Valorization of Olive Milling By-Products: Development and Application of an Antioxidant-Enriched Leavening Powder for Bakery Products

This research focuses on the synthesis of a novel baking powder enriched with bioactive molecules recovered from olive pomace via ultrasound-assisted extraction using a hydro-ethanolic mixture. The functional ingredient was engineered by anchoring the extracted phytocompounds onto a starch backbone through a sustainable grafting technique. Biscuits formulated with the innovative ingredient showed an increased concentration of phenolic compounds (2.162 mg GAE/g), encompassing both phenolic acids (0.372 mg GAE/g) and flavonoids (0.360 mg CTE/g). Enhanced antioxidant efficacy was recorded, mostly in aqueous media (IC50 = 0.554 mg mL−1 against ABTS radical) compared to organic environments (IC50 = 0.132 mg mL−1 against DPPH radical). Furthermore, Oxitest and oxidation stability reactor analyses revealed exceptional antioxidant capacity (induction period = 37 ± 2 h). By an accelerated shelf-life test, a marked instrumental color difference was observed with the fortified sample showing a darker, redder/brown color (ΔE > 16), as also confirmed by trained panelists. On the contrary, similar scores were achieved for the olfactory, textural and tasting attributes of the two samples, as well as values of the friability index (<1 mm−1) evaluated by instrumental techniques. This approach represents a sustainable strategy, transforming a high-polluting agri-food by-product into a source of bioactive compounds for nutritional and technological improvement of baked foods.