Process-induced structural properties and starch digestibility of high-fibre extruded products

Research output: ThesisDoctoral ThesisCollection of Articles

Abstract

This study focused on modification of rye bran to produce high fibre extruded cereal foods with a good texture and structure. Rye bran addition during extrusion is challenging due to high levels of insoluble dietary fibre, which leads to less expanded products and a hard texture. Bran modification by particle size reduction or fermentation significantly improved both the structural and textural properties of extrudates. Moreover, optimization of the processing parameters such as increasing the screw speed, lowering the water feed rate, as well as the use of in-barrel hydration regimens further improved the textural properties. The applicability of rye bran in extruded products could thus be improved by particle size reduction and fermentation.

The extruded food structure and texture had a direct effect on the mastication and bolus formation process in the mouth. A hard and dense extrudate structure required more mastication effort than a crispy structure. Crispy and porous structures easily disintegrated in the mouth and produced smaller bolus particles than a hard and dense structure. A smaller particle size of the bolus was associated with increased starch hydrolysis. The bolus particle size was more effective than the matrix composition in
altering the starch digestibility.

Increased dietary fibre intake via appealing snack products could help reduce chronic diseases. Knowledge obtained in this thesis on cereal matrix formation and digestion and the effects of added dietary fibre on the structural and textural properties of extruded solid foams will help the food industry to develop healthy and appealing products. Understanding process-structure-digestibility relationships of high fibre extruded matrices is essential for designing health promoting foods.
Original languageEnglish
Awarding Institution
  • University of Helsinki
Supervisors/Advisors
  • Sozer, Nesli, Supervisor, External person
  • Poutanen, Kaisa, Supervisor, External person
  • Katina, Kati, Supervisor
Award date10 Dec 2020
Publisher
Print ISBNs978-951-51-6857-3
Electronic ISBNs978-951-51-6858-0
Publication statusPublished - 10 Dec 2020
MoE publication typeG5 Doctoral dissertation (article)

Note regarding dissertation

To be presented, with the permission of the Faculty of Agriculture and Forestry of the University of Helsinki for public examination in auditorium 1041 of Biocentre 2, Viikinkaari 5, Helsinki, on 10’th December 2020, at 08.00 a.m.

Fields of Science

  • 416 Food Science

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