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NAME~e-1--- &^ UFID
EXAM I
FOS
Spring, 2008
Your signature and UF ID on the following pages of the exam verify that you have received all questions. You should have 7 pages total, for 100 points plus 9 bonus points. Read each page carefully and give concise answers. If drawings or equations can help explain your answer by all means use them but make sure they are correctly represented.
PART I-WATER
(2 pt) What is so unique about water, enabling it to form strong H-bonds? a. Its full ionic character b. Its tetrahedral structure c. Its static nature d. Its dipole e. a and b are correct f. b and d are correct
(6 pt) Draw the structure of water to show how it can participate in H-bonding and describe briefly why? Does H-bonding ability of water change with temperature? If so,
then how? ~ e~~ () ~ i- ~ l* .-^ / I "^0 /^ I l-t.-k ht.tlr v\ 4- rut ~
~v~i
'·0- H ~ h II \ b()V-J~ .+0 ~ o~.v" \V~.A.- ~
/,
I~ o T l' t H-- \oo~ds
R..u.2/t1~ ~ H-~ ~ ~'2-oj
(3 pts) Is the following statement TRUE or FALSE? "Freezing a food slow will lead to few nuclei that give rise to many small ice crystals"
(2 pt) Adding a solute to water will a. depress the freezing point b. decrease the vapor pressure of water c. will raise the boiling point of water d. a& conly e. all of these are correct
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(4 pt) Mark the two statements below that describe the properties of a weak acid a. completely dissociates when put in solution b. partially dissociates when put in solution
c. can be described by the relationship pH = pKa + Log [salt]/[acid]
d. can be described by the relationship pH = -log[acid] e. none of these statements apply
(2 pt) Weak acids are important to food systems as a. flavoring agents b. for microbial control c. buffers for food systems d. all of these are correct e. none of these are correct
COO' +I-bN-C-H^ I COO· (^) I H-C-CI-b +H.3N ----J ---H (^) c~I I (^) I CH.3 CH. A B C
(6 pts) Draw what a theoretical titration curve would look like when one of the compounds above is titrated with a strong base (your choice). Label the pKa and isoelectric point on the graph and show what both axes represent. You get 2 bonus points if you can show the ionization of the selected compound during the titration process and 1 more for identifying the amino acid.
cco
Ji-\ o..YL~-e.. ( It)
~J-t_~ G'OD-
-^ I+.,fl^ -t.^ _ Coo
+ I1jN~ fk.2..
~1-3 (^) v~lr~E- ('?» e.ool-t o\HM 'Lo^ h..~_c..tru...^ (^ c.) ~1-
2
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NAME _ (^) & UF In _
PART II-CARBOHYDRATES
A^ c CH 2 0H CH^2 0H
I
c=o (^) B (^) H-C-OHI^ D
I
HO-C-H (^) I
I HO-C-H
H-C-OH (^) :CH20HO I
I H-C-OH
H-C-OH I 4 OH^1 *^ H-C-OHI CH 2 0H 3 2
OH ~ OH I OH OH
OH CH^2 0H
(3 pt) What is the name for carbohydrate A ~~ and what is the configuration ofthis sugm@'or L (circle)? Is this an aldose 018(circle)?
(3 pt) What is the name for carbohydrate B ~ ~ and is this ~r ~
configuration (circle)? What is the carbon cal ed where the star is? a.nl)tv'..I,...r~e-
(2 pt) What is the name for structure C 'Sorb l.....ot (choose from the box at right) and what is the general name for these types of structures? $V ~ oleo ~\ ~
(2 pt) List one benefit and one drawback of using compound C in food products
l--'~ ~ 'v.A.J-~
Mannitol Sorbitol Xylitol Glucuronic acid
(4 pt) What is the name for carbohydrate D ~s.e.? What monosaccharides form it OS~~ 0 ~ and the bond called between the two monosaccharides
4t'~
~ k"",w 9.~\e-
and what is ?
(2 pts) Which of the above are reducing sugars? ~l.U.C~ (p.» ~ ~ (11)
(3 pts) Rank the sweetness of glucose, sucrose, fructose and sucralose
4
(2 pts) What is this reaction called:
A.VUL~ll~,nu.u~
(1 pt) What is the name of the product from this reaction:
~v..tQ~
(2 pts) What is the starting carbohydrate: L. e..J..,.~ ct... (3 pts) Why is it not digested in the small intestines? -ru)-\ 1L1u-o~~ bA.t
J.~\i-.A- fLn~
(2 pts) What is the reaction called that converts glucose to a mix of glucose, mannose and fructose over time under alkaline conditions? a. mutarotation b. carmelization c. dehydration d. enolization e. none of the above (4 pts) What chemical reaction is occurring below? Is it catalyzed at low or high pH? How are the two end products of relevance to food products? H-o-OI H. H-.OH H-r- (^0) De-h~ d-roAl'\SI-. H-C-OH ~ (^) H-c-O..............I .. ~ 0-0I D- Glucose (^) Ho-c- H HOH H-C- H I I -^ L^0 vJ^ P--^ +.,.."^ ()^ ('^ ~ 1,2-EOOiol 3-Deoxy-D gluoosulose t- llOH HOH J:::yCHO...l- f,.CHO O-CHO HOH;<C 0 HOH:t!"O~OH
o 5-Hydroxyrret
Furfural furfural _ ~ ~cL.c..~ --\r.
~~~ ftOceA-d~c:l ~ \l.V.'(L
(4 pts) What two compounds can also be formed from this same reaction above that gives a baked bread flavor. -----"------, 5
BONUS (6 PTS)
Explain in words and with the use of drawings the chemical basis of carbohydrate sweetness. Why is it thought that fructose is sweeter than glucose? Why are molecules like saccharine and chloroform sweet?
A- 1-. ~ - 13 - --0'
-<(JJ.1lJf
~.. .. l-t _-,L_
7
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