The accumulation of microplastics in the world oceans is one of the main global problems of the modern world. The Black Sea is the main source of seafood for people from several countries, including Bulgaria. The pollution of the Black sea is a result of various factors, especially anthropogenic. The aim of this study was to determine the presence and accumulation of microplastics in the Black Sea mussel Mytilus galloprovincialis L., 1819, harvested from different locations along the northern Bulgarian Black Sea coast. Within each microplastic morphological group, three size classes were recognized: 100-200 μm, 25-100 μm, and ≤ 25 μm. Microplastics were found in the soft tissues of all studied specimens but in a different ratio of pellets, fibers and fragments. Generally, the pellets were the most often registered particles, followed by irregularly-shaped fragments, whereas fibers were less numerous. The dominant part of the isolated plastics are made of polyethylene (PE), and polyethylene terephthalate (PET). Our results pointed out serious pollution with plastic particles in the Bulgarian Black Sea aquatory, which in the future may seriously affect the health of the mussel population and also human health.

The current study aims for the isolation and physicochemical characterization of inulin from defatted dandelion roots using green extraction techniques, including microwave extraction (MAE) and ultrasound-assisted extraction (UAE). The structure and degree of polymerization of inulin were elucidated by chromatographic techniques, as well as by FTIR and NMR spectroscopies. The color characteristics, water- and oil-holding capacity, solubility, swelling properties, wettability, angle of repose, flowability, and cohesiveness of dandelion inulin were evaluated. Moreover, the antioxidant and antibacterial potential of dandelion inulin were revealed. The results were compared with the conventional extraction and inulin from chicory. Dandelion inulin was evaluated as a powder substance with a degree of polymerization (DP) of 17–24. The highest yield (20%) was obtained by classical extraction; however, UAE and MAE demonstrated the highest purity. FT-IR and NMR spectra revealed that dandelion inulin is glucofructan with a molecular weight of 2.7–3.2 kDa that consists mainly of fructosyl units β-(2→1) linked to one α-D-glucose unit UAE was evaluated as the most perspective technique for the simultaneous extraction of inulin from dandelion roots, with the highest average DP 24 and high purity (82%), molecular mass, total fructose content, swelling index, and oil-holding capacity. Dandelion inulin exhibited intermediate cohesiveness, fair flowability, and moderate antimicrobial activity against Listeria monocytogenes 863 and Bacillus subtilis 6633. The physicochemical and functional properties of dandelion inulin reveal its future potential as an additive in food, cosmetic, and pharmaceutics formulations as a texture modifier, a fat replacer, and a drug carrier.

Microwave-assisted irradiation was performed for esterification of chicory inulin with high degree of polymerization with acetic anhydride without a solvent only with a catalyst. The resulting esters were characterized by melting point, hydrophilic-lipophilic balance, thin-layer chromatography, ultraviolet spectroscopy, Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Inulin acetate demonstrated a high degree of acetylation (2.5–3.0) and presented a white, water-insoluble substance with bitter taste. The FTIR and NMR spectra confirmed esterification and demonstrated the incorporation of hydrophobic residue to the water soluble inulin backbone. Swelling capacity, water holding, oil-holding capacities, the foamability, foam stability and emulsifying properties were also evaluated. Inulin acetate showed promising foam stability 52% for 60 min and formed stable emulsions at concentration 0.2 g/ L with 50 and 80% oil phases. Its water holding capacity was lower than the oil holding capacity. In addition to this, for the first time, the antimicrobial potential of inulin acetate was tested against seventeen microorganisms (Gram-positive and Gram-negative bacteria, yeasts and fungi). Inulin acetate (10 mg/ml) inhibited the growth of Bacillus cereus, Escherichia coli ATCC 8739, Salmonella abony, Candida albicans and Penicillium sp. However, inulin acetate demonstrated antimicrobial activity at concentration 1 mg/ml against Listeria monocytogenes 863, Escherichia coli 3398, Candida albicans 8673, Fusarium oxysporum and Aspergillus niger. The current study demonstrated the applications of “green” synthesized inulin acetate as a foaming agent, oil-in-water emulsion stabilizer and antimicrobial substance in pharmaceutical, agricultural and cosmetic preparations.

Yeasts are essential contributors to the ripening and flavor development of white brined cheeses. This study aimed to investigate and compare the microbial load and yeast species composition in artisanal and industrial white brined cheeses. The influence of key physicochemical parameters (salt content, acidity, fat content, moisture, and ripening stage) on yeast count and species composition was analyzed. A total of 100 white brined cheese samples produced in Bulgaria were analyzed. Yeast species were identified using MALDI–TOF MS, and physicochemical properties were assessed according to ISO standards. The predominant yeast species identified were Torulaspora delbrueckii, Debaryomyces hansenii, Saccharomyces cerevisiae, and Candida sphaerica. D. hansenii was the dominant species in industrial samples, while S. cerevisiae was more frequently isolated from artisanal cheeses. Statistical analyses showed that the physicochemical parameters most influencing yeast species composition were salt content and acidity. A statistically significant correlation between yeast count and salt content was observed only in industrial cheeses, with D. hansenii showing greater salt tolerance. Yeast counts were higher in cheeses with higher salt content, particularly in industrial samples. This study highlights the distinct influence of production methods and physicochemical parameters on the yeast ecology of white brined cheeses.

The present study reports on the determination of the antimicrobial activity of lactic acid bacteria (LAB) isolated from the Black sea mussel Mytilus galloprovincialis Lamarck, 1819. The samples were collected in the period of August 2018 until March 2021. The BIOLOG system was used for microbiological determination. From the mussel M. galloprovincialis Lam. four species of LAB were isolated - Sporolactobacillus kofuensis, Lactobacillus sakei, Streptococcus gallolyticus ss gallolyticus and Lactibacillus brevis. The activity of the strains was determined against test cultures (Escherichia coli 3398, Staphylococus aureus 745, Bacillus subtilis 6633, Salmonella typhimurium 3591, Listeria monocytogens 863 Enterobacter aerogenes 3691, Aspergillus niger, Penicillium claviforme, Saccharomyces cerevisae, Candida albicans 8673 and Candida glabrata 72). Before the analysis for antimicrobial activity, the LAB were cultured in media with different concentrations of sugars - 2, 5 and 10%. The results showed that 4 strains S. kofuensis, L. sakei, S. gallolyticus ss gallolyticus and L. brevis cultured on glucose and oligosaccharides completely lost their activity in all studied variants. Therefore, some carbohydrates (glucose) and oligosaccharides induce the synthesis outside the cell of biologically active molecules, which can probably be attributed to peptides/proteins.