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Winterization dewaxing refers specifically to a "dry fractionation" process that removes a small amount of wax fat or saturated fat in the fat, so as to achieve the purpose of preventing the fat from becoming turbid during cold storage.

Among them, wax is a kind of lipid combined with a high molecular fatty acid and a monohydric alcohol. It has acyloxy groups and has a weak polarity. Therefore, the solubility in grease is low, and the melting point is high (78~82℃), which cannot be absorbed by the human body and cannot be saponified.

Wax exists in many fats, such as rice bran oil, tea seed oil, peanut oil, sunflower seed oil, walnut oil, safflower seed oil, corn oil, peony seed oil, etc. The content ranges from a few ten thousandths to 0.2%.

The purpose of dewaxing is to ensure the cold storage stability and transparency of refined oil, and also to remove a small amount of saturated fat (usually in the range of 2% to 10%) contained in certain fats and oils. It is generally required to reduce the wax fat content in the oil to 10X10-6th power or less.

Typical peanut oil dewaxing process: After the peanut oil is slowly cooled to 5-10°C, keep it warm for at least 6 hours to crystallize the wax. After the crystallization is stable, the oil is usually raised to about 15°C to reduce the viscosity and facilitate filtration. Sometimes to promote crystallization and filtration, filter aids are usually added to the crystallizer. The amount depends on the wax content, generally in the range of 0.2% to 1%.

The basic process of conventional sunflower oil freezing-filtration dewaxing method includes:

1. Sunflower seed oil cooling and crystallization

It is usually carried out in a cooling room with a room temperature of 0~4 ℃, and the grease is placed in a stirred (10~13r/min) cooling tank, cooling tower or self-flow cooling tank, and indirect cooling with refrigerant (dilute brine or glycol) is used to cool down. To 6~10℃, the time is 48~72 hours. Controlling the cooling rate is conducive to wax crystallization. At the beginning, the average temperature is 2℃/h for about 24 hours, and then 0.5℃/h for about 10-24 hours, the temperature reaches 8~10℃, and the final crystal growth stage is about 8~24 hours, and the total temperature is only 1~3℃.

2. Sunflower seed oil wax fat filtration process

Generally, it is required to be carried out at room temperature 15~18℃. There are several methods such as bag hanging filtration for 10~12 hours, plate and frame filter press and horizontal leaf filter, centrifugal separation, and vacuum suction filtration. Among them, the bag filtration time is long, the output is low, and the oil content in the crude wax is relatively high (40%-45%). The filter press method can reduce the oil content of the wax paste to below 40%. Intermittent continuous production is also the most widely used method on the market. Continuous centrifugal separation or vacuum suction filtration has a large processing capacity but the wax paste contains 40%-55% oil. It is generally suitable for mass production and rice bran oil with high wax content.

Henan Zhongxing Grain and Oil Machinery mainly produces and sells oil equipment such as leaching equipment, oil refining equipment, edible oil production line equipment, peanut oil refining equipment, soybean leaching equipment, rapeseed oil refining equipment, walnut oil refining equipment, rice bran oil refining equipment, and engineering installation.