Chemical Evaluation of Saturated Fats and Unsaturated Oils
Fats and oils which are in the category of lipids contain coarsely hydrophobic molecules (repellent from the water). The formation of fats and oils is based on the reaction of three ester molecules (reactants of alcohol and acid) known as triglyceride which are hydrolysed with water to produce fatty acids and glycerol. Fatty acids maybe present in the esterification reactions or they are extracted from vegetable oils or animal fats. Chemical structure of fatty acids is identified by carbon chains which are generally quantified from four to 28 carbons (even numbers of unbranched tail of carbons). Fatty acids are classified as either saturated or unsaturated forms.
Saturated fatty acids
Saturated fatty acids comprise carboxylic acids within a long chain (12 to 24 carbons) with no double bond structure. They can be easily saturated with hydrogen atoms. Saturated fats are basically solid at ambient temperature and have more stability in terms of the resistance to oxygenation (rancidity). They are widely utilised in food industry for various purposes. Animal fats are used in dairy products (such as whole milk, butter, cheese and lard) and in meat products (such as beef, lamb and pork). Extracted oils from some specific plants such as coconut oil, palm kernel and cocoa butter are also used for different applications as the added ingredients or as the final food products.
Unsaturated fatty acids
There are two classifications of unsaturated fatty acids; monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA). The chemical structure of unsaturated fats consists of molecules with carbon atoms which are bound together with one /more than one double bond in between. Unsaturated oils are originated from an extensive range of food sources including vegetables, fruits, nuts and seeds which are widely used in the food industry with great versatility. Either type of unsaturated oils is able to reduce the blood cholesterol when consumed regularly and proportionally.
Monounsaturated fatty acids; Contain one double bonded carbon in the molecule. They are in the liquid state at ambient temperature while liable to become more viscous in the chilled condition. Oils extracted from various plants such as olives, peanuts, avocados and sunflower can provide a good sources of monounsaturated fatty acids after the ingestion.
Polyunsaturated fatty acids; contain more than one double bonded carbons in their fatty acid chains. They are physically in the liquid forms at room and chilled temperature and are highly prone to react with existing oxygen in the atmosphere that may lead to the rancidity (oxygenation).[Copyright note: http://www.labreports.info] Polyunsaturated fatty acids are found in a wide range of seeds, nuts and vegetables including sesame oils, grape seeds, sunflower seeds, flax seeds and walnuts.
Cholesterol accounts for a substantial component of bile acids, hormones and some lipophilic vitamins. Adequate proportion of cholesterol in the body is effective in the function of the cellular mechanism; helps maintain fluidity and permeability of the cell membrane. However, excessive or disproportional intake of cholesterol can result in developing cardiovascular disease. The most contributory factors to increasing the blood cholesterol include the excessive consumption of saturated fats and trans fats (carbon chains arranged at the opposite direction of the double bond).
Trans fatty acids which are in the category of unsaturated fats (monounsaturated or polyunsaturated), are capable of raising the LDL (bad) cholesterol or contributing to the increment of the total cholesterol level. They may also have the disadvantage of decreasing HDL (high density lipoproteins) bound cholesterol with consequent heart disease development. HDL cholesterol (namely the good cholesterol) is able to separate cholesterol from the existing atheroma (degeneration of the artery walls) in order to either send it to the liver for elimination or it is re-functioned in the body. Approximately 30% of cholesterol (in the blood stream) is transferred by HDL in a healthy human body.
Trans fatty acids are produced in consequence of the the chemical process of hydrogenation. This involves the addition of hydrogen to cis-unsaturated oils (carbon chains arranged in the same direction across the double-bond) during the food production that would undergo the saturation condition and higher melting point. Hydrogenation method is commonly used in a wide range of food applications to achieve more desirable flavour and longer shelf-life products plus the advantage of being financially economic. However frequent use of this process may have adverse influence on human health as the cis isomers are likely to convert into trans unsaturated fats i.e. “partially hydrogenated oil” rather than fully hydrogenation outcome. Commercial applications of trans fats are most common in bakery and confectionery (such as doughnuts, cookies and pizza dough), fast foods (like French fries) and many prepared foods in restaurants.
A proper level of saturated fats and polyunsaturated oils in the body helps maintain the optimum proportion of LDL to HDL in the blood stream. This facilitates obtaining the normal operation of lipoproteins in the regulating system.
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