Valorization of Orange Peel By-Products in Kefir Cream Cheese and Its Impact on Their Physicochemical, Microbiological, and Functional Properties

The valorization of fruit by-products offers a sustainable route for developing functional foods. This study explores the incorporation of orange peel—which is rich in phenolics and abundant in the juice industry—into kefir-based cream cheese made from cow's milk and yogurt. The peel was added directly into the cheese matrix at 1% and 5% (w/w), in non-fermented and fermented forms (in saline solution 2%, w/w), after drying at 60ºC and grinding. Its impact on physicochemical (pH, acidity, texture, color), microbiological, and functional properties was evaluated. Orange peel addition enhanced firmness, cohesiveness, and color (providing a yellow-orange hue). It slightly reduced the pH (3.2–3.5) and increased titrable acidity (3.6–4.9 g lactic acid/100 g), suggesting better acidification and water retention. Microbiological analysis showed higher lactic acid bacteria counts, indicating a possible prebiotic effect. Functional parameters were notably improved, with the total phenolic content reaching 50–300 mg GAE/100 g dw and antioxidant activity ranging from 40 to 140 µmol TE/g dw. These findings demonstrate the potential of orange peel as a value-added ingredient in fermented dairy products. Enriching kefir cream cheese with citrus by-products not only boosts it's nutritional value but also supports circular economy practices in the dairy sector.