Techno-economic analysis of amino acids production with subcritical water technology

Abstract

This study conducted a techno-economic assessment of amino acid production from brewers’ spent grains (BSG) using semi-continuous subcritical water hydrolysis. The process was operated at a pressure of 15 MPa, with a water flow rate of 5 mL/min, a solvent-to-feed ratio of 20 g water/g BSG, and at various temperatures (80 °C to 180 °C). The experimental results demonstrated that the amino acid yield of the single subcritical reactor (10.20 mg/g BSG) was higher compared to the two-sequential reactors (4.72 mg/g BSG). The hydrolysate obtained experimentally was composed mainly of tryptophan (215 µg/mL), valine (64 µg/mL), and aspartic acid (123 µg/mL). The economic analysis revealed that the manufacturing cost of amino acids ranged from 33.66 USD/kg to 49.42 USD/kg. The implementation cost of downstream processing represents the most significant fixed capital investment, as complex unit operations are required to isolate and purify amino acids.