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.
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