The Critical Role of Oilseeds Pretreatment in Edible Oil Production

The first step in oil extraction is the pretreatment of oil materials, followed by the extraction and refining stages. Although the materials have undergone initial selection, some impurities (generally around 1%-6%) may still be present when transported to the oil factory. These impurities are detrimental to oil production and must be removed.

Impurities in oil materials can be classified into three types: inorganic impurities, organic impurities, and oil-containing impurities. Inorganic impurities mainly include dust, sand, stones, tiles, and metals; organic impurities consist of stems, leaves, husks, grasses, hemp ropes, and various grains; oil-containing impurities primarily include grains damaged by pests, unripe grains, and other types of oil-bearing seeds.

Purpose of Cleaning:

Cleaning the materials to remove all these impurities offers the following practical benefits for oil production:

Improved Oil Yield 

Most impurities do not contain oil. If not removed beforehand and allowed to mix with the oil materials during pressing or extraction, they will absorb some of the oil and remain in the meal, reducing the oil yield. Excessive mud and dust in the oil materials reduce the plasticity of the material embryo, make it loose, unable to withstand significant pressure, and cause oil flow blockages, reducing the oil yield. Therefore, removing impurities can increase oil yield.

Improved Quality of Oil and Meal

Dirt, plant stems, husks, and other organic impurities darken crude oil, increase sediment, and raise refining costs. For meals, if impurities are excessive, they reduce the value of the meal, which could otherwise be used as food or as raw materials for chemical products. Some impurities, like tung seeds in rapeseeds or castor seeds in sunflower seeds, produce inedible crude oil and meal, making them unfit for use as food or animal feed. With the rapid development of the food industry, there is a growing demand for improved oil and meal quality, emphasizing the importance of removing impurities.

Reduced Equipment Wear 

Impurities like sand, stones, and metals cause significant wear on machinery, leading to quick part deterioration and shortened lifespans. Hard impurities, such as stones and metals, are especially hazardous to high-speed, high-pressure equipment, potentially causing serious damage. Removing impurities minimizes mechanical wear and extends equipment service life.

Prevention of Production Accidents

Metallic impurities in high-speed, high-pressure equipment (e.g., shelling machines, embryo rollers, and oil presses) can damage the equipment and cause accidents. Long-fiber impurities like hemp ropes and grasses easily entangle the rotating shafts of machinery, affecting efficiency, increasing power consumption, and even blocking equipment inlets and outlets. This can lead to production accidents or equipment malfunctions. Removing these impurities ensures smooth production.

Increased Equipment Processing Capacity

Impurities occupy space within oil materials. The more impurities present, the larger the space they occupy, especially organic impurities like stems and husks. Removing these impurities reduces the equipment’s burden, increasing its processing capacity.

Improved Working Conditions 

Dust in the oil materials can create dusty environments during processing, harming workers' health and causing environmental pollution. In severe cases, dust accumulation may even lead to explosions. Cleaning the materials helps maintain a hygienic environment, ensures workers' health, improves morale, stabilizes production, and enhances product quality.

Conclusion:

Pretreatment is an indispensable step in oil processing. It not only affects the yield and quality of oil but also plays a critical role in production efficiency and equipment maintenance. Scientific and reasonable pretreatment lays a solid foundation for subsequent pressing and refining, ultimately producing high-quality edible oil.