Oils vs. Extracts

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By Robert L. Wolke
Wednesday, January 18, 2006

I have always used anise oil (not extract) to bake my holiday pizzelles and biscotti, but I'm having a harder time finding it each year. I found anise essence at a cooking store and was told it would be more potent than the oil because it's not diluted. What is the difference among flavoring oils, extracts and essences ?

Anise oil is a pure essential oil, the chemical or chemicals responsible for an herb's distinctive flavor and aroma. (In anise seeds, it's mostly anethole.) Essential oils are so called because they can be thought of as the essence of the aromatic plant. Edible essential oils, including anise, caraway, dill seed, peppermint, rosemary and a host of others, are usually obtained by boiling the seeds, leaves or other plant parts with water and condensing the vapors. Citrus essential oils are simply squeezed out of the rinds.

Extracts, on the other hand, are essential oils dissolved in ethyl alcohol, glycerol or propylene glycol and may also contain water, a sweetening agent or a food color. They are therefore less strongly flavored than the undiluted oil itself. For example, McCormick anise extract is 73 percent alcohol, with water and a small percent of the essential oil.

The "essence" you bought is most likely some kind of extract, so I must be skeptical of the salesperson's statement that it is "not diluted" and more potent than the pure oil.

You can find many sources of anise and other oils by Googling "essential oils" and ignoring any site that uses the word "aromatherapy." We're talking food here.

My daughter has become something of a health nut in the feeding of her family. One of her latest interests is flaxseed oil. Now I know, as a biochemist, that flaxseed oil is rich in polyunsaturated fatty acids. However, as an amateur woodworker, I am familiar with the wood-finishing product raw linseed oil, also made from flax. Are the flaxseed oil sold in health food stores and the linseed oil sold in paint stores the same? If not, what is different?

It's true that flaxseed oil and linseed oil are the very same oil, extracted from the seeds of the flax plant, Linum usitatissimum . But I would not advise your daughter to do her grocery shopping in the hardware store. For one thing, the nuts are very hard to crack.

If the seeds of the flax plant (whose stem fibers are used to make linen textiles) are simply squeezed to express their oil ("cold pressed"), the oil is edible as flaxseed oil. But cold pressing isn't 100 percent efficient, so more drastic measures, such as heating and solvent extraction, are used to get the rest of the oil out. That's the raw linseed oil. Not only is it less pure, but by the time it gets to the hardware store it contains added chemicals to speed drying.

Flaxseed oil is the darling of many "health food" advocates because its fatty acids are about 20 percent monounsaturated and 66 percent polyunsaturated. Most prominent among the latter is alpha-linolenic acid, which in the body can change into an omega-3 fatty acid, and omega-3 fatty acids are believed to protect against heart disease. But according to the American Heart Association, the extent of this change is limited, and further studies are needed before a cause-and-effect relationship can be established between alpha-linolenic acid and heart health.

Because of its high degree of unsaturation, flaxseed oil breaks down at high temperatures and is not suitable for cooking. It is available, however, as a supplement in capsules and other forms.

A good review of flaxseed oil's health profile can be found at the University of Maryland Medical Center's Web site, http://www.umm.edu/altmed/ConsSupplements/FlaxseedOilcs.html .

We recently opened a bottle of extra-virgin olive oil. It was rancid, presumably because of age. There was no expiration date on the bottle. When we called customer service, we were told that according to the coding on the bottle, the oil had passed its "use by" date. They indicated that the shelf life of the oil was 17 to 20 months. What are the chemical reactions that take place in a sealed bottle of olive oil that cause it to go rancid? It seems that this would occur in other oil also, such as walnut, grape seed, etc.

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