Gelatin is a natural biopolymer derived from collagen. Due to its many advantages, such as swelling capacity, biodegradability, biocompatibility, and commercial availability, gelatin is widely used in the field of pharmacy, medicine, and the food industry. Gelatin solutions easily form hydrogels during cooling, however, the materials are mechanically poor. To improve their properties, they are often chemically crosslinked. The cross-linking agents are divided into two groups: Zero-length and non-zero-length cross-linkers. In this study, gelatin was cross-linked by three different cross-linking agents: EDC-NHS, as a typically used cross-linker, and also squaric acid (SQ) and dialdehyde starch (DAS), as representatives of a second group of cross-linkers. For all prepared gelatin hydrogels, mechanical strength tests, thermal analysis, infrared spectroscopy, swelling ability, and SEM images were performed. The results indicate that the dialdehyde starch is a better cross-linking agent for gelatin than EDC-NHS. Meanwhile, the use of squaric acid does not give beneficial changes to the properties of the hydrogel.

Plastics are commonly used for packaging in the food industry. The most popular thermoplastic materials that have found such applications are polyethylene (PE), polypropylene (PP), poly(ethylene terephthalate) (PET), and polystyrene (PS). Unfortunately, most plastic packaging is disposable. As a consequence, significant amounts of waste are generated, entering the environment, and undergoing degradation processes. They can occur under the influence of mechanical forces, temperature, light, chemical, and biological factors. These factors can present synergistic or antagonistic effects. As a result of their action, microplastics are formed, which can undergo further fragmentation and decomposition into small-molecule compounds. During the degradation process, various additives used at the plastics’ processing stage can also be released. Both microplastics and additives can negatively affect human and animal health. Determination of the negative consequences of microplastics on the environment and health is not possible without knowing the course of degradation processes of packaging waste and their products. In this article, we present the sources of microplastics, the causes and places of their formation, the transport of such particles, the degradation of plastics most often used in the production of packaging for food storage, the factors affecting the said process, and its effects.

Novel chitosan (Ch) films containing choline chloride and citric acid mixture as plasticizer (deep eutectic solvent, DES) and different amounts of quercetin (QUE) as antioxidant additive were prepared. Physicochemical and mechanical characteristics of the developed Ch/DES/QUE films were studied using FTIR, SEM, and AFM techniques. FTIR spectra revealed the possible interactions between all the components. The surface of the films was dense and rough. The addition of quercetin caused an increase in the tensile strength (TS) and Young's modulus, but significantly decreased the elongation at break. The films containing quercetin showed improved antioxidant activity in relation to Ch/DES film. Finally, the oxidation phenomena of rapeseed oils with and without chitosan films were evaluated as amounts of primary and secondary oxidation products and total oxidation index. The addition of Ch/DES films with quercetin to oil samples successfully retarded secondary lipid oxidation processes and improved its antioxidant activity under the accelerated storage condition.

In this study, thin, polymeric films consisting of poly(vinyl alcohol) (PVA) and chitosan (Ch) with the addition of poly(hexamethylene guanidine) (PHMG) were successfully prepared. The obtained materials were analyzed to determine their physicochemical and biocidal properties. In order to confirm the structure of PHMG, nuclear magnetic resonance spectroscopy (¹H NMR) was applied, while in the case of the obtained films, attenuated total reflectance infrared spectroscopy with Fourier transform (FTIR-ATR) was used. The surface morphology of the polymer films was evaluated based on atomic force microscopy. Furthermore, the mechanical properties, color changes, and thermal stability of the obtained materials were determined. Microbiological tests were performed to evaluate the biocidal properties of the new materials with and without the addition of PHMG. These analyses confirmed the biocidal potential of films modified by PHMG and allowed for comparisons of their physicochemical properties with the properties of native films. In summary, films consisting of PVA and PHMG displayed higher antimicrobial potentials against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria in comparison to PVA:Ch-based films with the addition of PHMG.