From Engine Rooms to Kitchen Spoons: Why Cold-Pressed Beats Refined Seed Oils

If your oil was cooked, bleached and deodorised before it even reached your pantry, how “fresh” can it be? Most supermarket seed oils (standard rapeseed/canola, soybean, sunflower) are RBD oils—Refined, Bleached and Deodorised—engineered to be pale, odourless and shelf-stable. Convenient? Sure. Delicious and nutrient-rich? Not so much.

Cold-pressed oils are the opposite: pressed, not processed. No solvent washes, no bleaching clays, no 200-plus-degree steam baths. Just the seed, squeezed—so you taste the plant and keep more of its naturally occurring goodness.

Ultra-processed oils 101 (RBD… it’s as fun as it sounds)

The usual ride for commodity seed oils:

• Solvent extraction (often hexane) after cooking seeds to wring out maximum oil.
  
• Degumming & neutralising to strip out gums and free fatty acids.
  
• Bleaching with activated clays/carbon to remove pigments (and, along the way, some antioxidants).
  
• Deodorising—high-temperature steam under vacuum to scrub smells and flavours.
  

End result: a near-colourless, “neutral” oil that behaves the same every day of the year—because much of what made it distinctive has been ironed out.

What refining quietly takes away

• Colour & character: Bleaching removes chlorophylls and carotenoids—the pigments that give oils their golden/green hues and antioxidant bite.
  
• Fragile nutrients: High-heat stages (especially deodorising) can reduce heat-sensitive compounds like some tocopherols (vitamin E).
  
• Process artefacts: Heavy processing can create tiny amounts of trans isomers and refining by-products (e.g., 3-MCPD esters, glycidyl esters). Regulators set limits and the industry works to minimise them—but it’s a reminder that aggressive processing changes food.
  

TL;DR: you gain uniformity and shelf life; you lose aroma, colour, and some of the seed’s native micronutrients.

Plot twist: some of these oils started in the engine room

Before “canola” was bred for the table in Canada in the 1970s, rapeseed oil (its ancestor) had a different day job. It clung to metal in wet environments better than other oils, so it was prized as a lubricant for steam engines and ships, and used for lamps. Only after plant breeders dramatically lowered erucic acid and bitter compounds did “canola” become the edible staple we know today. History doesn’t make canola “bad”; it just shows how far we had to re-engineer a plant oil to make it palatable at scale.

So… why go cold-pressed?

Because cold-pressed is closer to the seed:

• More of the native compounds: Better retention of natural antioxidants and plant sterols; real colour and aroma.
  
• Real flavour: Nutty, green, peppery—whatever the seed grew, you taste.
  
• Fewer industrial steps: No solvent extraction, no bleaching earths, no high-temp deodorising.
  

Use cold-pressed oils where they shine: dressings, dips, drizzling, finishing, and gentle heat. Save blow-torch sears for a separate high-heat workhorse.

Cook smarter: one pan, two oils

• High-heat jobs (sear, deep-fry): choose a stable, high-oleic oil designed for heat.
  
• Everything else: make flavour your friend—cold-pressed hemp seed oil, extra-virgin olive oil, cold-pressed rapeseed (yes, it exists and tastes wildly better than the commodity stuff), walnut or flax for no-heat finishing.
  

Why we rate cold-pressed hemp seed oil

Hemp seed oil brings a clean, nutty flavour and a beautiful green-gold hue. Because it’s cold-pressed, you keep more of what makes it special—fresh aroma and naturally occurring antioxidants—which is exactly why we don’t bleach or deodorise it.

How to use it:

• Whisk into vinaigrettes, drizzle over roast veg and grain bowls, or swirl into soups after cooking.
  
• Store in the fridge (or a cool, dark cupboard) and enjoy within 8–12 weeks of opening.
  
• Skip the deep-fryer—hemp is a finishing hero, not a chip-shop oil.
  

Label hacks: spot the real deal

• If it doesn’t say “cold-pressed”, “virgin” or “extra-virgin”, assume refined.
  
• Choose dark glass, check the press/best-before date, and store cool.
  
• Expect real colour and aroma—neutral ≠ better.
  
• Cold-pressed rapeseed is a thing—and it’s delicious. Don’t confuse it with the standard refined bottle.
  

Bottom line

RBD oils are brilliant at being… invisible. If that’s the brief, they nail it. But if you want flavour, freshness and fewer industrial detours, go cold-pressed—and use the right oil for the right job. Your cooking will taste better, and your pantry will look a lot less like a chemistry set.

Sources (normal links)

• American Oil Chemists’ Society (AOCS) primers on oil refining & deodorisation:
  https://www.aocs.org/resource/oil-refining/
  https://www.aocs.org/resource/deodorization/
  
• Pigments/bleaching & nutrient effects (review):
  https://pmc.ncbi.nlm.nih.gov/articles/PMC8767382/
  
• Process contaminants (3-MCPD esters, glycidyl esters) overview (EFSA and technical summaries):
  https://www.efsa.europa.eu/en/topics/topic/3-mcpd-and-glycidyl-fatty-acid-esters
  

Rapeseed history & canola breeding (industrial uses → edible oil):
https://www.canolacouncil.org/
https://www.canadianfoodfocus.org/
(General background on low-erucic canola and historical uses.)