2. Angelica Adraneda Carla Cadwallader
Charissa Marie Agustin Norilene Cayabyab
Reylan Vence Almarez Keisha Mae Dabu
Jance Venice Biliran

3. ● Carbohydrates, or saccharides, are
sugars and starches, which provide
energy for humans and animals, and
cellulose which make up many plant
structures.
● Carbohydrates are polyhydroxy aldehydes
or ketones and yield these products upon
hydrolysis. Carbohydrates are represented
by the general formula Cn(H2O)n and

4. Functions of Carbohydrates in human
body:
●
Carbohydrate oxidation provides
● Carbohydrates storage, in the form of glycogen,
provides a short-term energy reserve.
● Carbohydrates supply carbon atoms for the
synthesis of other biochemical substances
(proteins,lipids, and nucleic acids.)
● Carbohydrates form part of the structural
framework of DNA and RNA molecules.
● Carbohydrates linked to lipids are structural
components of cell membranes.
● Carbohydrates linked to proteins function in a
variety of cell-cell-molecule recognition process.

5. Test for Carbohydrates
● Molish Test
● Iodine Test
● Benedict's and Fehling's Test.
● Seliwanoff's Test
● Barfoed's Test
● Osazone Test

6. Principles behind the test of
Carbohydrates
● Molisch Test-When carbohydrates are
exposed to concentrated H2SO4 in the
presence of heat of dilution, they undergo
dehydration to form furaldehyde
derivatives. Hexoses form hydroxymethyl
furaldehyde. It condenses with a-naphthol
to form a colored chromogen.

7. Iodine Test
● Starch is made up of two polysaccharides
fractions amylase and amylopectin. Iodine is
trapped inside the helix and the complex is
responsible for the blue color. On heating, the
helical coil unwinds, which is equivalent to
denaturation. Iodine is released and the color
disappears. On cooling, renaturation takes
place and iodine is again bound to the reformed
helix.

8. Fehling's Test and Benedict's Test
● Under alkaline conditions, reducing sugars
tautomerize to enediol. These reducing sugars
cupric to cuprous ion. The cuprous hydroxide
formed is then converted to brick-red cuprous
upon heating

9. ● If reducing sugars are present, the
solution should begin to change
colors as a rust or red colored
precipitate forms. If reducing
sugars are not present, the
solution will remain blue or green.

10. Seliwanoff's Test
● The principle of the test is the formation of
hydroxymethyl furaldehyde and its
condensation with resorcinol, which forms a
colored chromogen.

11. Barfoed's Test (Modified)
● Under slightly acidic conditions,
monosaccharides easily reduce Cu+² to Cu+.
On treatment with phosphomolybdic acid, Cu+
reduces colorless phosphomolybdic acid to blue
phosphomolydous acid.

12. Osazone Test
● When reducing sugars are treated with
phenylhydrazone first, phenylhydrazone is
formed. On heating, the hydrazone further
reacts with phenylhydrazone to form
osazones.

13. Reducing and Non Reducing
Sugar(s)
● Reducing Sugars-Sugars that contain
aldehyde groups that are oxidised to
carboxylic acids.
● Non-Reducing Sugars-a carbohydrate that is
not oxidized by a weak oxidizing agent (an
oxidizing agent that oxidizes aldehydes but
not alcohols, such as the Tollen’s reagent) in
basic aqueous solution.
e.g sucrose, which contains neither a
hemiacetal group nor a hemiketal group and,
therefore, is stable in water.

14. ● Molisch Test-is a sensitive chemical test
for all carbohydrates, and some
compounds containing carbohydrates in a
combined form, based on the dehydration
of the carbohydrate by sulfuric acid to
produce an aldehyde which then
condenses with the phenolic structure
resulting in a red or purple-colored
compound.

15. ● Shows positive test
for:
All carbohydrates.
Monosaccharides give a
rapid positive test. Di
saccharides and
Polysaccharides react ● Reactions:
slower.
The test reagent
dehydrates pentoses to
form furfural (top reaction)
and dehydrates hexoses
to form 5-hydroxymethyl
furfural (left reaction). The
furfurals further react with
-naphthol present in the
test reagent to produce a
purple product

16. Violet ring means Carbohydrate is
present.

18. ● Observation: In hydrolysis, Disaccharides
hydrolyzed into simple sugar.
● Monosaccharides do not hydrolyzed because
they are simpler enough to undergo this
process.
● Positive color: brick precipitate

19. ● Glucose, Fructose and Galactose are the
sugars that are obtained through hydrolysis.
● Upon hydrolysis, sucorse hydrolyzed into
glucose and fructose; maltose into 2 moles of
glucose units; lactose into glucose and
galactose.

20. ● it is a qualitative test for detection of
polysaccharides.
● Iodine complexes with polysaccharides. Starch
form a blue-black product, while
● glycogen and partially hydrolysed starch give
red-brown color. As some of the
polysaccharides
● are not water soluble a suspension or a solid
can be directly tested by placing the iodine
solution

21. Shows positive test for:
● Starch
A positive test is indicated by: formation of blue-
black color. (bottom left shows positive result,
while bottom right is the control test.)
● Another example of
formation of blue-black
complex(bottom right).

22. Bial’s Test is to determine the presence of pentoses
(5C sugars). The components of this
reagent are resorcinol, HCl, and ferric chloride. In this
test, the pentose is dehydrated to
form furfural and the solution turns bluish and a
precipitate may form.

23. ● A positive test is indicated by: The formation of
a bluish. All other colors indicate a negative
result for pentoses. (Note that hexoses
generally react to form green, red or brown
products.)

24. ● Barfoed’s reagent, cupric acetate in acetic acid,
is slightly acidic and is balanced so that is can
only be reduced by monosaccharides but not
less powerful reducing sugars. Disaccharides
may also react with this reagent, but the
reaction is much slower when compared to
monosaccharides.

25. ● Shows positive test for: Reducing
Monosaccharides
● Reactions:reducing monosaccharides are
oxidized by the copper ion in solution to form a
carboxylic acid and a reddish precipitate of
copper (I) oxide within 3 minutes. Reducing
disaccharides under the same reaction but do
so at a slower rate.

26. ● The formation of reddish precipitate
(top right) indicate positive result.

27. ● Benedict's test allows us to detect the presence
of reducing sugars (sugars with a free aldehyde
or ketone group). All monosaccharides are
reducing sugars; they all have a free reactive
carbonyl group. Some disaccharides have
exposed carbonyl groups and are also reducing
sugars. Other disaccharides such as sucrose
are non-reducing sugars and will not react with
Benedict's solution. Starches are also non-
reducing sugars. The copper sulfate (CuSO4)
present in Benedict's solution reacts with
electrons from the aldehyde or ketone group of
the reducing sugar to form cuprous oxide

28. ● Benedict's Test
● Shows positive test for: Reducing Sugars
The formation of a reddish precipitate indicates
positive result
● Reactions:
Reducing sugars are oxidized by the copper ion in
solution to form a carboxylic acid and a reddish
precipitate of copper (I) oxide.

29. ● Glucose,Galactose and
Fructose gives positive
result while sucrose
shows negative result.

30. ● Seliwanoff’s Test distinguishes between aldose
and ketose sugars. Ketoses are distinguished
from aldoses via their ketone/aldehyde
functionality. If the sugar contains a ketone
group, it is a ketose and if it contains an
aldehyde group, it is an aldose. This test is
based on the fact that, when heated, ketoses
are more rapidly dehydrated than aldoses..

31. ● Reactions: The test reagent dehydrates
ketohexoses to form 5-hydroxymethylfurfural. 5-
hydroxymethylfurfural further reacts with
resorcinol present in the test reagent to produce
a red product within two minutes. Aldohexoses
react to form the same product, but do so more
slowly.
● Show positive test for: Ketoses

32. ● The dehydrated ketose then reacts with the
resorcinol to produce a deep cherry red color (top
right). Aldoses may react slightly to produce a
faint pink color.

33. ● Has function in identifying the aldehyde or
hemiacetal group that will be oxidated by
tollens reagent. Tollens' reagent is a chemical
reagent most commonly used to determine
whether a known carbonyl-containing
compound is an aldehyde or a ketone.

34. ● The Solution that produce positive is glucose and
fructose, but the lactose, sucrose and sample is
negative in result.
● Postive result will yield
silver mirror appearance.

35. ● Carbohydrate specific reaction in which carbs
react with phenylhydrazine to form osazones
i.e. crystals of specific shape,thus the test
confirms the presence of a particular sugar.
● This is a test for reducing carbohydrate,
reducing disaccharides and many
monosaccharides to be identified with the
formation of osazone crystals.

36. ● Color Reaction: C-Osazone Test: this test is for
lactose. Sugar is heated with phenyl hydrazine
hydrochloride, sodium acetate and acetic acid.
Yellow crystals of Osazone are formed. D-
Resorcinol test for ketoses: Crystals of resorcinol
are added to solution and heated with equal
volume of concentrated HCL. Pink color is
formed.

37. ● Positive Test: Carbohydrates and 1,2-diols.
● Osazone Formation involves hydrazone formation
at C-1 of an aldose (or C-2 of ketose) and
oxidation of C-2 (or C-1) of an alcohol group of a
ketone (or an aldehyde).

40. Hans Molisch
● Hans Molisch (December 6, 1856, Brünn,
Habsburg Moravia - December 8, 1937, Wien,
Austria) was a Czech-Austrian botanist.
● He taught as a professor at the German
University of Prague (1894-), Vienna University
(1909-1928), Tohoku Imperial University (now
Tohoku University, Japan; 1922-1925), and a
university in India.
● Hans Molisch expanded on Julius von Sachs's
work by developing ´starch pictures´ in intact
leaves by using actual photographic negatives
as masks over the illuminate leaves.

41. Bernard Coutois
● Bernard Courtois, also spelled Barnard
Courtois, (12 February 1777–27 September
1838) was a French chemist born in Dijon,
France.
● Courtois was extracting sodium and potassium
compounds from seaweed ash. Once these
compounds were removed, he added sulfuric
acid (H2SO4) to further process the ash. He
accidentally added too much acid and a violet
colored cloud erupted from the mass. The gas
condensed on metal objects in the room,
creating solid iodine. Today, iodine is chiefly

42. Stanley Rossiter Benedict
● Stanley Rossiter Benedict (17 March 1884 –
21 December 1936) is an American chemist
best known for discovering Benedict's reagent,
a solution that detects certain sugars.
● Benedict was born in Cincinnati, and went to
the University of Cincinnati. After a year, he
went to Yale's Department of Physiological
Chemistry for training in metabolism and
physiology.

43. Hermann von Fehling
● Hermann von Fehling, born 1812, discovered
Fehling's solution as an oxidizing agent and
an analytical reagent for aldehydes and
sugars; elucidated composition of paraldehyde
and metaldehyde; prepared phenyl cyanide.

44. Christen Thomsen Barfoed
● Christen Thomsen Barfoed (June 16, 1815 –
April 30, 1899) was a Danish chemist who
devised a way to detect monosaccharide
sugars in a solution, now known as the
Barfoed's test. Barfoed is also credited with
having introduced systematic chemical
analyses in Danish agricultural sciences.

45. Emil Fischer
● The famous German chemist Emil Fischer
developed and used the reaction to identify
sugars whose stereochemistry differed by
only one chiral carbon. It is used in
Osazone test.

46. Manfred Bial
● Manfred Bial (1869–1908) was a German
physician who invented a test for pentoses
using orcinol, now known as Bial's test.

47. Heinrich Hlasiwetz
● Austrian chemist Heinrich Hlasiwetz (1825-
1875) is remembered for his chemical analysis
of phloroglucinol.

48. ● Reference(s):
● http://www.pua.edu.eg/Version2/Courses2/Dentistry
● http://www.chem.boun.edu.tr/webpages/courses/Ch
● http://www.esu.edu/~scady/Experiments/Carbohydr
● http://www.authorstream.com/Presentation/raniasho
● http://en.wikipedia.org