Food Chemistry Chapter 17 in Green / Damjii F.1: Food Groups

Homework Read F1 – Food Groups - pp Do Qs 1-6 on p 490

F.1: Food Groups F.1.1: Distinguish between a food and a nutrient

Food Any substance we deliberately take into our mouths and swallow. Any natural or artificial material intended for human consumption Contains one or more nutrients

Nutrient Component of food that is used by the body to provide energy Aide in growth and/or repair of tissue A lack of these nutrients may cause malnutrition

Major Nutrients Lipids Carbohydrates Proteins

Other Nutrients Vitamins Minerals Water

F.1: Food Groups F.1.2: Describe the chemical composition of lipids (fats and oils), carbohydrates, and proteins.

Major Nutrient - Lipids Fats and Oils are… Source of Energy Vital in constructing cell membranes

Major Nutrient - Lipids Contain C, H, O Esters of glycerol and 3 fatty acids – Aka triglycerides if

Triglycerides “R” group can be… SATURATED (no double or triple bonds) – Tend to be SOLIDS at room temperature – Tend to come from animal products – “Fat” Unsaturated (has one double or triple bond) – Tend to be LIQUIDS at room temperature – Tend to come from plant material – “Oil” Polyunsaturated (has multiple double or triple bonds) Nature of “R” group determines physical and chemical properties.

Which of these lipids is saturated? Unsaturated? Polyunsaturated ? A B  C 

Which of these lipids is saturated? Unsaturated? Polyunsaturated ? horthand_formula.PNG/220px-Fat_triglyceride_shorthand_formula.PNG Citations for images on previous slide

What about this one? mistry/c4x5fatmolecule.jpg

Which of these lipids is saturated? Unsaturated? Polyunsaturated ?

Major Nutrient - Carbohydrates Carbohydrates are… Source of Energy Vital in cell construction

Major Nutrient - Carbohydrates Empirical Formula = CH 2 O

Major Nutrient - Carbohydrates Simple Carbohydrates Monosaccharides = (CH 2 O) n>2 = simplest carbohydrates Ex: Glucose fructose

Major Nutrient - Carbohydrates Disaccharide – formed from condensation of 2 monosaccharides.

Major Nutrient - Carbohydrates Polysaccharides – formed from condensation of many monosaccharides. Starch

Major Nutrient - Proteins Proteins … build up, maintain, and replace tissues (muscles, organs, imunne system) in your body Primary component in hair and nails make enzymes, hormones, and other body chemicals building block of bones, muscles, cartilage, skin, and blood.

Major Nutrient - Proteins Contain C, H, O, and N… – And some contain P and S Are polymers of amino acids 22 important amino acids – 13 body makes, 9 are “essential”

Major Nutrient - Proteins

The R groups represent side chains of the amino acids involved and can be the same or different.

Food Chemistry Chapter 17 in Green / Damjii F.2: FATS AND OILS

Read F2 – Fats and Oils - pp Do Q 7-11 on p 491 Homework (Done in advance!)

F.2: Fats and Oils F.2.1: Describe the difference in structure between saturated and unsaturated (mono- and poly-unsaturated) fatty acids Remember… 3 molecules of fatty acids react with 1 molecules of glycerol to form a lipid

F.2: Fats and Oils F.2.2: Predict the degree of crystallization (solidification) and melting point of fats and oils from their structure, and explain the relevance of this property in the home and in industry.

F.2: Fats and Oils Melting point and hardness (degree of crystallization) depend on – Length of hydrocarbon chain Longer chain = greater molar mass = more vdW forces = higher mp – Degree of unsaturation More double bonds = crooked chains = less contact = fewer vdW forces = lower mp – Cis or trans conformation more cis = more crooked chains = less contact = fewer vdW forces = lower mp more trans = less crooked chains = more contact = more vdW forces (compared to cis) = higher mp

Triglycerides SATURATED (no double or triple bonds) – Tend to be SOLIDS at room temperature – Tend to come from animal products – “Fat” – Examples: Coconut oil Butter lard

Triglycerides Unsaturated (has one double or triple bond) – Tend to be LIQUIDS at room temperature – Tend to come from plant material – “Oil” – Examples Olive oil Canola oil Peanut oil Polyunsaturated (has multiple double or triple bonds) – Example Sunflower oil Corn oil Fish oil

F.2: Fats and Oils F.2.3: Deduce the stability of fats and oils from their structure. Unsaturated – More reactive, less stable – C=C double bond reacts with oxygen (auto- oxidation) Especially in sunlight (photo-oxidation) Margarine gets discolored – Hydrogenation – Degradation by microbes

F.2: Fats and Oils F.2.4: Describe the process of hydrogenation of unsaturated fats. Hydrogenation Addition of hydrogen – high pressure – Temp ~ 200 C – Nickel catalyst

F.2: Fats and Oils F.2.5: Discuss the advantage and disadvantages of hydrogenating fats and oils. A hydrogenated product is –more saturated… or fully saturated… –semi-solid or solid… Advantages of a hydrogenated product is – Form is more convenient for some cooking techniques – More stable (rate of oxidation is decreased) – Texture can be controlled ( hardness / plasticity) can be controlled

F.2: Fats and Oils Disadvantages: …. health related Mono- and poly-unsaturated are healthier for the heart than saturated fat. Partial hydrogenation can form trans-fats – trans-fats don’t occur naturally – difficult to metabolize – accumulate in fatty tissues of body – Increase levels of LDL chloesterol (associated with atherosclerosis… strokes… heart problems)

What is this? Olestra – a fat substitute that is not digested by the body Copyright © 1997 by Daniel J. Berger. alphysiology/websites/2005/castle/page2.htm&usg=__Cs_ytB4MhyvgZs-tnVxiYR1rCrM=&h=360&w=341&sz=16&hl=en&start=11&um=1&itbs=1&tbnid=24- OiiaHITJTsM:&tbnh=121&tbnw=115&prev=/images%3Fq%3Dunsaturated%2Bfat%2B(ester)%26um%3D1%26hl%3Den%26safe%3Dactive%26rlz%3D1R2RNTN_enUS347%26tbs%3Disch:1