Integrating functional and techno-economic analyses to optimize black bean protein extraction: a holistic framework for process development

This study aimed to develop aqueous (AEP) and enzyme-assisted extraction processes (EAEP) for black bean proteins using an optimization framework that integrates functionality and industrial-scale profitability. A preliminary screening was performed to identify the best pH (AEP) and food-grade enzyme (EAEP) regarding total protein extractability (TPE), solubility, and in vitro protein digestibility. Techno-economic analyses revealed that the AEP at pH 7 and the EAEP with Alkaline Protease (AP) at pH 9 yielded the lowest overall cost of goods sold/kg of soluble and digestible protein. Experimental designs were performed to further guide the selection of solids-to-liquid ratio (SLR), extraction time, and enzyme concentration (EAEP only) to maximize discounted cash flow rate of return (DCFRR). The optimal conditions for the AEP (pH 7, 1:12 SLR, 15 min, 50 °C) and EAEP (pH 9, 1:12 SLR, 30 min, 0.5% AP, 50 °C) achieved TPEs of 66.2% and 80.8%, respectively, with DCFRRs (30-year project lifetime, $16.50/kg protein selling price) of 12.5% (AEP) and 18.2% (EAEP), demonstrating that despite the additional enzyme cost, the EAEP was more profitable. EAEP proteins exhibited significantly higher solubility (54%) in acidic conditions compared to AEP proteins (33%). However, higher enzyme loadings (0.5% AP) led to decreased emulsifying and foaming properties, especially in neutral conditions. This work offers valuable insights into the interconnected impacts of extraction conditions on protein yields, nutritional properties, and functionality, all while considering economic feasibility. Additionally, it underscores the effectiveness of holistic optimization strategies to develop protein extraction methods that are both efficient and commercially viable.