Lecture 7 Macronutrients FAT

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Lecture 7 Macronutrients - FAT
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Dietary Fat

• requirements
• energy value
• types
• related health issues

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Dietary Fat

• RDI
• lt 35 of Etotal general
• lt 30 of Etotal athletes
• Energy potential
• 37 kJ/g fat
• (9 kcal/g fat)

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Fatty Acids

• basic unit FATTY ACID
• a hydrocarbon chain
• carboxyl group (COOH) at one end
• methyl group (CH3) at other end
• gt 40 fatty acids in food

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Structure of Fatty acid molecule

• H H H H H H H O
• H C C C C C C C C OH
• H H H H H H H
• Methyl end Carboxyl end
• (Omega end) (Alpha end)

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Fatty Acids

• even number of CARBONS in chain
• 2 - 24 carbons in length
• simplest Acetic Acid (2 carbons)
• Vinegar

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Fatty Acids

• Acetic Acid is a two-carbon organic acid
• H O
• Methyl H C C OH Acid
• end end
• H

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Lipids

• Triglycerides
• storage fat
• food fat
• Phospholipids
• fat in cell walls

• Sterols
• cholesterol
• hormones

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Lipids

• insoluble in water
• soluble in organic solvents
• eg. chloroform, ether, alcohol
• oil liquid fat
• eg. Olive oil liquid triglycerides

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Fats in Food

• Visible fat
• butter
• margarine
• vegetable oil
• lard (dripping)
• cream
• fat on meat

• Hidden fat
• chicken skin
• marbled meat
• cakes
• fast-food

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Fatty Acids

• 3 types of fatty acid

• Saturated
• no double bonds between carbon atoms
• animal fat
• palm oil
• coconut oil

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Saturation

• H
• H C H
• H

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Saturated Fatty Acid
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Saturated Fat In Selected Foods

• Food Saturated fat (g/100g)
• Coconut - fresh 30
• - desiccated 54
• Butter 45
• Potato chips
• - cooked in palm oil 47
• - cooked in general veg oil 10
• Beef
• - lean 3
• - marbled 8-20

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Fatty Acids

• Polyunsaturated
• many double bonds between carbon atoms
• margarine
• some vegetable oils
• Sunflower
• Safflower

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Poly-unsaturation

• H H H H O
• H C C C C C C OH
• H
• more than ONE double bond between carbon atoms

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Polyunsaturated fatty Acid

• Structure of a polyunsaturated fatty acid
• FIGURE 5.6 P160 Whitnry Rolfes

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Fatty Acids

• Monounsaturated
• one double bond between carbon atoms
• olive oil
• peanut oil
• canola oil (rape seed oil)

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Mono-unsaturation

• H O
• H C C C C OH
• H H H
• Only ONE double bond between carbon atoms

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Monounsaturated Fatty Acid
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Fatty Acids

• HYDROGENATION
• adding of hydrogen atoms to a polyunsaturated or
  monounsaturated fat
• makes the fat more saturated
• makes the fat more solid
• (? more spreadable)

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Fatty Acids

• HYDROGENATION cont
• saturated fats are more resistant to oxidation
  (rancidity)
• produces trans - fatty acids
• relationship between heart disease trans -
  fatty acids

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Hydrogenated Fatty Acid
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Recommended Reading

• Whitney Rolfes (2005)
• Understanding Nutrition 10th Ed.
• Chapter 5. The Lipids
• The Chemists view of Triglycerides Fatty Acids
• Wahlqvist (2002)
• Food Nutrition
• Chapter 13. Fats