Influência de revestimentos à base de proteínas do soro lácteo e amido de mandioca, adicionados de curcumina e própolis, em queijo Minas Padrão

Abstract

In Brazil, Minas cheeses represent approximately 10% of national production, with the standard type being more durable than the fresh type due to ripening. However, during this process, physicochemical and microbiological changes can occur due to oxidation and the action of microorganisms such as Listeria monocytogenes. In this context, edible films and coatings represent a promising alternative, as they offer similar protection to synthetic films, with the advantage of being biodegradable and environmentally sustainable. Therefore, this research aimed to investigate the technological performance of edible films and coatings made from whey proteins and cassava starch, with added curcumin and propolis, applied to Minas Padrão cheese, to evaluate their effectiveness and potential use in preserving and improving product quality. To achieve these objectives, curcumin and propolis were evaluated for the presence of phenolic compounds, antioxidant activity, and in vitro antimicrobial activity against L. monocytogenes. From film-forming solutions of whey proteins and cassava starch, coatings S1 (starch-based), S2 (a mixture of starch and whey protein concentrate), and S3 (whey protein concentrate-based) were prepared and characterized by their rheological properties (apparent viscosity and viscoelasticity). Using the same film-forming solutions (S1, S2, and S3), films F1, F2, and F3 were obtained, respectively, and characterized by their water vapor permeability, degradation in water and soil, and contact angle. Cheeses previously inoculated with L. monocytogenes strains were coated and evaluated for moisture, water activity, pH, mass loss, color, and texture after 21 days of ripening. The growth count of L. monocytogenes in the cheeses was performed on days 1, 7 and 14. Propolis showed a higher total phenolic content (215.64 ± 6.40 mg EAG/g) and antioxidant activity (136.6 μmol EAA/g) compared to curcumin (197.26 ± 4.50 mg EAG/g; 83.1 μmol EAA/g). Antimicrobial assays demonstrated inhibition of L. monocytogenes at concentrations of 0.84% curcumin associated with 0.71% propolis, indicating an additive effect of the combinations. The film- forming solutions showed pseudoplastic behavior, with consistency indices (k) ranging from 0.0016 (S3) to 1.8483 (S1) Pa•sn and flow indices (n) between 0.49 and 0.99. The films obtained differed in water vapor permeability, ranging from 3.48 g•m−2•day−1 (F1 – starch) to 7.40 g•m−2•day−1 (F3 – CPS), and water solubility exceeding 40%. When applied to cheeses, the coatings reduced mass loss by up to 12% compared to the control, maintained water activity between 0.91 and 0.93, and a stable pH of around 5.2. After 14 days of ripening, the coated cheeses showed lower L. monocytogenes counts (≈2.5 log CFU/g) compared to the control (≈4.8 log CFU/g).