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Valorization of Orange Peel By-Products in Kefir Cream Cheese and Its Impact on Their Physicochemical, Microbiological, and Functional Properties
* 1, 2, 3 , 1 , 4 , 1, 5
1  Santarém Polytechnic University, School of Agriculture, Quinta do Galinheiro - S. Pedro, 2001-904 Santarém, Portugal
2  CERNAS - Research Center in Natural Resources, Environment and Society (CERNAS), Santarém Polytechnic University, Quinta do Galinheiro - S. Pedro, 2001-904 Santarém, Portugal
3  LEAF—Linking Landscape, Environment, Agriculture and Food Research Center, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal
4  Veterinary and Animal Research Centre (CECAV), Faculty of Veterinary Medicine, Lusófona University, 376 Campo Grande, 1749-024 Lisbon, Portugal
5  CIEQV – Life Quality Research Center, Complexo Andaluz, Apartado 279, 2001 -904 Santarém, Portugal
Academic Editor: Iris Loira

Abstract:

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.

Keywords: orange peel, by-products valorization, kefir, cream cheese

 
 
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