Subcritical Water Extraction of Rosa alba L.—Technology and Quality of the Products

The white oil-bearing Rosa alba L. was subjected to green subcritical water extraction. The two factor modeling process revealed that 150 °C and 30 min treatment resulted in the maximum yield of phytochemicals, including essential oils, phenolic compounds, total carbohydrates, proteins, and simple sugars. A quantitative and qualitative analysis of the products was performed. The essential oil contained mainly phenylethyl alcohol, citronellol, geraniol, and hydrocarbons (paraffins). The phenolic substances were represented by phenolic acids (gallic acid: 30.92–113.37 µg/mL; ferulic acid: 44.50–99.96 µg/mL; rosmarinic acid: 25.27–80.47 µg/mL; protocatechuic acid: 13.05–25.48 µg/mL), as well as flavonoids (both quercetin and kaempferol: 8.35–8.56 µg/mL) and their glycosides (15.91–58.08 µg/mL). The monosaccharides were determined to include glucose (3.09–15.29 mg/mL), galacturonic acid (1.02–2.34 mg/mL), galactose (0.18–0.78 mg/mL), rhamnose (0.17–0.48 mg/mL), and xylose (0.07–0.17 mg/mL). The content of total phenols, flavonoids, and antioxidant activity were reported by the DPPH, ABTS, FRAP, and CUPRAC methods. The complex composition and activity of the extracts suggests their application directly as a food supplement or in cosmetic preparations.