PRODUCTION OF EXTRACTS FROM VEGETABLE RAW MATERIALS BY CARBON DIOXIDE

Abstract

The unique properties of supercritical carbon dioxide as a solvent are widely used for extraction. In supercritical media, the dissolution of molecules of various chemical nature is possible. The purpose of this investigation was to study the extraction process and obtain extracts from valuable regional plant materials by applying CO2 extraction under pre- and supercritical conditions. The objects of research were: ground seeds of melon, pumpkin and licorice roots, as well as mint leaves, mulberry and jida flowers. For extraction, a laboratory setup was used that allows extraction when the CO2 is supplied by a high-pressure plunger pump in the sub- and supercritical state using a heat pump. The pressure range is 3-15 MPa, temperatures 295–330 K, and the volumetric flow rate above the critical CO2 is 800–900 g. Experiments with ground seeds of melon and pumpkin showed that as a result of 4 sequentially performed extraction cycles on a single load with supercritical CO2 parameters ( 315–330 K; 3–7.5 MPa) the decrease in the mass of melon seeds was 90 g (pumpkins 80 g). During the total extraction time (2.5 hours), 20 kg of CO2 were pumped through the reactor (25 l at 290 K and 6.8 MPa), while the average oil content in the extract was 4 g per 1 kg of CO2 (3.0 g per 1 l of SС-CO2) In experiments with jida flowers, the maximum amount of solid extractable substance (2% by weight of the raw material) was obtained at a temperature in the extractor of 308 K and a pressure of 7.5 MPa. Upon extraction under critical conditions in collection 2, the liquid phase was absent; only a yellow-green paste was released in it. According to the results of experiments with mint leaves, the maximum yield of a greenish liquid was observed at T = 315 K and P = 4 MPa., Mulberry - at T = 306 K and P = 6.0 MPa. The results of the extraction of oils and extracts from ground seeds of melon, pumpkin and licorice roots, as well as mint leaves, mulberries and jida flowers confirm that the maximum yield of the extracted substance is achieved with supercritical CO2 parameters in the extractor (310 K, 7.5 MPa). When liquid CO2 is extracted (300 K and 6-8 MPa), up to 2% of a yellow substance is extracted, which does not differ in appearance from a supercritical extract.