1. Graduate research assistant, South Dakota State University, Brookings, SD 57007.
2. Professor, South Dakota State University, Brookings, SD 57007.
3. Corresponding author. Phone: 605-688-5661. Fax: 605-688-6764. E-mail address: muthukum@sdstate.edu
4. Bioprocess Engineer, North Central Agricultural Research Laboratory, USDA, ARS, Brookings, SD 57006. Mention of a trade name, propriety product or specific equipment does not constitute a guarantee or warranty by the United States Department of Agriculture and does not imply approval of a product to the exclusion of others that may be suitable.