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Effects of Protease and Urea on a Granular Starch Hydrolyzing Process for Corn Ethanol Production
Author(s) -
Wang Ping,
Johnston David B.,
Rausch Kent D.,
Schmidt Shelly J.,
Tumbleson M. E.,
Singh Vijay
Publication year - 2009
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem-86-3-0319
Subject(s) - chemistry , proteases , protease , urea , starch , food science , grind , ethanol , biochemistry , enzyme , fermentation , chromatography , mechanical engineering , grinding , engineering
The dry grind process using granular starch hydrolyzing enzymes (GSHE) saves energy. The amount of GSHE used is an important factor affecting dry grind process economics. Proteases can weaken protein matrix to aid starch release and may reduce GSHE doses. Two specific proteases, an exoprotease and an endoprotease, were evaluated in the dry grind process using GSHE (GSH process). The effect of protease and urea addition on GSH process was also evaluated. Addition of these proteases resulted in higher ethanol concentrations (mean increase of 0.3–1.8 v/v) and lower distillers' dried grains with solubles (DDGS) yields (mean decrease of 1.3–8.0% db) compared with the control (no protease addition). As protease levels and GSHE increased, ethanol concentrations increased and DDGS yields decreased. Protease addition reduced the required GSHE dose. Final mean ethanol concentrations without urea (15.2% v/v) were higher than with urea (15.0% v/v) in GSH process across all protease treatments.