Replacing Wheat Flour with Debittered and Fermented Lupin: Effects on Bread's Physical and Nutritional Features

In this study the breadmaking potential of lupin flour from L. mutabilis after being debittered (DLF) and solid state fermented (FLF) was evaluated in lupin-wheat breads. Different levels of substitution (10, 15, 20%) were tested on dough rheology and the technological and nutritional (composition and in vitro digestibility indexes) properties of breads, as well as acceptability. Lupin weakened the dough during mixing, having shorter development time and stability, especially FLF. Less relevant was the effect of lupin flours along heating-cooling of the doughs recorded with the Mixolab. DLF and FLF significantly affected technological properties of the lupin-wheat breads at higher substitution (> 10%), particularly reducing bread volume, crust luminosity, crumb cohesiveness and resilience. Detrimental effects observed at the highest substitutions (20%) were diminished when using FLF, although breads received lower score due to the acidic taste detected by panelists. Both lupin flours provided lupin-wheat breads with rather similar composition, rising the average content of proteins, fat and dietary fiber by 0.8, 2.4, 6.5 %, respectively, compared to wheat breads. Likewise, lupin-wheat breads had significantly lower hydrolytic and glycemic indexes. Overall, debittered and fermented lupin could be used for enriching wheat breads, although better technological properties were observed with FLF.