chapter 11-- Food and Nutrition

parts 1-5 only

exam will not cover in greater detail than this outline

• carbohydrates
  • starch and sugars
  • generally C + H + O (2:1 H:O ratio)
  • sugars are energy source mainly
    • (calorie source)
  • glucose (C6) in bloodstream
    • food for muscle, etc.
  • 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
    • body accepts as glucose
• 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
      • stomach would destroy it
  • 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