Eco-conception d'un biscuit à base de drêche de brasserie et de farine de ver (larve de Tenebrio molitor).

Abstract

The resurgence of nutrition-related non-communicable diseases represents a major global public health challenge. In response to this concerning situation, it has become essential to rethink current dietary habits and to develop innovative, healthy, and nutritionally improved food products. Alongside this nutritional crisis, which is closely linked to the excessive consumption of ultra-processed foods, the introduction of new protein sources such as insects, combined with the valorization of agri-food by-products, particularly brewer’s spent grains, represents relevant and viable circular economy strategies. These approaches contribute to reducing the environmental footprint of our diet while improving its nutritional quality. Within this nutritional and environmental context, the objective of this work was to formulate a functional biscuit with high nutritional value based on brewer’s spent grains and insect flour (Tenebrio molitor). The choice of a biscuit as the food matrix was guided by its wide consumer acceptability across all age groups, its palatability, and its long shelf life. Each formulated Molitor biscuit contained 10 g of insect flour, with successive substitution rates of wheat flour by spent grain flour of 10%, 20%, and 30%. The biscuits were characterized using standardized and AOAC-recognized analytical methods. The combination of brewer’s spent grains and Tenebrio molitor flour doubled the protein content of the Molitor biscuits, increasing from 6.549 ± 0.231% in the control formulation to 13.849 ± 0.055% in the 30% BSG formulation. Fiber content increased from 3.6788% to 8.6707%, respectively, while ash content rose from 0.74 ± 0.01% to 1.35 ± 0.009%. This increase in fiber, protein, and mineral content is attributed to the intrinsic richness of brewer’s spent grains and insect flour. Based on the measured fiber and protein contents, the Molitor biscuits qualify for the “high in fiber” claim, although no protein-related claim can be made in accordance with Regulation (EC) No° 1926/2006. The control biscuit was thicker than the insect-enriched formulations, likely due to greater gluten network development promoting product expansion. The total color difference (ΔE > 5) indicates a clearly perceptible visual difference between the control and enriched biscuits, attributable to the naturally darker color of spent grains and insect flour compared to wheat flour. The water activity of all biscuits was approximately 0.15, confirming extended shelf stability since this value inhibits microbial growth and most biochemical spoilage reactions. The primary packaging in direct contact with the biscuit consisted of Ingeo propyl ester, a bio-based plastic derived from polylactic acid (PLA), offering superior moisture and gas barrier properties compared to conventional plastics. The results of this eco-design approach confirm the strong nutritional potential of brewer’s spent grains and Tenebrio molitor flour for the development of healthy and sustainable food products.