ingredient information
Soybeans Oil Expeller Pressed
First, a little background. Both cold-pressed and expeller oils cost more because their extraction processes are more expensive than those used for other oils. The act of pressing oil -- out of olives, soybeans, corn, safflower, nuts or whatever -- produces friction and therefore heat. Cold-pressed oils are extracted with presses that are kept at room temperature. Expeller oils come from the very first pressing and are generally also extracted at a slightly lower temperature than other oils. This is the method that produces the thick, extra-virgin olive oil that often has a slight greenish tint and a stronger flavor than most oils. But after the first pressing, there's still plenty of oil left. More pressings help extract this oil, which may also be treated with food-grade hexane, a chemical that helps squeeze out even more oil. And yes, further refinement is done with filtering, bleaching and deodorizing "to make the oils more stable and easier to use," notes Tong Wang, assistant professor of food science and human nutrition at Iowa State University. Each step of the way, the oil becomes lighter in color, until it reaches the golden hue and relatively bland taste of that found on most grocery shelves. So do these differences matter nutritionally? "Cold-pressed oil will have more antioxidants," Wang says. (These substances may help reduce the risk of cancer.) But the differences appear slight: A nutritional analysis conducted for the Canola Information Council, a farmers group in Canada, found "little difference nutritionally between cold-pressed, expeller and regular canola oil," notes Dorothy Long, a home economist with the council. As for finding anything unhealthful in more-processed oil, Wang says the likelihood is very small. One concern is formation of trans fatty acids during processing. "If the temperature is too high, it may produce very, very minor quantities of trans fat," Wang says. "But this is below 1 percent." In the end, it's wiser to focus your attention on what kind of oil you're consuming rather than how it's produced. Here's what experts recommend: Choose oils lowest in saturated fat. No need to sweat whether oils are rich in monounsaturated fat (like olive oil) or high in polyunsaturated fat (corn, safflower, soybean oil). Just make sure you choose oil with the least saturated fat, says Alice Lichtenstein, professor of nutrition at U.S. Department of Agriculture's Nutrition Research Center at Tufts University in Boston. Aim for oils rich in omega-3 fatty acids. Important for the heart, the brain and the joints, these fatty acids are often get less attention than omega-6 fatty acids. Canola and flaxseed oil are high in omega-3s. Easy does it. Whatever oil you pour, it's still fat, the most calorie-dense of nutrients. Each gram has nine calories -- more than twice the amount in protein or carbohydrates. That works out to about 120 calories per tablespoon. So go ahead and pour, but in moderation. Go for variety. That's one way to cover the nutritional bases. A few examples: Sesame oil contains phytosterols, which can help lower blood cholesterol. Soybean oil has carotenoids, which are converted in the body to vitamin A. Rice bran oil has the antioxidant oryzanol. Store oil in a cool, dark place. Once a bottle is opened, "the clock is ticking on the oil," because oxygen causes oxidation, notes Fereidoon Shahidi, a food chemist at Memorial University in St. John's, Newfoundland. His advice: Buy small quantities. -- Sally Squires Washington Post