University of Food Technologies

This study examines the digitalization of food systems in smart cities, focusing on the role of the Internet of Things (IoT). In much of the research, food systems are viewed as a logistical element rather than as part of the core urban infrastructure. At the same time, they are essential for the functioning of the urban environment, as they are directly related to sustainability, resource efficiency, and quality of life. The lack of a clearly defined architectural framework limits the possibilities for their systematic integration and management. This necessitates a new conceptual approach within which food systems are viewed as a separate infrastructure layer. In response, this paper proposes a conceptual architecture that positions IoT-based food systems as an equal component of the smart city. The proposed framework provides a clearer basis for the analysis and design of smart food systems. It supports better management, higher efficiency, and sustainable development of the urban environment.

This article describes the synthesis of a new Pd (II) complex by using 2,4-dithiouracil (2,4-DTu) as a starting reagent and its structure elucidation. The coordination compound was analyzed by several methods, including melting point determination, UV-Vis, 1H NMR-solution state, 1H- and 13C-NMR solid state, HSQC, 1H-1H COSY, ATR and Raman spectroscopy. The metal complex was formed by mixing aqueous solutions of metal salts with the ligand dissolved in DMSO and water, along with NaOH, in a metal-to-ligand-to-base ratio of 1:4:2. Furthermore, the compound's antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as yeasts, was assessed. It should be noted that for the first time a biologically active mixed ligand complex of Pd (II) with 2,4-DTu and 2-Tu was obtained. The ligands 2,4-DTu and 2-thiouracil (2-Tu) are bidentately coordinated to Pd(II) through a deprotonated nitrogen atom and the adjacent heteroatom—sulfur or oxygen, respectively. Tentative structures of the Pd(II) complexes are proposed, in which DMSO-h₆ and H₂O may be located either in the inner or outer coordination sphere. The new Pd(II) complex exhibited a coordination number of 6 or 4, respectively. The newly formed coordination compound of the corresponding pyrimidine-based ligands, i.e. 2,4-dithiouracil and 2-thiouracil, with Pd (II) demonstrated the strongest activity against Staphylococcus aureus. It, also, showed a significant improvement in its antifungal activity in comparison with free ligand 2,4-dithiouracil.

This study is the first to investigate the growth kinetics of Inonotus hispidus GA4B, a newly isolated wood-decay mushroom from Bulgaria, under in vitro cultivation, as well as its ability to utilize plant-derived waste materials as complex growth media. Using logistic and reversed autocatalytic growth models, the effects of nine media were assessed, identifying the binary medium SDLSWB as the most effective for promoting fungal growth (µmax = 0.480 ± 0.019 d⁻¹), though further optimization is needed to improve substrate efficiency. Similar growth potential was observed with WSWB and HERFWB media. Based on the kinetic analysis, it can be concluded that the optimal cultivation temperature for I. hispidus on SDLSWB medium is 28℃. A fourth-order polynomial model of the pre-exponential factor in the Arrhenius equation enabled accurate predictions of µmax across a 19 – 31℃ range, with strong agreement between theoretical and experimental results. Additionally, pH 5.5 was identified as optimal, and a pH-dependent kinetic model successfully predicted µmax values between pH 5.0 and 7.5. Overall, the findings provide a solid foundation for future research aimed at optimizing the use of various plant-derived waste materials as culture media for the growth of basidiomycete fungi.

This study evaluates the feasibility of using two affordable thermal cameras (UNI-T UTi260M and UTi260T), which are not designed as automotive sensors, for observing pedestrians and warm objects during night-time driving under low-illumination conditions. The experimental setup includes mounting the camera on the vehicle body (e.g., side mirror area/roof), recording road scenes in urban and rural environments, and selecting representative frames for qualitative and quantitative analysis. The study assesses: (i) observable pedestrian detectability in unlit road sections and under oncoming headlight glare, where visible cameras often lose contrast; (ii) the influence of low ambient temperature and strong cold wind on image appearance (including “whitening”/contrast shifts); and (iii) workflow differences, where UTi260M relies on a smartphone application for streaming/recording, while UTi260T supports PC-based image analysis and temperature-profile visualization. In addition, a calibration-based geometric method is proposed for approximate pedestrian distance estimation from single frames using silhouette pixel height and a regression model based on 1/hpx, valid for a specific mounting configuration and a known subject height. Results indicate that both cameras can highlight warm objects relative to the background and support visual pedestrian identification at low illumination, including in the presence of oncoming headlights, with UTi260M showing more stable behavior in parts of the tests. This work is a feasibility study and does not claim Advanced Driver Assist Systems (ADAS) functionality; it outlines limitations, repeatability considerations, and a minimal set of metrics and procedures for future extension. All quantitative indicators derived from exported frames are explicitly treated as image-level proxy metrics, not as physical sensor characteristics.

Comparative analysis of nanostructured multilayer Cr/(Cr/a-C)ml coatings on HS6-5-2 steel was carried out. The coatings were deposited at various chromium target power values using PVD technology, particularly the magnetron sputtering method. The effect of different technological regimes on the properties of the nanostructured multilayer Cr/(Cr/a-C)ml coatings was studied. Identical characterization methods were used for the three types of coatings obtained. Cross-sections of the coated samples were prepared in order to directly determine the thickness of the resulting coatings, their uniformity, and the presence of defects or imperfections, both at the substrate-coating interface and within the coatings themselves. Calotest and Daimler-Benz adhesion test were also performed to evaluate the coated layers' thickness and evaluate their adhesion strength. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses were carried out to define the chemical composition of the multilayered coatings. To evaluate the hardness and modulus of elasticity of the resulting coatings, nanoindentation measurements were also conducted. The data obtained under the three different deposition regimes were analyzed and compared, which allowed us to assess the influence of the chromium target power during the deposition process on the properties of the obtained coatings.

Nanotechnology has emerged as a promising option in combating the worsening situation with antibiotic resistance. We studied the antimicrobial effectiveness of four types of green synthesized zinc oxide nanoparticles (ZnO-NPs), obtained via Pluronic-assisted co-precipitation by lavender and thyme essential oils and their praseodymium-doped variants. Resazurin Microtiter Assay was applied to a panel of Gram-positive and Gram-negative bacteria from Risk 1 and 2 groups and the ESKAPE group. In relation to the pro-oxidative features of the ZnO-NPs, the production of superoxide dismutase (SOD) and catalase (CAT) in the tested microorganisms was also investigated, as these enzymes are important participants in the antioxidant defense of the bacterial cell and are considered virulence factors. We hypothesized that the sensitivity of microorganisms to the action of ZnO-NPs is related to their innate levels of antioxidant enzyme activity. The results showed that all types of studied ZnO-NPs had an antibacterial effect against the entire panel of tested strains, but with different potencies. The strongest effect was found for Arthrobacter nicotianae, Oerskovia paurometabola, Bacillus subtilis, and Escherichia coli. Less inhibition was observed for bacteria from Risk group 2 maybe due to their better antioxidant protection, especially for Pseudomonas aeruginosa. Praseodymium doping contributed to enhancing the bactericidal effect. A correlation between susceptibility of bacteria to ZnO-NPs and their antioxidant enzyme activity was observed.

The present study aimed to investigate the chemical composition and biological activity of yarrow essential oil (Achillea millefolium) from Bulgaria. Gas chromatography-mass spectrometry (GC-MS) analysis, total reflection X-ray fluorescence (TXRF) technique, antioxidant activity (ABTS and DPPH methods), antimicrobial activity tests were used. Through an optimized procedure with Ga as an internal standard, thirteen elements - S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Se, and Br - were quantified. The highest concentrations were observed for S, Ca, and Fe (12.35 - 7.26 mg kg⁻¹), followed by Cl, K, Ni, Cu, and Zn (2.23 - 0.53 mg kg-1). The dominant compounds identified by GC-MS analysis are monoterpene hydrocarbons, of which α-pinene (41.29 %) and β-pinene (27.15 %), limonene and p-cymene are predominant. The ABTS method a moderate degree radical neutralization with an IC50 value of 9.15 ±0.01 µg mL-1, while the DPPH method had a significantly lower IC50 of 205.00 ± 0.03 µg mL-1, indicating selective antioxidant activity depending on the type of radicals. The maximum inhibition observed at 100 µg mL-1 reached 95.13 % with the ABTS method and 29.82 % with the DPPH method. Bulgarian yarrow essential oil shows moderate activity against some Gram-negative bacteria, such as K. pneumoniae. and weak inhibitory activity against other pathogens, such as Staphylococcus aureus and Escherichia coli. It does not show activity against the molds Aspergillus niger and Aspergillus flavus.

In recent decades, species within the genus Amaranthus L. (amaranth) have garnered growing global interest due to their exceptional nutritional value, functional properties, and agricultural versatility. Traditionally consumed as leafy vegetables or pseudo-cereals, several Amaranthus species are now receiving renewed attention in the context of the development of modern functional foods. This review evaluates the data on nutritional composition, health-promoting properties, and potential applications of Amaranthus spp. in sustainable food systems in peer-reviewed publications from the last 25 years. Amaranth is rich in high-quality proteins, essential amino acids, dietary fibre, vitamins, and minerals, positioning it as a significant factor in addressing malnutrition and enhancing food security. Furthermore, its bioactive compounds, such as flavonoids, phenolic acids, and peptides, exhibit antioxidant, anti-inflammatory, and hypocholesterolemic activities, suggesting its potential as a part of healthy diets, alleviating the risk of non-communicable diseases. The presence of anti-nutritional factors, including saponins, phytates, and oxalates, has also been explored, with implications for nutrient bioavailability and overall health effects. In addition to its nutritional advantages, Amaranthus spp. demonstrate strong adaptability to diverse climatic conditions, thus performing as a crop resilient under climate stress. Their olfactory and sensory attributes are also considered important for consumers’ acceptance and market integration. By synthesising traditional knowledge and contemporary scientific research, this review underscores the potential of Amaranthus spp. as a multifunctional food source that could support health promotion, climate resilience, and agricultural sustainability.

Summer savory (Satureja hortensis L.) is an annual herbaceous plant belonging to the Lamiaceae family and widely used as a culinary spice. The present research aimed to investigate the physicochemical characteristics, phenolic profile, antioxidant potential, and antimicrobial activity of ten summer savory samples (dried leaves and flowers) grown in different regions of Bulgaria. The physicochemical analyses of the dried plant material demonstrated that the ash content varied from 19.51 to 26.92%, proteins from 16.25 to 22.78%, and carbohydrates from 5.37 to 10.01%. The values of the total phenolic content (TPC) ranged from 1.10 to 4.83 mg GAE/g dw (aqueous savory extracts—ASE) and from 3.98 to 9.54 mg GAE/g dw (methanolic savory extracts—MSE). The values of the total flavonoid content (TFC) were from 0.08 to 0.29 mg QE/g dw (ASE) and from 0.73 to 1.23 mg QE/g dw (MSE). The investigated samples exhibited significant antioxidant activity, with values determined by the DPPH method varying between 35.01 and 59.93 mM TE/g dw (ASE) and between 51.75 and 91.85 mM TE/g dw (MSE). The values by the FRAP method ranged from 74.49 to 134.85 µmol Fe2+/g dw (ASE) and from 108.20 to 215.48 µmol Fe2+/g dw (MSE). The high-performance liquid chromatography (HPLC) analysis showed that rosmarinic acid was predominant in all tested samples (3.54–5.90 mg/g dw), whereas ferulic, caffeic and p-coumaric acids were detected in trace amounts. The HPLC analysis of organic acids revealed that ascorbic acid was present in higher concentration in all samples (0.35–0.98 mg/g dw) compared to malic acid, which was found in trace amounts. The antimicrobial activity test demonstrated that methanolic savory extracts showed moderate to high inhibitory activity against most of the microorganisms used (most pronounced against Staphylococcus aureus 6538P, with diameters of the inhibition zones from 20 to 30 mm), while aqueous savory extracts exhibited antifungal rather than antibacterial activity. Based on the results obtained, we can conclude that savory is a plant with potential for use in the pharmaceutical and agricultural sectors, in addition to its culinary applications.

This paper proposes a practical and theoretical approach for optimizing the parameters of feeding devices based on the required productivity and specific part geometry. In machine and automation design, selecting suitable parameters, such as the length of linear feeders, is often a complex task. Machine designers commonly rely on empirical knowledge due to the absence of reliable predictive algorithms. A major challenge is ensuring the real productivity of the feeding system matches the projected productivity during the design phase. Systems with higher productivity allow for shorter linear feeders, while lower-productivity systems require longer tracks to provide a sufficient buffer. The paper presents a practical method based on experimental trials to determine the mean productivity and the resulting optimal feeder length. Furthermore, it develops a theoretical framework to estimate feeder parameters when experimental data is not available, considering part geometry, the number of stable states, and the probability of correct orientation. Additional recommendations are provided for selecting appropriate types of linear feeding tracks based on part properties and requirements. Key influencing factors such as part symmetry, surface conditions, and gravitational effects on linear tracks are discussed. Practical advice is offered on how to ensure system reliability by introducing safety margins in the design parameters. The study underlines the importance of early practical validation with real parts to avoid costly design errors. The proposed methodology is applicable across a wide range of industrial feeding systems and supports designers in achieving more compact, reliable, and efficient machine solutions.