Recovery of fiber in the corn dry-grind ethanol process: A feedstock for valuable coproducts

A new process was developed to recover corn fiber from the mash before ferm entation in dry-grind ethanol production. In this process, corn is soaked i n water (no chemicals) for a short period of time and then degermed using c onventional degermination mills. in the remaining slurry, corn coarse fiber is floated by increasing the density of the slurry and then separated usin g density differences. The fiber recovered is called quick fiber to disting uish it from the conventional wet-milled fiber. This study evaluated the pe rcent of quick fiber recovery for a normal yellow dent and high oil corn hy brid. The quick fiber was analyzed for levels of corn fiber oil, levels of ferulate phytosterol esters (FPE) and other valuable phytosterol components in the oil and compared with conventional wet-milled corn coarse and fine fiber samples. Fiber samples were also analyzed and compared for yields of potentially valuable corn fiber gum (CFG, hemi-cellulose B). Comparisons we re made between the quick fiber samples obtained with and without chemicals in the soakwater. An average quick fiber yield of 6-7% was recovered from the two hybrids and represented 46-60% of the total fiber (fine and coarse) that could be recovered by wet-milling these hybrids. Adding steep chemica ls (SO2 and lactic acid) to the soakwater increased the quick fiber yields, percent of FPE recoveries, and total percent of phytosterol components to levels either comparable to (for the dent corn hybrid) or higher than (for the high oil corn hybrid) those recovered from the total conventional wet-m illed fiber samples. CFG yields in the quick fiber samples were comparable to those from the wet-milled fiber samples. CFG yields in the quick fiber s amples were not significantly affected by the addition of chemicals (SO2 an d lactic acid) to the soakwater.