1. What are the principal saturated fatty acids found in edible fats and oils an
ID: 633312 • Letter: 1
Question
1. What are the principal saturated fatty acids found in edible fats and oils and what relative percentages could be expected in animal vs. vegetable fats?
2. Partially hydrogenated oils were introduced in the early 20th century for use in processed foods and cooking. What are the advantages of hydrogenated oils?
3. What is a trans fat? Why would partially hydrogenated oils contain higher amounts of trans fats than natural fats and oils?
4. Why are saturated and trans fats considered a risk factor for cardiovascular disease?
Explanation / Answer
1) unsaturated fats exposed to air oxidize to create compounds that have rancid, stale, or unpleasant odors or flavors. Hydrogenation is a commercial chemical process to add more hydrogen to natural unsaturated fats to decrease the number of double bonds and retard or eliminate the potential for rancidity. Unsaturated oils, such as soybean oil, which contain unsaturated fatty acids like oleic and linoleic acid, are heated with metal catalysts in the presence of pressurized hydrogen gas. Hydrogen is incorporated into the fatty acid molecules and they become saturated with hydrogen. Oleic acid (C18:1) and linoleic acid (C18:2) are both converted to stearic acid (C18:0) when fully saturated. The liquid vegetable oil becomes a solid saturated fat (shortening with a large percentage of tristearin). By comparison, animal fats seldom have more than 70% saturated fatty acid radicals.Lard, for example, has 54% unsaturated fatty acid radicals.
2)
The advantage to hydrogenation is that food does not go rancid as quickly and maintains its physical properties at room temperature. Hydrogenated food such as shortening and peanut butter can last for years without going bad.
The disadvantage is that through the process of hydrogenation saturated fats increase and trans-fat increases. This contributes to an elevation of LDL Cholesterol (bad cholesterol) and a decrease in HDL cholesterol (good cholesterol) resulting in increased health risks for such things as heart diease.
3)
Trans fat is the common name for unsaturated fat with trans-isomer (E-isomer) fatty acid(s). Because the term refers to the configuration of a double carbon-carbon bond, trans fats are sometimes monounsaturated or polyunsaturated, but never saturated. Trans fats do exist in nature but also occur during the processing of polyunsaturated fatty acids in food production.
The consumption of trans fats increases the risk of coronary heart disease by raising levels of LDL cholesterol and lowering levels of "good" HDL cholesterol. There is an ongoing debate about a possible differentiation between trans fats of natural origin and trans fats of man-made origin, but so far no scientific consensus has been found. Two Canadian studies, that received funding by the Alberta Livestock and Meat Agency and the Dairy Farmers of Canada, have shown that the natural trans fat vaccenic acid, found in beef and dairy products, may have an opposite health effect and could actually be beneficial compared to hydrogenated vegetable shortening, or a mixture of pork lard and soy fat, by lowering total and LDL cholesterol and triglyceride levels. In lack of recognized evidence and scientific agreement, nutritional authorities consider all trans fats as equally harmful for health and recommend that consumption of trans fats be reduced to trace amounts.
4)
Whether saturated fat is a risk factor for cardiovascular disease (CVD) is a question with numerous controversial views. in the mainstream heart-health, government, and medical communities hold that saturated fat is a risk factor for CVD, recent studies have produced conflicting results and notable authors have given opposing viewpoints.
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