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.

Onions, essential in various salads and cooked dishes, are sought after by producers for high yields, while consumers value their quality, particularly the presence of antioxidant compounds. This study investigates the impact of production methods and biostimulants on the biomass yield and quality of onions. The two-year experiment was conducted in Vojvodina, Serbia, and compared directly seeded (DS) and from-set (FS) onions with four biostimulant treatments: control (C), seaweed extracts (T1), humic and fulvic acids (T2), and Trichoderma sp. (T3). DS onions yielded significantly more biomass, while FS onions had higher dry matter content. DS onions treated with T1 showed a significant increase in phenols (↑ 5.30%), while T2 and T3 led to declines (↓ 8.66% and ↓ 7.55%, respectively). All biostimulants reduced phenol content in FS onions. T1 and T2 significantly increased the flavonoid concentration in DS onions, with no significant changes in FS onions. T1 enhanced antioxidant properties in DS onions and reduced them in FS onions. Additionally, T2 and T3 decreased antioxidant activity in both DS and FS onions, as evidenced by DPPH, FRAP, and ABTS tests. These findings guide onion production, advocating for the fresh consumption of DS onions with higher biomass and industrial processing suitability for FS onions, emphasizing the potential of bio-based products.

In the pursuit of maximizing onion (Allium cepa) yield and quality, farmers often face the challenges of unfavorable ecological conditions and inadequate agronomic practices. Therefore, our two-year study investigated the effects of biostimulants (BTs) of plant growth on bulb yield and the bioactive compounds of directly seeded onion. Four treatments were applied: control (C), seaweed extracts (BT1), humic and fulvic acid (BT2), and Trichoderma spp. (BT3). The results demonstrated a significant increase in bulb yield with BT1 (↑ 18.7%), BT2 (↑ 18.0%), and BT3 (↑ 24.3%). Intriguingly, all BTs markedly reduced phenolic content across both years. Additionally, BT1 and BT3 elevated flavonoid levels (↑ 16.8% and ↑ 16.7%, respectively), while BT2 decreased them (↓ 24.2%). Notably, in 2021, DPPH, FRAP, and ABTS tests indicated a significant reduction in antioxidant capacity compared to C. Our study underscores the important role of BTs in enhancing yield, influencing secondary metabolites and contributing to environmental sustainability in onion cultivation.