1. Carbohydrates

2. Carbohydrates: Energy molecules
Polyhydroxy aldehydes or ketones or a molecule that yields a polyhydroxy aldehyde or ketone upon hydrolysis.
Consist of carbon, hydrogen, & oxygen.
Basic building block is monosaccharide
(CH2O)n ; n = 3,5,6, etc…
Functions:
Quick energy
Energy storage
Cell wall structure
in plants
So, What about Acetic Acid [CH3COOH] 2:1
Lactic Acid [C3H6O3] :1
Mono: one
Di: two
Saccharide: sugar

3. Minerals of gluconates are used as nutritional supplements (Nutraceuticals)
 more soluble than mineral salts.

4. Classification of Carbohydrates Sugars Polysaccharides
Monosaccharides
Homopolysaccharides
Pentoses e.g. Arabinose
Glucosan
Hexoses e.g. Glucose & fructose
Fructosan
Disaccharides
Reducing e.g lactose & maltose
Oligosaccharides
Non-reducing e.g sucrose
Heteropolysaccharides
Trisaccharides
Tetrasaccharides

5. General Physical characters of carbohydrates
Sugars
Polysaccharides
White
Crystalline
Sweet
Soluble in cold H2O
Soluble in dil. alcohol
Yellowish white (except…)
Amorphous
Tasteless
Insoluble in cold H2O
Insoluble in dil. alcohol

6. General chemical tests
Procedure
(+ve) with
Molisch’s
1 ml CHO slou.
(Supersaturated)
+ 3 dps alc. α-naphthol
+ Drop wise 1ml Conc. H2SO4 on wall of t.t
Violet ring
All CHO.
- Ve with gelatine (not CHO, protein in nature forming gel)
Principle
H2SO4 either act as;
Hydrolysing agent (Oligosacc.,Polysacc. Monosacc.)
Dehydrating agent (Monosacc.)
Furfural and its derivatives
(+ alc. α-naphthol) Violet

7. Test Procedure Remarks Fehling’s 1ml Feh. (A) + 1ml feh. (B)
+ 2ml CHO solu
Direct flame 
Red, yellow, orange indicate positive test
Positive with
all reducing sugars
(glucose, fructose, lactose, maltose)
N.B. negative result
With sucrose (non reducing)
Principle
Feh. A: (CUSO4 + H2O)
Feh. B: (Na .K.Tartarate (Rochelle's salt) + NaOH)
Reducing sugar reduce CUSO4 (fehling A)
in presence of alkaline media (fehling B) Cuprous oxide ppt. (red in colour)

8. Test Procedure Remarks Barfoed’s (Supersaturated) +3 ml barfoed’s 
1 ml of conc. sugar solu
(Supersaturated)
+3 ml barfoed’s 
water bath
Faint red ppt. on base of t.t
Positive with
strong reducing sugars 0nly
(Monosaccharides)
(glucose / fructose)
Principle
Barfoed’s consist of (5 % cu acetate in water + glacial acetic acid)
Strong reducing sugar in acidic media
reduce cu acetate cuprous oxide ppt.
(Faint red)

9. Test Procedure Osazone (phenyl hydrazine test)
1 ml sugar soln. (Supersaturated) + 3 ml osazone soln.  shake well  boiling W.B
If ppt. appear after 15 min (Glucose,fructose ………monosaccharide)
If no ppt. appear after 30 min, (reducing disaccharides)
Remarks
Positive with all reducing sugars
(glucose, fructose (ppt. on hot after 15 min)
(lactose, maltose (ppt. on cold after 30 min)

10. Test Remarks Molisch`s Fehling`s Barfoed`s Osazone All CHO
Positive with
all reducing sugars
(glucose, fructose, lactose, maltose)
Barfoed`s
strong reducing sugar 0nly
(glucose / fructose)
Osazone
Positive with all reducing sugars
(glucose, fructose (ppt. on hot after 15 min)
(lactose, maltose (ppt. on cold after 30 min)

11. Sugars
Monosaccharides

12. Monosaccharides Building unit of carbohydrates
Not hydrolysable into simpler CHO
STRONG reducing character

13. General Chemical Tests
1-Molisch’s test ???
2- Fehling’s test ???
3- Barfoed’s test ???
4- Osazone (phenyl hydrazine test) ???

14. Special Chemical Tests Red stain on the paper strip
Sugar
Test
Result
5 C
Arabinose
Aniline acetate test
2ml sugar soln. +
2ml 12% HCL
 Hang moisten strip with aniline acetate on top of t.t
 Close t.t with piece of cotton
 On boiling W.B
Red stain on the paper strip
Pentose

15. Hexose Lead sub-acetate test Glucose Aldose Rapid furfural test
2ml of glucose soln. +
3ml of Pb Sub.Acetate +
0.5 ml of conc. NH3
 Shake well  Careful heating on direct flame
Pink-red color
Fructose
Rapid furfural test
2 ml Sugar soln. +
resorcine (few spikes 2-3) +
2ml (12 % HCL) 
 Shake well  direct flame
deep red color before boiling
Aldose
Hexose
ketose

16. Exercise Test Glucose Fructose Arabinose Comment Molisch’s ------
Fehling’s
Borfoed’s
Osazone
Special test