Leveraging functional and techno-economic analyses to guide the optimization of black bean protein extraction: a holistic framework for process development

While the optimization of protein extraction is often centered around maximizing yields, extraction parameters such as pH, time, solids-to-liquid ratio (SLR), and enzyme use can significantly influence protein functionality and large-scale economic feasibility. This study aimed to develop aqueous (AEP) and enzyme-assisted extraction processes (EAEP) for black bean proteins using an optimization framework considering both functionality and profitability. A preliminary screening was performed to select the best pH (AEP) and best food-grade enzyme (EAEP) regarding total protein extractability (TPE), solubility, and in vitro protein digestibility (IVPD). Techno-economic analyses for each screening condition were performed at an industrial production level (10,000 metric tons of protein/year), revealing that the AEP at pH 7 and the EAEP with Alkaline Protease (AP) at pH 9 yielded the lowest overall cost of goods sold (COGS)/kg soluble protein and COGS/kg digestible protein. Experimental designs were performed to guide the selection of SLR, time, and enzyme loadings (EAEP only) for the AEP (pH 7) and EAEP (AP) to maximize discounted cash flow rate of returns (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, 0.3% AP, 50 °C) achieved TPEs of 66.2% and 81.6%, respectively. The DCFRR at a selling price of $16.50/kg protein was 13.74% for the AEP and 17.7% for the EAEP, demonstrating that despite the additional cost of enzyme, the EAEP was more profitable. The optimized extracts exhibited similar solubility at pH 4 (28−33%) and IVPD (44−45%). The emulsification capacity was similar for both samples (367−443 g oil/g protein), while the foaming capacity of the AEP was significantly higher (92.1%) compared to the EAEP (63.7%) at pH 4. This work offers insights for efficient large-scale extraction, paving the way for profitable plant-based protein extraction methods that generate high-quality, functional ingredients.