Supercritical Extraction Technology of Obtaining Polyunsaturated Acids from Starfish (Lysastrosoma anthosticta Fisher, 1922)

Introduction. Starfish (Asteroidea) are marine echinoderms with more than 160 species. Starfish are a valuable source of protein and fats. The present research featured the chemical composition of starfish, which can be used as a commercial source of lipids. Study objects and methods. The study defined the optimal parameters for extracting the lipid fraction of Lysastrosoma anthosticta with supercritical carbon dioxide, as well as the qualitative composition of the obtained extracts. Results and discussion. The yield of fatty acids obtained with supercritical carbon dioxide co-solvent was 1.8 times higher than that obtained with standard extraction according to the Folch method. The content of impurities was lower than in the samples with chloroform-methanol system. The polyunsaturated fatty acids isolated from L. anthosticta mainly belonged to ω-3 (18.0%), ω-6 (11.7%), ω-7 (21.2%), ω-9 (10.1%), and ω-11 (6.5%). The rest was saturated fatty acids, mainly palmitic (14%) and myristic (6%). The qualitative composition of the lipid fraction did not depend significantly from the isolation method. However, the supercritical extraction increased the product yield, extraction rate, and the quality of the extraction residue. Supercritical carbon dioxide left a dry residue, which had no typical smell and was brittle enough for grinding. Such residue can presumably be used to produce protein concentrate. Conclusion. Supercritical extraction with chloroform can be recommended to isolate fatty acids from marine organisms at 60°C and 400 bar.

Efficacy of Water-Soluble Pearl Powder Components Extracted by a CO2 Supercritical Extraction System in Promoting Wound Healing

Pearl powder is a biologically active substance that is widely used in traditional medicine, skin repair and maintenance. The traditional industrial extraction processes of pearl powder are mainly based on water, acid or enzyme extraction methods, all of which have their own drawbacks. In this study, we propose a new extraction process for these active ingredients, specifically, water-soluble components of pearl powder extracted by a CO2 supercritical extraction system (SFE), followed by the extraction efficiency evaluation. A wound-healing activity was evaluated in vitro and in vivo. This demonstrated that the supercritical extraction technique showed high efficiency as measured by the total protein percentage. The extracts exhibited cell proliferation and migration-promoting activity, in addition to improving collagen formation and healing efficiency in vivo. In brief, this study proposes a novel extraction process for pearl powder, and the extracts were also explored for wound-healing bioactivity, demonstrating the potential in wound healing.

Activated Bio-Carbons Prepared from the Residue of Supercritical Extraction of Raw Plants and Their Application for Removal of Nitrogen Dioxide and Hydrogen Sulfide from the Gas Phase

The waste materials left after supercritical extraction of hop cones and marigold flowers were tested as precursors of activated bio-carbons. Adsorbents were produced by means of the physical (also called thermal) activation method using CO2 as the gasifying agent. All the activated bio-carbons were tested for the removal of NO2 and H2S from the gas phase under dry and wet conditions. The effects of the type of precursor and the activation procedure on the porous structure development, the acid-base properties of the surface, as well as the sorption capacities of the materials produced were also checked. The final products were bio-carbons of medium developed surface area with a basic surface nature, characterized by their high effectiveness in removal of gas pollutants of acidic character, especially nitrogen dioxide (sorption capacities in the range from 12.5 to 102.6 mg/g). It was proved that the toxic gas removal efficiency depends considerably on the sorption conditions and the activation procedure. All materials showed greater effectiveness in gas removal when the process of adsorption was carried out in the presence of steam.

APPLICATION OF SUPERCRITICAL EXTRACTION FOR ISOLATION OF CHEMICAL COMPOUNDS

This paper provides a review of the scientific literature on the study of the supercritical extraction process. The use of substances in a supercritical state as an extractant is the basis of the supercritical extraction process. In a supercritical fluid, there is a high intensity of mass transfer, which allows the supercritical fluid to easily penetrate into the raw material and efficiently extract the target components. Carbon dioxide is of particular interest, since its use as an extractant in the process of supercritical extraction meets the basic principles of «green chemistry». The paper presents the mechanisms of mass transfer of target components from plant raw materials that arise during the process of supercritical extraction using carbon dioxide. The kinetics of the supercritical extraction process is considered. During the process, three main periods are distinguished: a period of a constant extraction rate, a period of a falling extraction rate, and a period of a low extraction rate. The influence of temperature and pressure, the influence of water in the raw material on the yield of target components in the process of supercritical extraction is shown. Supercritical extraction requires special high-pressure equipment. The paper presents the main technological solutions for the implementation of the process. A comparison of the process of supercritical extraction with extraction in the Soxhlet apparatus is carried out. The supercritical extraction process makes it possible to obtain an extract of high purity, which is promising for the production of biologically active medicinal components and the separation of impurities from difficult-to-separate mixtures. Examples of the application of supercritical extraction in industry are given. In addition, the paper presents studies on the extraction of aralosides from Aralia mandshurica plant raw materials using the supercritical extraction process. Supercritical extraction is considered as a safe and more efficient way to extract target components from plant materials.