Gluten-free bread (GFB) is a food with a high glycemic index. Its frequent consumption can lead to rapid increases in blood glucose, potentially causing metabolic stress and contributing to insulin resistance and type 2 diabetes. To contrast this tendency, we studied different GFB formulations using a mixture design of experiments, substituting the control mix of flours (MF) with hypoglycemic ingredients like red lentil flour (RLF) and tapioca-resistant starch (RS). The primary aims focused on assessing how the mixture of ingredients affects the techno-functional and textural properties and predicted glycemic index (pGI) of GFB and optimizing the formulation to obtain a technologically acceptable GFB with a lower impact on pGI.
The crumb porosity analysis indicated that increased lentil content in the formulation led to higher pore density. Moreover, the RLF reduced the mean diameter of the pores both in the presence and absence of the resistant starch. In contrast, the circularity and area fraction did not show a specific trend. The texture analysis results confirmed an increase in hardness proportional to the addition of RLF. However, adding RS helps mitigate this effect, improving the softness of the bread. On the contrary, cohesiveness tends to decrease in samples enriched with lentils, especially when RS is also present. Even though GFB samples showed a pGI above 70, a tendency towards a reduction in pGI was observed with an increase in the percentage of RLF. The desirability function suggested two formulations with the best techno-functional and textural parameters. However, the one with the lowest pGI contained 0% RS, 20% RLF, and 80% MF. In conclusion, incorporating different hypoglycemic ingredients offers a promising strategy for producing GF bread with a lower glycemic index and acceptable technological and textural characteristics.