Composição e caracterização química da fração sacarídica do coproduto da biofermentação etanólica da batata-doce (Ipomoea batatas (L.) Lam)

Abstract

The growing in the demand and need for fuels lead to the search for a renewable and clean source. The biofermentation of sweet potato (Ipomoea batatas (L.) Lam) for the production of biofuel generates a waste which is in the most times disposable in field, but the characteristics of this waste (rich in protein and carbohydrate) makes it susceptible for being studied and other uses exploited, making it a coproduct of the production. The goal of this work was the study of the composition and chemical structure of the carbohydrates found in the coproduct of the fermentation of sweet potato. Underwent this coproduct to two consecutive water extractions, cold-water extraction (CWE) and hot-water extraction (HWE). The extracted, fractioned (oligosaccharides and polysaccharides), hydrolyzed and purified carbohydrates underwent to different chromatography techniques (Thin layer chromatography, high precision liquid chromatography and gas chromatography with mass spectrometry) to clarify the composition and quantity of monosaccharides. Nuclear magnetic resonance (NMR) was used to the structural characterization of the carbohydrates. With the use of high precision techniques (GC-MS and HPLC) it was possible to identify and quantify the sugars. Glucose is the main component founded in the oligosaccharide fraction and galactose in the polysaccharides, was possible to identify the presence of mannose, xylose, rhamnose and arabinose in fewer quantities. The structural analyses show that the polysaccharide fraction has a type I arabinogalactana (composed by (1→4)-β-Galp as the backbone). Those polymers are highly studied because of the benefits when ingested, for example the combat to virus, bifidogenic activity, related to be beneficial to the immune system and to cancer. Therefore, the continued study of this coproduct is necessary and the possible health benefits.