Selection of Conditions of Ultrasound-Assisted, Three-Step Extraction of Ellagitannins from Selected Berry Fruit of the Rosaceae Family Using the Response Surface Methodology

Abstract

AbstractThe study examined the influence of the method of grinding the fruit—homogenisation and grinding using a cryogenic mill—on the extraction efficiency of the ellagitannins (ETs). Two methods of extraction support were compared: sonication and shaking. In the second stage, selection of the extraction with the best conditions was carried out using the response surface methodology (RSM). Ellagitannins were extracted in different variants of acetone concentration (40, 60, and 80%), duration of sonication (5, 10, and 15 min), and temperature (20, 35, and 50 °C). The extracts obtained were subjected to quantitative analysis by high-performance liquid chromatography with a diode-array detector (HPLC–DAD) and identification using a mass spectrometer. Grinding is an important stage in the extraction of ellagitannins from berries. Extracts from fruit shredded with a cryogenic mill were characterised by an average of 20% lower content of ellagitannins than extracts from homogenised fruit. Studies using RSM showed that the most important factor affecting the amount of extracted ellagitannins from all tested fruits is the concentration of acetone. The highest ETs concentration was obtained using 80% acetone solution (in the tested range 40–80%). In the case of raspberries, strawberries, and wild strawberries, under the conditions used, the temperature and duration of sonication did not significantly affect the extraction efficiency. An interaction between extraction time and solvent concentration was observed for blackberries, indicating optimal conditions for this fruit as 15 min and an acetone concentration of 80%, respectively.