chem 100
chapter 11-- Food and Nutrition
parts 1-5 only
exam will not cover in greater detail than this outline
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carbohydrates
starch and sugars
- generally C + H + O (2:1 H:O ratio)
- sugars are energy source mainly
- glucose (C6) in bloodstream
- fructose, isomer, much sweeter
- sucrose (table sugar, C12)
- can split: glucose and fructose
starch-- polymer
- string of C6 sugars
- still good energy source, easier to store
- saliva and stomach splits starch
corn syrup
corn meal (starch)
hydrolyzed (split)
sweetener
high fructose sweet, fewer calories
cellulose-- also a polymer of simple sugar units
- stiff, structural material in plants
fats and oils
- distinction: fats are solid at room temperature
- oils are liquids
- come from both plants and animals
- animals generally yield fats
- fish often yield fats or oils
- plants more often yield oils
- mostly found in seeds
-
- recall ester- carboxylic acids, alcohols
- glycerol (also called glycerin)
- 3 C atoms, 3 OH groups
- fats are triglycerides
- acid chains are typically 12-20 carbons in length
-
- soap-- cook fat in NaOH solution
- split esters
- get glycerin
- get salt of long carbon acid chain
- that's a soap
- ionic end likes water
- carbon chain likes oils
- can get dirty oils from clothing
- also reduces surface tension
-
- saturated and unsaturated acids
- carbon chain-- does it contain double bonds?
- no- saturated fat
- yes-- unsaturated fat
- many -- polyunsaturated fat
- structurally, saturated fats are more rigid/ solids
- corn oil unsaturated
- treat with hydrogen
- adds across double bond
- becomes saturated
- turns into a solid
- (Crisco, margarine)
-
- medically, polyunsaturated fats are better for you
- however, US diet generally has far too much of all fats
- fats add to taste
- fats are metabolized (ok)
- excess fats get stored by the body (generally bad)
- fats are essential to some cooking
- deep fat fried crispness
- prevent burning
- selection of fats
- some bad choices: palm oil, lard, coconut, butterfat, beef tallow
- (often used to fry french fries)
- better: canola, safflower, olive oil, avocado oil, fish oils
Olestra (PPG)
- almost fat, but body can't metabolize
- passes through
- (does extract oil sol. vitamins/other problems)
cholesterol
- more complex material
- forms coating on arteries, obstructs flow of blood
- major cause of Coronary Artery Disease
- strokes, heart attacks
- labeled on foods
- irony-- body doesn't absorb from food
- tends to make its own (from diet)
- can be controlled
-
proteins
- polyamides, discussed in the polymer chapter
- from amino acids
- 20 amino acids used
- 9 essential amino acids
- body does NOT make most of these
- we need to eat directly
- protein we eat
- digestion separates the amino acids
- used to make new protein
- (excess is metabolized)
- why drugs like insulin not available as pills
- vegetarian diet--
- can be low in specific amino acids
- lysine is one key species
- balanced diet can get enough of all species
- meat protein
- roughly matches our dietary need
- not too surprising
- wide range of functions
- muscle
- hair and nails
- enzymes
- part of bone
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