Canola oil is one of the most widely consumed edible oils in the world. But the crude oil that comes directly from the screw press or extractor contains phospholipids, free fatty acids, pigments, and odorous compounds – it cannot be consumed directly. To become clear, stable RBD (refined, bleached, deodorized) canola oil that meets international standards, it must pass through a precisely engineered refining line.
On this refining line, one core metric stands above all others: free fatty acid (FFA) content must drop from 1%–3% in crude oil to below 0.1%. This is not only a product quality threshold but also a direct reflection of the refining equipment’s process capability.
This article breaks down the equipment configuration and process parameters for canola oil refining, with a focus on how precise temperature control achieves FFA compliance while keeping trans fatty acids to a minimum.
I. Crude Oil Pre‑treatment: The Bridge from Pressing to Refining
Canola oil production begins in the field. Rapeseed contains 38%–48% oil on a dry matter basis. After harvest, the seed is dried to below 8% moisture and cleaned of mechanical impurities. It then enters a screw oil press for pre‑pressing – the seed is preheated to 70–90°C, and the pressing stage recovers 70%–80% of the oil. The press cake, with a residual oil content of 8%–14%, is then sent to an extractor for hexane extraction, achieving an extraction efficiency of 98%–99% of total oil.
The combined crude oil from pressing and extraction enters the first station of the refining workshop – degumming.
II. Degumming: The First Threshold in Refining
The purpose of degumming is to remove phospholipids (gums) from the crude oil. Canola crude oil has a relatively high phospholipid content. If not thoroughly removed, these gums will carbonize in subsequent high‑temperature stages, darkening the oil, degrading flavour, and even impairing deodorizer performance.
Typical process: Crude oil is heated to 60–70°C in a degumming tank, and phosphoric or citric acid is added to convert non‑hydratable phospholipids into hydratable forms. The coagulated gums are then separated from the clear oil using a disc centrifuge separator. Degumming can remove up to 90% of gums and reduce oil viscosity by approximately 30%, creating more efficient operating conditions for downstream stages.
Core equipment: Degumming tank, acid metering and dosing system, disc centrifuge separator.
Impact on FFA: Degumming has limited direct effect on FFA, but it is decisive for soapstock separation in the subsequent neutralization stage. Incomplete degumming significantly increases neutral oil loss carried away by soapstock.
III. Neutralization: The Key Step That Drops FFA from 3% to Below 0.1%
Neutralization (alkali refining) is the core stage that directly determines FFA compliance in canola oil refining.
Process principle: A sodium hydroxide (caustic soda) solution is added to the degummed oil. The alkali reacts with free fatty acids to form soapstock. The soapstock is separated from the neutral oil by a high‑speed centrifuge separator.
Key process parameters:
- Alkali concentration: Precisely calculated based on crude oil FFA content, typically 12–16 °Be
- Reaction temperature: 85–95°C – too low and the reaction is incomplete; too high and the soapstock hardens, making separation difficult
- pH control: The reaction system pH is maintained around 9.5 to optimize soapstock separation
- Centrifugal separation: Using a disc centrifuge separator with a capacity of 20–50 tonnes per hour
After neutralization, FFA content in the crude oil can be reduced from 1%–3% to below 0.1%, meeting RBD canola oil specifications.
Core equipment: Alkali preparation tank, neutralization reactor (continuous stirred tank or tubular reactor), disc centrifuge separator, washing tank.
Note: Neutralization causes some neutral oil loss, mainly through soapstock entrainment. Soapstock should be acidulated to recover acid oil as a by‑product, reducing overall losses. Studies show that the phytosterol loss rate during neutralization is 7.3%–9.23%, higher than in degumming (0.87%–3.01%) and bleaching (1.18%–2.75%), but lower than in deodorization (8.27%–9.97%). This means neutralization is not only the key stage for FFA removal but also one of the main sources of sterol loss.
IV. Bleaching: Improving Colour and Stability
The neutralized oil still contains pigments such as chlorophyll and carotenoids, as well as residual soaps and trace metal ions. Bleaching uses adsorption to remove these impurities.
Typical process: Under vacuum, the oil is heated to 100–110°C, and activated bleaching earth (0.5%–1.5% by oil weight) is added and mixed for about 30 minutes. Pigments and impurities are adsorbed onto the earth, which is then separated from the oil using a leaf filter.
Core equipment: Bleaching tower (vacuum agitated vessel), bleaching earth metering and dosing system, leaf filter, vacuum system.
Impact on FFA: Bleaching has a minor effect on FFA, but it effectively removes residual soaps and trace metals. If these impurities enter the deodorizer, they can catalyse oil oxidation and trans fatty acid formation.
V. Deodorization: Final FFA Removal and Trans Fatty Acid Control
Deodorization is the final stage of canola oil refining and the key step that determines the finished oil’s flavour and stability.
Process principle: Under high temperature and high vacuum, direct steam (stripping steam) is passed through the oil, carrying away residual free fatty acids, aldehydes, ketones, and other volatile odorous compounds, which are then condensed and recovered.
Key process parameters:
- Temperature: 240–260°C (under vacuum)
- Vacuum: 2–5 mbar (absolute pressure)
- Stripping steam: Direct steam injection, typically 1%–3% of oil weight
- Residence time: Depending on equipment design, typically 30–90 minutes
Trans fatty acid control – the most critical quality variable in the deodorization stage.
A study published in the Journal of the American Oil Chemists’ Society conducted a systematic kinetic study on canola oil deodorization at 204°C to 230°C over 2 to 86 hours. The study found that increasing deodorization time and temperature both led to higher isomerization of linolenic and linoleic acids: after deodorization, trans linoleic acid could rise from <1% to nearly 6% of total fatty acids, while trans linolenic acid could rise from <1% to over 65%. The study also developed a practical kinetic model that allows refineries to predict trans fatty acid levels based on given deodorization conditions and calculate the process conditions needed to meet increasingly stringent consumer requirements.
Another study confirmed the critical nature of deodorization conditions from a different angle: when extreme conditions of 250°C for 5–6 hours were used, trans fatty acid content in low‑erucic acid rapeseed oil exceeded 5% of total fatty acids, while 650 mg/kg of cyclic fatty acid monomers were also formed. Importantly, the study confirmed that degumming, neutralization, and bleaching – the three preceding stages – hardly change the fatty acid composition. The formation of trans fatty acids and cyclic fatty acid monomers is caused entirely by the deodorization stage. In addition, α‑linolenic acid is the main precursor for cyclic fatty acid monomers.
This means: while ensuring FFA compliance, deodorization temperature should be kept as close as possible to the critical point for linolenic acid isomerization, avoiding excessive heating that leads to trans fatty acid exceedance. Modern refining equipment achieves this through:
- High‑vacuum systems: Lower vacuum allows the same FFA stripping effect at lower temperatures
- Multi‑stage deodorizer design: Packed or tray tower structures increase vapour‑liquid contact area and shorten residence time
- Heat recovery systems: Oil‑to‑oil heat exchangers recover heat from deodorized oil, reducing energy consumption
With proper control, geometric isomers (trans fatty acids) in refined canola oil can be kept below 1%, and often below the detection limit of reference analytical methods.
Core equipment: Deodorizer tower (stainless steel construction with packing or trays), steam ejectors (to generate high vacuum), fatty acid trap (to recover fatty acid by‑products), oil‑to‑oil heat exchanger.
VI. RBD Canola Oil Finished Product Specifications
After the four refining stages – degumming, neutralization, bleaching, and deodorization – canola oil meets the following RBD specifications:
| Parameter | Typical Value | Test Method |
|---|---|---|
| Free fatty acids (FFA) | < 0.1% | AOCS Ca 5a-40 |
| Peroxide value (PV) | < 2 meq O₂/kg | AOCS Cd 8b-90 |
| Smoke point | Approx. 230°C | AOCS Cc 9a-48 |
| Trans fatty acids | < 1% (often below detection limit) | AOCS Ce 1h-05 |
| Colour | Light yellow, below Lovibond 2.0R | AOCS Cc 13b-45 |
| Shelf life (sealed packaging) | 12 months | — |
Refined canola oil has a neutral flavour and odour, with a smoke point of about 230°C, making it suitable for industrial frying. Its oxidative stability can be assessed by OSI (Oxidative Stability Index) – standard frying applications require a minimum OSI of 8 hours, while continuous frying requires more than 20 hours. High‑oleic canola varieties can significantly increase OSI values and extend frying life.
VII. The Polish Canola Oil Industry: A B2B Market Worth Watching
Poland is one of the EU’s major rapeseed producers, with annual production of 3–4 million tonnes. In 2023, Poland produced 541,000 tonnes of refined canola oil, holding a significant share of the EU refined canola oil market. Polish canola oil is produced entirely from “double‑low” (00) varieties – low erucic acid (<0.1%) and low glucosinolates (<25 µmol/g) – in compliance with EU regulations.
Poland’s canola oil production involves three segments: crushing plants (daily capacity 500–3,000 tonnes), refineries, and packers. Many producers integrate multiple stages of the value chain. For equipment buyers, the Polish market is characterized by a strong emphasis on process precision and certification compliance.
VIII. Frequently Asked Questions (FAQ)
Q1: How can canola oil FFA be reduced to below 0.1%?
The key lies in the neutralization (alkali refining) stage. At 85–95°C, a precisely metered sodium hydroxide solution is added, causing free fatty acids to react with the alkali to form soapstock, which is then separated from the neutral oil by a high‑speed centrifuge separator. A well‑controlled neutralization stage can reduce FFA from 1%–3% to below 0.1%.
Q2: How does deodorization temperature affect trans fatty acid content?
Deodorization temperature is the main controlling variable for trans fatty acid formation. Studies show that within the 204–230°C range, each increase in temperature significantly raises the isomerization rate of linolenic and linoleic acids. Under extreme conditions of 250°C for 5–6 hours, trans fatty acid content can exceed 5% of total fatty acids. Keeping deodorization temperature near the critical point for linolenic acid isomerization, combined with a high‑vacuum system, is the key to controlling trans fatty acids.
Q3: Which stage causes the greatest sterol loss in canola oil refining?
Neutralization and deodorization cause the greatest sterol losses. Phytosterol loss during neutralization is 7.3%–9.23%, and during deodorization it is 8.27%–9.97%, both higher than in degumming (0.87%–3.01%) and bleaching (1.18%–2.75%). Selecting mild process conditions and optimizing equipment design can help reduce sterol loss.
Q4: What are the key B2B procurement points in the Polish canola oil market?
Polish canola oil producers typically require suppliers to provide a Certificate of Analysis (CoA), Certificate of Origin (CoO), and raw material traceability audit capability. Procurement should focus on certification compliance (EU organic, non‑GMO, Halal, Kosher), packaging formats (bottles, drums, bag‑in‑box, IBC containers, tank trucks), and flexible pricing models.
IX. What KMEC Can Do for You
Whether you are planning a 10 TPD small refining workshop or a 500+ TPD large continuous refinery, KMEC offers complete canola oil refining equipment solutions.
Our product line covers the entire refining process:
- Degumming section: Degumming tank, acid metering and dosing system, disc centrifuge separator
- Neutralization section: Alkali preparation tank, neutralization reactor, disc centrifuge separator, washing tank
- Bleaching section: Bleaching tower (vacuum agitated vessel), leaf filter, vacuum system
- Deodorization section: Deodorizer tower (stainless steel with packing or trays), steam ejectors, fatty acid trap, oil‑to‑oil heat exchanger
KMEC engineers can provide the optimal equipment configuration based on your crude oil quality (FFA content, phospholipid content, colour), capacity targets, and target product grade (RBD or high‑oleic) – from single machines to complete turnkey EPC plants.
Contact KMEC today for a customized canola oil refining equipment solution and quotation!
Data sources: AOCS Official Methods, Journal of the American Oil Chemists’ Society, PLoS ONE, Journal of Agricultural and Food Chemistry, European Commission, USDA Foreign Agricultural Service, and peer‑reviewed research literature.