Abstract
Oats are rich in dietary fibre (DF) especially in
ß-glucan which has several health-promoting effects. Oats
are not commonly used in extruded snacks because they
often result in a poor expansion and hard structure. In
the present study, defatted wholegrain oat flour (WF) and
defatted endosperm oat flour (EF) were used as starch
sources for extrudates. Five differently treated oat bran
fractions (untreated, ultra-fine ground, enzymatically
hydrolysed and hot water-extracted solubles and residue)
were added to EF (10 or 20 %), and their influence on the
chemical, textural and structural properties of
extrudates was investigated. Extrudates made of WF had a
poor expansion (151 %) and hard texture (399 N), whereas
EF formed a better expanded (199 %) and less hard product
(149 N). Addition of oat bran concentrate (OBC) decreased
the expansion (171-176 %) and resulted in a harder
texture (200-265 N) compared to that of EF 100 %
extrudates. The lower expansion of WF and OBC-enriched
extrudates was due to the higher content of insoluble
fibre. However, no statistical differences were detected
between the untreated, ultra-fine ground and
enzyme-hydrolysed OBC. The water-insoluble (WIS-OBC) and
water-soluble (WS-OBC) fractions had opposite effects on
the EF-based extrudates: 10 % addition of WIS-OBC
fraction significantly decreased the expansion (163 %)
and increased the hardness (313 N), whereas the addition
of WS-OBC (10 or 20 %) enhanced the expansion (218-226 %)
and resulted in less hard textures (131-146 N). The
soluble fibres and low protein content in WS-OBC fraction
were hypothesised to cause the improved expansion and
decreased hardness. The results demonstrated that
extrudates with acceptable expansion and hardness can be
produced with defatted oat endosperm flour and oat bran
fractions. However, the water-insoluble bran components
had a negative effect on the textural properties of
extrudates.
Original language | English |
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Pages (from-to) | 445-458 |
Journal | Food and Bioprocess Technology |
Volume | 8 |
Issue number | 2 |
DOIs | |
Publication status | Published - Feb 2015 |
MoE publication type | A1 Journal article-refereed |
Keywords
- defatted oat flour
- oat bran concentrate
- soluble dietary fibre
- insoluble dietary fibre
- beta-glucan
- extrusion processing