Improved extraction of arabinoxylans from rye bran and production of health beneficial oligosaccharides

Dissertação de mest., Engenharia Biológica, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011

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.