Optimization of Green Extraction of Oil from Black Chia Seed Using Supercritical CO2 and Study of Its In-vitro Antioxidant Characteristics

Abstract

Chia (Salvia hispanica L.) is an emerging oilseed crop renowned for its rich nutritional profile and diverse health-promoting properties. Black chia seed oil (BCO) is particularly valued for its high content of omega-3 fatty acids and bioactive compounds, making it a promising functional ingredient. Supercritical fluid extraction (SFE) using liquid CO₂ is preferred over conventional extraction methods, as it preserves thermolabile omega-3 fatty acids and bioactive compounds due to SFE’s controlled conditions. Therefore, optimizing the SFE process for BCO is essential to maximize yield and maintain oil quality. The extraction process was optimized using RSM with a specific focus on variables such as oil yield (%), iodine value (gI2/100g), and total phenolic content (TPC) (mg GAE/100g), having extraction independent variables: extraction pressure (X1), extraction time (X2), and CO2 flow rate (X3). A backpropagation-trained ANN has been utilized for optimal configuration prediction of each RSM response. Data analysis reported extraction pressure and CO2 flow rate as key factors. Optimal conditions were: 400 bar pressure, 3.24 h extraction time, and 18.24 g/min CO2 flow rate. These parameters showed a 28.96 % oil yield, an iodine value of 213.78 g I2/100g, and a TPC value of 3.563 mg GAE/100g. The oil sample obtained with optimized extraction conditions was further characterized for in vitro antioxidant activities based on DPPH radical scavenging assay (64.91%), ferric reducing antioxidant power (FRAP) assay (411.78 µgAAE/g), and other assays collectively showed the potent antioxidant properties of black chia seed oil, suggesting its potential health benefits in reducing oxidative stress and enhancing overall well-being. The substantial presence of polyunsaturated fatty acids (PUFAs) and antioxidant content in black chia seed oil underscores its potential as a valuable natural resource suitable for various applications in food, cosmetics, and pharmaceuticals.