Aronia melanocarpa by-product from filter-tea factory was used for the preparation of extracts with high content of bioactive compounds. Extraction process was accelerated using sonication. Three level, three variable face-centered cubic experimental design (FCD) with response surface methodology (RSM) was used for optimization of extraction in terms of maximized yields for total phenolics (TP), flavonoids (TF), anthocyanins (MA) and proanthocyanidins (TPA) contents. Ultrasonic power (X₁: 72-216 W), temperature (X₂: 30-70 °C) and extraction time (X₃: 30-90 min) were investigated as independent variables. Experimental results were fitted to a second-order polynomial model where multiple regression analysis and analysis of variance were used to determine fitness of the model and optimal conditions for investigated responses. Three-dimensional surface plots were generated from the mathematical models. The optimal conditions for ultrasound-assisted extraction of TP, TF, MA and TPA were: X₁=206.64 W, X₂=70 °C, X₃=80.1 min; X₁=210.24 W, X₂=70 °C, X₃=75 min; X₁=216 W, X₂=70 °C, X₃=45.6 min and X₁=199.44 W, X₂=70 °C, X₃=89.7 min, respectively. Generated model predicted values of the TP, TF, MA and TPA to be 15.41 mg GAE/ml, 9.86 mg CE/ml, 2.26 mg C3G/ml and 20.67 mg CE/ml, respectively. Experimental validation was performed and close agreement between experimental and predicted values was found (within 95% confidence interval).

Ultrasound-assisted extraction was used for extraction of bioactive compounds and for production of Allium ursinum liquid extract. The experiments were carried out according to tree level, four variables, face-centered cubic experimental design (FDC) combined with response surface methodology (RSM). Temperature (from 40 to 80 °C), ethanol concentration (from 30% to 70%), extraction time (from 40 to 80 min) and ultrasonic power (from 19.2 to 38.4 W/L) were investigated as independent variables in order to obtain the optimal conditions for extraction and to maximize the yield of total phenols (TP), flavonoids (TF) and antioxidant activity of obtained extracts. Experimental results were fitted to the second order polynomial model where multiple regression and analysis of variance were used to determine the fitness of the model and optimal condition for investigated responses. The predicted values of the TP (1.60 g GAE/100 g DW), TF (0.35 g CE/100 g DW), antioxidant activity, IC50 (0.71 mg/ml) and EY (38.1%) were determined at the optimal conditions for ultrasound assisted extraction: 80 °C temperature, 70% ethanol, 79.8 min and 20.06 W/L ultrasonic power. The predicted results matched well with the experimental results obtained using optimal extraction conditions which validated the RSM model with a good correlation.

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The aim of this study was to valorize the oil recovery from red and white grape seeds (Vitis vinifera L.) that remains as by-product after the winemaking process. Oils were extracted by modern techniques, ultrasound assisted (UAE), microwave assisted (MAE) and supercritical fluid extraction (SFE), and compared to the Soxhlet extraction (SE). Firstly, SFE was optimized at different operating conditions: pressure (250–350 bar), temperature (40–60 °C), CO2 flow rate (0.2, 0.3 and 0.4 kg h−1), and particle size (315–800 µm and >800 µm). The highest extraction yields were achieved by SFE at the optimal conditions: 350 bar, 60 °C, 0.4 kg h−1. Afterwards, SFE was compared to SE, UAE and MAE with respect to oil extraction yields, and analyzed for fatty acid composition and antioxidant capacity. Considering the general classification of fatty acids, it was found that samples had high content of polyunsaturated fatty acids, regardless of extraction technology. Tocopherol content was significantly influenced by all extraction methods, whereas UAE and MAE resulted in extracts richer with lipophilic antioxidants. In conclusion, modern extractions that are suited for industrial applications had better performance as compared to SE, as judging by the oil yield and quality.

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