Chemistry of Food

Fresh baked bread Would you like some butter on it? Or margarine? Or Benecol? Or Smart Balance?

Lipids Organic substance found in living systems that is not soluble in water Fats & oils 95% of lipids in diet are these Steroids Extremely important in cell function, hormones Waxes Fats solids Oils liquids

Lipids and Health Diets that are high in saturated fats are associated with an increased risk of coronary artery disease

Saturated fats Found in animal derived fats Usually solids Butter is a saturated fat, also high in cholesterol

cis Unsaturated fats Naturally occurring unsaturated fat Found in plant derived fats About 30% of our daily calories should be from fat

Trans unsaturated fats Formed from hydrogenation of unsaturated fats This is done to make the fat more solid, ex. Peanut butter TFA associated with increased heart disease

Margarines Margarines do not have cholesterol, they are made from plant derived fatty acids, originally unsaturated To give them solid consistency, they are hydrogenated, resulting in trans fatty acids (TFA) Can’t believe has 1g of TFA per 10 g total fat in 1T serving Blue bonnet has 2 g of TFA per 7 g total fat in 1 T serving

“Health” Spreads These spreads are made from unsaturated vegetable oils, no cholesterol, lower saturation Also do not have trans fatty acids Better for you?

Fake fats Olestra (Proctor & Gamble) Replaced glycerol with sucrose, 6 to 8 fatty acids No calories, not digested Removes oil soluble vitamins & cartenoids Severe gastrointestinal problems

Carbohydrates Good or Bad?

Carbohydrates Carbohydrates: Hydrates of carbon Have general formula: Cx(H2O)y in which x and y are whole numbers Carbohydrates consist of: Monosacchadrides Disaccharides Starch Cellulose

Carbohydrates in Diet Typically half the calories in the human diet are made up of carbohydrates The Atkins diet limits the amount of carbohydrates in your diet

Monosaccharides What is the difference between these sugars? They are isomers of one another. Isomer: Same formula but different arrangement of the connectivity/ geometry of the molecule.

Disaccharides These are 2 simple sugars combined together (with elimination of 1 H2O) General formula: C12H22O11 Average daily Western consumption of simple sugars is 170g

Density Demonstration Density = Mass/ Volume The density of water is 1g/mL Why do the two kinds of pop behave differently? Different densities Majority of both pops is composed of water but the added sugar in the sweetened pop increases the density and causes it to sink

Carbohydrates & Health Simple sugars are responsible for dental cavities Simple sugars contribute to obesity Simple sugars are thought to be important in the development of Type II Diabetes

Artificial Sweeteners Saccharin: Not digested, no caloric value, bitter aftertaste, possible carcinogen, not used as much Aspartame (NutraSweet): Does have caloric value but more sweetness per gram than sucrose

Aspartame Decomposes10% per month at room temperature How is rate affected by temperature? Increased Temp. Increased Rate Cooking rapidly decomposes NutraSweet

Polysaccharides Consist of many sugars bonded together Polymer: A large molecule with a repeating unit Common polysaccharides include: cellulose, glycogen, and starch

Biomolecules Geometry Chirality Chirality = Handedness Molecules that cannot be superimposed on their mirror images are called chiral. Molecules that can be superimposed on their mirror images are achiral

Chirality Which of the following objects is chiral? A table knife, a pencil, a pair of gloves, a shirt that has buttons, a TV set

Chirality Enantiomers: Chiral pair of molecules, have same exact formula but are different molecules Racemic: Equal portions of both enantiomers Examples: Aleve, thaliomide, ibuprofin