Abstract
The aim of this study was to investigate under which
processing conditions the extrusion of rye bran could
produce a material with a long shelf life in terms of
lipid chemistry and possibilities to link lipid stability
with physical properties of the extrudates. In addition
to water content (13-30%) and temperature (80-140°C) as
variables during extrusion, the effect of rye bran
particle size (633 and 15 µm) was studied. Stability of
lipids was measured by volatile compounds and the loss of
tocopherols and tocotrienols. Of the studied process
parameters, the water content had a significant effect
both on the physical properties and on lipid stability.
Low water content (13 or 16%) in the extrusion of coarse
or fine bran led to the highest expansion and porosity
and the most stable lipids during storage. The improved
oxidative stability when processed at low water contents
in extrusion was connected with a higher formation of
Maillard reaction products, which could have acted as
antioxidants. In spite of the loss of tocols during
grinding, the lipids in the fine rye bran extrudates were
at least as stable as the lipids in the coarse rye bran
extrudates when processed at low water content. However,
the high furfural content in the fine rye bran extrudate
at 13 % indicated that Maillard reaction was extensive
which could lead to undesirable flavour. Thus, the
overall best performance was obtained when the coarse rye
bran was processed at the lowest water content.
Original language | English |
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Pages (from-to) | 49-60 |
Journal | European Food Research and Technology |
Volume | 241 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2015 |
MoE publication type | A1 Journal article-refereed |
Keywords
- food science
- rye bran
- dietary fibres
- lipid oxidation
- extrusion
- grinding