Lavandula angustifolia is one of the most widely cultivated non-food crops used in the production of essential oil; it is used in perfumery, aromatherapy, pharmaceutical preparations, and food ingredients. In this study, supercritical fluid extraction (SFE) and molecular distillation (MD) were combined, primarily to enrich scCO₂ extracts with lavender oxygenated monoterpenes, avoiding thermal degradation, hydrolysis, and solvent contamination, and maintaining the natural characteristics of the obtained oils. Molecular distillation was developed for the first time for the extraction of crucial lavender fragrance ingredients, i.e., from two scCO₂ extracts obtained from dry flower stems of lavender cultivated in Poland and Bulgaria. The best results for high-quality distillates were obtained at 85 °C (EVT) and confirmed that linalyl acetate content increased from 51.54 mg/g (initial Bulgarian lavender extract, L-Bg-E) and 89.53 mg/g (initial Polish lavender extract, L-Pl-E) to 118.41 and 185.42 mg/g, respectively, corresponding to increases of 2.3 and 2.1 times in both distillate streams, respectively. The distillates, light oils, and extracts from lavender were also evaluated for their antimicrobial properties by determining the minimum inhibitory concentration (MIC) by the broth microdilution method. Generally, Gram-positive bacteria and Candida spp. were more sensitive to all distilled fractions and extracts than Escherichia coli (Gram-negative bacteria).

This study investigated the impact of subcritical water extraction parameters on the polyphenols and flavonoids content in extracts made of the bark of walnut (Juglans regia L.), as well as antioxidant activity measured using the DPPH and FRAP methods. The total polyphenols (TPC) and flavonoid (TFC) were determined using the spectrophotometric (UV-Vis) method. The response surface methodology (RSM) was employed to optimize the yield of bioactive compounds. On the basis of developed model, the highest polyphenols (192.2 mg (GAE)/100 g (dry mass)) (GAE—gallic acid equivalent), flavonoids (88.3 mg(QE)/100 g (dry mass)) (QE—quercetin equivalent) contents and antioxidant activity (21.3 × 10⁻⁶ MTE/1 g (dry mass)) (TE-Trolox equivalent) were obtained under the following extraction conditions: temperature 131.6 °C, raw material fraction size 0.9 mm and process time 10 min. The greatest impact on the extraction yield was observed in the case of the temperature, whereas the raw material fraction size and the process time had a secondary impact. Obtained results indicate that a smaller particle size and a shorter time may improve the process; however, a reduction in particle size can be challenging for a pressure cell filtration system and consequently increase the cost of the raw material pretreatment process. With the reduction in the process time, a lower cost of extract production can be achieved. This study confirmed the importance of a proper selection of extraction parameters to obtain the demanded extract composition.

The Box–Behnken experimental design was used to investigate the effect of subcritical water extraction parameters such as temperature, process duration, and extractor shape on the extract composition and antioxidant activity of Norway maple (Acer platanoides L.) bark extracts. Spectrophotometric (UV-Vis) techniques were employed to evaluate the total polyphenols (TPC) and flavonoids (TFC). The DPPH radical scavenging method was used to evaluate the antioxidant activity of the extracts. The yield of the process was evaluated through the utilization of response surface methodology (RSM). The total polyphenol and flavonoid contents, together with antioxidant activity, are highly dependent on water temperature. The influence of changes in the process duration and the shape of the pressure cell was not observed. A temperature increase from 110 °C to 170 °C caused a 8.9-fold increase in the polyphenol content, 7.2-fold increase in the flavonoid content, and 12.6-fold increase in the antioxidant activity. The highest values for polyphenols, flavonoids, and antioxidant activity occurred at a temperature of 170 °C, which is the upper limit of the temperature variability range for these studies. This study demonstrates the importance of the appropriate selection of extraction parameters in order to obtain the desired chemical composition of the extract.

Zaprojektowano ekstraktor (40 L) do pozyskiwania polifenoli i flawonoidów z kory dębu (Quercus robur L.) za pomocą wody w warunkach podkrytycznych. Aktywność antyoksydacyjną oceniano metodą zmiatania rodnika 2,2-difenylo-1-pikrylohydrazylowego DPPH. Do analizy ekstraktów wykorzystano spektrofotometrię UV-Vis. Stwierdzono istotną korelację między temperaturą procesu a jakością ekstraktu. Zarówno całkowita zawartość polifenoli i flawonoidów, jak i aktywność antyoksydacyjna wzrastały wraz ze wzrostem temp. odpowiednio do 117,2°C, 116,5°C i 123,2°C. Dalszy wzrost temperatury powodował pogorszenie jakości ekstraktu. Doświadczenia prowadzono wg planu Boksa i Behnkena.