THESIS - ROC CH ... - FINAL - resubmission.pdf - University of Guelph

6.3.8 STATISTICAL ANALYSIS
Statistical analysis of reported data was performed as described in Section 4.3.9.
6.4 RESULTS AND DISCUSSION
6.4.1 EXTRUSION OBSERVATIONS
Extrusion conditions with the addition of the cellulose fibers remained very similar to the
process as described in Section 4.0. However, the addition of cellulose created complications
mainly due to high hydrophilicity and the self-interacting nature of the biopolymer. These
problems were seen during mixing, and throughout the extrusion stages. During mixing, a
programmable peristaltic pump was used to continually dose liquid fractions (water and glycerol)
of the formulation into the dry SPI powder. With the addition of cellulose fibers into the liquid
fraction, the viscosity dramatically increased impeding the pumping process. As shown in Figure
6.1, changing the fiber concentration from 0.5 to 1% w/w SMF/SPI also changed the texture of
the solution towards a gel-like state. At 3% w/w SMF/SPI, the texture reflects a semi-solid state
unable to be controllably mixed with powdered SPI. The selected maximum loading of 2.5%
w/w SMF/SPI as tested was the limit at which the viscosity of the solution was low enough,
suitable for controlled dosing. Additional water could have been used to increase cellulose
concentration, but this would require an additional drying step which might confound previous
findings for film formation.
Another complication arose during compounding and extrusion steps. From the
compounding stage, flakes of material were observed to separate from the extruded protein
strands (Figure 6.2b). Depending on the SMF loading, the flakes emerged from the extruder
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