Biomaterials based on polyelectrolyte complexation are an innovative concept of coatings and packaging production to be applied in a wide range of food products. The aim of this study was to obtain and characterize a sodium alginate–chitosan complex material with variable degree of polyion interactions by complexation of oppositely charged polysaccharides. In order to characterize polyelectrolyte complexes, theromogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), matrix-assisted laser desorption/ionization technique with time of flight analyzer (MALDI-TOF), and scanning electron microscopy (SEM) were performed. TGA analysis showed that thermal decomposition temperature depends on the polymer ratio (R) and thermal resistance of samples was improved by increasing chitosan dosage. Accordingly to DMTA results, polyelectrolyte complexation led to obtain more flexible and resistant to mechanical deformation materials. Comparative analysis of the FTIR spectra of single polyelectrolytes, chitosan and alginate, and their mixtures indicated the formation of the polyelectrolyte complex without addition of reinforcing substances. MALDI-TOF analysis confirms the creation of polyelectrolyte aggregates (~197 Da) in samples with R ≥ 0.8; and their chemical stability and safety were proven by NMR analysis. The higher R the greater the number of polyanion–polycation aggregates seen in SEM as film morphology roughness.

The aim of the study was to obtain alginate oligosaccharides by using two degradation methods of sodium alginate (SA): with hydrochloric acid (G—guluronate, M—mannuronate and G + M fractions) and hydrogen peroxide (HAS—hydrolyzed SA), in order to assess and compare their biological activity and physico-chemical properties, with an attempt to produce gels from the obtained hydrolysates. The efficiency of each method was determined in order to select the fastest and most efficient process. The ferric ion reducing antioxidant power (FRAP), the ability to scavenge DPPH free radicals, rheological properties, Fourier Transformed Spectroscopy (FTIR) and the microbiological test against Escherichia coli and Staphylococcus aureus were performed. In order to check the functional properties of the obtained oligosaccharides, the texture profile analysis was assessed. The hydrolysis yield of acid SA depolymerization was 28.1% and from hydrogen peroxide SA, depolymerization was 87%. The FTIR analysis confirmed the degradation process by both tested methods in the fingerprint region. The highest ferric reducing antioxidant power was noted for HSA (34.7 µg), and the highest hydroxyl radical scavenging activity was obtained by G fraction (346 µg/Trolox ml). The complete growth inhibition (OD = 0) of alginate hydrolysates was 1%. All tested samples presented pseudoplastic behavior, only HSA presented the ability to form gel.

The challenge for food industry is developing gentle processes concept, which will prevent food spoilage and leave a food natural, minimally processed, fresh-like and safe. A new technique of food preservation could be usage of combined methods of green process, such as cold gas plasma with bioactive substances, and protective coatings. The aim of this study was to determine the antibacterial activity of chitosan films incorporated with lysozyme exposed to helium plasma treatment as well as evaluate their physical properties. The edible films have been prepared basing on low molecular weight chitosan by casting from lactic acid solution with water solution of lysozyme in three various concentrations (0, 0.5 and 1 %). Dried films were then modified by exposition on cold helium plasma treatment for 0, 5 and 10 min. Obtained films were tested against growth of Listeria monocytogenes, Yersinia enterocolitica and Pseudomonas fluorescens. In order to characterize chitosan-based films, their mechanical properties, theromogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), contact angle measurement, water vapour permeability (WVP) and scanning electron microscopy (SEM) were evaluated. The films with 1 % lysozyme incorporation enhanced the inhibition efficiency of chitosan-based films against gram-positive (L. monocytogenes) and gram-negative (P. fluorescens) bacteria, where reduction zones were 42.5 and 69.8 mm, respectively. Besides that, hydrolytic changes of chitosan chain caused by lysozyme activity were confirmed by TGA and DMTA. Contact angles and WVP of tested films were not significantly affected by helium plasma exposition, nor lysozyme dosage. Hydrophilic natures of chitosan-based films were confirmed by both tests. Microscopy image of cross-section structure was smooth and continuous due to lysozyme addition in film composition. Application of chitosan films incorporated with lysozyme and low-pressure plasma treatment could be used as innovative preservation method in a wide range of food products.

Meat is one of the most challenging food products in the context of maintaining quality and safety. The aim of this work was to improve the quality of raw/cooked meat by coating it with sodium alginate (A), chitosan (C), and sodium alginate-chitosan polyelectrolyte complex (PEC) hydrosols. Antioxidant properties of A, C, and PEC hydrosols were determined. Subsequently, total antioxidant capacity (TAC), sensory quality of raw/cooked pork coated with experimental hydrosols, and antimicrobial efficiency of those hydrosols on the surface microbiota were analysed. Application analyses of hydrosol were performed during 0, 7, and 14 days of refrigerated storage in MAP (modified atmosphere packaging). Ferric reducing antioxidant power (FRAP) and (2,2-diphenyll-picrylhydrazyl (DPPH) analysis confirmed the antioxidant properties of A, C, and PEC. Sample C (1.0%) was characterized by the highest DPPH value (174.67 μM Trolox/mL) of all variants. PEC samples consisted of A 0.3%/C 1.0% and A 0.6%/C 1.0% were characterized by the greatest FRAP value (~7.21 μM Fe²⁺/mL) of all variants. TAC losses caused by thermal treatment of meat were reduced by 45% by coating meat with experimental hydrosols. Application of PEC on the meat surface resulted in reducing the total number of micro-organisms, psychrotrophs, and lactic acid bacteria by about 61%, and yeast and molds by about 45% compared to control after a two-week storage.