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Application of Protease and High-Intensity Ultrasound in Corn Starch Isolation from Degermed Corn Flour

¹Department of Food Science, University of Arkansas, Fayetteville, AR 72704. ²Corresponding author. Phone: 479-575-3871. Fax: 479-575-6936. E-mail: yjwang@uark.edu

The conventional corn wet-milling process requires a long steeping time and has environmental and health concerns from the use of SO₂. A recently proposed two-stage enzymatic milling procedure with the first stage of water soaking and coarse grinding of corn and the second stage of incubating with enzymes has been shown to reduce the soaking time and possibly eliminate the need for SO₂ addition. This current work explored the applications of protease and high-intensity ultrasound in the second stage of the two-stage enzymatic milling for corn starch isolation to further shorten the process time without use SO₂. of The starch yield from sonication alone was 55.2–67.8% (starch db) as compared with 53.4% of the water-only control with stirring for 1 hr and 71.1% of the conventional control with SO₂ and lactic acid steeping for 48 hr. Protease digestion alone for 2 hr was not effective (45.8–63.9% yield) in isolating corn starch, but the starch recovery was increased to 61.2–76.1% when protease was combined with sonication. The preferred combination was neutral protease digestion for 2 hr followed by sonication at 75% amplitude for 30 min. The results demonstrated that combinations of high-intensity ultrasound and neutral protease could replace SO₂ and shorten the steeping time in the enzymatic wet-milling process for corn starch isolation.