A combined mechanistic and empirical models for tailored microwave-assisted extraction of rice bran phenolic

Rice bran is a promising source of functional food due to its high phenolic content. Microwave-assisted extraction (MAE) has become a widely used method for optimizing phenolic extraction from rice bran. However, understanding the phenolic extraction process using the MAE method is challenging due to the system's complexity. Modeling and simulation are powerful tools to provide a better understanding of how the system behaves and can be optimized. This study proposes a novel approach that combines mechanistic and empirical models (gray box) to predict the phenolic content in rice bran extraction using MAE. It involved phenolic extraction using different ethanol concentrations (40%, 60%, 80%), microwave application time (1 min, 2 min, 3 min), and microwave power (90 W, 180 W, 270 W). The results showed a good agreement between experimental and computed extraction yields, as indicated by the reported statistical parameters and gray box model. The optimum conditions were reached at 60% ethanol concentration, 2-min microwave application time, and 180 W microwave power with the phenolic content at 0.534 mg/mL (model) and 0.561 mg/mL or 25.06 mg/g (experiment). Following the study, this combined approach can potentially reduce the time and cost required for optimization studies of phenolic extraction.