WHAT ARE LIPIDS? Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, pages 216-240.

DEFINITION of LIPIDS Lipids are a category of organic compounds that are insoluble in water and have a greasy feel. Contain mostly carbon, hydrogen and some oxygen. Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, page 217.

How do LIPIDS differ from CARBOHYDRATES? They are not polymers (large molecule that consists of large numbers of small molecular units, which are linked). Do not provide structure to foods. Cannot be dissolved in water; they are non-polar thus they are soluble in organic compounds.

Why are Lipids important? Used to store lots of energy (lipids/fat) Lipids more difficult to break down (metabolize), but store more energy than carbohydrates Form cell membranes (the “skin” of the cell) Cell communication Hormones Many others…

More Lipid information... Lipids are an integral part of our daily diet. Most oils and milk products that we use for cooking and eating, like butter, cheese, etc., are composed of fats. Vegetable oils are rich in various polyunsaturated fatty acids. Lipid-containing foods undergo digestion within the body and are broken into fatty acids and glycerol, which are the final degradation products of fats and lipids. http://en.wikipedia.org/wiki/Biochemistry

What do Lipids look like? Each molecule has a “head” with a “tail” Tail usually consists of two or three strands http://www.biochemweb.org/lipids_membranes.shtml

Cell Membranes of Lipids Phospholipids make up cell membranes Cell membranes are predominantly composed of phospholipids and cholesterol. Cell membranes provide stability to cells and control entry or release of chemicals into or from the cell. Water is polar Phospholipids have polar and non-polar ends So water and phospholipids don’t mix well (one end likes water, the other doesn’t) http://www.encyclopedia.com/topic/lipids.aspx

What are Lipids? Fats Oils Shortening Grease Phospholipids Sterols Cholesterol Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, pages 226-229. These are all terms used for lipids and their related compounds. http://en.wikipedia.org/wiki/Shortening Shortening is a semisolid fat used in food preparation, especially baked goods, and is so called because it promotes a "short" or crumbly texture (as in shortbread). Shortening is fat or lard from an animal or vegetable. The term "shortening" can be used more broadly to apply to any fat that is used for baking and which is solid at room temperature, such as butter, lard, suet, and margarine. Shortening often has a higher smoke point than butter and margarine, and it has 100% fat content, compared to about 80% for butter and margarine. Although the term has been in use for many years, it is now known that shortening works by inhibiting the formation of long protein (gluten) strands in wheat-based doughs. http://www.bigoven.com/glossary/Shortening In general, the term shortening can apply to any oil- or fat-based ingredient – liquid or solid - used in baking. More specifically, recipes use the term to mean solid vegetable shortening rather than those made from animal fats (including lard, which is from pork). Vegetable-based shortening is lower in saturated fats than butter. There are other advantages – shortening does not require refrigeration and does not burn when used for sauteeing. It’s a staple for many cooks and adds a light and fluffy texture to baked goods such as cakes and pie crusts.

GLYCERIDES Molecules that have a glycerol base are called glycerides (a type of lipid). Fatty acids are organic molecules that consist of a carbon chain with a carboxyl group at one end. Fatty Acids + Glycerol = Lipids Most lipids found in foods and in the body are triglycerides. Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, pages 217-218. TRIGLYCERIDES Triglycerides can have many different combinations of fatty acids attached to a glycerol base. These options create molecules with different characteristics. The chemical variations lead to differences in: cooking performance shelf live nutritional value

GLYCERIDES continued… Some glycerides are partially soluble in water such as mono- and diglycerides. These are added to processed foods such as butter and margarine to keep mixtures of water and fats stable.

PHOSPHOLIPIDS A phospholipid is a glycerol base with two fatty acids and a phosphorus-containing acid attached. Important role in the body - help carry fats back and forth across cell membranes. Important role in food products – help fats stay mixed in water-based solutions like mayonnaise (keeps it from separating). Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, page 218.

STEROLS Sterols are complicated molecules derived or made from lipids. Sterols include: Cholesterol Vitamin D Steroid hormones Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, page 218.

CATEGORIES OF LIPIDS Saturated – when fatty acids have the maximum number of hydrogen atoms. Unsaturated – if fatty acid does not contain all the hydrogen atoms it could. Monounsaturated – fatty acids that have one double bond in the carbon chain. Polyunsaturated – fatty acids have two or more double bond bends in the fatty chain. Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, pages 218-219.

Why be concerned about Trans-Fatty Acids? Found in many margarines. A product of hydrogenating vegetable oil. Humans may not be able to digest the trans-form of these fatty acids & may add build up in blood vessels. More study is required. Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, page 221. Hydrogenation – process of adding hydrogen atoms to an unsaturated lipid to increase its saturation level. Some recommend to eat a moderate amount of margarine until more studies are done.

PHYSICAL STATE of LIPIDS Fats – lipids solid at room temperature Oils – lipids liquid at room temperature Melting Point – temperature at which a lipid is completely liquid Hydrogenation – process of adding hydrogen atoms to an unsaturated lipid to increase its saturation level. Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, pages 220-223.

PHYSICAL CHARACTERISTICS of LIPIDS Three physical characteristics impact the way lipids perform in food products: Melting Point Solidification Point Reaction to Oxygen Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, page 224.

RESOURCES Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, pages 216-240. http://www.bigoven.com/glossary/shortening http://en.wikipedia.org/wiki/Shortening http://en.wikipedia.org/wiki/When_You're_Hot,_You're_Hot http://www.youtube.com/watch?v=Bzewk-FMgS0 http://www.landolakes.com/Products/Butter/ http://www.landolakes.com/TestKitchen/TipsAndTechniques/FAQ/Butter.aspx http://www.wisegeek.com/what-is-whipped-butter.htm http://en.wikipedia.org/wiki/Mayonnaise http://www.brooklynfarmhouse.com/basic-techniques/how-to-make-mayonnaise/ http://www.ask.com/wiki/Condiment http://en.wikipedia.org/wiki/Biochemistry http://www.biochemweb.org/lipids_membranes.shtml http://www.encyclopedia.com/topic/lipids.aspx