Along the food production chain of animal, fish, and vegetable products, a huge amount of by-products are generated every year. Major nutritional, financial, and environmental advantages can be achieved by transforming them into functional ingredients for food formulation and fortification. In this review, we investigated various conventional and emerging treatments recently employed to obtain functional ingredients rich in proteins, fibers, and bioactive compounds from vegetables, fish, meat, and dairy by-products. The optimal enrichment level in food as well as the nutritional, techno-functional, and sensory properties of the final food were also discussed. Novel technologies such as ultrasounds, microwaves, and high pressure have been successfully adopted to enhance the extraction of target compounds. The functional ingredients, added both in liquid or powder form, were able to improve the nutritional quality and antioxidant potential of food, although high levels of fortification may cause undesired changes in texture and flavor. This review provides important considerations for further industrial scale-up.

Fruits and vegetables represent an important business in the food industry. Unfortunately, huge amounts of by-products are generated during their processing, and companies must face considerable management efforts and disposal costs. This study investigated the valorization of tomato and cauliflower by-products as combined sources of bioactive compounds for functional bakery applications. Tomato powder (TP) and cauliflower floret and leaf powders (CFP, CLP) were incorporated into savory muffins. Four formulations containing constant cauliflower by-product of 20% (C20) and three TP levels (C20T10, C20T20, C20T30) were prepared. Bioactive ingredients were chemically characterized for total phenols, glucosinolates, carotenoids, and tocopherols, while enriched muffins were evaluated for physicochemical, texture, and sensory properties. TP showed the highest contents of total phenols, lycopene, β-carotene, and α-tocopherol, whereas CLP was particularly rich in lutein. Muffins exhibited a progressive increase in bioactive compounds with higher enrichment levels. The C20T30 formulation was the most appreciated for aroma and taste, providing approximately 255 µg retinol equivalents and 2.8 mg vitamin E per serving, meeting the requirements for the nutritional claims “high in vitamin A” and “source of vitamin E”. Overall, tomato and cauliflower by-products represent promising ingredients for innovative functional bakery products.