The review of the effect of FOS or inulin supplementation on
weight management and satiety showed that those prebiotics
may have a greater role to play than merely energy dense food substitution
and their traditional prebiotics effects. They may help a
certain category of people actively manage their weight. Who
these people are and what are the optimum dosages still remain
unknown. More work is also required on the physiological mechanism
linking the prebiotics to weight loss.
It was found that the effect of inulin/FOS substitution on the
textural and sensory properties depended on the type of prebiotic
added; flour type; substitution level; the degree of polymerisation
and how the prebiotic is introduced (e.g. powder or gel). In all
cases, technical challenges were apparent in terms of dough
machinability resulting in end product quality slightly lower than
that of the control. The main inulin/FOS impacts reported were
lower bread loaf volumes, increased crumb hardness and darker
crust. While inulin appears to integrate well to the gluten network,
it also dilutes it resulting in lower gas retention ability. A darker
colour and increase in aroma compounds characteristic of the
Maillard reaction were attributed to a larger number of reducing
ends. Those in turn, may be partly due to inulin/FOS degradation
upon baking as there is evidence that both yeast invertase and
dry heat degrade inulin. Whether prebiotics remain fully active
in the end product is still to be established.
A supplementation of 5% inulin appears to be achievable and
should contribute 0.7–1.2 g of inulin per slice of bread toward daily
intake.