COTINUS COGGYGRIA ETHANOL EXTRACT AS CROSSLINKING AGENT IN FORMULATION OF THE PROTEIN FILMS

The study explores the potential application of smoketree (Cotinus coggygria Scop) ethanol extract (STE) as a natural cross-linking and active component in the formulation of films based on collagen (CL), gelatin (GL) and soy protein isolate (SPI). After casting and drying of the respective film-forming solutions, elastic and homogeneous films were obtained. A significant color difference was found for all protein films with added STE compared to the control series (mainly due to an increase in yellowness). The degree of cross-linking was highest in CLSTE (60 %), followed by GLSTE (27 %) and SPISTE (18 %). The antioxidant activity of the films, determined by the DPPH radical scavenging assay, increased significantly after the addition of STE. The observed increase in tensile strength (TS) for the films with STE ranged from double (CLSTE and SPISTE) to more than 4 times (GLSTE). In addition, there was a significant improvement in the light barrier properties of the extract-incorporated films, but also a reduction in their transparency up to 1.5 times compared to their respective controls. No significant influence was observed on physical characteristics such as thickness, moisture absorption and total soluble matter. Research results show that STE can be successfully used as a natural cross-linking agent in protein films, resulting in improved light barrier properties as well as increased strength and antioxidant activity.