"Olive oil can be put into the refrigerator or freezer without harm, which will greatly extend its shelf life. Waxes in the oil may crystallize out into needles or a slurry when the oil is chilled. Warming the oil back to room temperature will re-liquefy it."
oliveoilsource.com
"Fats and oils are made of a combination of three kinds of fatty acids: saturated, monounsaturated, and polyunsaturated. If there are enough saturated fatty acids, the fat is solid at room temperature or colder; heated, it usually melts. If a monounsaturated (single) fatty acid dominates, the fat is a liquid or an oil at room temperature or warmer, but it will partially solidify when it is chilled. When polyunsaturated (two) fatty acids dominate, the fat is a liquid and inclined to stay so even when it is chilled, because it has a more mobile molecular structure.
Refrigeration gradually slows the molecular activity of monounsaturated oils--olive, peanut, avocado, and macadamia--and they will become firm (although not as hard as butter), and turn cloudy or opaque. Returned to room temperature or heated, they quickly liquefy.
If your salad dressing <marinade> is made with a monounsaturated oil and stored for a week or more in the refrigerator, chances are the oil will turn paler in color and get lumpy or solidify; but at room temperature it returns to liquid and is fine to use."
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