Rapeseed is the oil crop for cool climates: it tolerates light frost, yields 1,000-2,000 lb of seed per acre at 40-44% oil, and gives about 200-616 lb of pressed oil an acre at 50-70% recovery. Only canola, the low-erucic-acid variety, is safe to eat in quantity; oil from traditional rapeseed should go to lamps, soap and lubricant.
Part of Oil Pressing at Scale
Rapeseed and canola as the cold-climate oil crop: sowing, yield, the erucic acid and glucosinolate cautions, and what to do with the oil and the meal.
Cool Climates Favour Rapeseed Over Sunflower
The carrier lists rapeseed for cool temperate climates and notes that it tolerates light frost. It is sown in early spring, or in late summer for winter rapeseed that overwinters, and the seed is tiny and broadcast. Where the season is too short or cool for a good sunflower crop, rapeseed is the practical alternative, and a village may grow both.
Yield After The Press
The carrier gives 1,000-2,000 lb of seed per acre at 40-44% oil, or 400-880 lb of oil (50-110 gallons) in the seed. Check and apply the press:
- In the seed: 1,000 x 0.40 = 400 lb and 2,000 x 0.44 = 880 lb. At 7.68 lb per US gallon that is 52 and 115 gallons, so the carrier’s 50-110 is the same order.
- Pressed at 50-70%: 1,000 x 0.40 x 0.50 = 200 lb and 2,000 x 0.44 x 0.70 = 616 lb, which is 200 / 7.68 = 26 and 616 / 7.68 = 80 gallons.
Know Which Rapeseed You Have
Traditional rapeseed varieties contain erucic acid, mildly toxic in large amounts. Canola is the bred low-erucic variety. If only the traditional type is available, the carrier’s advice is to use its oil primarily for industrial purposes (lamp oil, soap, lubricant) and limit dietary use. Do not assume seed is canola because it is called rapeseed; if you cannot tell, treat it as traditional. The press cake contains glucosinolates; the carrier lists it as cattle feed and says to limit it for poultry (Meal and Cake Utilization).
What You Need
- Seed of known type, canola for food
- Fine screens, because the seed is tiny and cleans and presses differently from sunflower
- A press (Screw Press Design)
Method: From Sowing To Oil
Step 1: Sow in early spring or late summer. Broadcast the tiny seed thinly.
Step 2: Harvest when the pods ripen and dry, and dry the cut crop thoroughly before threshing.
Step 3: Clean with fine screens and dry to the pressing moisture (Seed Cleaning and Drying).
Step 4: Press as for other oilseeds, warming the crushed seed within the corpus limit (Crushing and Heating).
Step 5: Label the oil. Mark every jar canola (food) or rapeseed (industrial).
Worked Example: Acreage For A Barrel
To press 384 lb of oil (50 US gallons) from canola at 42% oil and 60% recovery needs 384 / (0.42 x 0.60) = 1,524 lb of seed; at 1,500 lb per acre that is 1,524 / 1,500 = 1.0 acre.
Common Mistakes
- Cooking with unlabeled rapeseed oil. Keep food and industrial jars distinct.
- Feeding the cake like sunflower meal. Limit it for poultry.
- Sowing too thick. The tiny seed needs very light broadcasting.
Erucic acid and combustible dust
Large dietary amounts of traditional rapeseed oil are mildly toxic; the carrier limits it to industrial use. Seed dust is combustible: sweep it, keep flame out and never test for dust with a flame.
What’s Next
- Learn next: Olive and Nut Oils - the warm-climate alternatives
- Combine with: Meal and Cake Utilization - feeding the cake safely