Aleksandar Z. Kostic

The aim of this research was to establish the optimal composition of functional ingredients based on skimmed goat's milk and grape pomace seed extract. A central composite design was used to test the influence of grape pomace content and pH on total phenolic content (TPC), antioxidant (ABTS, DPPH, and FRP) and chelating (CHE) properties as response variables of analyzed mixtures. Significant linear regression was observed for TPC, ABTS•+ radical scavenging activity, and FRP, while significant linear and squared regression was determined for DPPH•scavenging activity and chelating ability. No significant correlation between tested responses and the interaction term was detected. By applying the desirability function, optimal conditions were set, and predicted values of responses were compared to experimental results. Good agreement was obtained only for TPC and FRP, contrary to other properties whose experimental values were much higher than predicted.

Bee-collected pollen (BCP), due to its valuable nutrient content, is considered a natural food suitable for human consumption. On the other hand, it should be noted that the rich nutritional value of BCP is also relevant in the context of potential contamination with fungal secondary metabolites, such as mycotoxins. In this study, a total of 26 pollen samples were collected from different locations in order to investigate the potential presence of mycotoxins. All BCP samples were obtained from beekeepers who produce pollen for further commercialization. The analyzed mycotoxins included ochratoxin A (OTA), aflatoxin B1 (AFB1), zearalenone (ZEN), T-2 toxin, HT-2 toxin, deoxynivalenol (DON), and fumonisins (FUMs), which were measured by direct competitive enzyme-linked immunosorbent assays. The obtained results indicated the presence of at least three toxins in all samples. AFB1, OTA, and ZEN were detected above the limit of quantification (LOQ) in all samples, whereas T-2 and HT-2 were below the LOQ in five samples and DON in four samples. FUMs were below LOQ in all samples. Due to the significant content of AFB1 determined in all samples, there is a potential risk for future consumers, demanding constant monitoring as well as improvement of BCP production.

The aim of this study was to formulate and optimize a novel functional ingredient based on thermally treated skimmed goat milk enriched with Agrocybe aegerita mushroom extract (ME) and grape pomace seed extract (GPE), intended for application in a dehydrated soup model. A central composite design was applied for preliminary optimization and the formulation based on antioxidant properties. The optimized ingredient exhibited enhanced antioxidant activity, with GPE identified as the dominant factor influencing the responses. However, deviations between predicted and experimental values were observed, reflecting moderate model fitting and differences in assay mechanisms. ATR-FTIR spectra were dominated by milk compounds, while DLS and electrophoretic analysis revealed structural modifications, including polymodal particle size distribution and alterations in the protein profile, indicating interactions between milk proteins, polyphenols, and mushroom-derived compounds. UHPLC-QToF-MS analysis confirmed a high content of grape-derived phenolic compounds. Following simulated gastrointestinal digestion, several phenolic compounds were detected in the soluble fraction, with catechin and ethyl gallate exhibiting the highest bioaccessibility (12.58% and 4.54%). The enriched ingredient showed modified techno-functional properties, including reduced emulsifying capacity but improved foaming behavior, which was attributed to protein structural changes and intermolecular interactions. Application in a dehydrated soup model demonstrated good solubility, stability, and high sensory acceptability without negative effects on flavor. Furthermore, the enriched soup showed enhanced antioxidant properties after simulated gastrointestinal digestion. The developed formulation represents a promising natural functional ingredient, combining enhanced bioactive properties with satisfactory technological performance.

This study included the nectar of nine standard apple (Malus × domestica) cultivars (‘Red Aroma’, ‘Discovery’, ‘Summerred’, ‘Rubinstep’, ‘Elstar’, ‘Asfari’, ‘Eden’, ‘Fryd’, and ‘Katja’) and two crab apple (Malus sylvestris) cultivars (‘Dolgo’ and ‘Professor Sprenger’). The aim was to determine the diversity of chemical compounds in the floral nectar of the two different apple species and their cultivars. Chemical analysis identified five sugars, two sugar alcohols, two organic acids, forty phenolic compounds, and five phenylamides. The crab apples ‘Dolgo’ and ‘Professor Sprenger’, along with the commercial cultivar ‘Rubinstep’, had the highest levels of all three main sugars (glucose, sucrose, and fructose). The cultivar’s ‘Katja’ nectar had the highest level of total phenolic content (60.7 mg/100 g GAE), the nectar sample from ‘Dolgo’ exhibited the greatest ability to neutralise DPPH radicals (83.4 mg/100 g TE), and the ‘Dolgo’ (100.6 mg/100 g TE FW) and ‘Katja’ (72.1 mg/100 g TE FW) nectars proved to be the best reducing agents. Floral nectar from ‘Eden’ and ‘Fryd’ showed very high levels of isorhamnetin, 49.04 mg/kg and 50.83 mg/kg, respectively, while nectar from ‘Katja’ had the highest level of gentisic acid at 39.06 mg/kg. Besides being vital for insects, apple floral nectar is a significant reservoir of phenolic compounds and can be considered a “superfood” for the human diet.

The notion of generalized metric, more commonly known as the rectangular metric, was introduced by Branciari in 2000, replacing the triangle inequality of metric spaces by the so-called rectangular inequality. In this paper we further generalize this notion by adding two more terms to the right-hand side of the rectangular inequality. We study basic properties of spaces endowed by such distance functions, and prove the modified versions of Banach and Kannan fixed point theorems on these spaces. The results are substantiated by examples. Finally, we state some open problems related to topological structure and fixed point theory on generalized Branciari metric spaces.

Onion ( Allium cepa L.) is the most widely cultivated species of the genus Allium and one of the most consumed vegetables globally. With the aim of supporting onion cultivation practices and breeding programs, this study examined the main classes of bioactive compounds, soluble sugars, antioxidant properties (measured via TAC, CUPRAC, DPPH ^• and ABTS ^•+ assays) and yield indicators of the widely grown onion cultivar Hamilton F1 (Bejo Zaden BV, Warmenhuizen, Netherlands) under the agroecological conditions of Vojvodina, Serbia. The onion was established by direct sowing in 4 × double-row strips, using a randomized block design with three replications. Extraction was performed with 80% methanol in order to prevent protein extraction and potential interferences with phenolics. The results revealed that total phenolic content (TPC), total flavonoid content (TFC), and soluble sugars content (SSC) were 0.76 mg/g GAE, 0.29 mg/g QE, and 106.9 mg/g Glc, respectively. The highest antioxidant activity was observed in TAC and ABTS ^•+ assays, with values of 6.57 mg/g AAE and 3.67 µmol/g TE, respectively. The content of total hydroxycinnamic acid derivatives was below the detection limit. The dry matter content was 8.11%. Additionally, the total yield of the Hamilton F1 onion was 108.01 t/ha, with a first-class yield of 104.4 t/ha and a high proportion of marketable bulbs. The results indicate that the Hamilton F1 cultivar is characterized by a considerable content of the examined bioactive compounds that contribute to better agronomic traits, including improved performance under stress conditions, longer storage potential and greater disease tolerance. From consumers’ perspective, these compounds provide also health benefits. The findings emphasize the potential of Hamilton F1 as a reliable option for farmers and highlight the importance of breeding programs focused on developing onion cultivars with similar or improved functional properties, combining high yield potential with enhanced nutritional value.

This research, conducted over two consecutive years in the production fields of the Iceberg Lettuce Centar in Belgrade, aimed to investigate the impact of biostimulants on the morphological and phytochemical characteristics of iceberg lettuce in two seasons (spring and autumn), using greenhouse and open field cultivation. The biostimulator was derived from a seaweed (Kelpak). The effects of different applications (seedling soaking and foliar treatment once, twice, and three times during the growing season) on plant growth (total plant mass, leaf mass, and stem mass) and phytochemical properties, including pigments (chlorophyll a, chlorophyll b, carotenoids), as well as antioxidant activity (TAC, polyphenols), were investigated. The results showed that the application of biostimulators, particularly through the seedling soaking method, contributed to an increase in plant mass and greater biomass accumulation, whereas foliar treatments enabled better development in both seasons. Plants grown in the greenhouse had more stable growth and better quality, while the spring season proved to be more favourable than autumn. Biostimulators also had a positive effect on the content of photosynthetic pigments and antioxidants, which improved the nutritional value and stress resistance of plants.

Onion (Allium cepa L.), either fresh or processed, is widely consumed for its unique aroma, flavor, and taste. While farmers aim to maximize yield, consumers demand high-quality products. These goals can conflict under certain cultivation conditions but can be balanced through appropriate agronomic practices. Therefore, this study aimed to investigate the effects of two sowing methods, the standard sowing method (SSM) and the new sowing method (NSM), characterized by reduced seed rates and wider row spacing on selected quality parameters (onion bulb weight and total soluble sugars [TSS]), key bioactive compounds content, total phenolic content (TPC), total flavonoid content (TFC), hydroxycinnamic acids (HCAs), total monomeric anthocyanins (TMA), and antioxidant properties of 10 new onion genotypes (G1–G10). The results revealed statistically significant differences (p < 0.005) among both sowing methods and genotypes, indicating that these factors substantially impact the measured parameters. Bright violet, skin-colored genotype G8 stood out with the highest values of TPC, TFC, HCAs, TMA, TSS, and antioxidant activity (measured in three assays) in the NSM and bulb weight in the SSM. These findings suggest that the NSM may offer economic benefits for farmers, while selected genotypes provide consumers with high-quality onions.