Thursday, September 27, 2007
All About Cooking Oils
How Is it Made?
People have been extracting vegetable oil from plant materials for thousands of years. The very earliest methods of pressing vegetable matter probably yielded at best 10% of the available oil. More modern methods involving chemical solvent extraction can extract all but 1% to 2% of the oil.
Some cooking oils, including olive, peanut, and some coconut and sunflower oils, are expeller-pressed, meaning that the plant part from which oil is derived is crushed and pressed to produce the oil. The oil is then left crude or refined. Crude oils may have a cloudy appearance and are more flavorful, but they have a shorter shelf life than refined products.
Some manufacturers label their products cold-pressed to indicate that the plant materials were not heated during oil extraction. However, this label term is largely unregulated and cannot always be relied on to mean that the oil was never exposed to high heat.
Most cooking oils are extracted from ground plant material with a chemical solvent. After extraction, the oil is cleaned, refined, and filtered and/or distilled. This process produces a bland, clear oil.
What Happens When You Heat It?
All cooking oils will oxidize and therefore hydrogenate to a small degree if repeatedly heated to a very high temperature, as is done in commercial frying. This means the fats become more saturated and start to contain some trans fat over time. However, it is almost impossible to oxidize fat to this degree in home cooking.
Cooking oils differ in their “smoke point,” or the temperature to which they can be heated before they smoke, discolor, and break down. At the smoke point, the oil not only smokes and begins to emit unpleasant odors, but it also imparts unsavory flavors onto the food. Reaching the smoke point means you are approaching the “flash point,” which is when the oil can erupt into flames.
Cooking oils with a high smoke point can be heated to high temperatures before burning. Knowing a cooking oil’s smoke point gives you some indication of whether it is good for cooking and frying. In general, the best oils for high-temperature cooking methods such as deep-fat frying are safflower, sunflower, peanut, soy, and canola oils.
Storing oils
All cooking oils, whether refined or unrefined, are sensitive to light, heat, and exposure to oxygen (air). Cooking oil that is spoiled (rancid) will have an unpleasant smell and taste. To prevent spoilage, store oils in the refrigerator or in a cool, dark place. Oils may thicken in the refrigerator, but they will return to liquid if left standing at room temperature. Refined oils that are high in monounsaturated fats will keep for up to a year. Cooking oils high in polyunsaturated fats such as soybean, corn, safflower, and canola spoil more quickly: If stored properly, these oils will keep for up to six months. Some manufacturers put “use by” dates on product labels.
Choosing An Oil
For heart health, select cooking oils with the lowest levels of saturated fat and the highest levels of monounsaturated and omega-3 fatty acids. Examples of heart-healthier oils include canola oil, olive oil, flaxseed oil, and walnut oil. If you are looking for an oil to add flavor to your cooked dishes or salad dressing, choose a nut oil, toasted sesame oil, or an unrefined olive oil.
About Some Common Oils
Oils high in monounsaturated fat:
Olive oil. The oils extracted from olives range from light amber to green in color and from bland to very strong and even spicy in flavor. Olive oil can be graded or classified as virgin, refined, or pure. Virgin or extra-virgin means the oil has been produced by the use of physical means (expeller-pressed) and there has been no chemical treatment during processing, resulting in a full-flavored oil. Extra-virgin oil is the highest grade and comes from the first pressing of the olives. Refined means the oil has been chemically treated to neutralize strong tastes and acids. Pure olive oil and products simply labeled “olive oil” may be a combination of virgin and refined oil. Unfiltered means the oil contains small particles of olive flesh. Light refers to flavorless or refined olive oil; it is not lower in calories. Olive oil blends are mixtures of olive oil and other, often less expensive, oils.
Corn oil. This tasteless oil is made from the germ of the corn kernel and is widely used in cooking because it is inexpensive and has a high smoke point. Corn oil is a common ingredient in margarine.
Cottonseed oil. This oil is extracted from the seeds of the cotton plant after the cotton lint has been removed. It is commonly used to make snack foods such as potato chips.
Flaxseed oil. This oil is made from the seeds of the flax plant and is often used as a dietary supplement rather than a cooking oil. It is high in omega-3 fatty acids and contains a group of chemicals called lignans that may play a role in cancer prevention.
Grapeseed oil. This light-tasting, medium-yellow oil is pressed from seeds of various varieties of grapes and is a by-product of wine making. It has a high smoke point and is typically used in salad dressings and marinades and for stir-frying.
Safflower oil. This oil made from the seeds of the safflower plant is almost flavorless and colorless. It is a favorite for salad dressing, because it does not solidify when chilled, and is also used in cooking. Safflower oil that is labeled “high-oleic” has a higher monounsaturated fat content than safflower oil that is not so labeled.
Soybean oil. This refined, mild oil is produced by cracking soybeans and chemically extracting the oil. Soybean oil is high in omega-3 fatty acids and is used extensively in commercially prepared foods but less often as a home cooking oil.
Sunflower oil. This light, odorless oil is pressed from sunflower seeds and is a good all-purpose oil. Like safflower oil, sunflower oil labeled “high-oleic” is higher in monounsaturated fat than sunflower oil not labeled with that term.
Oils high in saturated fats
Coconut oil. This oil, also known as coconut butter, is extracted from the inner flesh of coconuts. It has a longer shelf life than other vegetable oils and is highest in saturated fat of all cooking oils. Unrefined, or virgin, coconut oil is derived from fresh coconut. Refined coconut oil is derived from copra, the dried coconut meat.
Palm oil. Palm oil is obtained from the fruit of the palm tree. It is reddish in color because it contains high amounts of beta-carotene. It is also high in saturated fat and semisolid at room temperature. Palm oil is the most widely produced vegetable oil in the world and is used primarily in processed foods.
Palm kernel oil. Palm kernel oil is extracted from the seeds, or kernels, of the palm fruit. It is also high in saturated fat and is most widely used in processed foods.
More Info Here!
People have been extracting vegetable oil from plant materials for thousands of years. The very earliest methods of pressing vegetable matter probably yielded at best 10% of the available oil. More modern methods involving chemical solvent extraction can extract all but 1% to 2% of the oil.
Some cooking oils, including olive, peanut, and some coconut and sunflower oils, are expeller-pressed, meaning that the plant part from which oil is derived is crushed and pressed to produce the oil. The oil is then left crude or refined. Crude oils may have a cloudy appearance and are more flavorful, but they have a shorter shelf life than refined products.
Some manufacturers label their products cold-pressed to indicate that the plant materials were not heated during oil extraction. However, this label term is largely unregulated and cannot always be relied on to mean that the oil was never exposed to high heat.
Most cooking oils are extracted from ground plant material with a chemical solvent. After extraction, the oil is cleaned, refined, and filtered and/or distilled. This process produces a bland, clear oil.
What Happens When You Heat It?
All cooking oils will oxidize and therefore hydrogenate to a small degree if repeatedly heated to a very high temperature, as is done in commercial frying. This means the fats become more saturated and start to contain some trans fat over time. However, it is almost impossible to oxidize fat to this degree in home cooking.
Cooking oils differ in their “smoke point,” or the temperature to which they can be heated before they smoke, discolor, and break down. At the smoke point, the oil not only smokes and begins to emit unpleasant odors, but it also imparts unsavory flavors onto the food. Reaching the smoke point means you are approaching the “flash point,” which is when the oil can erupt into flames.
Cooking oils with a high smoke point can be heated to high temperatures before burning. Knowing a cooking oil’s smoke point gives you some indication of whether it is good for cooking and frying. In general, the best oils for high-temperature cooking methods such as deep-fat frying are safflower, sunflower, peanut, soy, and canola oils.
Storing oils
All cooking oils, whether refined or unrefined, are sensitive to light, heat, and exposure to oxygen (air). Cooking oil that is spoiled (rancid) will have an unpleasant smell and taste. To prevent spoilage, store oils in the refrigerator or in a cool, dark place. Oils may thicken in the refrigerator, but they will return to liquid if left standing at room temperature. Refined oils that are high in monounsaturated fats will keep for up to a year. Cooking oils high in polyunsaturated fats such as soybean, corn, safflower, and canola spoil more quickly: If stored properly, these oils will keep for up to six months. Some manufacturers put “use by” dates on product labels.
Choosing An Oil
For heart health, select cooking oils with the lowest levels of saturated fat and the highest levels of monounsaturated and omega-3 fatty acids. Examples of heart-healthier oils include canola oil, olive oil, flaxseed oil, and walnut oil. If you are looking for an oil to add flavor to your cooked dishes or salad dressing, choose a nut oil, toasted sesame oil, or an unrefined olive oil.
About Some Common Oils
Oils high in monounsaturated fat:
Olive oil. The oils extracted from olives range from light amber to green in color and from bland to very strong and even spicy in flavor. Olive oil can be graded or classified as virgin, refined, or pure. Virgin or extra-virgin means the oil has been produced by the use of physical means (expeller-pressed) and there has been no chemical treatment during processing, resulting in a full-flavored oil. Extra-virgin oil is the highest grade and comes from the first pressing of the olives. Refined means the oil has been chemically treated to neutralize strong tastes and acids. Pure olive oil and products simply labeled “olive oil” may be a combination of virgin and refined oil. Unfiltered means the oil contains small particles of olive flesh. Light refers to flavorless or refined olive oil; it is not lower in calories. Olive oil blends are mixtures of olive oil and other, often less expensive, oils.
Canola oil. This oil is extracted from rapeseeds (a plant in the mustard family). It is versatile, neutral tasting, high in omega-3 fatty acids, and very low in saturated fat. It can be used in salad dressings or in cooking.
Sesame oil. This pressed oil is made from either untoasted sesame seeds, resulting in a light-colored oil, or toasted sesame seeds, for a dark-colored oil. Light sesame oil has a nutty flavor and is good for frying, while dark sesame oil has a strong flavor and is generally added to dishes in small quantities for flavor just before serving. Sesame oil has a high smoke point and is the least prone among oils to turn rancid. It is a good source of both monounsaturated fat and polyunsaturated fat.
Oils high in polyunsaturated fatCorn oil. This tasteless oil is made from the germ of the corn kernel and is widely used in cooking because it is inexpensive and has a high smoke point. Corn oil is a common ingredient in margarine.
Cottonseed oil. This oil is extracted from the seeds of the cotton plant after the cotton lint has been removed. It is commonly used to make snack foods such as potato chips.
Flaxseed oil. This oil is made from the seeds of the flax plant and is often used as a dietary supplement rather than a cooking oil. It is high in omega-3 fatty acids and contains a group of chemicals called lignans that may play a role in cancer prevention.
Grapeseed oil. This light-tasting, medium-yellow oil is pressed from seeds of various varieties of grapes and is a by-product of wine making. It has a high smoke point and is typically used in salad dressings and marinades and for stir-frying.
Safflower oil. This oil made from the seeds of the safflower plant is almost flavorless and colorless. It is a favorite for salad dressing, because it does not solidify when chilled, and is also used in cooking. Safflower oil that is labeled “high-oleic” has a higher monounsaturated fat content than safflower oil that is not so labeled.
Soybean oil. This refined, mild oil is produced by cracking soybeans and chemically extracting the oil. Soybean oil is high in omega-3 fatty acids and is used extensively in commercially prepared foods but less often as a home cooking oil.
Sunflower oil. This light, odorless oil is pressed from sunflower seeds and is a good all-purpose oil. Like safflower oil, sunflower oil labeled “high-oleic” is higher in monounsaturated fat than sunflower oil not labeled with that term.
Oils high in saturated fats
Coconut oil. This oil, also known as coconut butter, is extracted from the inner flesh of coconuts. It has a longer shelf life than other vegetable oils and is highest in saturated fat of all cooking oils. Unrefined, or virgin, coconut oil is derived from fresh coconut. Refined coconut oil is derived from copra, the dried coconut meat.
Palm oil. Palm oil is obtained from the fruit of the palm tree. It is reddish in color because it contains high amounts of beta-carotene. It is also high in saturated fat and semisolid at room temperature. Palm oil is the most widely produced vegetable oil in the world and is used primarily in processed foods.
Palm kernel oil. Palm kernel oil is extracted from the seeds, or kernels, of the palm fruit. It is also high in saturated fat and is most widely used in processed foods.
More Info Here!
Labels: cooking oil, healthy cooking, healthy living, olive oil
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