The material response in the dynamic frequency sweep
(Fig. 2b) is typical for a weak gel. In the frequency range
applied, G0 is larger than G00 with both moduli showing a
frequency dependence. However, below ca. 1Hz the rate of
increase in G0 and G00 was greater (92 and 48 Pa/Hz,
respectively) than the increase between 1 and 5Hz (34 and
18 Pa/Hz, respectively). Thus, the material shows liquidlike
behaviour at low frequencies and near solid-like
behaviour at higher frequencies. These findings are in
general agreement with Mason and Friis (2001) who
describe the rheological behaviour of rapeseed oil body
emulsions (recovered under different conditions as applied
in this study) at pH 3.1 as reminiscent of the behaviour of a
weak gel. However, values for G0 and G00 reported by
Mason and Friis were much lower (175 and 60 Pa,
respectively) which is perhaps due to the lower fat content
(15%) of their preparations. Nonetheless, these values may
be inflated above expected values for emulsions with this
fat content due to the likely presence of significant levels of
extraneous material/protein in their crude preparations.
Samples were increasingly shear thinning with increasing
disperse phase content (Fig. 3). At concentrations below
40% w/w oil content and above shear rates of 50 s1, the
sample showed Newronian behaviour. The shear thinning
behaviour is likely to be the result of weak droplet
flocculation occurring in this emulsion system at pH 7;
depletion flocculation seems unlikely in our system since
obtained from a separate more rigorously washed Sunflower-
seed oil body preparation with 1.2% protein (dry
weight basis) compared with the 7.3% protein (dry weight
basis) present in this preparation. For simplicity of data
interpretation, further studies into the effects of pH and
CaCl2 concentration were carried out on oil body emulsions
with p20wt% oil phase content where the flow
behaviour is Newtonian