in this study, the FOS, is an interesting strategy for the industry. Besides being directed to the general public, it could also be used for people with celiac disease, contributing to diet diversification, nutritional value, better amino acid composition when compared to cereals and legumes, and meeting the demand for innovative and practical products.