Have you ever encountered oil that solidified, displaying a non-uniform appearance with white crystals settling at the bottom of the bottle? This phenomenon, observed in virgin cold-pressed oils, is a quality indicator. During temperature changes, these residues naturally initiate a crystallization process.
Simply store the oil at a mild room temperature and, if necessary, filter it using a paper filter. The non-uniform appearance arises from the varying proportions of saturated and unsaturated fatty acids in vegetable oils. When exposed to cooler temperatures, saturated fatty acids solidify while unsaturated fatty acids remain liquid. This duality can result in an oil being liquid at 20-25°C but solidifying at lower temperatures, presenting as a crystallized portion in the bottle.
Why does an oil sometimes have a non-uniform appearance?
A vegetable oil is a mixture of saturated and unsaturated fatty acids in different proportions. When stored at cooler temperatures, the saturated fatty acids in the oil solidify, while the unsaturated fatty acids remain liquid even when exposed to low temperatures. As a result, the same oil can be liquid at a temperature of 20-25°C but solidify when the temperature drops (for example, in the refrigerator). This is why your oil may appear non-uniform, with a crystallized portion at the bottom of the bottle while the rest remains liquid.
Why are some oils solid?
The consistency of an oil depends on its fatty acid composition. Saturated fatty acids are solid at room temperature (20°C) and melt at temperatures exceeding 30°C. Tropical butters like Shea, Mango, and Cocoa, which are liquid in their countries of origin (Africa, Latin America, Asia), solidify in Europe due to the lower average temperature (20°C).
The solidification of oils increases with higher proportions of saturated fatty acids. Oils from tropical regions (Coconut, Macadamia, Tamanu, Jojoba) solidify due to their significant saturated fatty acid content
Why do some oils solidify in cold temperatures?
To determine whether your oil is prone to solidification in cold temperatures, it is sufficient to know the region of its origin.
- Oils from Tropical Regions:
- Examples: Coconut oil, Macadamia oil, Tamanu oil, Jojoba oil, etc.
- These oils contain a significant proportion of saturated fatty acids that solidify at cool temperatures. They undergo solidification, causing the oil to freeze in the bottle.
- These oils are not sensitive to heat and are less susceptible to oxidation. Refrigeration is generally unnecessary.
2. Oils from Mediterranean Regions:
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- Examples: Argan oil, Avocado oil, Sesame oil, Apricot oil, etc.
- These oils also contain saturated fatty acids and consequently crystallize at cold temperatures or when placed in the refrigerator. Small white beads may appear in the bottle.
- Less prone to oxidation, these oils can be stored outside the refrigerator (in a cupboard, protected from light and heat).
3. Oils from Temperate Regions:
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- Examples: Safflower oil, Borage oil, Evening Primrose oil, Pumpkin Seed oil, Grape Seed oil, etc., or oils from Nordic countries like Sea Buckthorn, Hemp, Rosehip, etc.
- These oils are predominantly composed of unsaturated fatty acids, remaining fluid even when refrigerated.
- However, these oils are more delicate and should be protected from heat.
Does Cold Damage Oils?
Cold preserves the vitality of ingredients, including fruits and vegetables. Therefore, oils can be stored in the fridge. Add vitamin E, an antioxidant, to protect more fragile oils from air radicals that cause degradation (rancidity).
What to do if your oil solidifies?
Solidification merely indicates some fatty acids have solidified, not altering the oil’s composition. To return the oil to a liquid and homogeneous state, place the bottle in warm water to re-dissolve the crystals.
How to store oils?
In general, oils should be stored at an ideal temperature of 7°C and at least below 12°C. Additionally, it is important to keep the oil protected from light in a smoked glass or terracotta bottle.
Oils to be refrigerated:
- Some oils are more sensitive compared to others: flaxseed, evening primrose, and borage. These must be stored in the refrigerator both before and after opening and consumed within 45 days after opening!
- If the taste of these oils becomes bitter and sharp, it indicates oxidation, and the oil should no longer be consumed.
- Walnut, wheat germ, grape seed, hemp, pumpkin, black seed, and hazelnut oils are also better preserved in the refrigerator.
- Canola oil, in general, is a basic oil that should be consumed fresh within a month of purchase. If kept for a longer period, it is preferable to store it directly in the fridge.
Oils with longer shelf life:
- Olive, sesame, macadamia, sunflower, safflower, argan, and coconut oils have a longer shelf life, so it is not necessary to refrigerate them, where they may tend to solidify.
Best sources of Omega-3:
- Flaxseed oil (58%)
- Canola oil (14.5%)
- Walnut oil (12%)
