Processing of oat dietary fibre for improved functionality as a food ing redient: Disssertation

Juhani Sibakov

Research output: ThesisDissertationCollection of Articles

Abstract

A dry fractionation process was developed based on defatted oats. Lipid removal by supercritical carbon dioxide extraction enabled concentration of the main components of oats: starch, protein, lipids and cell walls into specific fractions. A defatted oat bran concentrate (OBC) with 34% beta-glucan was obtained after two grinding and air classification steps. Ultra-fine grinding was needed to further dissociate the macronutrients of oat bran particles. Electrostatic separation was used to separate particles rich in beta-glucan and starch from those rich in arabinoxylan. The betaglucan from defatted OBC was enriched from 34 to 48% after two steps of electrostatic separation. The 48% beta-glucan fraction was further enriched by a combination of jet-milling and air classification, yielding a fraction with up to 56% betaglucan. OBC was further processed by partial depolymerisation of beta-glucan with acid- or enzyme-catalysed hydrolysis at relatively low water content using a twin-screw extruder as a bioreactor. The hydrolysed oat brans were extracted with hot water and centrifuged to obtain a water-soluble phase and an insoluble residue. The timedependent gelling of the water-soluble phase was monitored for 14 weeks at 5 °C. Acid hydrolysis depolymerised the beta-glucan molecules from their original average molecular weight (Mw) of 780 to 34kDa (polydispersity 4.0-6.7), and enzymatic hydrolysis down to 49 kDa (polydispersity 19.0-24.2). At 1.4-2.0% beta-glucan concentration, solutions of beta-glucan molecules with Mw>50 kDa agglomerated rapidly, whereas solutions of smaller molecules (34-49 kDa) remained as stable dispersions for longer. Gelling was strongly concentration-dependent; at 1.4 to 1.6% beta-glucan concentration gelling occurred after 7 to 12 weeks of storage, whereas at 1.8 to 1.9% concentration gelling occurred already after 2 weeks. OBC was used in extruded products in five different forms (untreated, ultra-fine ground, enzymatically hydrolysed and hot-water extracted solubles and insoluble residue). Addition of untreated OBC decreased the expansion (172%) and resulted in harder texture (258 N) compared to extrudates based on 100% endosperm flour (EF) (199% and 148 N, respectively). When OBC was separated into water-insoluble (WISOBC) and water-soluble (WS-OBC) fractions, significant differences were observed in the resulting extrudates. Ten percent addition of WIS-OBC fraction significantly decreased the expansion (163%) and increased the hardness (313 N) of EF-based extrudates, whereas 10 or 20% addition of WS-OBC enhanced the expansion (218-226%) and resulted in less hard textures (131-146 N). The improved texture was most probably due to the high amount of soluble fibres and low protein content.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • Aalto University
Supervisors/Advisors
  • Laakso, Simo, Supervisor, External person
Award date31 Oct 2014
Place of PublicationEspoo
Publisher
Print ISBNs978-951-38-8165-8
Electronic ISBNs978-951-38-8166-5
Publication statusPublished - 2014
MoE publication typeG5 Doctoral dissertation (article)

Fingerprint

oat bran
oats
dietary fiber
beta-glucans
concentrates
gelation
water
texture
grinding
endosperm
flour
oat starch
molecular weight
air
soluble fiber
arabinoxylan
extruders
depolymerization
acid hydrolysis
enzymatic hydrolysis

Keywords

  • oats
  • oat bran
  • dietary fibre
  • beta-glucan
  • arabinoxylan
  • defatting
  • supercritical carbon dioxide extraction
  • dry fractionation
  • grinding
  • air
  • classification
  • electrostatic separation
  • jet-milling
  • acid hydrolysis
  • enzymatic hydrolysis
  • low water content
  • extrusion
  • oat-based
  • extrudates

Cite this

Sibakov, J. (2014). Processing of oat dietary fibre for improved functionality as a food ing redient: Disssertation. Espoo: VTT Technical Research Centre of Finland.
Sibakov, Juhani. / Processing of oat dietary fibre for improved functionality as a food ing redient : Disssertation. Espoo : VTT Technical Research Centre of Finland, 2014. 182 p.
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title = "Processing of oat dietary fibre for improved functionality as a food ing redient: Disssertation",
abstract = "A dry fractionation process was developed based on defatted oats. Lipid removal by supercritical carbon dioxide extraction enabled concentration of the main components of oats: starch, protein, lipids and cell walls into specific fractions. A defatted oat bran concentrate (OBC) with 34{\%} beta-glucan was obtained after two grinding and air classification steps. Ultra-fine grinding was needed to further dissociate the macronutrients of oat bran particles. Electrostatic separation was used to separate particles rich in beta-glucan and starch from those rich in arabinoxylan. The betaglucan from defatted OBC was enriched from 34 to 48{\%} after two steps of electrostatic separation. The 48{\%} beta-glucan fraction was further enriched by a combination of jet-milling and air classification, yielding a fraction with up to 56{\%} betaglucan. OBC was further processed by partial depolymerisation of beta-glucan with acid- or enzyme-catalysed hydrolysis at relatively low water content using a twin-screw extruder as a bioreactor. The hydrolysed oat brans were extracted with hot water and centrifuged to obtain a water-soluble phase and an insoluble residue. The timedependent gelling of the water-soluble phase was monitored for 14 weeks at 5 °C. Acid hydrolysis depolymerised the beta-glucan molecules from their original average molecular weight (Mw) of 780 to 34kDa (polydispersity 4.0-6.7), and enzymatic hydrolysis down to 49 kDa (polydispersity 19.0-24.2). At 1.4-2.0{\%} beta-glucan concentration, solutions of beta-glucan molecules with Mw>50 kDa agglomerated rapidly, whereas solutions of smaller molecules (34-49 kDa) remained as stable dispersions for longer. Gelling was strongly concentration-dependent; at 1.4 to 1.6{\%} beta-glucan concentration gelling occurred after 7 to 12 weeks of storage, whereas at 1.8 to 1.9{\%} concentration gelling occurred already after 2 weeks. OBC was used in extruded products in five different forms (untreated, ultra-fine ground, enzymatically hydrolysed and hot-water extracted solubles and insoluble residue). Addition of untreated OBC decreased the expansion (172{\%}) and resulted in harder texture (258 N) compared to extrudates based on 100{\%} endosperm flour (EF) (199{\%} and 148 N, respectively). When OBC was separated into water-insoluble (WISOBC) and water-soluble (WS-OBC) fractions, significant differences were observed in the resulting extrudates. Ten percent addition of WIS-OBC fraction significantly decreased the expansion (163{\%}) and increased the hardness (313 N) of EF-based extrudates, whereas 10 or 20{\%} addition of WS-OBC enhanced the expansion (218-226{\%}) and resulted in less hard textures (131-146 N). The improved texture was most probably due to the high amount of soluble fibres and low protein content.",
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author = "Juhani Sibakov",
note = "Project code: 86161",
year = "2014",
language = "English",
isbn = "978-951-38-8165-8",
series = "VTT Science",
publisher = "VTT Technical Research Centre of Finland",
number = "67",
address = "Finland",
school = "Aalto University",

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Processing of oat dietary fibre for improved functionality as a food ing redient : Disssertation. / Sibakov, Juhani.

Espoo : VTT Technical Research Centre of Finland, 2014. 182 p.

Research output: ThesisDissertationCollection of Articles

TY - THES

T1 - Processing of oat dietary fibre for improved functionality as a food ing redient

T2 - Disssertation

AU - Sibakov, Juhani

N1 - Project code: 86161

PY - 2014

Y1 - 2014

N2 - A dry fractionation process was developed based on defatted oats. Lipid removal by supercritical carbon dioxide extraction enabled concentration of the main components of oats: starch, protein, lipids and cell walls into specific fractions. A defatted oat bran concentrate (OBC) with 34% beta-glucan was obtained after two grinding and air classification steps. Ultra-fine grinding was needed to further dissociate the macronutrients of oat bran particles. Electrostatic separation was used to separate particles rich in beta-glucan and starch from those rich in arabinoxylan. The betaglucan from defatted OBC was enriched from 34 to 48% after two steps of electrostatic separation. The 48% beta-glucan fraction was further enriched by a combination of jet-milling and air classification, yielding a fraction with up to 56% betaglucan. OBC was further processed by partial depolymerisation of beta-glucan with acid- or enzyme-catalysed hydrolysis at relatively low water content using a twin-screw extruder as a bioreactor. The hydrolysed oat brans were extracted with hot water and centrifuged to obtain a water-soluble phase and an insoluble residue. The timedependent gelling of the water-soluble phase was monitored for 14 weeks at 5 °C. Acid hydrolysis depolymerised the beta-glucan molecules from their original average molecular weight (Mw) of 780 to 34kDa (polydispersity 4.0-6.7), and enzymatic hydrolysis down to 49 kDa (polydispersity 19.0-24.2). At 1.4-2.0% beta-glucan concentration, solutions of beta-glucan molecules with Mw>50 kDa agglomerated rapidly, whereas solutions of smaller molecules (34-49 kDa) remained as stable dispersions for longer. Gelling was strongly concentration-dependent; at 1.4 to 1.6% beta-glucan concentration gelling occurred after 7 to 12 weeks of storage, whereas at 1.8 to 1.9% concentration gelling occurred already after 2 weeks. OBC was used in extruded products in five different forms (untreated, ultra-fine ground, enzymatically hydrolysed and hot-water extracted solubles and insoluble residue). Addition of untreated OBC decreased the expansion (172%) and resulted in harder texture (258 N) compared to extrudates based on 100% endosperm flour (EF) (199% and 148 N, respectively). When OBC was separated into water-insoluble (WISOBC) and water-soluble (WS-OBC) fractions, significant differences were observed in the resulting extrudates. Ten percent addition of WIS-OBC fraction significantly decreased the expansion (163%) and increased the hardness (313 N) of EF-based extrudates, whereas 10 or 20% addition of WS-OBC enhanced the expansion (218-226%) and resulted in less hard textures (131-146 N). The improved texture was most probably due to the high amount of soluble fibres and low protein content.

AB - A dry fractionation process was developed based on defatted oats. Lipid removal by supercritical carbon dioxide extraction enabled concentration of the main components of oats: starch, protein, lipids and cell walls into specific fractions. A defatted oat bran concentrate (OBC) with 34% beta-glucan was obtained after two grinding and air classification steps. Ultra-fine grinding was needed to further dissociate the macronutrients of oat bran particles. Electrostatic separation was used to separate particles rich in beta-glucan and starch from those rich in arabinoxylan. The betaglucan from defatted OBC was enriched from 34 to 48% after two steps of electrostatic separation. The 48% beta-glucan fraction was further enriched by a combination of jet-milling and air classification, yielding a fraction with up to 56% betaglucan. OBC was further processed by partial depolymerisation of beta-glucan with acid- or enzyme-catalysed hydrolysis at relatively low water content using a twin-screw extruder as a bioreactor. The hydrolysed oat brans were extracted with hot water and centrifuged to obtain a water-soluble phase and an insoluble residue. The timedependent gelling of the water-soluble phase was monitored for 14 weeks at 5 °C. Acid hydrolysis depolymerised the beta-glucan molecules from their original average molecular weight (Mw) of 780 to 34kDa (polydispersity 4.0-6.7), and enzymatic hydrolysis down to 49 kDa (polydispersity 19.0-24.2). At 1.4-2.0% beta-glucan concentration, solutions of beta-glucan molecules with Mw>50 kDa agglomerated rapidly, whereas solutions of smaller molecules (34-49 kDa) remained as stable dispersions for longer. Gelling was strongly concentration-dependent; at 1.4 to 1.6% beta-glucan concentration gelling occurred after 7 to 12 weeks of storage, whereas at 1.8 to 1.9% concentration gelling occurred already after 2 weeks. OBC was used in extruded products in five different forms (untreated, ultra-fine ground, enzymatically hydrolysed and hot-water extracted solubles and insoluble residue). Addition of untreated OBC decreased the expansion (172%) and resulted in harder texture (258 N) compared to extrudates based on 100% endosperm flour (EF) (199% and 148 N, respectively). When OBC was separated into water-insoluble (WISOBC) and water-soluble (WS-OBC) fractions, significant differences were observed in the resulting extrudates. Ten percent addition of WIS-OBC fraction significantly decreased the expansion (163%) and increased the hardness (313 N) of EF-based extrudates, whereas 10 or 20% addition of WS-OBC enhanced the expansion (218-226%) and resulted in less hard textures (131-146 N). The improved texture was most probably due to the high amount of soluble fibres and low protein content.

KW - oats

KW - oat bran

KW - dietary fibre

KW - beta-glucan

KW - arabinoxylan

KW - defatting

KW - supercritical carbon dioxide extraction

KW - dry fractionation

KW - grinding

KW - air

KW - classification

KW - electrostatic separation

KW - jet-milling

KW - acid hydrolysis

KW - enzymatic hydrolysis

KW - low water content

KW - extrusion

KW - oat-based

KW - extrudates

M3 - Dissertation

SN - 978-951-38-8165-8

T3 - VTT Science

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -

Sibakov J. Processing of oat dietary fibre for improved functionality as a food ing redient: Disssertation. Espoo: VTT Technical Research Centre of Finland, 2014. 182 p.