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Cereal Extrusion - An investigation of extrudate properties and differences between powder and pellets feeding

Ek, Martina LU (2015) KLT920 20151
Food Technology and Nutrition (M.Sc.)
Abstract
Extrusion cooking is a technique that has been extensively developed in the last decades and is today strongly associated with the production of snack foods and breakfast cereals. This project aimed to map the extrudate properties of four different cereal materials extruded at two different moisture contents and three different temperatures. Rye bran, rye flour, Barley Amylopectin Starch and β- glucan flour were included in the project and fed to the extruders as pellets. The extrudate properties were investigated by analysing the macrostructure, microstructure, radial expansion index, breaking strength and elastic modulus. It was also investigated whether there are any differences between feeding the materials as powder or as pellets.
In... (More)
Extrusion cooking is a technique that has been extensively developed in the last decades and is today strongly associated with the production of snack foods and breakfast cereals. This project aimed to map the extrudate properties of four different cereal materials extruded at two different moisture contents and three different temperatures. Rye bran, rye flour, Barley Amylopectin Starch and β- glucan flour were included in the project and fed to the extruders as pellets. The extrudate properties were investigated by analysing the macrostructure, microstructure, radial expansion index, breaking strength and elastic modulus. It was also investigated whether there are any differences between feeding the materials as powder or as pellets.
In general the results showed that high temperature and low moisture content favour foaming of the materials. It was also shown that bran particles inhibit foaming and the pure starch had the largest radial expansion of all materials. Moreover it was found that bran particles are not subjected to dispersive mixing during extrusion but do instead migrate to specific locations in the extrudate.
It was shown that the pellets are in most cases to prefer as feeding material before powder as they alleviate feeding, produce less extrusion failures and generate more stable operational conditions. The β-glucan material was however an exception. The β-glucan pellets extrusions suffered from feed ejection and poor conveying in the feeding zone and the powder extrusions were consequently more feasible. (Less)
Popular Abstract (Swedish)
En uppsjö av extruderade livsmedelsprodukter återfinns idag på butikshyllorna inom dagligvaruhandeln och antalet produkter ökar ständigt. Det rör sig om allt från snacks som ostbågar och tortilla chips till majskrokar och frukostflingor. Trots den stora mängden produkter är extrudering en för allmänheten ofta okänd teknik. Denna typ av produkter har ofta ansetts vara onyttiga men nya rön antyder att det i framtiden är i det extruderade sortimentet som man kommer att hitta hälsosamma fiberrika produkter.
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author
Ek, Martina LU
supervisor
organization
course
KLT920 20151
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Cereal extrusion, Rye bran, Extrusion, Rye flour, Beta-glucan, BAP, Radial Expansion, livsmedelsteknik
language
English
id
7470928
date added to LUP
2015-09-22 20:59:49
date last changed
2015-09-22 20:59:49
@misc{7470928,
  abstract     = {Extrusion cooking is a technique that has been extensively developed in the last decades and is today strongly associated with the production of snack foods and breakfast cereals. This project aimed to map the extrudate properties of four different cereal materials extruded at two different moisture contents and three different temperatures. Rye bran, rye flour, Barley Amylopectin Starch and β- glucan flour were included in the project and fed to the extruders as pellets. The extrudate properties were investigated by analysing the macrostructure, microstructure, radial expansion index, breaking strength and elastic modulus. It was also investigated whether there are any differences between feeding the materials as powder or as pellets.
In general the results showed that high temperature and low moisture content favour foaming of the materials. It was also shown that bran particles inhibit foaming and the pure starch had the largest radial expansion of all materials. Moreover it was found that bran particles are not subjected to dispersive mixing during extrusion but do instead migrate to specific locations in the extrudate.
It was shown that the pellets are in most cases to prefer as feeding material before powder as they alleviate feeding, produce less extrusion failures and generate more stable operational conditions. The β-glucan material was however an exception. The β-glucan pellets extrusions suffered from feed ejection and poor conveying in the feeding zone and the powder extrusions were consequently more feasible.},
  author       = {Ek, Martina},
  keyword      = {Cereal extrusion,Rye bran,Extrusion,Rye flour,Beta-glucan,BAP,Radial Expansion,livsmedelsteknik},
  language     = {eng},
  note         = {Student Paper},
  title        = {Cereal Extrusion - An investigation of extrudate properties and differences between powder and pellets feeding},
  year         = {2015},
}