Evaluation of solid-state fermentation of edible insects (S. purpurascens and T. molitor) with Aspergillus Oryzae and its potential use in bread and gluten-free bread

Interest in incorporating edible insects into the diet is increasing due to their nutritional content. The most critical challenges are related to the low acceptability of the consumer due to changes in taste, color, and textural properties of the final product when edible insect flour is added. This work proposes the study and use of solid-state fermentation (SSF) of edible insects to improve its incorporation in food products. Tenebrio molitor (yellow mealworm) and Sphenarium purpurascens (grasshopper “chapulín” in Spanish) were suggested as study objects of SSF with Aspergillus oryzae. Fermented and unfermented insect powder was chemically and techno-functionally characterized. The effect of the incorporation of fermented and unfermented insects’ powder in wheat bread (with yellow mealworm and chapulín), maize and rice bread (with chapulín) were evaluated on different stages. Rheological characterization of dough and physical, chemical, textural, nutritional, and sensory analysis of bread was used to compare the effect of fermentation. Incorporating grasshopper powder into gluten-free and wheat bread significantly increased protein, ash, fat, and total dietary fiber content. Fermentation significantly increased protein and dietary fiber and produce changes on techno- functional properties on T. molitor and S. purpurascens powders. Techno-functional changes were reflected on dough rheology and then on wheat bread texture decreasing hardness as positive result. In both, wheat and gluten-free bread (maize and rice), rheological analysis revealed that fermented grasshopper flour reduced setback viscosity, an important factor in bread quality as it is linked to starch retrogradation and shelf-life stability. This reduction in setback suggests that fermentation may improve the freshness of bread. This study indicates that fermentation modifies insect powder which impacts on bread quality, potentially due to changes in protein, enzymes interactions, and techno-functional properties. The findings suggest that fermentation provides greater benefits for Sphenarium purpurascens than for Tenebrio molitor. Moreover, fermented grasshopper powder shows improved performance in terms of dough rheology and bread texture in wheat-based formulations compared to gluten-free ones. Additionally, the data support the potential of S. purpurascens as an ingredient capable of significantly enhancing the nutritional value of bread. These results align with recent research emphasizing the nutritional advantages of edible insects as protein-rich food sources.

https://orcid.org/0000-0003-1737-2639