Eastern Regional Research Center Site Logo
ARS Home About Us Helptop nav spacerContact Us En Espanoltop nav spacer
Printable VersionPrintable Version     E-mail this pageE-mail this page
Agricultural Research Service United States Department of Agriculture
Search
  Advanced Search
 
Programs and Projects
Subjects of Investigation
 

Title: THE USE OF PROTEASES TO REDUCE STEEP TIME AND SO2 EMISSION IN A CORN WET- MILLING PROCESS

Authors
item Johnston, David
item Singh, Vijay - UNIVERSITY OF ILLINOIS

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 15, 2001
Publication Date: April 1, 2001

Interpretive Summary: The processing of corn by wet milling to obtain starch is done by first soaking (steeping) the corn for 24-36 hours in a chemical solution (sulfur dioxide dissolved in water). The corn is then ground and the products separated using physical techniques (screening, centrifuging, washing, etc.). The long processing times due to the soaking step and the quantities of chemicals required make this a costly process having significant environmental concerns. In this study, we develop and demonstrate (at a laboratory scale) an enzymatic process that substantially shortens the corn processing time and decreases and possibly eliminates the need for sulfur dioxide addition.

Technical Abstract: To eliminate the diffusion barriers associated with enzyme addition during conventional steeping, we have developed a two-stage procedure to evaluate the effects of enzyme addition on corn wet-milling. The current study compares the effects of the addition of commercially available enzymes during conventional steeping to their addition in the developed two-stage procedure. Results are presented in terms of yields of fiber, starch, germ and gluten. The results demonstrate that the application of enzymes to the normal steeping step of wet milling is not an effective means of decreasing the steeping time or sulfur dioxide usage. Only when specific enzymes are added to the hydrated ground corn, using the modified two-stage procedure, are enzymes effective in decreasing the steeping time and sulfur dioxide requirements. This approach removes the diffusion barriers and allows the enzymes to interact with the endosperm associated proteins that encapsulat the starch granules. The overall steeping time with the two-step modified procedure will range from 6 to 8 hours, representing a 67-83% reduction over the conventional process. The modified process greatly decreases and possibly eliminates the need for sulfur dioxide addition and gives starch yields and quality equivalent to that from the conventional process. The reduced steep time and sulfur dioxide requirements will have a significant effect on reducing energy consumption and environmental pollution.

   
 
 
Last Modified: 06/19/2013
ARS Home | USDA.gov | Site Map | Policies and Links 
FOIA | Accessibility Statement | Privacy Policy | Nondiscrimination Statement | Information Quality | USA.gov | White House