Preparation of Black Soybean (Glycine max (L.) Merr.) Components by Supercritical Carbon Dioxide (SC-CO2) Extraction: A Box–Behnken Process Optimization, Component, and Oxidation Resistance Analysis

Black soybeans have a long history in China, with rich nutrition and efficacy. The extraction of its active ingredients is mostly focused on methods such as ultrasound, microwave, Soxhlet extraction, and distillation. These methods rely heavily on solvents, which are not environmentally friendly and healthy, and limit the development and utilization of their functional compositions. This study utilized supercritical fluid extraction technology to prepare functional components of black soybeans and optimized the supercritical CO₂ fluid extraction process of black soybean components through response surface methodology. The qualitative and quantitative analyses of fatty acids in black soybean extracts were mainly conducted, and the free radical scavenging ability of the extracts was studied. The results showed that the black soybean compositions extracted by supercritical fluid were rich, mainly including unsaturated fatty acids and terpenes and had a certain scavenging ability for DPPH and hydroxyl radicals. This study provides a theoretical reference for the industrial preparation of black soybean extractions and also provides ideas for the preparation of functional compositions of other medicinal and edible homologous substances.