LIPIDS

• A lipid is an organic substance found in living systems that is insoluble in water but is soluble in organic solvents.
• Lipids vary widely in their structures and have mostly C,H and some have a few polar atoms/ functional groups.
• Unlike carbohydrates, lipids contain a smaller proportion of oxygen and a larger proportion of hydrogen and carbon.
• Fats & oils make up 95% of the nutritional lipids, the other 5% are steroids.
• The frying methods used in the research include deep frying, pan frying, and stir frying.
• The research article discusses the effects of frying to different types of oils.
• The types of oils used for comparison in the research include sunflower oil, olive oil, and coconut oil.
• The conclusion of the research recommends using sunflower oil as the better oil based on the results of the study.
• The research objective of the article is to investigate the effects of frying to different types of oils.
• Fats are solid triglycerides, while oils are liquid triglycerides – component of body (fat cells).
• Phospholipids are the component of cell membrane.
• Waxes are functional only.
• Triglycerides/fatty acids are characterized/named by: 1) The length/number of carbons in the side chains and 2) The number of carbon-carbon double bonds in the side chains(the degree of unsaturation).
• Solid fats have longer chains and are saturated(only C-C), examples include animal fat and butter.
• Liquid fats have unsaturations (C=C), examples include many vegetable oils such as olive and sunflower.
• Physical properties of fatty acids: Long carbon chains are non-polar, and things with long carbon chains on them do not dissolve in water.
• Short chain fatty acids are slightly water-soluble, because the carboxyl group (-COOH) is polar.
• Melting points of fatty acids increase with increasing molar mass, so the longer the carbon chain, the higher the melting point of the fatty acid.
• Hydrogenation of a triglyceride can happen if the triacylglycerol has unsaturated fatty acid chains, converting C-C double bonds to C-C single bonds.
• Saturated fatty acids have carbon chains filled with hydrogen atoms (no C=C double bonds), while unsaturated fatty acids have carbon chains that lack some hydrogens (>1 C=C double bond).
• Production of semi-solid cooking margarine from liquid vegetable oil needs to go through hydrogenation to increase the melting point, which increases the molar mass and makes it semi-solid.
• Almost all natural unsaturated fatty acids have cis stereochemistry in C=C’s, with small amounts of trans produced in stomachs of ruminating animals by partial enzymatic hydrogenation of polyunsaturated fats.
• Saponification of a triglyceride yields fatty acid salts, which contain anions (negative ions) with long carbon chains and both polar and non-polar components.
• Hydrogenation is a commercial reaction of fats and oils and is often used in the production of semisolid cooking shortening (margarines) from liquid vegetable oils.
• Commercial hydrogenation of fatty acids produces 'cis' unsaturated, saturated, and 'trans' unsaturated fats.
• In aqueous environments containing grease/oil, these anions form ball-shaped structures called micelles, which are able to interact with both polar and non-polar molecules and serve as soaps/detergents.
• Some cis fatty acid in hydrogenation isomerizes to trans fatty acid.
• Oxidation of the C-C double bonds in fats can lead to the formation of short-chain aldehydes and carboxylic acids, which have bad smells.
• The presence of double bonds (all cis-stereochemistry) lowers the melting point (makes it easier for the fatty acid to melt) because these double bonds cause the molecule to become bent (less attractions between chains).
• Fats do not melt sharply but soften over a range of temperature because fats are generally mixed triglycerides, each one having its own melting point.
• In foods, fats provide energy (9 kcal/gm), contribute flavor, aroma, and tenderness, provide satiety, carry fat-soluble vitamins (A,D,E & K), and provide a source of essential fatty acids.
• Hydrolysis is a chemical reaction where triglycerides, which are tri-esters, can undergo hydrolysis to yield carboxylic acids and glycerol (1,2,3-Propanetriol).
• In certain cases, triglycerides are only partially hydrolyzed (partial hydrolysis) – this happens when only one or two of the fatty acid groups are removed from the triglyceride by hydrolysis.
• Phospholipid Bilayer = Cell Membrane/Wall has a hydrophilic surface and a hydrophobic interior of cell wall.
• High Density Lipoproteins (HDLs) transport excess cholesterol to the liver for disposal.
• 7-dehydrocholesterol, which functions as a cholesterol precursor in blood serum, gets converted in vivo (epidermal cells) to Vitamin D by the action of sunlight.
• Humans have earwax.
• Both HDL and LDL contain apolipoproteins and phospholipids which are oriented with hydrophobic part on inside and outer hydrophilic edges exposed.
• Omega-3 fatty acid and Omega-6 fatty acid are different types of fatty acids.
• High levels of cholesterol in blood may contribute to cardiovascular disease.