The term “rape grain” refers to the small, dark seeds of the plant Brassica napus, a member of the mustard family. Despite the name, it is an oilseed rather than a true cereal grain like wheat or corn; its value lies in its high oil content. This crop has become the third-largest source of vegetable oil globally, establishing itself as a major commodity. The seed is primarily processed to extract oil for various food and industrial applications.
Identifying the Plant and Its Seeds
The plant belongs to the Brassicaceae family, placing it alongside common vegetables like cabbage, broccoli, and mustard. It is an annual or biennial plant that produces striking, bright yellow flowers, which develop into slender, sickle-shaped pods containing the valuable seed.
The seeds are tiny, dark spheres, typically ranging from black to reddish-brown, and are dense with lipids. Each seed contains approximately 40 to 45 percent oil by weight, making it an economically significant crop. The use of the word “grain” is a holdover from historical terminology, but modern classification recognizes it strictly as an oilseed crop.
Transformation into Edible Oil (Canola vs. Rapeseed)
The primary commercial use is oil extraction, typically involving crushing, solvent extraction, and refining. The resulting oil is categorized into two distinct types based on chemical composition, a difference rooted in decades of plant breeding. Traditional, or industrial, rapeseed oil naturally contains high levels of erucic acid, a monounsaturated fatty acid historically linked to potential health issues in animal studies.
Traditional rapeseed oil also contained elevated levels of glucosinolates, which imparted a pungent, bitter taste and limited consumption. To address these limitations, Canadian scientists developed new cultivars through conventional breeding to significantly lower both compounds. The resulting “double-low” variety must contain less than two percent erucic acid and less than 30 micromoles of glucosinolates per gram of oil-free meal.
This new, edible-grade oil was trademarked “Canola,” a contraction of “Canadian oil, low acid,” to distinguish it from high-acid varieties. Today, nearly all rapeseed grown for human consumption globally is this low-erucic acid and low-glucosinolate variety, often marketed as Canola oil. High-erucic acid varieties are still cultivated, but their oil is strictly reserved for non-food industrial uses.
Secondary Uses and Co-Products
Oil extraction yields rapeseed meal, the solid material remaining after the oil is pressed out. This meal is a highly valued feed ingredient in the livestock industry, second only to soybean meal globally. Rapeseed meal typically contains 35 to 40 percent protein, making it an excellent supplement for feeding dairy cattle, beef cattle, pigs, and poultry.
Beyond animal feed, the oil has various industrial applications. It is extensively used as a feedstock for producing biodiesel, a sustainable alternative to petroleum-based diesel fuel. High-erucic acid rapeseed oil is also utilized in manufacturing lubricants, hydraulic fluids, and specialized plastics where its unique fatty acid profile is beneficial.
Global Production and Environmental Role
Oilseed rape is cultivated across temperate regions worldwide, with the largest producers including Canada, the European Union, China, India, and Australia. Its economic importance stems from its high oil yield and utility as a rotational crop in intensive farming systems. The plant plays a valuable role in sustainable agriculture as a “break crop.”
Farmers incorporate it into rotation schedules, often between cereal crops like wheat. Its deep taproot structure helps aerate and improve soil structure. Cultivating the plant also interrupts the life cycles of pests and diseases affecting cereals, reducing the need for chemical interventions and aiding long-term soil health.