Abstract
Guar galactomannans effectively reduce post-prandial glycaemic responses and can be used to improve the health impact of white bread. Here we compare the impact of four guars containing galactomannans with varying weight-average molecular weight (Mw) at three different wheat flour substitution levels (5, 10 and 15%) on bread quality. The negative impact of galactomannan incorporation on bread quality becomes more pronounced at higher substitution levels and with higher Mw. However, Mw is likely to be an important parameter for the efficacy of such breads. But we observed a degradation of galactomannan during baking, which was likely caused by enzymatic activity in the dough. A decreased contact time between wheat flour and guar gum, along with pre-hydration of the guar, improved sensory attributes such as texture, markedly decreased the presence of large air holes in the crumb and reduced the degree of depolymerisation of galactomannan during baking. The results from this study give an important starting point for future work of optimizing the baking procedure of guar fortified breads keeping in mind not only bread quality but also a retained Mw of the active ingredient.
Highlights
Due to their high content of starch, most breads have a high gly caemic index GI (Atkinson, Foster-Powell, & Brand-Miller, 2008)
Viscous dietary fibres such as guar galactomannan are highly effective at reducing postprandial glycaemic responses when incorporated into foods or drinks containing available carbohydrates such as glucose solutions (Jenkins et al, 1978), mashed potatoes (Fuessl, Adrian, Bacarese-Hamilton, & Bloom, 1986), soup (Wolever, Jenkins, Nineham, & Alberti, 1979), breakfast cereals (Fairchild, Ellis, Byrne, Luzio, & Mir, 1996), crispy bars (Williams et al, 2004) and white bread (Apling, Khan, & Ellis, 1978; Jenkins et al, 1976; Wolever et al, 1979), alone or in combination with other viscous fibres
The effect has been ascribed to the highly viscous properties of galactomannan and was abolished when hydro lysed non-viscous galactomannan was used in a glucose drink (Jenkins et al, 1978)
Summary
Due to their high content of starch, most breads have a high gly caemic index GI (Atkinson, Foster-Powell, & Brand-Miller, 2008). As a diet rich in high-GI foods is associated with increased risk of develop ment of diabetes (Barclay et al, 2008; Ludwig, 2002), reducing the GI of bread, which is a staple food worldwide, could have tremendous health implications Viscous dietary fibres such as guar galactomannan (referred to hereafter as just galactomannan) are highly effective at reducing postprandial glycaemic responses when incorporated into foods or drinks containing available carbohydrates such as glucose solutions (Jenkins et al, 1978), mashed potatoes (Fuessl, Adrian, Bacarese-Hamilton, & Bloom, 1986), soup (Wolever, Jenkins, Nineham, & Alberti, 1979), breakfast cereals (Fairchild, Ellis, Byrne, Luzio, & Mir, 1996), crispy bars (Williams et al, 2004) and white bread (Apling, Khan, & Ellis, 1978; Jenkins et al, 1976; Wolever et al, 1979), alone or in combination with other viscous fibres. The effect has been ascribed to the highly viscous properties of galactomannan and was abolished when hydro lysed non-viscous galactomannan was used in a glucose drink (Jenkins et al, 1978)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
