Corn wet-milling
The four main component such as oil, protein, starch, and fiber are the primary product from the corn wet-milling process.
The corn is soaked in this solution to soften the kernel so that the oil in the germ will not contaminate other products and is easy to separate.
The compositional analysis of yellow dent corn carried out at the Center for Crops Utilization Research, Iowa State University, is recorded in the table below.
[citation needed] In this process, the corn is hydrated in order to loosen starch granules from the protein matrix while leaving the germ resilient to milling.
Lactic acid breaks down the endosperm protein matrix and helps in better separation of starch.
SO2 reacts with the disulphide bonds and weakens the matrix, allowing starch granules to separate out cleanly.
The clean corn is steeped in large tanks with water at 125-130˚F containing lactic acid and sulphur dioxide for nearly 40 hours.
The steepwater is then drained using appropriately sized mesh screens and concentrated using multiple effect evaporators.
[4] Use of concentrated steepwater: This extract is protein-rich and can be used as nutrient media for fermentation to produce enzymes or antibodies.
Water is added to the ground material to make a thick slurry of macerated kernels and whole germ.
[citation needed] Germ meal is a good source of amino acids and is a carrier of micro-ingredients in animal food formulations.
The water from each stage is recycled to the previous hydrocyclones to ensure the maximum amount of starch is separated.
The fiber, concentrated steepwater and germ meal are mixed to produce corn gluten feed.
[7] A typical solid yield (on db) data for yellow dent corn is shown in the table below.
[8] The wet-milling process will have five major products: steep water solids, germ, fiber, starch, and gluten.
[9][10] Though corn wet-milling has been used for years to produce food, animal feed, and fuel, researchers continue seeking efficiencies.
[11] Another study, showed that adding cellulase and an enzyme to degrade phytic acid reduces steeping time.
