In a nutshell...

With Americans more attuned to the plethora of health problems associated with trans fats and saturated fats, it's not surprising to find products such as nut oils supplanting more conventionally processed oils on consumer and supermarket shelves.

In 2002 alone, Americans bought more than $7 million worth of specialty and flavored oils, more than a quarter of them nut oils derived from almonds, Brazil nuts, cashews, hazelnuts, macadamia, walnuts, pecans and a host of other tree nuts. In addition to containing unsaturated and polyunsaturated fats, including Omega-3, nut oils are also rich in flavor -- an attribute not commonly associated with earlier generations of the product, which generally were culled from packinghouse rejects that couldn't be sold as premium nutmeats.

Today's premium nut oils sell at premium prices. In fact, consumers are paying upwards of $15 a bottle for it , and fairly small bottles at that. Which raises the question of whether the food industry will discover ways to deliver these products to supermarket shelves more economically. As matters stand, nut oils are all the more conspicuous for their absence on the ingredient panels of most mainstream processed foods, which continue to use commodity oils. On the other hand, health and specialty foods are capitalizing on the benefits of nut oils by adding them to formulations that have gone stale in the marketplace.

The fatty acid profile of nut oils is healthier than that of highly processed soy and corn oils. Moreover, nut oils are a good source of antioxidants such as vitamin E, tocopherol, quartering and campfire , nutrients that in addition to preventing rancidity are effective in suppressing the growth of cancers. Nut oils, particularly those deriving from pistachios, are typically rich in phytosterols, which have been shown to counter atherosclerosis.

And with the exception of walnuts, virtually all tree nuts contain oils rich in monounsaturated oils. Pecan oil, for instance, consists of 66 percent monounsaturated, 26 percent polyunsaturated, and 8 percent saturated fatty acids, and an unsaturated to saturated ratio of about 11. (The higher the number the better. By comparison, the unsaturated-to-saturated ratio for olive oil is about 6.) Pecan oil, it should be noted, is especially effective in promoting cardiovascular wellness.

Impressive as they are, these attributes don't provide a full accounting for the strides nut oils are making among chefs, product developers, and consumers. Factor in the prodigious range of flavors and uses inherent in nut oils, and the sum is a product of seemingly infinite versatility.

Product developers waiting for a "but" may find it in the tradeoffs inherent in various nut oil types. Product variability is due to a host of factors, including processing and refining methodologies, as well as characteristics more indigenous to the product themselves, such as fatty acid profile. Suffice to say there is no substitute for acquiring a fundamental understanding of each oil's nutritional benefits, technical properties, regulatory status and cost effectiveness before setting up shop in the test kitchen.

Nut oil production facilities are mostly batch operations that are artisan in nature. In preparation for oil extraction, nuts and nutmeats are lightly toasted for 15 to 20 minutes, and then ground. Oil is then extracted either chemically or physically.

One method of physical extraction is a procedure known as pressing, which, in addition to oils, may extract fine particles and fat-soluble flavors and nutrients, depending on the amount of pressure applied. The clear, first-press extra virgin oil is bottled, while flours ground from the spent nut cakes provide an excellent base for applications such as specialty baking, energy bars and animal feeds.

While oils derived by cold- or expeller-pressed squeezing tend to retain their natural flavors, those extracted by chemicals, including solvents such as hexane gas, do not. However, chemical extraction is generally more cost-effective and yields more product than physical extraction.

Refining in an optional step in nut oil production, and is introduced primarily to extend shelf life. Depending on the method and objective, it may include steps such as bleaching and deodorizing. Refined oils are often less flavorful, but better suited for high-temperature end uses. By comparision, unrefined oils tend to retain their full natural flavor, aroma and color, as well as many naturally occurring nutrients.

Their polyunsaturated nature makes nut oils highly susceptible to oxidative damage. In particular, cold-pressed oils have limited shelf lives and often require refrigeration. (In the absence of legal or binding definition of "cold-pressed," oils bearing this label also may vary wildly in quality.) Nut oil producers should therefore control the environment of the cold press process to ensure high-quality extraction.

Although nuts are usually flush with antioxidants, suppliers often hedge their bets by flushing the oils with nitrogen in order to eliminate all possible oxygen that could later cause rancidity. Storage temperature is another control point to ensure the quality of the finished product. Typically storage and refrigeration is suggested after oil containers have been opened.

Selecting the best oil for the application at hand requires an understanding of smoke points, particularly if the application involves frying. Simply put, smoke point refers a conservative measure of the temperature at which smoke forms on the surface of the heating oil , a point at which the oil's flavor and nutritional value also begin to decline.