Enzyme treatments on corn fiber from wet-milling process for increased starch and protein extraction

Complete starch extraction has been a problem in the corn wet-milling, and here enzymes affecting different structures were used to provide a thorough understanding of the contribution of those structures to starch and protein retention for a way to achieve higher extraction rates. The combination of Frontia Fiberwash® (mix of cellulases and xylanases) and Olexa® (protease) led to an increase in starch (4.5 %) and protein (3.0 %) extraction. Enzymes changed secondary structure composition of proteins due to change in concentration of protein sub-fractions. The protein matrix around starch granules, the key factor for starch retention, was weakened with reducing agents/acids or ultrasound, which better separated starch and protein bodies. Chemicals led to 3.3–5.4 % and 0.7–1.7 % increase in starch and protein extraction, respectively, whereas an ultrasound treatment resulted in 2.2 % and 0.6 % increase. Overall, the study showed starch granules and protein bodies can be freed from wet-milled fiber fraction leading to higher extraction rate when the protein matrix is loosened.