Dietary fat contains mixtures of saturated, monounsaturated and polyunsaturated fatty acids. Saturated fats and certain unsaturated fatty acids must be minimized because they are harmful to health. Most fat is obtained from commercial oils, which are categorized according to the predominant fatty acid they contain. Olive and canola are the two main monounsaturated oils, which is the fatty acid least harmful to the body.
The seeds, beans, nuts, kernels and fruits of plants contain enormous amounts of energy in the form of fat. Except for olives, this fat is stored in the endosperm or inner fruit of the seed. These fuel stores are the sole energy source for the developing embryo and when pressed and extracted provide the oils that are used to prepare and flavor food.
The properties that determine the use for a given oil are based on the the physical properties of the oil.
Smoke point of is a measure of its thermal stability when heated and is the temperature that an oil can be heated to before it begins to smoke. Its discoloration is a visual indication of the molecular damage done to the oil. Smoke Point is related to the free fatty acid content of the oil. The more free fatty acids, the lower the smoke point. A high smoke point is desirable for cooking.
Flash point is the temperature that causes the creation of volatile products. These volatile components are probably carcinogenic. The more free fatty acids the oil contains, the lower its flash point.
Free fatty acids are formed when long chained fatty acids are attacked by free radicals. Fragments are cleaved off the chain creating many small free fatty acids with low molecular weights. Free fatty acids lower the smoke and flash points of an oil. This makes the oil unhealthier over time. Oils that are subjected to extended use, have an increase in their free fatty acid content, resulting in a lower of the smoke, flash, and fire points.
Cooking oils should not be reused too often.
Saturated oils are associated with an increase risk of heart disease. Coconut (cocus nucifera) oil or for lack of a better term, coconut fat, (it is a solid at room temperature due to the high degree of saturation) is ninety-two percent saturated and is a common ingredient in commercially prepared cookies and baked goods.
Both coconut oil, and palm kernel (seed) oil are edible plant oils derived from the fruits of palm trees. Palm oil is extracted from the pulp of the oil palm fruit and is a semi -solid at toom temperature. It is less saturated and less refined than palm kernel oil and coconut oil.
Like all vegetable oils, palm oil does not contain cholesterol. Cholesterol is found only in animal fats.
Palm oils’ saturation increases both the low or lousy cholsterol as well as the high or healthy version.
Palm (Elaesis guineensis) contains a very concentrated source of energy in the pulpy fruit of the plant. Palm oil is fifty-one percent saturated fat and was favored by the Industry in the 1960s and the 70s because baked products that were made with them had long shelf lives. Health concerns and a better understanding of fat metabolism has limited its use, replaced with partially hydrogenated oils.
Polyunsaturated oils, which were previously believed to be safe, have now been linked with the production of free radicals and improper lipid metabolism.
Improper lipid metabolism is linked to atherosclerosis and free radical attacks are associated with cancer formation.
Palmitic and stearic acids are the most common long chain, fatty acids found in saturated fat. These fatty acids contain 18 carbons and are frequently found in animal fat, milk, eggs, ice cream and butter. Certain plants including coconut and palm also are high in saturated fat. Cholesterol, a 27 carbon-ring structure is only found in animal fat.
Palm oil is an agricultural commodity that threatens the rainforests of the world. Palm oil is used in over half the consumer goods purchased by Americans.c They range in form from lipstick to body lotion, from packaged foods to biofuels.
Over 80% percent of palm oil is grown in Indonesia and Malaysia.. Palm oil production damages the environment by deforestation, endangering species and increasing greenhouse gaess.
Pollution is exacerbated when rainforests are destroyed. Greenpeace claims that deforestation, caused by making way for oil palm plantations, is far more damaging to the climate than the benefits gained by switching to biofuel.
Despite its harm to health, demand for palm oil has tripled in the last five years. This is due to its use as a replacement for fossil fuels. Demand has pushed palm oil cultivation into the rainforests and made this plant one of the key causes of rainforest destruction. The Indonesian rainforest is being decimated by corporations and consumer demand. Their need for cheap vegetable oil and biofuel has fueled this destruction.
Agribusiness companies like Cargill own many palm oil plantations in Southeast Asia, which makes them a powerful force in rainforest destruction.
Cargil is the biggest palm oil plantation owner in the world. And they and their subsidiaries place palm oil in as many food products they can. Over a hundred General Mills products alone contain it. The list includes Cheerios, Betty Crocker, Stovetop Hamburger Helper and Bisquick
Safflower (Carthamus tinctorius) oil is the most unsaturated of the oils and is well suited for cold temperatures. Safflower oil is used in salad dressings and margarine that are kept refrigerated.
There was an initial flurry of interest in safflower oil, as it was believed that it improved health. This view is now in decline. Safflower oil contains seventy-five percent linoleic acid, sixteen percent oleic acid and six and a half percent saturated fat. Like all commercial polyunsaturated cooking oils safflower is partially hydrogenated to reduce its susceptibility to oxidation and decrease it’s rate of rancidity.
Soybean oil extracted from the soy pea (Glycine max) contains nine percent linolenic acid that due to its three double bonds becomes subject to chemical attack and rancidity.
Soybean oil contains fifty-five percent linoleic acid, twenty-five percent oleic acid and fifteen percent saturated fat.
Soybean oil is used for cooking and in salads.
Both safflower and soybean oils have high smoke points and are therefore used in deep fat frying.
Corn oil (Zea mays) is a polyunsaturated vegetable oil. Corn oil contains natural antioxidants that provide protection against oxidation reactions.
Corn oil has high levels of linoleic acid but lack alpha-linolenic acid, the essential omega-3 fatty acids. Corn oil smokes when heated to a high temperature.