2002 Annual Report
Research
An Ozone-Aided Corn Steeping Process
Roger Ruan, Professor
William Wilcke, Professor
R. Gary Fulcher, Professor, Food Science and Nutrition
Paul Chen, Senior Research Associate
Xiangyang Lin, Visiting Scholar
Hanwu Lei, Research Assistant
Shaobo Deng, Graduate Student
Funding Source
Colorado Sweet Gold Co.; Minnesota Agricultural Experiment Station; Private
Gifts
Objective
The objective of this project is to develop a clean and environmentally-friendly
ozone-aided steeping (OS) process to replace the current SO2-steeping
(SS) process. In Phase I we will investigate the feasibility of using
ozone in the steeping process and compare the starch yields between OS
and SS processes. If this proves feasible, Phase II will be focused on
optimization of the process.
Project Description
Steeping water normally contains 0.1%-0.2% sulfur dioxide. During the
steeping process, lactic acid, which is believed to help the steeping
process, is produced. The role of sulfur dioxide in the steeping process
is two-fold. First, it prevents the growth of putrefactive microorganisms,
and second, it reacts with disulfide bonds in the endosperm protein matrix
to reduce the molecular weight of the proteins, making them more hydrophilic
and more soluble. However, the role of lactic acid is not clear, although
it has been noted to have a softening effect on the kernel and enhances
starch recovery. Since residual SO2 in starch products jeopardizes the
“organic products” claims, and SO2 pollutes water and air, alternatives
to SO2 must be examined. One of the alternatives is ozone. Ozone, a strong
oxidant and disinfectant, can be used at minimum to control the growth
of putrefactive microorganisms in the steeping system, and probably also
to break down large molecules through oxidation. However, use of ozone
in corn steeping has never been tested.
Results
It was demonstrated in this study that the OAS process was as good as the conventional SS process in terms of starch yield. The study also shows that OAS process can be conducted at a lower temperature (e.g., 20°C) for a shorter time (e.g., 36 h) compared with the conventional SS process, suggesting a significant energy savings and productivity increase. It was found that the timing of ozone application is of great importance to the performance of the OAS process. Two hybrids of corn were studied to validate this ozonation steeping method.