Chemistry Reference
In-Depth Information
Table 7.1 Evolution of glass-transition temperature of
sunflower proteins according to their water
content.
23
Water Content
(% DM)
d
n
9
r
3
n
g
|
5
R.H. (%)
T
g
(1C)
-
0
180.8
8
3.05
129.5
33
5.95
113.1
43
7.40
111.9
54
9.03
77.8
d
y
y
f
n
n
3
.
62
11.67
68.4
75
13.47
46.1
80
15.73
39.6
85
17.09
33.8
92
26.12
5.3
Figure 7.4
Dependence of denaturation temperature (TD, solid line) and glass
transition temperature (TG, dashed line) of proteins on the water content.
Adapted from reference.
18
temperature (T
d
) line, allowing both thermodynamic denaturation (T4T
d
) and
sucient chain mobility (T4T
g
). When processing is considered, this condition
can be achieved in three ways:
by increasing the water content, allowing processing at 'low' temperature;
by increasing the temperature, which is particularly effective at low water
content;
by adding structure breakers/denaturants (e.g. urea), which reduce T
d
at a
given water content.
7.2.5 ''Melt'' Rheology of Oilseed Proteins
While extrusion of protein-based materials is of great interest for food appli-
cations,
24
few studies have been performed to characterise the rheological
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