Starch-based composite formulation of chickpea flour and black carrot ( Daucus carota l .) pomace in extruded snacks: In vitro gastrointestinal behavior and stability of bioactive compounds

Black carrot pomace (BCP) is a by-product of colorant production, containing various valuable components with the health promoting effects. In this study, for the first time, BCP was incorporated into a starch-based extruded snack formulation using wheat semolina and corn starch. Total phenolic content, total antioxidant capacity, phenolics, and anthocyanins after processing and in vitro gastrointestinal digestion were investigated, and physical and textural properties of the snack products were determined. Incorporating BCP significantly raised the TPC and antioxidant levels, notably achieving peak levels in snacks enriched with 20 % BCP. The phenolic acids and anthocyanins were increased significantly (48-382 %) (p < 0.05) with simulated gastric digestion whereas no anthocyanins were detected after simulated intestinal digestion. On the other hand, the extrusion process resulted in a negative impact on anthocyanin concentrations, particularly marked by a significant reduction in some cyanidin derivatives indicating the detrimental effect of extrusion on the molecular integrity of anthocyanins under high temperature and pressure, leading to their degradation. In the final product, the snacks displayed lower expansion indices, water absorption index, water solubility index, and lightness; but had higher hardness and redness values compared to the control and turned slightly darker. The study proposes to evaluate BCP as a value-added ingredient that imparts functional properties to foods along with the utilization of starch in the extrusion process. Additionally, the integration of wheat semolina and corn starch contributed to the structural integrity and texture of the extruded snacks, highlighting the importance of polysaccharides in the formulation.