Advantages of Cold Pressing Technology for Walnut Oil Production

Walnuts are rich in nutrients, containing trace elements such as copper, magnesium, potassium, vitamin B6, folic acid, and vitamin B1. They are known as "longevity fruit" and "imperial nut." In China, walnuts are mainly produced in North China, Northwest China, Southwest China, and East China. The walnuts produced are primarily used as food ingredients, health product ingredients, and for walnut oil processing. Walnut oil is extracted from walnut kernels through pressing or extraction processes. Due to its light taste and rich nutrition, it is favored by consumers.

The processing technology of walnut oil can be divided into pressing and extraction methods. The pressing method can be further divided into cold pressing and hot pressing. The pressing method mainly uses hydraulic oil presses and screw oil presses.

Screw oil presses belong to the hot pressing process. During the pressing process, the dynamic pressing form of the material in the press chamber easily causes the temperature of the press chamber to rise, leading to protein denaturation in the material. However, the walnut oil produced by the hot pressing process has a stronger aroma, darker color, and higher yield. The product contains fewer residues and is easier to preserve.

Hydraulic oil presses belong to the cold pressing process. The static pressing form during the pressing process helps maintain a low temperature, protecting the heat-sensitive nutrients in the oil from being destroyed and preventing protein denaturation. This results in high-quality cold-pressed walnut oil and low-denatured walnut protein, improving the comprehensive utilization of walnuts. Cold-pressed walnut oil has a lower oil yield, lighter color, and fewer impurities, preserving more nutrients, making it suitable for producing high-end specialty oils.

Cold Pressing Process Flow: Walnuts → Shelling → Pressing → Crude Oil Filtration → Crude Oil Refining → Finished Walnut Oil

The crude walnut oil obtained through pressing is refined by removing acid, gum, color, odor, and wax, eliminating impurities and harmful substances, resulting in marketable finished walnut oil.

Using the cold pressing method to produce walnut oil retains the trace nutrients in the oil, achieving high-quality health walnut oil, and produces low-denatured walnut protein, improving the comprehensive utilization of walnuts.

Both processes are commonly used in production. Oil factories can choose different processing methods based on their positioning. Whether using cold pressing or hot pressing, the walnut oil needs to be refined to remove impurities and harmful substances before being tested and qualified as finished oil for market distribution.