Content of biologically active substances and antioxidant activity of aqueous-ethanol extracts of cultivated rosehip fruit obtained by ultrasonic extraction

¹ Trakia University, Stara Zagora, Faculty of Technics and Technology, 8600 Yambol, Bulgaria
² University of Food Technologies, 4002 Plovdiv, Bulgaria
³ University of Ruse “Angel Kanchev”, Branch-Razgrad, 7200 Razgrad, Bulgaria.
⁴ University of Ruse “Angel Kanchev”, 7017 Ruse, Bulgaria

^* Corresponding author: inikolova@uni-ruse.bg

Abstract

The aim of the current work is to determine the main biologically active substances and antioxidant activity of aqueous-ethanolic extracts of cultivated rosehip fruit obtained by ultrasonic treatment. The extraction was performed under the following technological parameters: ultrasound frequency 37 kHz, solvents 50 and 70% ethanol, raw material: solvent ratio = 1:20, temperature 20, 40 and 60°C, duration 15, 30 and 60 min. Tannins, ascorbic acid and total phenolic contents were determined in the extracts. The highest tannin content (1.90%) was obtained by extraction with 50% ethanol, temperature 60°C and process duration 60 min. The total phenolic content under the different process conditions is comparable. Higher values of total phenols (45.43 mg GAE g-1) were determined at 50% ethanol solvent, 40°C temperature and 60 min process duration. The highest values of antioxidant activity, by the DPPH method, were reported in extracts with 50% ethanol, temperature 40°C and duration 60 min (422.5 μmol TE/g), and by FRAP method under the same extraction conditions - the value was almost twice lower (231.9 μmol TE).