Bioactive Materials from Brewery Yeast Cell Wall Residues with the Addition of Refined Liquid Smoke: Development and Study of Functional Properties

Brewery yeast cell wall residues were used as a matrix for the development of bioactive films with refined liquid smoke extract. The extract and bioactive films were fully characterised in terms of their functional properties. Refined liquid smoke extract is a commercial additive used as a preservative agent in various food products. Minimum Inhibitory Concentration (MIC) values for foodborne pathogens of the refined liquid smoke extract ranged from 0.403 to 1.612 mg/mL. Its total phenolic content, as determined by the Folin-Ciocalteu method, was 450 mg/L, and its antioxidant capacity, as determined by IC 50 (ABTS), was 593 mg/L. The functional properties of the bioactive films depended on the concentration of liquid smoke extract added. At low concentrations, the extract retarded the thermal degradation and improved the mechanical properties by increasing the tensile strength due to crosslinking between the carbonyl groups of the liquid smoke extract and the amino groups of the residual yeast cell wall film. However, high concentrations of extract functioned as a plasticiser and increased the hydration of the samples. The bioactive films containing 10% liquid smoke extract achieved the highest radical scavenging activity (RSA > 90%) among the tested samples. The findings indicated that incorporating liquid smoke extract into residual yeast cell wall films could represent a promising and innovative substitute for bioactive materials in the field of food packaging development.