Hydrocolloids Structure and Properties - · PDF fileHydrocolloids Structure and Properties The building blocks for structure Timothy J. Foster. Natural Materials This shows a layer

18 month Meeting, Unilever Vlaardingen, March 29‐31, 2010

Hydrocolloids Structure and PropertiesThe building blocks for structure

Timothy J. Foster

Natural MaterialsThis shows a layer of onion (Allium) cells.

Manufactured MaterialsFoams Emulsions

Targeting Hydrocolloids For Specific Applications:

Approach

Ingredient

Microstructure

ProcessOral

Response

Material Properties

Ingredient(enzymes)

DECONSTRUCTION

Controlled oral response

(taste, flavour, texture)

In body functionality

Process(mouth/gut)

PackagingDistributionStorage

Process

Ingredient

CONSTRUCTION

Controlling Structure

Designed texture/appearance/behaviour

ReconstructionReconstructionInteraction with body mucins(associative and new phase separation)

Microstructure changes as a function of enzyme action

Re-assembly of structures as a function of digestion breakdown products and body secretions

(micelle formation, delivery vehicles)

Impact on / of starting materials / structures

Single Biopolymer systems

Hydrocolloid Structure/ FunctionNeed:

- define biopolymer primary structure

- understand the nature of the interaction / rates

- understand the solvent effects

- measure material properties

- test influence of primary structure variation and changes in environmental conditions on mechanical properties.

ThickeningPectinAlginateStarchLBGGuar gumXanthan

Emulsification• Gelatin• Milk proteins• Egg proteins• Soya proteins• Pea proteins• Gum Arabic

Hydrocolloid Materials & Function

GellingPectinAlginateStarchAgarCarrageenanGellanGelatinMilk proteinsEgg proteins

Gelling• Pectin• Alginate• Starch• Agar• Carrageenan• Gellan• Curdlan• Celluosics• Succinoglycan• Scleroglucan• Mixtures

Thickening• Pectin• Alginate• Starch• LBG• Guar Gum• Xanthan• lamda Carrageenan• Cellulosics• Beta Glucan

Emulsification• Gum Arabic• Propylene glycol Alginate• Sugarbeet pectin• OSA starch

Hydrocolloid Materials & Function

A protein is a polymer of amino acids

• Primary structure– amino acid sequence

• Secondary structure– spatial structure through interactions between amino acids that 

are near along the amino acid chain (e.g. α‐helix, β‐sheet)

• Tertiary structure– spatial structure through interactions between amino acids that 

are far away along the amino acid chain

• Quaternary structure– association of different amino acid sequences (e.g. haemoglobin)

Protein structure

Protein

Protein Structure:Backbone

random coilsbeta sheetalpha helix

Charge

Determines Properties:Interfacial properties

foamsemulsions

Gel forming

Color caption:

α-Helix

β-Sheets

Cysteines

Structure of globular proteins

α‐lactalbumin (α‐la)

β‐lactoglobulin (β‐lg)dimeric form at neutral pH

bovine serum albumin(BSA)

Turbid Gels

• How do they differ?

OH

OHOH

OH

CH2OHO

H

H

H

H

Carbohydrates…what do they look like?

1

23

4

5

6CH2OHO

OH OH

OH

OHHH

H

HH

CH2OHO

OH

OH OH

OHH

H H HH

Glucose

OH

CH2OHO

OH OH OH

HH

H

H

HMannose

CH2OHO

OH

OH

OH

OHH

H

H

HH

Galactose

Gulose

Sugar Interactions• Glycosidic linkage

OH

OHOH

OH

CH2OHO

H

H

H

H

HOH

CH2OHO

H

H

HOH

OH

OH

OH

OHOH

O

CH2OHO

H

H

H

H H

HOH

CH2OHO

H

HOH

OH

+H20

Polysaccharide Structure /

Functionality

Sources of hydrocolloidsBotanical

starch, cellulose, galactomannans, pectin, gum arabic, karaya, tragacanth, beta glucan

Seaweeds

agar, carrageenan, alginate

Animal

gelatin, chitosan, hyaluronan

Bacterial

xanthan, gellan, dextran

Structural Features 

• Linear – (homo- and hetero-)

• Linear – branched– (homo- and hetero-)

• Branched– (homo- and hetero-)

• Ordered helices– (single, double, triple)

Polysaccharide thickeners

• The most efficient thickeners are;

• Linear, • High molecular mass• Charged

Alternative HydrocolloidsAloe Gum

Cashew Gum Gum GhattiGum Karaya Oat gumOkra Gum Gum TragacanthCaramania Gum (almond) Cassia Gum Cassava Starch Cherry GumChia Gum Chickpea FlourCocoyam Flour Combretum GumCowpea protein /starch CyclodextrinsDetarium microcarpum polysaccharide Fenugreek gumFlaxseed Gum Gleditsia macracanthaHsian-tsao Leaf gum (Taiwan/China) Lesquerella GumLichenin Lucaena galactomannanLupin Protein Manna GumMoussul Gum (Plum) Opuntia FicusPortulaca Oleracea Prickly PearPsyllium gum Quince seed gumRice Flour Rye bran (beta d glucan / arabinoxylan)Sassa Gum Sorghum flourSoy Bean Polysaccharide Tamarind gumTara Gum Tremella Aurantia PoysaccharideTropical Starches YamYellow Mustard Gum

Typical Solution Properties

Hydrocolloid Structure/ Function

Need:

- define biopolymer primary structure

- understand the nature of the interaction / rates

- understand the solvent effects

- measure material properties

- test influence of primary structure variation and changes in environmental conditions on mechanical properties.

Galactomannans• Galactomannans include guar gum, locust bean gum (carob), 

fenugreek, cassia and tara gum.

• They have a high molecular mass (~ in excess of 500kDa) and  consist of β 1,4 linked mannose residues with galactose units linked α 1,6.

• The M:G ratio is ~2:1 for guar, 3:1 for tara and 4:1 for locust bean gum.

• The galactose units are not evenly distributed along the chain.

• LBG can be fractionated wrt temperature of solubility.• Cold soluble LBG (30C) has a higher G/ M than that soluble at high temperature (80C).• LBG soluble at 80C has a galactose content of 16.6%, and gels at ambient temperature.• Cold soluble LBG does NOT gel even when frozen & thawed.• Not necessary for ice to be present, a non‐ionic interaction, dependent on solvent quality.

LBG Structure / Functionality

Gelation Rate Gelation Rate Gelation Rate

[LBG]1.0 1.3 2.0

Sucrose (%)20 50 65

Temperature-8 10

- Self association is kinetically controlled as a function of the number of available junction zones

- The distribution of galactose sidechains is all important in dictating functionality.

Properties of Hydrocolloids

0 10 20 30 40 50 60 700

0.01

0.02

0.03

0.04

0.05

0.06

Strain (%).

Load (KN).

3%Gelatin

3%Agar

Typical polymer gel propertiesDependent on Solvent quality, Polymer fine structure, Junction zone type / quantity

Effect of Shear during Gelation: Fluid gel Particle formation

• Composite properties are dependent upon the number and size of particles produced.

• This in turn is dependent upon the polymer used, the polymerconcentration and the shear field.

0 1 2 3 4 510

100

1,000

10,000

100,000

1,000,000

[Agar]

G'(Pa)

Quiescent

Sheared

Storage Modulus of Agar Gels FormedQuiescently and Under Shear

Measurement Temperature = 10C

POURABLE

SPREADABLESPOONABLE

0.1 10.01

0.1

1

Level of Dilution

Viscosity (Pas)

Xanthan

Fluid gel

• Due to the colloidal nature of their properties they providebetter dilution characteristics than their molecular counterparts.

Mixed Biopolymers

Aqueous-based two-phase systems

Microstructure

o/w emulsion water-in-water emulsion

25 μm

0 2 4 6 8 10 12 14 16 18 200.0

0.2

0.4

0.6

0.8

1.0

1.2L

BG

(W

T%

)

MICELLAR CASEIN (WT%)

*

**

25% LBG / 75% PR75% LBG / 25% PR 50% LBG / 50% PR

Phase diagram measured at 5C

Phase Separation phenomena is used in the creation of foodproducts.

Aqueous-based two-phase systems

Example: Aqueous mixture of gelatin and maltodextrin

Top phase: Gelatin

Bottom phase: Maltodextrin

For charged polymers (polyelectrolytes) salt (type and concentration) as well as pH are important parameters.

Influence of varying polymer characteristics

0 2 4 6 8 10 12 14

0

2

4

6

8

10

12

Isothermal Binodal Evolution Owing to Ordering

δ [SA2] / δt = 0.4 % / min

LH1 / SA2 No Salt20oC

[LH

1] /

% w

/w

[SA2] / % w/w

• Schematic phase diagram showing the binodal as a function of ordering at 20 °C

Phase separation driven by molecular ordering of one of the biopolymers.

Process effectsStructure induced phase separation.• Measure of gelatin helices required to induce phase separation in a 4% LH1e:4% SA2 mixture , in water, when quenched to 20oC (top) and 25oC (bottom).• Morphology when quenched to 20oC.

2 4 6 8 100

2

4

6

8

10

12

14

16

% Helix% Helix%

Hel

ix

t / min

0.0

0.5

1.0

1.5

TurbidityTurbidity

τ / cm-1

10 20 30 40 500

2

4

6

8

10

12

14

16

% Helix

% H

elix

t / min

0.0

0.5

1.0

1.5

τ / cm-1

Turbidity

1min

4min

29min

20oC

25oC

Effect of shear during cooling / gelation of the gelatin

Process effects on mixed biopolymer systems.

Gelling biopolymer forms the dispersed phase.

Structures based on aqueous-based two-phase systems

Scheme developed by Tolstoguzov*

*V Tolstoguzov Journal of Texture Studies 11, 3 (1980) 199-215

Gel particle suspensions

Modification of (shear) rheology: Effect of fibre alignment

0.01 0.1 1 10 1001

10re

lative

vis

cosi

ty

shear stress [Pa]

50 μm

Dispersed phase volume: 20%

Gel particle suspensions

Deposition: Non-food example

SEM micrograph by M Kirkland WO2003061607 A1

κ-carragenan fibres deposited on a hair. Spherical particles of the same composition wash off during rinse.

Milk ProteinLBGAirIce

Ice Cream

Short textureie. snaps

Comparative Properties

-0.00020

0.0002

0.0004

0.0006

0.0008

0.001

0.0012

0.0014

0.0016

0 20 40 60 80 100Displacement (mm)

Load

(kN

)

Conventional Formulation

MarasFormulation

Extensible textureie. stretches

GB 9930531US 20010031304

0%

20%

40%

60%

80%

100%

120%

140%

160%

Sahlep

Guar

Xanthan

CM

C

LBG

Gelatin

Carrageenan

% m

ean

stra

in to

failu

re

All products here compared at 30% Overrun

Prior Art formulations

Hydrocolloid functionality in Maras Ice Cream

Conclusion

• The fine structure of hydrocolloids plays a role in their properties (viscosity and gelation)

• Influence of process can alter the functionality (single and mixed systems)

• Hydrocolloid:Hydrocolloid interactions determine the gross properties of composites

0

500

1000

1500

2000

2500

3000

3500

4000

0 300 600 900 1200 1500 1800 2100 2400 2700

Time / s

Visc

osity

/ cP

STRUCTURE CREATION

150 um

STRUCTURE RETENTION

150 um

Point of dilution

Acknowledge ALL past and present colleagues for support and stimulation