Cooking oil -5

PRESSED VS. CHEMICALLY EXTRACTED

      Olive, avocado and walnut oils, for example, are from soft fruit or nuts and need only expeller pressing and centrifuging; they may be labeled “cold pressed.” Hard oilseeds such as soy or canola usually require some pre-treatment such as steam before pressing, but natural extraction methods do not rely on chemical solvents.
      In contrast, common mass-market oils generally are extracted with toxic chemical solvents such as hexane. These oils then undergo harsh treatment to remove the toxic solvent. More chemicals, very high heat and straining are used to deodorize and bleach the oils, rendering them inferior in taste, fragrance, appearance and especially nutritional quality. Food companies prefer to use chemical solvents to get maximum yields compared to mechanical pressings.

Storing oils

      All oils, especially unrefined oils, should be refrigerated after opening to prevent oxidation and rancidity. Natural oils should smell and taste fresh and pleasant. If in doubt, throw it out. Rancid fat isn’t just unpleasant in odor and taste, it’s also unhealthy. Studies indicate that rancid fats may promote cancer and heart disease.
       We suggest keeping a small dispenser of your everyday oil in the pantry for what you’ll use in a week or so and keep the larger bottle refrigerated. Oil that’s firmed up in the refrigerator will liquefy at room temperature in a few minutes. Place the bottle in a container of warm — not hot — water for five minutes. The quality will not be harmed.

Hydrogenated oils
        Avoid products with hydrogenated or trans-fats. Hydrogenated fats are highly refined oils that are hardened artificially in a chemical process so they cannot oxidize. They raise cholesterol and are the main source of dangerous trans-fats. Hydrogenated and trans-fats are found in many shortenings, margarines and processed snack foods that require a long shelf life.
        The National Academy of Sciences has declared trans-fats unsafe in any amount. The Food and Drug Administration has ordered food manufacturers to disclose trans-fat levels on all nutrition labels by 2006.