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Dingsheng Machine provides a complete set of corn oil processing solutions and corn germ oil extraction plant

Date:Aug 30th, 2022
Corn oil is extracted from the germ component of corn and this germ is rich in oil and nutrients. The oil which directed comes out of the germ needs to be refined before it can be used for cooking and other purposes. Also known as maize oil, this oil has many health benefits and nutritional facts.

The corn germ is the necessary part of the corn grain to make corn oil and it can also be used in feed formulations. Usually the corn/maize germ is around 8% percentage in the total corn grain, and the corn/maize germ’s oil content is approx. 50%. The corn crops are abounded in the American countries and China is also the big country to plant corn.

The corn germ is dried in a kiln, and the oil is extracted by either a hydraulic or a screw press; the pressed cake is further treated by washing it with a solvent, ordinarily hexane, and the dissolved oil is recovered by evaporating the solvent.

Almost all corn oil is expeller-pressed, then solvent-extracted using hexane or 2-methylpentane (isohexane). The solvent is evaporated from the corn oil, recovered, and re-used. After extraction, the corn oil is then refined by degumming and/or alkali treatment, both of which remove phosphatides. Alkali treatment also neutralizes free fatty acids and removes color (bleaching). Final steps in refining include winterization (the removal of waxes), and deodorization by steam distillation of the oil at 232–260 °C (450–500 °F) under a high vacuum.

Broadly speaking, corn processing is broken up into wet milling and dry milling.

Processing Corn by Wet Milling
Wet milling is primarily used to make food ingredients: sweeteners, starch, corn oil, and so on. (Ethanol can be produced this way, but it’s less common; only about 10 percent of U.S. ethanol production starts with wet milling.)

This process is called “wet milling” because the corn is pre-soaked to soften the kernel and begin separating it into its constituent parts. It’s then fed through a series of mills and centrifuges. These separate the germ, starch, fiber, and gluten proteins. These are then separately processed to create various food additives and other products:

The fiber is pressed and dried to become animal feed
Some of the starch becomes cornstarch for baking, or is refined into sugar
Enzymes and yeast are added to a different portion of the starches to begin the fermentation and distillation processes needed to make ethanol
Solvents are used to extract corn oil from the germ… and so on

The corn oil that comes out of the wet-milling process is primarily intended for human consumption, and is held to those standards. It’s often called “crude corn oil” (CCO).
Wet milling is a very versatile process—it can be tuned to produce many different co-products in differing ratios. But it is also capital intensive, and relatively slow.

Processing Corn Dry Milling
Dry milling provides the bulk of U.S. ethanol, in addition to animal feed, and some corn oil. This corn oil—used to supplement feed, or as the basis of biodiesel—is often called “distiller’s corn oil” (DCO), or sometimes “technical corn oil” (TCO).

In contrast to wet milling, dry milling starts with grinding the entire corn grain to a fine flour. This is then mixed with water and other ingredients to break it up into starches and simple sugars. Those are fermented to create ethanol, which is then purified via distillation and dehydration. The remaining “distillers grains” are spun down through a series of centrifuges to extract corn oil, and the remaining stillage is mixed with any nutrient-rich wastewater from the earlier steps, then dried to become animal feed (called “dry distillers grain and solubles” or “DDGS”).

Dry milling is a more limited process—it only has a few possible products, primarily animal feed, and ethanol. That said, it is also extremely efficient, pumping out large volumes to feed high demand.

How Is Corn Oil Extracted Differently in Different Plants?
Wet milling—as primarily a food production process—relies on a traditional food-production friendly solvent-based method of extracting corn oil, which usually relies on hexane. Hexane is extremely effective in this role (capturing 90 percent of the corn oil), and relatively easy to remove from the resulting extract, leaving pure corn oil behind. That’s good news if you’re looking to make food-grade oil. While a solvent-based extraction is very consistent, it’s also a slow and expensive process.

Dry-grind plants take a different approach, largely relying on two-phase centrifuges. This is fast and inexpensive—but the yields can seem to vary quite unpredictably. That’s because this process is newer—something ethanol producers really only started reliable pursuing over the last dozen or so years—and subject to a large number of contributing factors that (everything from daily variations in stillage to centrifuge speed to ambient temperature).

Dingsheng Machine provides a complete set of corn oil processing solutions, and designs a suitable corn oil production process according to your output, budget and refined oil requirements. If you are interested in our corn oil extraction equipment, please contact us, we reply you within 24 hours.