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rom steeping to extraction: What really happens in those little-known, mysterious steps of corn wet milling
Wet milling of corn is a complex process that breaks down corn kernels into their component parts, including corn oil, protein, cornstarch and fiber. This process is not only an important part of American manufacturing, but also has indispensable value to the food and animal feed markets. This article will take you deep into these little-known and mysterious steps and explore the various processes involved, from cleaning, soaking, extraction to the final product, gradually demystifying the mystery of corn wet grinding.
History
The corn wet grinding industry has developed in the United States for more than 150 years. The establishment of this process allows corn kernels to be separated into a variety of value-added products. The four main components, such as oil, protein, starch and fiber, are extracted from this process. In 1913, when the related corn refining companies successfully developed, the Corn Products Association was established, symbolizing the maturity and expansion of this industry.
Process Steps
Cleaning
According to USDA standards, Grade 5 corn is typically used for wet milling. Harvested corn must be cleaned before being ground, using a lap detector with a specific screen to remove unwanted particles such as cobs, foreign seeds, metal flakes, leaves and debris. The cleaned corn will be analyzed for composition using a near-infrared spectrometer to ensure the effectiveness of the subsequent process.
Soak
In this step, the corn is hydrated in water to loosen the starch granules from their protein matrix. This process also adds some chemicals, such as sulfur dioxide and lactic acid, which help break down the protein matrix and promote the separation of starch. After about 40 hours of soaking, the liquid is drained and concentrated for subsequent production and application.
Germ recovery
The purpose of this step is to separate the germ from the rest of the corn. In order to prevent oil contamination and not damage the integrity of the germ, slow grinding equipment is usually used for processing, and then the oil is further extracted through water and colloid separation technology.
Fiber recycling
The residue recovered from the hydrocyclone contains fiber, protein and starch, and multi-stage grinding and screening equipment is used to separate these components. The fiber is intercepted by the screen and the resulting corn bran bait becomes part of the animal feed.
Protein recovery
The mixture of protein and starch is dehydrated and then separated using centrifugal force to form different starch and protein streams. This process ensures that large quantities of high-protein feed can be recovered.
Starch processing
After multi-stage cleaning, the starch is dried through a centrifuge, and finally a starch product with extremely high purity is obtained, which can assist in the subsequent production of high fructose corn syrup and other products.
By-product manufacturing
The output of by-products accounts for 34% of the output of wet milling. The fiber separated during processing, concentrated soaking liquid and germ powder are mixed to make corn bran bait to supply the nutritional needs of animals.
Research and the future
Although corn wet grinding technology has been widely used for many years, researchers are still working to find ways to improve efficiency and explore the impact of new technologies on production.
Scientists have found that adding enzymes can shorten the soaking process and increase overall yield. In addition, improved processing techniques can further optimize output.
When we delve into the various applications of corn and its preparation process, it is not only a contribution to the food industry, but also a contribution to sustainable development. In the future, we should think about the science behind these processes and how they affect our lives?
