High-conversion hydrolysates and corn sweetener production in dry-grind corn process:

Background and Objectives: Industrial processing of the US corn is primarily for fuel ethanol, distillers dried grains with solubles (DDGS), and crude oil production, using the dry-grind process. Refining of corn starch for glucose syrup production requires wet-milling process. However, wet-milling process is capital expensive, labor and energy intensive, compared with dry-grind process. The liquefaction and saccharification steps of the corn dry-grind process are similar to those used for processing wet-milled starch into glucose syrup. The objective of this study was to determine the feasibility of adapting the corn dry-grind process for corn syrup production. Findings: In the adapted conventional dry grind with modified refining process, the starch to glucose conversion efficiencies (95.69 ± 0.29%) were similar with that from wet-milled corn starch (95.05 ± 0.88%). High soluble protein content in starch hydrolysate can affect its conversion to syrup. The protein content of hydrolysates from the dry-grind process was 0.4%, which is higher than the maximum concentration (0.3%) specified by the starch refining industry. To reduce the protein content, a thermal treatment was developed to remove soluble protein. Thermal treatment removed the soluble protein to negligible level without affecting the high starch to glucose conversion efficiency (94.61 ± 1.34%). Conclusions: High-purity corn syrup production was achieved in a conventional dry-grind process with a modified refining process. Modified dry-grind process has a comparable starch conversion efficiency with wet-milling process. Significance and novelty: Production of refined corn syrup (starch hydrolysate) from the dry-grind process would be advantageous for expanding the number and value of possible co-products. The potential of refined corn syrup production in dry-grind process was evaluated.