第4章Lipids1-1学案.ppt

Chapter 4 Lipids Lipids Definition of Lipids Naturally occurring biological substances made from C, H and O of pronounced hydrophobicity that are soluble in organic solvents but not water Petroleum distillates (e.g. hexane) Chloroform Ethers Also classified as “biological molecules containing fatty acids or the corresponding alcohols or sphingosine bases” Lipids have more C and H than carbohydrates, which is why they generate more energy when utilized ? 2.25 times more = 9 kcal/g vs. 4 kcal/g. Lipids Biological role A. Structural - found in membranes - protective barriers B. Regulatory - steroids/prostaglandins - phospholipids C. Storage - triglyceride is storage for energy D. Vitamins - solvent - precursor Lipids Role in foods A. Calories (kcal) – energy 30% of all calories (ideal) - satiety B. Essential fatty acids - linoleic acid, linolenic acid arachadonic acid C. Flavor - most lipid soluble (usually off-flavors) D. Texture – mouth feel appearance E. Color - carotenoids F. Heat transfer medium 脂肪酸摄入的健康比例 (1)WHO,FAO,中国营养协会推荐 1： 1： 1 5~10 : 1 Lipids Classification of lipids (structure) 1) Simple lipids Mono, Di and Triacylglycerols Waxes 2) Compound lipids Phospholipids Glycolipids Sphingolipids (amide to alcohol) 3) Derived lipids Free fatty acids Sterol esters Tocopherol (Vit-E) ?-carotene 1) Non-polar lipids (neutral lipids) Fatty acids Mono-, di-, triacylglycerols Waxes Sterols Carotenoids Tocopherols 2) Polar lipids Glycerophospholipid Glyceroglycolipid Sphingophospholipid Sphingoglycolipid 2.命名 Nomenclature(1) Nomenclature of Fatty Acid( FA) Structure properties of fatty acids Fatty acid are composed of a hydrocarbon chain with methyl group (CH3) on one end and a carboxyl group (COOH) on the other. Basic properties common to most fatty acids 1. Most are even carbon # 2. Most are monocarboxylic acids 3. Most are part of triacylglycerides (triglycerides) ①系统命名法 ②数字命名法 (2) Nomenc