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CARBOHYDRATES. Carbohydrate - polyhydroxy aldehyde, ketones and their derivatives. Functions - structure material storage material for carbon and energy. CONCEPTS OF ISOMERS . Two or more different compounds which contain the same number and types of atoms and the same molecular weights.

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slide1

CARBOHYDRATES

Carbohydrate - polyhydroxy aldehyde, ketones and their derivatives.

Functions - structure material storage material for carbon and energy.

slide2

CONCEPTS OF ISOMERS

Two or more different compounds which contain the same number and types of atoms and the same molecular weights.

Projection formula (spatial arrangement to represent 3-dimensional structure):

slide3

D-glyceraldehyde (hydroxy group at the highest numbered asymmetric carbon atom is written to the right):

L-glyceraldehyde (hydroxy group at the highest numbered asymmetric carbon atom is written to the left):

D-Erythrose is the mirror image of L-Erythrose.

slide4

Glyceraldehydes: Model compounds of monosaccharides

D-Glyceraldehyde L-Glyceraldehyde

D-Erythrose L-Threose

slide5

POLARIMETER

Dextrorotatory -plane polarized light rotated to clockwise (or to the right)

Levoratatory - plane polarized light rotated to counterclockwise.

slide6

FISHER PROJECTION FORM

Anomeric Carbon --- The carbon atom which is involved in hemiacetal or acetal formation.

slide9

OH

H

OH

H

C

C

H

C

OH

H

C

OH

O

HO

H

HO

C

H

C

O

H

C

H

C

OH

H

C

H

C

OH

CH

OH

CH

OH

2

2

H

O

C

H

C

OH

HO

H

C

H

C

OH

H

C

OH

CH

OH

2

HO

H

H

HO

C

C

H

C

OH

H

C

OH

O

HO

H

C

HO

H

C

O

H

C

H

C

OH

H

C

OH

H

C

CH

OH

2

CH

OH

2

HAWORTH PROJECTION FORMULAS FOR SUGARS

a

-D-Glucopyranose

(35%)

a

-D-Glucofuranose

(0.5%)

Aldehydo-D-glucose

(0.03%)

b

-D-Glucofuranose

b

-D-Glucopyranose

(0.5%)

(0.5%)

slide10

MONOSACCHARIDE

Hexoses

1. Glucose (dextrose) --- rotate the polarized light to the right.

slide11

Glucose (dextrose)

Most common monosaccharide.

Commercially from starch.

Cereal roots, legumes, animal tissue, and liver.

Mutarotation --- The optical changes of glucose in water solution to constant value

a20D = +520

a - D - glucose -> D - glucose <-b - D - glucose

a20D = 113 a20D = 52 a20D = = 19

At equilibrium = 35% of a - form and 65% of b - form.

slide14

Fructose (levulsoe)

CH

OH

CH

OH

2

2

OH

H

C

O

C

CH

OH

O

2

HO

HO

H

H

C

C

OH

H

H

O

C

C

OH

OH

OH

OH

H

H

C

OH

C

OH

OH

H

C

CH

OH

2

H

b - D - Fructofuranose a - D - Fructofuranose

Naturally-occurring free form

slide15

Disaccharides (anydrides of 2 monosaccharides):

Maltose: 4-0-a-D-Glucopyranosyl (1->4) a-D-Glucopyranose

slide16

Cellobiose

4-0-b-D-Glucopyranosyl (1->4)-b-D-Glucopyranose

slide17

Sucrose

2-0-a-D-Glucopyranosyl b-D-Fructofuranoside

Invert Sugar --- when sucrose in solution, the rotation changes from detrorotatory (+66.5) to levorotatory (-19.8). So, sucrose is called “Invert Sugar”. Sucrose has been hydrolyzed into glucose and fructose.

slide18

Lactose

Principal sugar in milk

4-0-b-D-Galactopyranosyl (1->4)-a-D- Glucopyranose

4-0-b-D-Galactopyranosyl (1->4)-b-D-Glucopyranose

slide19

RELATIVE SWEETNESS OF DIFFERENT SUGARS

Sucrose 100

Glucose 74

Fructose 174

Lactose 16

Invert Sugar 126

Maltose 32

Galactose 32

slide20

Oligosaccharide

Raffinose (Galactose + Glucose + Fructose)

6-0-a-D-Galactopyranosyl (1->6)-2-0-a-D-Glucopyranosyl (1->2)-b-D-Fructofuranoside

slide21

Stachyose (Galactose + Galactose + Glucose + Fructose)

6-0-a-D-Galactopyranosyl (1->6)-6-0-a-D-Galactopyranosyl (1-> 6) -2-0-a-D-Glucopyranosyl-b-D-Fructofuranoside

“Flatulence Factor”

slide22

POLYSACCHARIDE

Anhydrides of Monosaccharides Through ether b linkages.

Cellulose --- polymer of b-D-Glucose (1, 4) linkage.

Repeating cellobiose moiety.

slide23

STARCH

The reserve carbohydrate of plants. Occurs as granules in the cell. Made of amylose and amylopectin.

Amylose --- ploymer of a-D- Glucose (1->4) linkage-straight-chain.

slide24

Amylopectin

Polymer of a-D-Glucose (1->4) linkage in addition to a-D-Glucose (1->6) linkage.

The length of linear units in amylopectin is only 25.

a-(1->4) linkage (25) to a-(1->6) linkage.

slide25

GLYCOGEN

Animal starch.

a - (1 -> 4) linkage and a - (1 -> 6) linkage

12 : 1

slide26

PECTIN

Polymer of 4-0-a-D-Galacturonic acid (1 -> 4) & Methylgalacturonate

slide27

DEGREE OF METHYLATION (DM)

The higher the degree of methylation, the higher the temperature at which the gel forms.

For gel formation at least 50% of the carboxyl group are methylated. Pectin (about 74 DM) is used in jams. For jellies DM is about 60.

slide28

FUNCTIONAL PROPERTIES OF POLYSACCHARIDES (GUMS)

1. Viscosity control

2. Texture control

3. Emulsifying agent

4. Water-binding capacity

5. Stabilizer

slide29

CORN SYRUP

The higher the DE, generally the greater the glucose content in corn syrup.

slide30

HIGH FRUCTOSE SYRUPS

Generally: Glucose 50%

Fructose 42%

Maltose 1.5%

Isomaltose 1.5%

Higher Saccharides 5.0%

slide31

High Maltose Syrup

Low DE

High DE

Pentose

24

55

12

CORN SYRUP

% Dry Weight

Glucose

9

14

43

Maltose

52

12

32

Triose

13

10

3

Tetrose

2

9

5

slide32

MODIFIED STARCHES

1.  Pregelatinized Starch --- simple precooked and roll dried to give product that readily disperses in cold water.

2.  Thin-boiling or Acid-modified Starch --- suspending granular starch in a very dilute acid under somewhat below its gelatinization temperature (somewhat mild).

3. Oxidized Starches --- oxidation of starch with alkaline hypochloride to get -coo- at C6.

slide33

CARBOHYDRATE DETERMINATION

1. Monosaccharides and Oligosaccharides

A. Enzymatic Method

1. Glucose oxidase

2. Hexokinase

B. Chromatography Method

1. Paper or thin layer chromatography

2. Gas chromatography

3. Liquid column chromatography

2. Polysaccharides

slide34

Glucose Oxidase System

Glucose Oxidase

D-Glucose + O2 Gluconic Acid + H2O2

Peroxidase

H2O2+ 0 - Dianisidine 2 H2O + Oxidized 0-Dianisidine

(Colorless) (Brown)

slide35

Hexokinase System

Hexokinase

Glucose + ATP G - 6 - P + ADP

G - 6 - P DH

G - 6 - P + NADP+ Gluconate - 6 - phosphate + NADPH + H+

NADP+: (Nicotinamide Adenine Dinucleotide Phosphate)

The amount of NADPH formed in this reaction is stoichiometric with the amount of glucose.

NADPH is measured by its absorption at 334 nm.

slide36

QUALITATIVE ANALYSES OF CARBOHYDRATES

Thin Layer chromatography

Silica gel as stationary phase (250 mm)

Quantitative by densitomer (time - varies with solvent, generally overnight):

slide37

Gas Liquid Chromatography

Requirement: compounds must be volatile.

Sugars form Trimethylsilyl Ether:

Ether linkage Trimethyl chlorosilane

slide38

Liquid Chromatography

Carbohydrate Analysis (Waters Assocs. 840380 Stationary Phase)

Solvent: H2O/CH3CN

slide39

POLYSACCHARIDES

Usually, quantitation depends on chemical or enzymatic hydrolyses of them, followed by analysis of the monomers.

Starch

1. Amylose + I- -> Blue complex

Use spectrometer for determining the amylose - iodine blue color - according to spectrophotometric reading.

2. Amylopectin + I- -> Reddish color.