This study investigates the influence of extraction method and solvent on the UV spectral characteristics of extracts obtained from selected agro-industrial waste materials. Conventional maceration and ultrasound-assisted extraction (UAE) were applied using distilled water and 70% (v/v) ethanol as solvents. The analyzed materials included spent coffee grounds, orange peel, rosehip, milk thistle, eucalyptus leaves, and chili pepper. UV spectrophotometric analysis (190–400 nm) was used to compare the absorption profiles of the obtained extracts and to evaluate the effect of extraction conditions on spectral features. The results showed that both solvent type and extraction technique significantly influenced the intensity and shape of the absorption spectra. Ethanol generally resulted in higher absorbance values and more defined spectral features in the 250–350 nm region, while aqueous extracts exhibited stronger absorption in the lower UV range. Overall, UV spectroscopy proved to be a rapid and effective screening tool for evaluating extraction performance and comparing spectral characteristics of complex plant extracts, supporting the valorization of agro-industrial waste. Total phenolic content (TPC) was additionally determined to support the evaluation of extraction efficiency.

Polymer waste poses significant environmental challenges and polymers’ replacement with biodegradable biopolymers is therefore crucial. Protective coatings are recognized as a problem in the graphics industry, since they are based on synthetic polymers that are not biodegradable. To be effective, coatings in this industry must meet several key criteria, including stability, functionality, recyclability, and a suitable shelf life. One potential alternative is starch, a highly abundant biopolymer that has been researched for its application in coating preparation. However, its poor mechanical properties have limited its use in this area. This paper investigates the functional properties of starch-based biopolymer coatings enhanced with D-sorbitol and bioactive components: trans-ferulic and L-ascorbic acid. The impact of these additions on the mechanical stability and UV protection potential of the coatings was evaluated. Thermochromic pigments are highly sensitive to UV radiation, making them a useful indicator for evaluating the UV protection factor of a given coating. The colour change of the coated thermochromic prints after UV irradiation was quantitatively evaluated using spectrophotometric analysis. Mechanical properties were assessed through tensile strength, elongation at break, burst strength, and folding endurance. Overall, coatings increased burst strength and improved key mechanical properties depending on the additive combination.

This study explores the use of natural substances as resources in the development of UV protective coatings, offering an environmentally sustainable alternative to toxic and synthetic materials, mostly organic compounds used as UV stabilizers in various industrial and commercial applications. Therefore, the focus of this study is on different natural sources possessing protective properties. To ensure adequate protection, it is necessary to carefully consider and properly blend various substances that possess protective properties against UV radiation and free radical formation. UV radiation poses a constant threat to materials, promoting oxidative stress that can cause serious damage. In this context, UV stabilizers play a crucial role in protecting materials from degradation caused by solar radiation. Their ability to absorb or reflect UV radiation is crucial for preserving the physical and chemical properties of polymeric materials, coatings, inks and coloration. On the other hand, antioxidants are additives that protect against oxidative stress by neutralizing free radicals - reactive compounds that are formed under the influence of UV radiation and can cause material damage. UV stabilizers, in synergy with antioxidants, often result in optimal material protection, ensuring durability and preservation of the aesthetic and functional properties of products. Therefore, a formulation that includes carefully selected UV stabilizers and antioxidants, is crucial for achieving a high level of protection against the harmful effects of UV radiation and free radicals. This integrated approach not only ensures material durability but also contributes to sustainability. This study emphasizes the need for further research aimed at developing new technologies that could enhance the interaction between UV stabilizers and antioxidants to achieve optimal material protection.