The aim of this study was to examine the microbiological quality of raw donkey milk of an indigenous Serbian breed as well as the changes in the microbial populations during storage at 4 °C. In addition, antibacterial activity of donkey milk against E. coli, L. monocytogenes and S. aureus at 15 °C as well as the content of the two main antibacterial proteins lysozyme and lactoferrin were investigated. Microbiological examination of 137 individual milk samples collected over a period of 21 months showed good microbiological quality since foodborne pathogens such as Salmonella spp. and L. monocytogenes were not detected in any of the analyzed samples, while the number of E. coli, Enterobacteriaceae, total coliform bacteria, sulfite-reducing Clostridia and aerobic sporogenic bacteria was below the limit of quantification (<1 cfu mL⁻¹). During the six-days storage at 4 °C, total bacterial counts and the counts of lactic acid bacteria remained at the initial level while pathogenic bacteria were not detected. The strongest antibacterial activity of the tested milk was observed against E. coli, while S. aureus was the least sensitive to milk antibacterial compounds. Although further research is needed to fully elucidate the antibacterial mechanism and synergistic activity of different compounds in donkey milk, the high content lysozyme (2.63 ± 0.03 g L⁻¹) and lactoferrin (15.48 mg L⁻¹) observed in tested milk could contribute to its strong antibacterial activity and extension of the storage period during which it can be safely consumed.

The olive fruits are rich source of oil, vitamins, minerals, organic acids and pigments. The fruits contain high level of bioactive compounds. The aim of this study was to examine the effect of heat treatment on tocopherols, total phenolics and antioxidant activity in green and black olives, as well as their fatty acid composition. The instrumental methods used in this experiment were high performance liquid chromatography (HPLC), gas chromatography with flame ionization detection (GC/FID) and spectrophotometric methods. The results revealed that the β+γ-tocopherols content after the heat treatment had the biggest reduction, which was 68.4% for green and 80.2% for black olives. Also, a significant loss of total phenolic content was observed after heat treatment in green and black olives by 18.6% and 18.4%, respectively, as well as antioxidant activity (decrease up to 28.1%). The most abundant fatty acids in green and black olives were oleic (C18:1), palmitic (C16:0) and linoleic acid (C18:2). The changes in fatty acids composition during the heat treatment occurred mostly at the level of polyunsaturated fatty acids, especially linolenic acid (C18:3) in black olives had the significant reduction (by 57.4%) in relation to the initial quantity.

Road traffic, aircraft, waste trucks, construction equipment, and industrial facilities are just a few important noise sources that pollute the environment and affect human health. Considering that noise pollution is increasing due to urbanization and more traffic vehicles on roads, solving this problem is necessary. Optimization of total noise emissions in Belgrade (Serbia) was done since noise has always been a source of pollution. This paper presents the use of GIS to establish a multi-factor assessment model to divide infected grids and select control sites, along with the TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method, IDW (Inverse Distance Weighting) interpolation technique, zonal GIS (Geographic Information System) statistics, and noise optimization in the investigated area. The analysis was based on noise data recorded (Lden - the average noise level over a 24-hour period) values in spring and autumn measuring cycles at 34 measuring points in 11 Belgrade municipalities in 2023. The results showed that noise emission in some control sites requires more than 25% reduction. The improvement of the environment is required to control the background of noise pollution in Belgrade.

Limited reserves of fossil fuels, as well as economic and environmental reasons, have caused an increasing demand for biofuels. Biodiesel, as an alternative to fossil fuel, is an increasingly common biofuel today, especially in the developed European market, and it is primarily produced from vegetable oils. The main obstacle to the greater use of biodiesel is the high cost of production due to the high price of edible vegetable oil. In addition, European countries do not have the ability to provide sufficient quantities of raw materials for the production of biodiesel, because the increase in the production of vegetable oils is limited by agronomic and climatic conditions. Therefore, we are looking for alternative raw materials, which will ensure economical production with the rationalization of operating costs, the greatest possible degree of energy independence and efficiency, and all this while implementing environmental protection measures, i.e. alternative raw materials are being sought, the application of which could ensure the sustainable production of biodiesel. One of the options for achieving that goal is the production of biodiesel from lipids left behind and collected after their use in restaurants and in the food industry, which are mostly discarded at the place of their creation. Biodiesel can also be produced from the by-products of the technological process of the production of edible vegetable oil, from oils and fats as secondary products of animal origin, from waste mineral oils, from lipids from sewage sludge, etc. The permanent availability and low price of these lipid materials, as well as the problem of their disposal in the environment, make them potential alternative raw materials for the production of biodiesel. Therefore, research was conductedon the possibility and development of biodiesel production from the aforementioned lipids and waste lipids, the results of which are presented in this scientific paper.