Green solvent extraction of health boosting phenolics from pigeon pea husk

The optimization of phenolic compound extraction from pigeon pea (Cajanus cajan L.) husk was explored by manipulating three key process variables: aqueous ethanol concentration (20-60% v/v), extraction temperature (30-60 °C), and extraction time (2-6 h). Utilizing a Box-Behnken design under Response Surface Methodology (RSM), we meticulously optimized these variables to maximize extract yield, total phenolic content, and DPPH radical scavenging activity. The ideal extraction conditions determined via desirability function analysis were found to be 41.83% (v/v) ethanol concentration, 59.36 °C extraction temperature, and 6 h extraction time. These parameters yielded an impressive 9.67 ± 0.02% extract yield, 47.99 ± 0.60 mg GAE/g total phenolic content, and 51.24 ± 0.43% DPPH radical scavenging activity, closely aligning with predicted values. LC-MS (ESI-Q-TOF) metabolite profiling of the optimized extract revealed a rich presence of flavonoids, alkaloids, terpenoids, lignans, phenols, xanthones, and glycosides. This study underscores the valorisation potential of pigeon pea husk-a typically discarded by-product-for sustainable extraction of valuable phenolic compounds under optimal conditions.