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92 IV.Resultados y discusión. Capítulo I
As could be observed, both non-homogenised samples presented
bimodal and polydisperse distributions in terms of volume percentage
(Figure 1 a, c) but monomodal in terms of the number of particles (Figure 1
b, d), which indicates that there is a very small number of big particles. The
finest particle fraction is probably mainly constituted by proteins, whereas
fat droplets and remains of cellular tissue constitute the biggest particles.
Nevertheless, particle aggregates could also be present in the biggest
particle fraction. Particle size distribution became monomodal when
samples were homogenised and the biggest particles of the initial product
were greatly reduced in size. However, some finest particles evidenced in
the first peak of the distribution of untreated samples seem to aggregate
since they are not appear in the tail of the peak of HPH samples. A part of
the protein bodies could be unfolded or aggregated by the high pressure
effect. The increase in homogenisation pressure progressively reduced the
mean particle diameter while distributions became narrower due to the
reduction in size of oil droplets and plant cell remains. This can also be
deduced from Table 2, where the overall decrease in both the mean particle
diameters and the difference between D 4,3 and D 3,2 in MF samples can be
seen. No significant differences (p > 0.05) in these parameters were found
when applying 103 (MF2 treatment) or 172 MPa (MF3 treatment) pressures.