Chemistry Reference
In-Depth Information
other organoplasts have an oblong shape and seem to be aggregated. These
aggregates could correspond to the insoluble protein found in high amount
(Table 7.4).
Oil extraction does not affect the thermal stability of the corpuscular proteins
of sunflower seed but is responsible for the aggregation into a large extent of
protein with polyphenolic compounds.
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n
9
r
3
n
g
|
5
7.4 Twin-Screw Extrusion of SFOC
Twin-screw extrusion is a versatile tool well known for:
d
y
y
f
n
n
3
.
the defibration or pulping of lignocellulosic fibres;
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the texturation of protein;
24
the compounding of thermoplastic materials: mixing additives, pelletising,
etc.
Twin-screw extrusion could then in a one step process, plasticise the protein
fraction and defibrate the husk fragments of SFOC.
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A classical screw profile
and the operating conditions used are shown in Figure 7.10.
Using this kind of basic process: only water is needed (the moisture content is
set at 30%), the temperature is limited at 100 1C and specific mechanical energy
is kept under 300 W h/kg, SFOC microstructure is completely changed.
The small and hard particles of SFOC (Figure 7.9) are transformed during
extrusion into small and soft fibre aggregates (Figure 7.11). The bulk relative
density of the extruded sunflower oil cake (ESFOC) decreases from 0.45 after
the grinding of the granules to 0.29 g cm
-3
after extrusion. The softness of the
ESFOC can be attributed to the moistening of the initial mixture and to the
defibration of the fibrous fragments of hull.
Figure 7.10
Twin-screw extruder configuration and operating conditions for the
processing of SFOC.
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