Dietary fibre enrichment of white bread with inulin-rich carbohydrate (IRC) powder
extracted from Jerusalem artichoke tubers (IRC-J) was studied. Previously, it was shown
that this IRC-J powder had higher prebiotic activity score than a commercial chicory inulin
(IRC-C) powder, used for comparison. For bread making, 2.5 and 5.0 g of either IRC-J or IRC-C
were added to 100 g of wheat flour, and the effects on dough viscoelastic properties and
bread quality properties were analyzed, relative to a Control sample (no IRC added). The
lowest IRC concentration of both fibres had no significant effect on the elastic modulus (G0)
of the dough, but the highest IRC level decreased G0, with a stronger effect of IRC-J. This was
attributed to disruption of the starch–gluten matrix due to fibre replacement of flour. In turn,
this was thought to impair gas retention (known as diluting effect), resulting in the observed
decrease of bread specific volume and cell/total area ratio, and the increase in crumb
hardness and chewiness. IRC addition also had a significant effect on crumb and crust
colour, and other crumb grain features. These effects were more significant at the highest
IRC concentration of both fibres. Breads with 5.0 g of IRC-J were significantly darker, flatter,
and more humid. All the sensory attributes of breads with 0 (Control sample), 2.5 g IRC-J, and
2.5 g IRC-C were acceptable, and no significant differences were found between the three
samples, in any of the attributes.