Successive extraction of key protein and polysaccharide from distillers' grains: Optimization, characterization, and economic analysis

Abstract

Distillers' grains (DGS) are rich in various functional components and have received widespread attention from researchers for their extraction. However, current extraction methods typically isolate only a single component, which leads to low extraction efficiency and high processing costs. This study developed an integrated extraction strategy combining flash extraction with sequential enzymatic hydrolysis to obtain key proteins and polysaccharide components from DGS. Under optimized conditions, the method achieved recoveries of 92.70 %, 78.70 %, and 84.83 % for prolamin, polysaccharide, and gluten, with corresponding purities of 77.53 %, 95.96 %, and 84.81 %. Notably, the flash extraction significantly improved the recovery and purity of prolamin by 57.83 % and 49.54 %, respectively. FTIR spectroscopy comparisons revealed that prolamin exhibited lower solubility (17.19 %) and weaker emulsifying properties (EAI: 43.42 m²/g; ESI: 37.41 min), which were attributed to its high β-sheet content. Conversely, gluten demonstrated higher solubility (52.37 %) and superior emulsifying performance (EAI: 61.23 m²/g; ESI: 47.17 min) due to increased β-turn content. Moreover, the preliminary economic assessment of flash extraction and enzymatic hydrolysis for processing DGS showed a material cost of $952.29 per ton, yielding products with a total market value of $2793.94, indicating a profit margin approximately 2.93 times the material costs, highlighting the potential for industrial-scale implementation in sustainable biorefinery processes. This study successfully achieved the co-extraction of multiple components in DGS and provided a novel approach for the value-added utilization of DGS.