Chemistry of Fats, Oils, and Waxes Centeno, Kathryn
Decem brano, Katrin Mae
Ram iscal, Michael Gabriel
Villalba, Shaira Phel
Lipids Lipids are a class of biological molecules defined by low solubility in water and high solubility in nonpolar solvents.
Role of Lipids 1. They store energy and protect and insulate internal organs. In human bodies they are stored as fat cells and in animal bodies as starch. 2. They are found in nerve fibers and hormones as steroids, which act as chemical messengers. 3. Because they are not soluble in water, a major function of lipids is to build the cell membranes that separate the internal contents of cells from the surrounding aqueous environment.
Classification of Lipids 1. Triglycerides - derived from glycerol and three fatty acids 2. Phospholipids - contains glycerol and two fatty acids 3. Steroid - composed of four fused rings of carbon where functional groups are attached 4. Waxes -organic compounds that characteristically consist of long alkyl chains.
Fatty Acids A fatty acid contains a long chain attached to carboxylic acid group at one end. Normally, fatty acid contains an even number of carbon atoms, usually between 12 and 20. They are insoluble in water because the size of the nonpolar portion is bigger than the size of polar portion (carboxyl group). They form micelle in water.
Types of Fatty Acids 1. Saturated Fatty Acids no C=C bonds 2. Unsaturated Fatty Acids a. Monounsaturated one C=C bond b. Polyunsaturated two or more C=C bond c. Cis/Trans
Saturated Fatty Acids Generally found in animal, palm, cocoa and coconut and the foods made from them. Single carbon-carbon bonds. General formula CnH2n+1 COOH Certain fatty acids are already 'naturally saturated' in that they cannot be made 'harder' than they are in nature. Saturated fatty acids are extremely stable i.e. they do not easily become rancid, meaning they have good keeping properties (shelf life).
Unsaturated Fatty Acids Generally found in plant and fish and the foods made from them. Carboxylic acids Stability depends on the number of C=C bonds. Carbon double bonds are highly reactive making it unstable. As the amount of unsaturation increases the stability decreases.
Unsaturated Fatty Acids Classifications: 1. Mono-unsaturated fat – contains fatty acids with 1 C=C double bond. Ex: olive, canola and peanut oils. 2. Poly-unsaturated fat – contains fatty acids with 2 or more C=C double bonds. E.g. safflower, sunflower, corn, fish oils). 3. Cis and Trans Fat
a. Cis Unsaturated Fat - H atoms on the same side of the double bond. have lower melting points than trans fats since this configuration causes more “kinking” of the chain. The molecules are not as closely packed, decreasing the strength of the van der Waals forces between them. b. Trans Fat - H atoms on opposite sides of the C=C double bond. Occurs in processed unsaturated fats commonly through hydrogenation process
Fats and Oils Fats and oils are made through esterification, a reaction in which the hydroxyl groups of glycerol form ester bonds with the carboxyl groups of fatty acids. It is the reaction between glycerol and three fatty acids to produce triglycerides (fat) and water.
Reactions Triglycerides Undergo 1. Hydrolysis – important for fat and oil digestion. Triglycerides are hydrolysed (split by water) in the presence of strong acids or digestive enzymes called lipases. The products of hydrolysis of the ester bonds are glycerol and three fatty acids.
Reactions Triglycerides Undergo Hydrogenation - converts carbon-carbon double bonds to single bonds. The hydrogen gas bubbled through the heated oil the presence of a nickel catalyst (or another transition metal).
3. Oxidative Rancidity - Results in the formation of a small carboxylic acid and an aldehyde. - Responsible for the foul odor associated with fat decomposition Triglyceride + O2 → Small organic molecules
Fats
Generally crystalline solids at room temperature. Contains more saturated fatty acids As the length of the fatty acid chain increases the number of atoms and number of electrons increases. The strength of the Van der Waals forces between the fat molecules increases, increasing the melting point. Ex: butter, cheese
Oils Generally liquids at room temperature. Contains more unsaturated fatty acids. The double bond in unsaturated fatty acids produces a ‘kink’ in the chain which means that the fat molecules can not pack closely together. As the number of C=C double bonds increases the amount of kinking increases and the distance between the fat molecules increases. This decreases the strength of the Van der Waals forces between the molecules, decreasing the melting point.
Waxes The word "wax" is derived from the old English "weax" for the honeycomb of the bee-hive. Thus, bee wax can be considered as the reference wax. Wax is the water resistant protective coatings of leaves, fruits, and trees, also in animals, algae, fungi and bacteria. Wax is hydrophobic in nature produced by combining fatty acids with alcohols. All waxes are water-resistant materials made up of various substances including hydrocarbons (normal or branched alkanes and alkenes), ketones, diketones, primary and secondary alcohols, aldehydes, sterol esters, alkanoic acids, terpenes (squalene) and monoesters (wax esters), all with long or very long carbon chains (from 12 up to about 38 carbon atoms) and solid in a large range of temperature (fusion point between 60 and 100°C). They are soluble in aromatic solvents, chloroform, ethers, esters and ketones.
Good Fats vs. Bad Fats Good Fats: Monounsaturated Polyunsaturated – Omega 3, 6 Bad Fats: Trans Fat
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Essential Fats 1.
Omega – 3 Fats Once eaten, the body converts (alphalinolenic acid) ALA to (eicosapentaenoic acid ) EPA and (docosahexaenoic acid) DHA, the two types of omega-3 fatty acids more readily used by the body.
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Sources
ALA: ALA is found in flax seed (18-22%) and flax seed oil (50-60%), and in small amounts in some nuts, green leafy vegetables, canola, wheat germ and black current seeds. EPA and DHA: EPA and DHA are found in fatty fish like salmon, mackerel and tuna. Depending on the source, fish oils vary in the amount of EPA and DHA they provide. Fish oil supplements often contain 18% EPA and 12% DHA, with more concentrated oils containing 30% EPA and 20% DHA. Algal sources of EPA and DHA are also widely available
Essential Fats 2. Omega – 6 Fats Linoleic acid is converted in the body to the longchain polyunsaturated fatty acids gamma-linolenic acid (GLA) and arachidonic acid (AA)
Sources
LA: LA is present in many vegetables and most vegetable oils – sunflower (65-75%), safflower (79%), evening primrose seed (72%), corn (57%), peanut (31%), canola (19-26%), and olive (8%). LA is abundant in the food supply and thus there is no need to supplement. GLA: The richest sources of GLA are borage (starflower) oil,GLA (20-24%); evening primrose oil (8-10%); and black currant oil (15-17%). GLA is present in small amounts in human breast milk and some foods, but the typical diet provides very little GLA. AA: Found in high amounts in eggs, fish and meat, AA is abundant in the food supply and supplementation is not usually necessary.
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Omega 3-Omega 6 Ratio In the human body, LA and ALA compete for metabolism. Too high intake of LA would reduce the amount of omega6-desaturase available for the metabolism of ALA, which may increase the risk of heart disease. It has been estimated that the ratio of omega-6 to omega-3 fatty acids in the typical diet is almost 10:1 due to increased use of vegetable oils rich in omega-6 fatty acids as well as reduced fish consumption
Health Benefits
Both omega-3 and omega-6 fatty acids are important components of cell membranes and are precursors to many other substances in the body such as those involved with regulating blood pressure and inflammatory responses. They are necessary in treatment and prevention of: Heart disease Arthritis and other joint conditions Skin disorders Mental disorders gastrointestinal disorders, diabetes, obesity, PMS, mastalgia (breast tenderness), hypertension, multiple sclerosis, lupus, asthma, allergies and cancer.
Deficiency Abnormalities in the liver and kidney Changes in the blood Reduced growth rates Decreased immune function Depression Skin changes, including dryness and scaliness, Eczema Mental disorders Diabetes Atherosclerosis Hypertension, PMS, and inflammatory conditions such as rheumatoid arthritis.
Health Risks of Trans Fat Increases the amount of harmful LDL (low density lipoprotein) cholesterol in the bloodstream and reduces the amount of beneficial HDL cholesterol. Trans fats create inflammation, which is linked to heart disease, stroke, diabetes, and other chronic conditions. They contribute to insulin resistance, which increases the risk of developing type 2 diabetes.
Sources of Trans Fat
Commercially baked goods (cookies, crackers, cakes, muffins, pie crusts, pizza dough, breads like hamburger buns) Packaged snack foods (crackers, microwave popcorn, chips, candy) Solid fats (stick margarine, vegetable shortening) Fried foods (French fries, fried chicken, chicken nuggets, breaded fish, hard taco shells) Pre-mixed products (cake mix, pancake, chocolate milk) Anything with “partially hydrogenated” oil listed in the ingredients
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