Environmental Engineering Reference
In-Depth Information
T
(°C)
Denatured
T
d
Rubbery
T
g
Glassy
0%
100%
Figure 6.21
Dependence of denaturation temperature (
T
d
, solid line) and glass transition
temperature (
T
g
, dashed line) of proteins on water content.
encapsulation of foods and drugs. The main barrier to greater commercial success
has been its historic high cost until recently. It is argued that one solution might be
to extract zein as a by-product of bioethanol production. From a high-value-added
perspective, Chinese researchers have conducted intensive research on the use of
zein as biomedical material [33].
The main properties of wheat grain, especially in pastries, reside primarily in
the storage protein in its endosperm, gluten. It has many specific properties that
are used in various food products but also some interesting viscoelastic properties
and low water solubility that can be used for non-food applications [34]. Two
technological approaches are usually employed - wet and dry processes - with
the latter taking most advantage of the specific properties of these proteins. They
possess thermoplastic properties under low moisture conditions, allowing their
formation through extrusion and injection-moulding, but are also capable of
cross-linking through sulphydryl-disulphide interchange, giving them elasto-
meric-like properties when highly plasticised. The company Syral in France com-
mercialises Meriplast®, a gluten-based material that is transformed and behaves
like an elastomer (low-temperature extrusion section and high-temperature mould
section), but is biodegradable and entirely bio-based.
6.3.6.4
Animal Proteins
The animal kingdom also produces many different kinds of proteins which can be
used for various non-food applications and, in particular, in the production of
materials.
