Chemistry Reference
In-Depth Information
are similar to the triglyceride crystal structure and network in the low-fat
spread.
Although most of the work carried out on water-in-water emulsions
has been directed at soft products, which are used from chill or ambient
temperatures, they can also be used in products that are cooked, for
example meat products such as low-fat sausages (Baumanis
et al.
, 1995).
This is again possible as a result of using crystallising biopolymers,
which are used to replace the crystalline structure produced by saturated
fats.
10.3.6
Self-structuring systems
As discussed earlier in this chapter, an area of research interest is to
understand and control the rheological behaviour of foods inside the
human gastrointestinal tract. The problem is that viscosity alone seems
to have a marginal effect on people's food intake. So how do we go
beyond this? The idea is to have systems that self-assemble inside the
stomach to give a rigid three-dimensional structure. If this is to be
achieved, then we need to have the ability to use environmental changes,
which occur on entering the stomach and control the rate and extent of
structuring.
As an approach, this seems to stand a chance as demonstrated from
work carried out by Marciani
et al
. (2000, 2001a, 2001b). In this study,
they fed already gelled beads to their participants and then visualised
how they behaved in the stomach and how this affected their feelings of
hunger. The particles used were large (cm) and were swallowed intact
by the volunteer. These particles were shown to affect gastric emptying
rates. More recently, smaller particles have been studied by Rayment
et al
. (2009) and Hoad
et al
. (2009) followed on from an idea put forward
by Norton
et al
. (2006a) in which these authors suggested that one way
to get stomach structuring was to use sheared calcium-set alginate gels
that then partially unfold and rearrange as a consequence of the acidity
in the stomach.
10
.
3
.
6
.
1
Alginate
So if rheological control of the stomach contents offers a way to control
the eating habits and calorific intake of the general population, what
materials are available to test the idea and achieve the goal? There is
a whole area of science on self-structuring systems using a range of
different materials including polymers (Norton
et al
., 2006a).
However, none of these are food allowed. More recently, however,
researchers have started to consider the physical and chemical aspects
of the stomach and intestine and how pH changes, enzymes, etc. can
