Fibre enrichment of wheat bread with Jerusalem artichoke inulin: Effect on dough rheology and bread quality

Abstract

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.