Industrial Use of Oil Cakes for Material Applications - The Economic Utilisation of Food Co-Products - page 147

The use of continuous or semicontinuous processes, such as extrusion and
injection moulding is more problematic due to classic aggregation following the
denaturation phenomenon. Basically, three different ways have been studied to
overcome this problem:

d n 9 r 3 n g | 5

the use of a coconstituent like starch, 39 a biodegradable polyester, 40-42 or
lignocellulosic fibres; 43
processing at temperatures below T d ; 22,28,44
the addition of large amounts of plasticisers. 45

d y y f n n 3 .

7.2.7 Other Applications of Oilseed Proteins
Apart from their thermoplastic properties, many other properties of oilseed
proteins have been investigated for industrial applications. Among them, and
nonexhaustively, they can be used as binders in cellulosic paper 46 or in parti-
cleboards, 47,48 some hydrolysates have some interesting foaming and emul-
sifying properties, 49 or they may replace carbohydrates in encapsulation. 6

7.3 Injection Moulding of Sunflower Oil Cake
Oilseed proteins possess interesting plastic properties but their complicated
behaviour when submitted to shear and heat hinders their industrial devel-
opment as a biopolymer. For thermomechanical processes (i.e. extrusion,
injection moulding) complete coagulation has to be avoided and a way to
succeed is to add some lignocellulosic fibres.
Oil cake is the crude byproduct of the oil extraction. It contains residues of
the seed kernel (protein, cell walls, etc.) and the whole hull, which is constituted
of lignocellulosic fibres. It is therefore an interesting substrate to illustrate
the transformation of a complete industrial byproduct

into a ''plastic''

biocomposite.
We can note that only soy meal and sunflower oil cake have been tested for
protein-based materials. 11,50,51 In the case of soy, protein concentrate or isolate
are more likely used since the industrial protein extraction process yields an oil
cake poor in fibres. Other oilseeds currently used for the production of oil such
as rapeseed or linseed have not been considered.

7.3.1 Structure and Composition of Sunflower Oil Cake (SFOC)
7.3.1.1 Oil-Extraction Process
The complete analysis of SFOC structure and composition has to start with the
description of the industrial oil extraction process as it involves a large numbers
of steps that could cause drastic changes in the physical and chemical properties
of its constituents. The main steps of the industrial extraction and their
consequences are summarised in Table 7.2.