Pressing Rapeseed Oil


When Is the Right Time – and What Really Matters?

Anyone looking to press their own rapeseed oil faces a question that determines both yield and quality: when is the seed truly ready – and what conditions must be met during pressing? This guide gives you practical answers.

1. Harvest Timing: The Most Critical Factor for High-Quality Rapeseed Oil

When is rapeseed ready to harvest?

Rapeseed should be harvested when the moisture content of the seed has dropped to 8–10%. This typically corresponds to the stage when the pods have turned brownish-yellow and a slight rattling sound can be heard when shaking the plant.

  • Pod colour: Brownish-yellow to dark brown
  • Seed colour: Dark brown to black
  • Moisture content: below 10% (use a moisture meter)
  • Typical period: late July to mid-August in Central Europe

What happens if you harvest too early or too late?

Harvesting too early leads to elevated chlorophyll content – the oil turns greenish and bitter. Harvesting too late increases the risk of pod shattering and crop losses, as well as a higher risk of fungal contamination.

2. Seed Preparation: How to Achieve Optimal Pressing Results

Drying and cleaning

Before feeding rapeseed into the press, the seed should be cleaned and dried to a moisture content of no more than 8%. Moist seed leads to reduced yield, blockages in the screw, and increased wear on the press cylinder and nozzle.

  • Cleaning: Remove dirt, straw and foreign matter
  • Storage before pressing: Dry, ventilated, temperature 15–20 °C
  • Target moisture: ideally 6–8 %

Pre-warming the seed

Gently pre-warmed seed (30–40 °C) flows more evenly into the press and improves oil yield.

3. Temperature Management During Pressing – the Key to Quality

What does ‘cold-pressed’ actually mean?

For oils other than olive oil, there are hardly any specific legal EU definitions for “cold-pressed.” This refers to a generally recognized production method without the application of heat (often mechanically below 40 °C), but it is not as strictly controlled as with olive oil.

How to control temperature

Temperature can be regulated via pressing speed, nozzle diameter, and – in advanced machines such as the Oleo P 20 or Oleo P 40 – via integrated temperature control systems.

4. Maximising Yield – Proven Practical Tips

Typical yields with rapeseed

Depending on machine settings and seed quality, 1 kg of rapeseed yields 350–430 ml of oil. The press cake still contains approximately 12–18% residual oil and can be used as high-quality animal feed or fertiliser.

  • Optimal yield: 380–420 ml per kg of seed
  • Residual oil in press cake: 12–18%
  • Pressing speed: slower = more pressure = higher yield (but also higher temperature)

5. Maintenance: What Is Often Overlooked

Check wear parts regularly

The most common problems when pressing rapeseed oil stem from worn screws, damaged press cylinders or clogged nozzles. Regular inspection significantly extends machine life and ensures consistent quality.

  • Screw (press worm): check for material loss and scoring
  • Press cylinder: look for cracks and even wear
  • Nozzle: clean after each pressing batch

Conclusion

Pressing your own rapeseed oil is a rewarding endeavour – provided that harvest timing, drying, temperature and machine maintenance are all on point. With the right knowledge and a reliable oil press, you can produce high-quality, cold-pressed rapeseed oil at a consistent standard.