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Improved extraction of arabinoxylans from rye bran and production of health beneficial oligosaccharides
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Resumo(s)
The purpose of this work is to investigate and improve different technical aspects in
the extraction of soluble dietary fibres, mostly AX, from rye bran and to characterize
the fibres throughout the process, as well as perform enzymatic hydrolysis of
arabinoxylans, producing health promoting oligosaccharides: Xylan-oligosaccharides
and arabinoxylan-oligosaccharides. These hydrolysis products may serve as candidate
supplements in food and feed industry because of their prebiotic proprieties. They can
act as substrates which selectively stimulate the growth of probiotic bacteria that
produce metabolic active compounds which can contribute, for instance, to lowering
risk of colon cancer incidence, decrease cholesterol absorption and might have a
positive influence on type II diabetes and obesity.
The work included several enzymatic steps, using alpha-amylases, proteases and
xylanses as well as extraction with steam, separation steps and purification using
solvent precipitation, dialysis and freeze drying. Different analytical techniques were
used to follow the enzymatic steps and to characterize the carbohydrates, including an
OPA-based spectrophotometrical method to study the protein hydrolysis, acid
hydrolysis in combination with High Performance Anion Exchange Chromatography
with Pulsed Ampherometric Detection (HPAEC-PAD) and size-exclusion
chromatography (SEC) to study the carbohydrates.
As main results, regarding the extraction final product, a visible improvement in is
physical appearance is achieved, as well as a significant improvement in its content in
arabinoxylans which increases from 37.57% (using the previous method) up to 60.45%.
Regarding the arabinoxylan / glucose ratio, it also improved from 1,84 up to a
maximum of 10.02.
The objective of this work was achieved with success as a significant improvement on
the product composition and characteristics was achieved as well as the heath
beneficial oligosaccharides were obtained, therefore, this work result on a small but
good contribution for the project of my colleagues in Lund University.
Descrição
Dissertação de mest., Engenharia Biológica, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011
Palavras-chave
Alimentos funcionais Arabinoxilanos Xilanase Prebióticos Probióticos Functional foods Arabinoxylan Xylanase Prebiotics Probiotics