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United States Department of Agriculture

Agricultural Research Service

Title: Role of Lactic Acid in Corn Wet-Mill Steeping: the Relationship Between Protein Solubilization and Starch Yield

Authors
item Dailey Jr, Oliver
item Dowd, Michael
item Mayorga, Julio

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: January 31, 2000
Publication Date: N/A

Technical Abstract: As a follow-up to previously reported steeping experiments on a single yellow dent corn hybrid, steeping studies were performed on seven different hybrids at 52 C for 24 h using four solutions [water; 0.50% lactic acid (LA) (w/v); 0.20% sulfur dioxide (S02)(w/v); 0.50% LA/0.20% SO2]. Although there was considerable variation in protein solubilization among hybrids, protein release was higher when LA was included in the steepwater than when it was excluded (both with and without S02). The role of lactic acid in protein solubilization and starch release during corn milling is not well understood. Several groups have reported that starch recoveries are improved when steepwater contains LA. The above results suggest that the improved starch recoveries occur because of direct dissolution of the endosperm protein matrix by LA. To further support this hypothesis, a number of yellow dent corn hybrids were steeped in 0.20% SO2 and 0.50% LA/0.20% SO2 solutions and milled to recover starch by a modified 100-g laboratory corn wet- milling procedure. Based on preliminary data, there is a strong correlation between enhanced protein solubilization and improved starch yield, as facilitated by lactic acid. The exact nature of the relationship and its ramifications will be discussed.

Last Modified: 4/21/2014
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