1. Lecture XI Polysaccharides III
Classification, Structure, Function, Hydration/Dispersion
Lecture #11 - Polysaccharides III - Classifi-cation, Structure, Function, Hydration/Dis-persion - general overview (more specifics when get into individual gums)
NOTE: Info in these first few lectures on PSs very impt! Foundational! Principles you need to understand. Specifics on individual gums in future lectures.

2. Classification of PSs
By Source

4. Classification of PSs
Source
Structure
Composition
Properties
Other

6. Classification of PSs
4346

7. Structure/Function of PSs
Minor changes = Major effects
Amylose vs Cellulose, e.g.
Structure determines function
Similar to proteins

8. O
CH2OH OH n
Amylose O
CH2OH OH n
Cellulose

9. Primary Secondary Quatinary Tertiary
Kelco CR Sem
4345

10. Major Hexose Sugars (related to Glucose)6
CH2OH 5 O 1 4 OH OH OH 3 2
OH- to here =
Mannose
OH- to here =
Galactose OH
a-D-GLUCOSE
(a-D-Glucopyranose)

11. Distribution of CHO UnitsOH
COOH
b-D-Mannuronic Acid
a-L-Guluronic Acid
Polymer Structure: M G
Mannuronic Block
Guluronic Block
Mixed Block

12. Structure/Function of PSs
Importance of substituent
Kind of sugar
Branches
Charged groups

13. Structure/Function of PSs
Importance of glycosidic linkage
Polysaccharide Confirmations
Type A
E.g. b-1,4-glucan
a-1,4-galactan
b-1,4-mannan
Type B
E.g. a-1,4-glucan
b-1,4-galactan
a-1,4-mannan

14. Structure/Function of PSs
Glucose-based Polymers
Amylose & Amylopectin
Glycogen
Cellulosics
Chitin & Chitosan
Xanthan Gum
Gellan Gum

15. Segment of Linear Chain
Precipitate
Dilute
Solution
Segment of Linear Chain
Gel
Concentrated
Solution

17. O
CH2OH OH n
Amylose O
CH2OH OH n
Cellulose

18. Cellulose products used in foods
a Cellulose
Chemical
Derivatization
Chemical
Depolymerization
Wet Mechanical
Disintegration
Soluble
Cellulose
Derivative
Drying
Dispersing Agent
+ Water
Powdered
Avicel
(PH/FD Grades
Colloidal Avicel
Hydrocolloid
Solution
+ Water
Aqueous Colloidal
(RC/CL Grades)

19. Microcrystalline Cellulose
Polymers in solid ("dry") state
Crystalline (ordered) vs Amorphous (disordered)
Bundles of
Microcrystals
Paracrystalline
(amorphous) area
Cellulose microfibril

20. Cellulose Derivatives
CH2OR OR 6 5 4 3 2 1
b-D- anhydroglucose unit
R = -CH2COONa = NaCMC
R = -CH3 = MC
R = -CH2(CHOH)CH3 = HPC
R = -CH2(CHOH)CH3 and -CH3 = HPMC
R = -CH2CH2OH = HEC

21. XANTHAN GUM STRUCTURE Primary Aspect M = Na+, K+ or Ca++ n CH2OH
CH2OAc OH
COO-M+
OCH2 C
CH3 n
CH2OH
XANTHAN GUM
STRUCTURE
Primary Aspect
M = Na+, K+ or Ca++

22. From Sphingomonas elodea organism
Gellan Gum Repeat Unit
CH2OR1
COO- M+
CH2OH O
CH3 O O OH O OH HO
OR2 OH OH OH OH n
R1 = CH3C=O (acetate) - for “Native”, or H- for deacylated Gellan Gum
R2 = HOCH2CH(OH)C=O (glycerate) - for “Native”, or H- for deacylated Gellan Gum
From Sphingomonas elodea organism

23. Structure/Function of PSs
Mannose-based Polymers
Alginates
Locust Bean Gum (LBG)
Tara
Guar

24. Mannose-based Polymers LBG & Guar

25. Algin Basic Structure a-L-Guluronic Acid Polymer Structure: M GOH
COOH
b-D-Mannuronic Acid
a-L-Guluronic Acid
Polymer Structure: M G
Mannuronic Block
Guluronic Block
Mixed Block

26. Propylene Glycol Alginate (PGA) StructureOH
COOH
COOCH2CHCH3

27. Structure/Function of PSs
Galactose-based Polymers
Pectins
Agar
Carrageenans

28. Galactose-based Polymers High Methoxyl Pectin (H-bonding at pH 3)= n C
COCH3 OH
C=O H
COOCH3
D-galacturonic acid

29. Repeating Unit of Agaran
CH2 OH
CH2OH

30. Repeating Unit of k-Carrageenan
CH2 O OH n
CH2OH
-O3SO

31. Function of Hydrocolloids Hydration & Dispersion Definitions
Dispersion - The separation of individual dry gum particles added to a liquid.
Hydration - The disappearance of gum particles as a result of water surrounding each individual polymer molecule, causing it to swell and then slough away from the starting particle, forming a uniform “solution” (colloidal sol).

32. Function of Hydrocolloids Hydration & Dispersion
Polymers in solid ("dry") state
Crystalline (ordered) vs Amorphous (disordered)
Bundles of
Microcrystals
Paracrystalline
(amorphous) area
Cellulose microfibril

33. Function of Hydrocolloids Hydration & Dispersion= n C
COCH3 OH
C=O H
COOCH3 HO d- d+

34. Function of Hydrocolloids Hydration & Dispersion

35. Function of Hydrocolloids Hydration & Dispersion
Comparative hydration effect of linear and branched polymers
of equal molecular weights

36. Stages of Particle Hydration
Dispersion
Swollen Particles,
Unhydrated Center
Wet but unhydrated particles
Full Hydration
Swelling
“Solution”
Intimate Mixing
with Solvent

37. Function of Hydrocolloids Hydration & Dispersion
Polymer Solubility Characteristics I

38. Function of Hydrocolloids Hydration & Dispersion
Polymer Solubility Characteristics II

39. Function of Hydrocolloids Solution Properties I
Comparative hydration effect of linear and branched polymers
of equal molecular weights

40. Function of Hydrocolloids Solution Properties II
Comparative hydration effect of linear and branched polymers
of equal molecular weights

41. Hydration Rate Comparison vs Hydration Medium
100 90 80 70
80 mesh XG 60
Torque (% of Max) 50
80 mesh XG w/ 0.5% NaCl 40
80 mesh XG w/ 0.5% NaCl
+ 12.5% Vinegar 30 20 10 1 2 3 4 5 6
Time (minutes)

42. Function of Hydrocolloids Solution Properties III
Based on structure of polymer
Effects of various solutes
Salts, alcohols, etc
Other gums
General guidelines for optimum hydration

43. Dispersion & Hydration Rate
Hydration Rate/ 4 Factors
1. Dispersion
2. Particle Size
3. Mixer Speed/Shear
4. Hydration Medium - “Solvent”

44. Hydration Rate Comparison as a Function of Particle Size
100 90 80 70 60
200 Mesh XG 50
80 Mesh XG 40 30
16 Mesh XG 20 10 1 2 3 4 5 6 7 8 9
Time (minutes)

45. “High” shear mixer
Using careful addition, the dry gum is added directly to a vortex slowly enough to get good separation of the particles prior to wetting and swelling.

46. Dispersion - Mechanical
High Shear Mixer II
Uses High agitation rate to mechanic-ally separate par-ticles to allow uni-form wetting by the hydration medium.
Examples: Blender, Breddo Liquifier, Silverson, Arde Barinco Reversible Homogenizer

47. Dispersion - Mechanical
Eductor Funnel
Uses vacuum to aspirate the gum particles into the hydration medium.

48. Dry Blending - Solid Dispersant
Sugar
Partially hydrated particles
Fully hydrated particles
Using 5 to 10 parts of a diluent such as sugar, starch or spices, the gum is blended prior to incorporation into the liquid.
Salt is generally not recommended.
Good “Solution”

49. Dispersion - Liquid Slurry
Pre-mix with non-solvents
Water miscible liquids
alcohols
glycols
liquid sugars
nonmiscible liquids
vegetable oil
mineral oil
Keep mixed to avoid settling

50. Preservation of Gum Solutions
Most gum solutions need preservation
Food product & pH determine “preservative”
Neutral systems
Acidic systems (pH < 5)

52. Colloids/Colloidal State Viscosity
Brookfield RVF Viscometer (courtesy of Brookfield)

55. Hydrocolloid Pricing: Typical $ Cost/lb
2006
2012
Guar
6.00 – 6.80↑
LBG
no change*
Konjak
no change
Na+ alginate ↓
K+ alginate ↓
PGA
Agar ↑
Arabic ↑
Xanthan ↓
Pectin ↑
CMC ↑
MC/HPMC
Carrageenan
Tragacanth
no change**
* can reach $12.00-$17.00/lb in times of shortage
** depends on availability (Source = John Keller)