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Pasting Properties and Surface Characteristics of Starch Obtained from an Enzymatic Corn Wet-Milling Process

¹Assistant professor, Department of Agricultural Engineering, University of Illinois, Urbana, IL 61801. Mailing address: U.S. Department of Agriculture, Eastern Regional Research Center, Agricultural Research Service, 600 E. Mermaid Lane, Wyndmoor, PA 19038. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. Phone: 215-233-6714. Fax: 215-233-6406. E-mail: vsingh@arserrc.gov. ³Research food technologist, U.S. Department of Agriculture, Eastern Regional Research Center, Agricultural Research Service, 600 E. Mermaid Lane, Wyndmoor, PA 19038.

Recently, we reported the development of an enzymatic corn wet-milling process that reduces or eliminates sulfur dioxide requirements during steeping, considerably reduces steep time, and produces starch yields comparable to that of conventional corn wet-milling. The best results so far, using the enzymatic corn wet-milling procedure, were achieved when a particular protease enzyme (bromelain) was used. In this study, pasting properties and surface characteristics of starch obtained from six different enzyme treatments (three glycosidases [β-glucanase, cellulase, and xylanase] and three proteases [pepsin, acid protease, and bromelain]) using the enzymatic corn wet-milling procedure were evaluated and compared with those from starch obtained using the conventional corn wet-milling procedure. Significant effects from enzymatic milling were observed on all the three starch pasting properties (peak, shear thinning, and setback). The setback viscosities of starch from all enzyme treatments were significantly lower compared with those of the control sample, indicating that starch polymers from enzymatic corn wet-milling do not reassociate to the same extent as with the control. Comparison between bromelain treatment and the control sample showed that starch samples obtained from bromelain treatment are very similar to control starch in water-binding capacity, molecular breakdown, and time to swell when cooked in water. Significant effects from enzymatic milling were observed on the surface characteristics of starch granules. The glycosidase treatments, especially the β-glucanase samples, showed holes in the starch granules. No visual differences were observed in starch granules between bromelain and control samples.