Sustainable extraction techniques (ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and pressurized-liquid extraction (PLE)) were applied and compared with conventional solvent extraction to evaluate their efficiency in maximizing the bioactive compound content and antioxidant activity of black and red currants. The influence of ethanol concentrations (30%, 50%, 70%) were studied in all extraction methods, while different temperatures (30, 50, 70 °C/80, 100, 120 °C) were evaluated in UAE and PLE, respectively. Generally, higher total phenolics were determined in black currant extracts (1.93–3.41 g GAE/100 g) than in red currant extracts (1.27–2.63 g GAE/100 g). The results showed that MAE was the most efficient for the extraction of bioactives from black currants, with 3.41 g GAE/100 g and 0.7934 g CE/100 g, while PLE provided the highest TP and TF for black currant samples (2.63 g GAE/100 g and 0.77 g CE/100 g). Extracts obtained by MAE (10 min, 600 W, 30% ethanol) and PLE (50% ethanol, 10 min, 120 °C) had the highest antioxidant activity, as determined by various in vitro assays (DPPH, FRAP, and ABTS). In conclusion, sustainable extraction techniques can be considered an efficient tool to maximize the content of bioactive antioxidants from black and red currants.

The influence of biostimulants (B) and nitrogen (N) fertilization on the yield and quality of onions were investigated. Experiments in the field with directly seeded (DS) onions and those from sets (FS) were carried out in 2021 in the Autonomous Province of Vojvodina (Serbia). HumiBlack^® (B1), Tifi^® (B2), and Agasi^® (B3) were used as B, and there was a control without B. Four N doses were used: 64, 100, 150 (standard dose), and 200 kg N/ha. The highest yields of DS onions (63.9 t/ha) and FS onions (52, 1 t/ha) were measured on treatment B2 × 150 kg N/ha. The highest total sugar content (80.6 g/100 g DM) was measured in FS onions under treatment B2 × 100 kg N/ha. Total nitrogen and protein content were the highest in DS onions treated with B2 × 200 kg N/ha, where total nitrogen was 2.3 g/100 g DM and protein content was 14.5 g/100 g DM. Depending on B and N, titratable acidity ranged from 1.7 to 3.6 g/100 g DM. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to analyze onions and showed that FS onions have lower values of total phenolics and crude fiber content, DPPH, FRAP, and ABTS compared to DS onions. In this study, a chemometric approach was suitable for grouping onions according to treatment effect and main interactions between B and N.

Sour cherries were first dried by vacuum drying and then used as material for obtaining extracts rich in bioactive compounds by ultrasound-assisted extraction (UAE). The first step was to apply a factorial design for the preliminary experiments to determine the most influential UAE factors, and thus the three studied parameters were chosen as the most suitable for the design of the main experiment (temperature, liquid–solid ratio and ethanol concentration). In this part, the contents of total phenols and the total content of monomeric anthocyanins were taken for responses. For the further optimization of UAE, experimental design (face-centered) was applied, and the yield, total phenolics, flavonoid content and content of monomeric anthocyanins and antioxidant activity (DPPH, ABTS and FRAP assays) were analyzed. Temperature (40–80 °C), ethanol concentration (40–80%, w/w) and liquid–solid ratio (10–30 mL/g) were investigated as independent variables. The obtained experimental results were fitted to a second-order polynomial model and analysis of variance was used to determine the fit of the model and the optimal conditions for investigated responses. High quality extracts with high concentrations of polyphenols and anthocyanins were also obtained, which could be used as food additives.

The following article describes new research about the design, construction and installation of the new prototype of a vacuum dryer with an ejector system. Moreover, the testing of this new prototype involved comparing the qualities of fruit dried in a vacuum drier with an ejector system to fruit dried in a convectional vacuum drier. The data obtained were then analyzed and presented. Due to their economic relevance and highly valuable nutritional value and sensory properties, sour cherries and apricots have been chosen to be the subjects for the testing. The most appropriate quality indicators for analyzing were moisture content, a_w value, share and penetration force, total phenol, flavonoid and anthocyanin content and antioxidant activity (FRAP, DPPH and ABTS test). The main results of this study were achieved by designing, constructing, installing and testing the usage of the innovative prototype of a vacuum dryer with an ejector system in the laboratory of the Technology of fruit and vegetable products of the Faculty of Technology Novi Sad, University of Novi Sad. Based on our analyses of the obtained data, it was concluded that vacuum dryer with an ejector system are similar to vacuum dryer with a vacuum pump in terms of all tested physical, chemical and biological properties of dried samples. We observed similarities in some of the most important parameters, including product safety and quality, such as the a_w value and the total phenol content, respectively. For example, in dried sour cherry, the a_w values ranged from 0.250 to 0.521 with the vacuum pump and from 0.232 to 0.417 with the ejector system; the total phenol content ranged from 2322 to 2765 mg GAE/100 g DW with the vacuum pump and from 2327 to 2617 mg GAE/100 g DW with the ejector system. In dried apricot, the a_w ranged from 0.176 to 0.405 with the vacuum pump and from 0.166 to 0.313 with the ejector system; total phenol content ranged from 392 to 439 mg GAE/100 g DW with the vacuum pump and from 378 to 428 mg GAE/100 g DW with the ejector system.