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item Johnston, David

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2005
Publication Date: 7/20/2005
Citation: Johnston, D., Singh, V. Enzymatic milling product yield comparison with reduced levels of bromelain and varying levels of sulfur dioxide. 2005. Cereal Chemistry,V.82(5)p.523-527.

Interpretive Summary: Corn wet milling is the industry process used to 'refine' corn into a series of food and feed products, including corn oil, corn starch, corn gluten and corn gluten feed. Enzymatic milling (E-Milling) is a process that could potentially eliminate or reduce the use of sulfur dioxide, a hazardous processing chemical, currently used in all commercial corn wet milling facilities. E-Milling uses a modified process incorporating a short water soaking step for hydration of whole corn kernels, a coarse kernel grinding step followed by the enzyme treatment prior to physical separation methods. The E-Milling process does not require sulfur dioxide for processing; however, it will require the use of an antimicrobial agent for commercial use to replace the antimicrobial effects of sulfur dioxide. Low levels of sulfur dioxide are being proposed in this work as a method of controlling microbial growth during the E-Milling process. The work presented in this manuscript is designed to determine the effects on the wet milling product yields in the presence of low levels of sulfur dioxide during the milling procedure. The results show that the use of E-Milling with low levels of sulfur dioxide could be an effective method for controlling microbial growth while maintaining the time and yield benefits of the E-Milling process

Technical Abstract: Enzymatic Milling (E-Milling) is a process that could potentially replace the sulfur dioxide procedure currently used in all commercial wet milling facilities. E-Milling incorporates the use of a short water soaking step (6 h or less), a coarse grind and the use of a protease to release the starch granules from the corn endosperm. E-Milling does not require sulfur dioxide to obtain starch yields equivalent to conventional wet milling; however, the antimicrobial effects of sulfur dioxide are not duplicated by the enzymatic process. The use of low levels of sulfur dioxide (sufficient for antimicrobial activity) is being proposed as an easily implemented means of microbial control during E-Milling. In order to assess the effectiveness of E-Milling under these conditions, fraction yields for milling experiments adding sulfur dioxide with and without added enzyme were compared to fraction yields from conventional 24 h steeping with SO2 and lactic acid. The results show significant differences in starch, fiber, total gluten and insoluble gluten recoveries between samples milled with SO2 and enzyme compared to those at the same SO2 level without enzyme addition. No significant differences were observed for soakwater or germ yields regardless of the SO2 level used. The yield benefits from adding both enzyme and SO2 are clearly shown over the addition of each individually.