Ultrasonication enhances the performance of apple pomace and lemon albedo blends in 3D printed snacks

Using natural sources to create high-value products can meet the growing consumers demand for eco-friendly foods. Exploring 3D printed foods and their role as nutraceutical carriers may lead to customized nutrition and develop "green" products tailored to specific dietary needs. This study aimed at developing 3D printed snacks based on the combined use of apple pomace (AP, 95-85 %) and lemon albedo (LA, 5-15 %) flours pretreated with Ultrasound (US). The effects of US on the techno-functional properties of the individual flours, the binary blends as well as the final product were assessed in terms of color, hydration capacity, texture and rheological properties, spectral characteristics (FTIR), total phenolic content and antioxidant activity. In vitro studies were also carried out to evaluate the release of phenolic compounds during gastrointestinal digestion. The application of US showed the potential to increase the extraction yield of bioactive compounds (up to 40 %) from the formulated mixtures. US pretreatment also induced significant improvements in the technofunctional properties, elastic and viscous moduli, printability, extrusion force and superficial smoothness of the mixtures. Higher amounts of LA flour led to increased lightness, and phenolic content, detected especially when added to the formulation with percentage up to 10 % (w/w). After microwave drying, utilized to stabilize 3D printed snacks, bioactive compounds and antioxidant activity were well retained. These promising results demonstrated the potential to create 3D printed snacks with improved printability, functional properties, and potential health benefits using affordable and natural ingredients.