Properties and in vitro digestibility of a bread enriched with lentil flour at different leavening times

The effects of three leavening times (60, 105 and 150 min) on structure and some physico-chemical and nutritional properties of bread added with 20 % of green lentil flour were investigated. Leavening time largely affected bread physico-chemical properties, leading to a significant reduction in moisture content, an increase in weight loss and a darker appearance of bread crumb as leavening time increased. Besides, crumb of bread leavened for the longest time (B150) showed a compact structure and the highest resistance to the compression, while the Young’s modulus increased linearly with the rising of leavening time. By contrast, breads leavened for shorter times (B60 and B105) had a more porous structure with more circular bubbles compared to B150, exhibiting lower deformation resistance.

Different bread macrostructure had a significant impact on the in vitro protein and starch digestibility. The α amino nitrogen release and the estimated Glycemic Index (eGI) at the end of digestion reached the lowest values in bread leavened for the longest time (B150). In particular, eGI showed a linear correlation both with the Young’s modulus (R² = −0.926) and macrostructural properties (R² = 0.902), suggesting that modelling bread structure by acting on leavening time can be a novel approach to develop healthier products.