1. DISACCHARIDES
The disaccharides consists of two
monosaccharide units joined covalently by an
O-glycosidic linkage.

3. SUCROSE
Saccharose or table sugar
On hydrolysis yields one molecule each of D-glucose
and D- fructose.

4. Sucrose contains no free anomeric carbon
atom,therefore it is without reducing
properties,NON REDUCING SUGAR.

5. INVERT SUGAR
Sucrose is dextrorotatory,because glucose
and fructose(furanose form) are
dextrorotatory.
When sucrose is hydrolysed it becomes
levorotatory(its fructose is released in
pyranose form that is levorotatory).

6. Levorotatory activity of fructose is more than
glucose.
Because rotation is reversed the process is
called INVERSION and the products are called
INVERT SUGAR.

7. Inversion can be brought about by hydrolysis
with dilute acids or with specific enzyme called
invertase or sucrase(Mucosal lining the small
intestine).
Honey is rich in invert sugar.
Invert sugar is more sweeter than sucrose due
to the presence of free fructose.
Jams and jellies also contain invert sugar.

8. Source of sucrose is sugar beets
and sugar cane.
Caramel is solid residue produced by
heating sucrose.
used pharmaceutically to make syrups.

9. MALTOSE
It is formed by O-glycosidic linkage between one
molecule of α-D- glucose with another molecule of α-
D- glucose


10. Because of presence of free anomeric carbon
it is reducing sugar.
Malt sugar,present in germinating seeds.
Formed in vivo by the action of salivary
amylase on starch and in vitro by the partial
hydrolysis of starch by acids.
Used as fementive reagent.

11. ISOMALTOSE
Isomaltose is a disaccharide similar to
maltose, but with a α-(1-6)-linkage instead of
the α-(1-4)-linkage.
It is a reducing sugar.
The linkage between the sugars is 1,6.

12. LACTOSE
Contains O-glycosidic linkage between one
molecule of galactose with another molecule
of glucose.

13. Milk sugar,cows milk contains 5%
lactose,human milk contains 7%.
Contains free anomeric carbon so its reducing
sugar.
Lactase in mucosal cells hydrolyzes lactose to
its constituent monosaccharides.

14. Lactulose
galactose-b-(1,4)-fructose
a semi-synthetic disaccharide (not naturally
occurring)
not absorbed in the GI tract
used as a laxative to treat constipation.

15. Cellobiose consists of 2 molecules of glucose linked by a beta-1,4 glycosidic bond
It is usually obtained by the partial hydrolysis of cellulose

16. Trehalose is a disaccharide that occurs naturally in insects, plants, fungi, and bacteria.
The
major dietary source is mushrooms. Trehalose is used in bakery goods, beverages,
confectionery, fruit jam, breakfast cereals, rice, and noodles as a texturizer, stabilizer,
humectant, or formulation aid with a low sweetening intensity
Trehalose
O
CH2OH
H
O O
H
H
H
HO
H
OH
OH
H
OH H
H
OH
OH
H
HOH2C
TREHALOSE

17. OLIGOSACCHARIDES