Poly(butylene succinate) Film Coated with Hydroxypropyl Methylcellulose with Sea Buckthorn Extract and Its Ethosomes—Examination of Physicochemical and Antimicrobial Properties Before and After Accelerated UV Aging

The new generation of food packaging should not only be biodegradable, but also provide additional protective properties for packaged products, extending their shelf life. In this paper, we present the results of research on cast-extruded poly(butylene succinate) (PBS) films coated with hydroxypropyl methylcellulose (HPMC) modified with CO₂ extract from sea buckthorn (ES) or its ethosomes (ET) at amounts of 1 or 5 pph per HPMC. In addition, the developed films were exposed to accelerated aging (UV radiation and elevated temperature) to determine its effect on the films' properties. Based on SEM, it can be concluded that accelerated aging results in the uncovering of the extract and ethosomes from the coating's bulk. GPC showed a decrease in the molecular weight of PBS after treatment, additionally amplified by the presence of HPMC. However, the addition of ES or ET in low concentrations reduced the level of polyester degradation. The presence of the modified coating and its treatment increased the oxygen barrier (a decrease from 324 cm³/m² × 24 h for neat PBS to 208 cm³/m² × 24 h for the coated and modified PBS ET5). Despite the presence of colored extract or ethosomes in the coating, the color differences compared with neat PBS were imperceptible (ΔE < 1). The addition of 5 pph of sea buckthorn extract or its ethosomes in combination with accelerated aging resulted in the complete inhibition of the growth of <i>E. coli</i> and <i>S. aureus</i>, which was not observed in non-aged samples. The results obtained demonstrate an improvement in bioactive properties and protection against the negative effects of UV radiation on the film due to the presence of ET or ES in the coating. The developed systems could be used in the food industry as active packaging.