Unsaturated, fats/oils

RandomiZation/Interesterification. Transesterification occurs when a carboxyUc acid (acidolysis) or alcohol (alcoholysis) reacts with an ester to produce a different ester (20). Ester—ester interchange is also a form of transesterification. If completely unsaturated triglyceride oil (UUU) reacts with a totally saturated fat (SSS) in the presence of an active catalyst such as sodium, potassium, or sodium alkoxide, triglycerides of intermediate composition may be formed. 

Natural fats are glycerol esters of fatty acids known as triglycerides. Unsaturated fats are generally liquids (oils) at room temperature, while triglycerides rich in saturated fatty acids are generally solids. View tristearin and triolein. Which one of these is saturated and which is unsaturated Are die double bonds in the unsaturated fat cis or transl... 

Hydrogenation of unsaturated fats and fatty oils is one of the oldest heterogeneous catalytic processes of industrial significance, and is carried out exclusively by gas-liquid-particle operation, the vaporization of the fats being impracticable. Stirred-slurry operation is the normal mode of operation, the suspended catalyst being finely divided by Raney nickel (B2). 

Saturated fats like the tristearin in beef fat have higher melting points than the unsaturated fats in vegetable oils like trilin-olein or trilinolenin. 

The double bonds that make this an unsaturated fat prevent the molecule from bending they lower the melting point making a liquid oil rather than a solid fat. 

The oils from which factices are manufactured are unsaturated vegetable and animal oils, which react with sulphur. Fatty oils with iodine number greater than 80 (iodine number is defined as the number of grammes of iodine absorbed by 100 g of fat/oil) are generally used, i.e., oils with three or more double bonds per triglyceride molecule. Rapeseed oil is the most common oil used for general purpose grades and castor oil is used for oil resistant factice. Other oils are used in preference by other countries due to local availability and cost. 

In the past various marine oils were used in biscuits but this practice had now ceased. Most biscuits contain vegetable fats. It was common to use hydrogenated fat in biscuits because vegetable oils were too soft physically and too unsaturated to be stable against oxidation. If an unsaturated fat is hydrogenated until it is completely saturated then a saturated fat results however, if it is only partially hydrogenated a partially hydrogenated fat with several double bonds is produced. 

CN139 Muller, H., A. S. Lindman, A. Blomfeldt, I. Seljeflot, and ]. I. Pedersen. A diet rich in coconut oil reduces diurnal postprandial variations in circulating tissue plasminogen activator antigen and fasting lipoprotein (a) compared with a diet rich in unsaturated fat in women. J Nutr 2003 133(11) 3422-3427. 

CLA Formation in the Rumen. The fat depots of ruminant species contain mostly saturated fat. They are subject to little modification by dietary changes, including the feeding of relatively large amounts of unsaturated fats or oils. Dietary fats are modified in the rumen via hydrolysis and biohydrogenation reactions. 

Diets high in saturated fats are considered unhealthy because of the danger of developing fatty deposits in the arteries, particularly the arteries of the heart. On the other hand, the intake of limited amounts of unsaturated vegetable oils is actually considered beneficial. 

Much research is currently underway to determine whether a correlation exists between cholesterol levels in the blood and diet. Cholesterol not only comes from the diet, but is also synthesized in the body from carbohydrates and proteins as well as fat. Therefore, the elimination of cholesterol rich foods from the diet does not necessarily lower blood cholesterol levels. Some studies have found that if certain unsaturated fats and oils are substituted for saturated fats the blood cholesterol level decreases. 

Unsaturated fats, as noted in Section 13.3, tend to be liquids at room temperature. They can be transformed to a more solid consistency, however, by hydrogenation, a chemical process in which hydrogen atoms are added to carbon—carbon double bonds. Mix a partially hydrogenated vegetable oil with yellow food coloring, a little salt, and the organic compound butyric acid for flavor, and you have margarine, which become popular around the time of World War II as an alternative to butter. Many food products, such as chocolate bars, contain partially... 

The iodine value (IV) is used to determine the level of unsaturation in a fat/oil system. It is expressed as the number of grams of iodine that add to/react with 100 g of sample. The traditional iodine value method using the Wijs reagent requires carbon tetrachloride (CC14). For safety reasons, CC14 is no longer considered to be an acceptable chemical and it is not readily available for purchase, and if offered it is extremely expensive. Therefore the traditional method has been modified to a more human-friendly system which uses cyclohexane. 

Ke, P.J., Nash. D.M., and Ackman, R.G. 1977. Mackerel skin lipids as an unsaturated fat model system for the determination of antioxidative potency of TBHQ and other antioxidant compounds. J. Am. Oil Chem. Soc. 54 417-420. 

The oxidation of unsaturated fats and oils is initiated with the formation of free radicals. This reaction occurs on the methylene groups adjacent to the carbon-carbon double bond ... 

To illustrate, consider the catalytic hydrogenation of compounds with C = C double bonds, a reaction used in the food industry to convert unsaturated vegetable oils to solid fats. The simplest reaction of this type is the hydrogenation of ethylene, which is catalyzed by finely divided metals such as Ni, Pd, or Pt ... 

This addition of hydrogen to an alkene, often called hydrogenation, is used commercially to convert unsaturated vegetable oils to the saturated fats used in margarine and cooking fats. 

Pasta sauces based on fresh vegetables and olive oil are good sources of vitamins, fiber, complex carbohydrates, and unsaturated fat. 

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