Oilseed Rape

Oilseed Rape

　　Oilseed Rape

　　Oilseed rape belongs to the Brassicaceae family, genus Brassica. It is an annual or biennial herbaceous plant and one of the major oil crops and nectar plants in China. Its stem is cylindrical with many branches. The leaves are alternate. It produces racemes of light yellow flowers. The fruit is a long pod, and the seeds are spherical, coming in colors such as black, yellow, brown, or purplish-red. The thousand-seed weight is generally 2–5 grams. The oil content of the seeds is 35–48%, making it a major cooking oil in southern China. Oilseed rape thrives in warm and moist conditions but is also relatively cold-resistant, with strong adaptability to various soils, though fertile loam is most ideal. The main varieties currently cultivated in China include the Brassica napus type (such as Shengli, Qianyou No. 9, and Qin 2 hybrid oilseed rape), the Brassica rapa type (such as Baiyoucai and Poyang rapeseed), and the Brassica juncea type (such as Zhuyayoucai and Mayou rapeseed). It is generally sown in autumn and harvested in summer, though spring-sown varieties are also planted in northern regions. The seeds can be pressed for oil used for both culinary and industrial purposes, while the oil cake can serve as feed or fertilizer.

　　Rapeseed oil is a semi-drying oil, primarily composed of triglycerides of erucic acid, oleic acid, and linoleic acid. It is used for cooking, lubricants, and more. The fatty acid composition of domestic rapeseed varieties is characterized by having less than a small amount of saturated fatty acids, with over 95% being unsaturated fatty acids. Erucic acid accounts for about half of the total fatty acids on average. Oleic and linoleic acids are easily absorbed by the human body, whereas linolenic acid tends to cause oil rancidity, which is unfavorable for storage. Varieties with high erucic acid content are best suited for industrial use.

　　Rapeseed oil has a wide range of industrial applications. Rapeseed oil with erucic acid content above 45% can enhance the stability of rubber, preventing aging and deformation. In the leather industry, it is used in tanning to improve the softness and toughness of leather. In the wool textile industry, it serves as a chemical agent for bleaching, washing, and dyeing, and can also be used as a raw material in making varnishes, inks, soaps, nylon fibers, and more. It is also an important ingredient in the food industry. With the development of industry, the uses of rapeseed oil will undoubtedly become even more extensive and significant.

　　The rapeseed meal left after oil extraction contains approximately 30–40% crude protein, with amino acid levels close to those of soybeans. It also has about 10% crude fat, 4.6–5.5% nitrogen, 2.5% phosphorus, and 1.4% potassium, making it a high-quality feed and fertilizer. It can also be used as a source for protein extraction. However, since rapeseed meal contains glucosinolates, which can cause livestock poisoning, it must be heat-treated or fermented to destroy its toxicity before being used as animal feed. Currently, it is mainly used as fertilizer.