Enhancing mechanism of extrusion pretreatment on bioconversion of distiller’s grains into microbial protein feed

Abstract

The production of microbial protein feed has emerged as a promising way to convert distiller’s grains (DGs) into high-value utilization products, while the fermentation efficiency is limited by their large amount of difficultly degraded lignocelluloses. In this work, extrusion pretreatment was employed for DGs to facilitate the bioconversion into microbial protein feed. Results indicated that extrusion pretreatment led to the significantly increased crude protein and true protein of fermentation products (EDGF), which were 34.4 % and 34.2 % higher than those before fermentation. Glucose production during fermentation showed a good correlation with the change trend of cellulase activity, exhibiting a great potential for degradation. It could be also found sufficient evidences from the highly distinct morphological, thermogravimetric and chemical group characteristics. Eventually, amino acids in proteins of EDGF were generally higher than those of Control, especially for most essential amino acids. The application of extrusion pretreatment provided a potential solution for efficient bioconversion of DGs into microbial protein feed.