Chemistry Reference
In-Depth Information
shown that the properties of the interface in a protein:polysaccharide
phase-separated system is determined by the interaction of the pro-
tein with the polysaccharide in the bulk solution, the mixing ratio, the
ionic strength and the order of adsorption (simultaneous adsorption of
protein/polysaccharide complexes or interaction of the polysaccharide
with a protein already adsorbed). Such stabilising effects could be close
to providing the viscoelastic interfaces created by hydrophobins (Cox
et al
., 2009; Tchuenbou-Magaia
et al
., 2009).
Current trends in developing an increased understanding of the rhe-
ological properties of the respective phases in mixed systems have in-
volved the use of reporters within the phases. Dinsmore
et al
. (2001)
and Valentine
et al
. (2001) reported the use of multiple particle track-
ing, which has also recently been used for food-like microstructures
(Moschakis
et al
., 2006). Loren
et al
. (2009) have used NMR to track
the diffusion of small molecular weight dendritic polymers through
microstructures.
4.5
HYDROCOLLOIDS IN FOODS - ROLE
AND INTERACTIONS
The previous section has covered scientific developments in the inter-
actions of hydrocolloids with a view that such types of interactions
are experienced when the hydrocolloids are used in food products. The
predominance of the hydrophilic nature of hydrocolloids means that
they ordinarily reside in the water phase of foods. Foods can contain
high amounts of water, for example sauces, emulsions, or low levels,
for example baked goods and confectionary. The rheology of hydrocol-
loids varies, depending on water content, and has been summarised by
Kasapis
et al
. (2004), showing a mastercurve, spanning dilute solutions
through to the glassy state.
In identifying the role of hydrocolloids in foods, the mantra which
should be followed is one of hydrocolloid structure functionality. There-
fore, the choice of hydrocolloid should be determined by the position
of the hydrocolloid in the food microstructure and the function it has.
The functionality of the hydrocolloid is determined by the way it mixes
with other ingredients (covered in the previous section) and the proper-
ties of the individual polymer itself, as a function of its molecular fine
structure, which, as we have shown above, determines the viscosify-
ing or gelling potential of the hydrocolloid. Knowing these parameters
may then allow for replacement strategies if a particular hydrocolloid
becomes too expensive to use, ethically unacceptable or nutritionally
deficient.
