What’s

 in  a  Twinkie?  

Lesson  2  –  1.8.15  
 Learning  Objec=ves  
2.1  –  Explain  how  the  proper=es  of  water  (hydrogen  
bonds  and  pH)  affect  food  molecules  
2.2  –  Compare  and  contrast  the  structures  and  
proper=es  of  carbohydrates,  fats,  and  proteins  and  
give  examples  of  each  
2.3  –  Predict  how  a  food  molecule  might  change  if  
exposed  to  different  condi=ons  
 Key  terms  
Know definitions and how to apply them

•  Hydrogen  bond   •  Starch   •  Smoke  point  

•  Polar   •  Cellulose   •  Protein  
•  Non-­‐polar   •  Fat   •  Amino  acid  
•  pH   •  Lipid   •  Denature  
•  Carbohydrate   •  Hydrophobic   •  Coagulate  
•  Monosaccharide   •  FaWy  acid   •  Enzyme  
•  Polysaccharide   •  Glycerol  
•  Hydrophilic   •  Unsaturated  fat  
•  Glucose   •  Saturated  fat  
•  Sucrose   •  Double  bond  
 What  would  happen  if  you  only  ate  
Twinkies  for  10  weeks?  
Mark Haub of Northwestern did this (plus other snack foods)
He lost 27 pounds
He only had 1800 Calories/day (needed 2600 Calories/day)
But was he healthier?
How do you know what's in a Twinkie?
 Enriched  Bleached  Wheat  Flour  [Flour,  Reduced  Iron,  B  
Vitamins  (Niacin,  Thiamine  Mononitrate  (B1),  Riboflavin  
(B2),  Folic  Acid)],  Corn  Syrup,  Sugar,  High  Fructose  Corn  
Syrup,  Water,  ParLally  Hydrogenated  Vegetable  and/or  
Animal  Shortening  (Soybean,  CoNonseed  and/or  Canola  
Oil,  Beef  Fat),  Whole  Eggs,  Dextrose.  Contains  2%  or  Less  
of:  Modified  Corn  Starch,  Glucose,  Leavenings  (Sodium  
Acid  Pyrophosphate,  Baking  Soda,  Monocalcium  
Phosphate),  Sweet  Dairy  Whey,  Soy  Protein  Isolate,  
Calcium  and  Sodium  Caseinate,  Salt,  Mono  and   Carbs
Diglycerides,  Polysorbate  60,  Soy  Lecithin,  Soy  Flour,  
Cornstarch,  Cellulose  Gum,  Sodium  Stearoyl  Lactylate,  
Natural  and  ArLficial  Flavors,  Sorbic  Acid  (to  Retain  
Freshness),  Yellow  5,  Red  40.   Water  not  listed  
How  many  of  these  are  carbohydrates?  Fats?  Proteins?  
 O
Water  
H
Freezes  at  32oF  (0oC)  
H Boils  at  212oF  (100oC)  
Freezing/boiling can have huge effects on food

Meat  
~60%  
water  

hWp://www.oilyskinblog.com/wp-­‐content/uploads/2013/03/Vegetables-­‐Fruits-­‐Water-­‐Hydra=on.jpg  
 What  does  it  mean  that  water  is  polar?  
A  –  An  en=re  water  
molecule  is  nega=vely  
charged  
B  –  An  en=re  water  
molecule  is  posi=vely  
charged  
C  –  Part  of  a  water  molecule  
is  nega=vely  charged  and  
part  is  posi=vely  charged  
O  
 
 
The oxygen end is more negative, while
the hydrogen end is more positive. H   H  
Water,  
acids,  
and  
bases  

•  pH  is  a  measure  of  how  many  hydrogen  ions  

are  in  a  solu=on  
•  Most  foods  are      slightly acidic

•  pH  can  affect  taste,  molecular  structure,  and  

food  texture  
 What  are  common  kitchen  ingredients  
used  to  change  pH  of  food?  
•  Make  food  acidic:  
–       lemon juice / citrus
tomato juice
–      vinegar
alcohol
–      milk
cream of tartar

•  Make  food  basic  (alkaline):  

–      baking soda
 pH  scale  and  food  
•  Put  the  following  common  food  items  in  order  
from  lowest  pH  to  highest  pH  
3.3 6.5
 
3.0

8.0
7.5

7.2 The whole egg is a bit acidic,

but egg white is basic.
 Which  statement  about  
carbohydrates  is  FALSE?  
A  –  Carbohydrates  are  aWracted  to  water  hydrophilic
loving)
(water

B  –  Starch  is  a  polysaccharide  made  of  glucose  

C  –  Cellulose  is  a  polysaccharide  made  of  glucose  
D  –  Carbohydrates  are  made  up  of  only  carbon  
and  oxygen  atoms   Also has hydrogen atoms

 
Carbs are polar (hydrophilic; like dissolves like)

Starch/cellulose are made of long chains of glucose

Glucose
 Do  all  carbohydrates  dissolve  in  water?  
Different structures mean that they have different
Why  or  why  not?   properties

Sucrose (sugar) Corn starch

polysaccharide Fiber (cellulose)
disaccharide Didn't dissolve (just
Dissolved Didn't dissolve (just floated)
a suspension)
 What  can  you  conclude  about  this  fat?  

A  –  It  is  made  up  mostly  of  

saturated  fats  
B  –  It  is  made  up  mostly  of  
unsaturated  fats  
C  –  It  is  made  up  mostly  of  
trans  fats  
What  are  fats  made  of?   Three fatty acid plus one glycerol
Do  fats  mix  with  water?   No; oil is hydrophobic
Oil is non-polar, water is polar

What  is  true  about  the  

fat  on  the  right?  
A  –  it  is  saturated  
B  –  it  is  monounsaturated  
C  –  it  is  polyunsaturated  
What  is  true  about  the  
fat  on  the  right?  
A  –  it  is  solid  at  room  temperature  
B  –  it  is  liquid  at  room  temperature  
 Saturated  &  unsaturated  fats  
•  Refers  to  number  of  double  
bonds  in  faWy  acids   this double bond
–  FaWy  acids  1  and  2  are       doesn't count
for determining
saturated (no double bonds)
  sat/unsat fat

–  FaWy  acid  3  is  unsaturated

 near
  the kink),
(double bond
missing some H's
–  Overall  this  fat  would  be  
called  a      monounsaturated fat
•  Satura=on  affects  fluidity  at  
room  temperature  
Saturated fat is solid at room temperature
–     
(Straight, so the fatty acids can pack together well)
Heating saturated fast makes them liquid
   
Unsaturated fat is liquid at room temperature
(1+ has kink, can't pack, more free to move)
Polyunsaturated fat means that there's multiple double bonds 1      2                        3  
 What  is  true  about  the  fat  on  
the  right?  
A  –  it  is  unsaturated  and  solid  at  room  
temperature  
B  –  it  is  saturated  and  liquid  at  room  
temperature  
C  –  it  is  saturated  and  solid  at  room  
temperature  
D  –  it  is  unsaturated  and  liquid  at  room  
temperature  
no  double bonds or kinks, so saturated and solid at room temperature

ie of saturated fat: bacon fat

Fats  don’t  turn  to  gas  –  they  smoke!  
hWp://www.youtube.com/watch?v=ibDb07BNVGg  
Experiment:  Heated  different  oils  for  different  periods  of  =me,  
measured  smoke  point  of  the  oil  

Which  oil  has  the  highest  smoke  point  at  all  fry  =mes?  
A  –  High  oleic  rapeseed  oil  
B  –  Par=ally  hydrogenated  rapeseed  oil  
C  –  High  oleic  sunflower  oil  
D  –  Palmolein  oil  
Experiment:  Heated  different  oils  for  different  periods  of  
=me,  measured  smoke  point  of  the  oil  

What  statement  about  these  data  is  TRUE?  

inversely proportional
A  –  As  fry  =me  increases,  smoke  point  decreases   (negatively correlated)
B  –  As  fry  =me  increases,  smoke  point  increases  
C  –  As  fry  =me  decreases,  smoke  point  decreases  
proportional (positively correlated)
 Which  statement  about  
proteins  is  FALSE?  

A  –  Proteins  are  chains  of  amino  acids  

B  –  All  proteins  are  hydrophilic   Proteins in cells (even cucumber has protein)
They're hydrophilic and hydrophobic (depending on the side groups)
C  –  Protein  func=on  depends  on  protein  structure  
D  –  Enzymes  are  a  type  of  protein  

20  different  R  groups  =  20  different  amino  acids  

Proteins  have  levels  of  structure  
Primary structure
Amino
acids Amino acids

Secondary structure
Hydrogen
bond

Tertiary structure

Quaternary structure
Protein  func=on  depends  on  structure  

Myoglobin Collagen
Stores oxygen in muscles Provides structures in tendons
and skin
•  What  factors  affect   Salt, heat/temperature, pH
protein  structure?  
•  What  happens  if     Protein becomes denatured
(loses its shape)
temperature  increases  too  
much  or  pH  or  salt  
changes  too  much?    
•  Denatured  proteins  can  
then  coagulate  and  form  
new  structures  

hWp://www.sumanasinc.com/webcontent/anima=ons/content/proteinstructure.html  
How  does  temperature  affect  enzyme  
func=on?  
Enzymes are proteins that are catalysts

Draw  a  graph  for  how  temperature  affects  

enzyme  func=on  
Enzyme  func=on  

the enzyme function accelerates

before stopping

Temperature  
 Which  graph  is  correct?  
A   B  

Enzyme  func=on  
Enzyme  func=on  

C   Temperature   D   Temperature  

Enzyme  func=on  
Enzyme  func=on  

Temperature   Temperature