John Mitchell

Structuring Foods with

Polysaccharides

John.Mitchell@Nottingham.ac.uk

Countries with most Carbohydrate Polymers

downloads

Usage % Usage % Usage %

Country 2008 2009 2010

China 151306 19.7 184154 19.1 250159 20.7 United States 77093 10 89134 9.2 143788 11.9 Thailand 55054 7.2 64774 6.7 80644 6.7

Malaysia 29680 3.9 43903 4.5 49424 4.1

Iran, Islamic Republic

22196 2.9 34960 3.6 46067 3.8

Brazil 31737 4.1 39165 4.1 41952 3.5 Taiwan 23361 3 33118 3.4 41783 3.5 Korea, Republic 30939 4 36080 3.7 40361 3.3

France 28818 3.8 36407 3.8 38983 3.2 United Kingdom 29733 3.9 32941 3.4 36445 3 Japan 26762 3.5 31524 3.3 35318 2.9

Total 767416 100 965851 100 1210621 100

- Gelling

• Pectin

• Alginate

• Starch

• Agar

• Carrageenan

• Gellan

• Curdlan

• Celluosics

• Mixtures

- Thickening

• Pectin

• Alginate

• Starch

• Guar Gum

• Xanthan

• Konjak Glucomannan

• Xanthan

• Lamda Carrageenan

- Emulsification

• Gum Arabic

• Propylene Glycol Alginate

• Sugar Beet Pectin

• OSA starch

Hydrocolloid Materials & Function

Structuring Foods with

Polysaccharides

Innovation

A Couple of Eureka Moments

Oranges

Crude

pectinaceous

gelling material

with a pectin

degree of

esterification

preferably less

than 10%

Why a pectin with a very low degree of

esterification (DE)?

Change in viscosity on

autoclaving (120OC

10mins) pectin solutions of

different DEs as a function

of pH.

Pilnik, W. and MacDonald,

R.A. (1968) Gordian,

68,531

Why did pectate work and alginate fail?

• Pectate will gel at a lower calcium level than alginate.

• On autoclaving slight increase in available calcium achieved calcium level not enough to gel alginate

Pectate pulp process

Mitchell J. and Taylor, A (1983) pp 247-265 in Upgrading Waster for Food and Feed; edited

Ledward, DA et al, Butterworths, London

A short history of pectate pulp

• Developed and patented in 1938 (Wilson) – Some production of material,

– Non-food applications explored

• New application discovered in 1974 (Mitchell) – Production restarted

• Food application patent runs out in 2000. Some increased interest in material

• The future??

What is the gelling systems for the whole product

Carrageenan

Plus

Cosynergist e.g. locust bean gum,

konjak glucomannan

Cosynergist does not normally gel on its own but

makes the carrageenan gel stronger and more

elastic

Department of Food Science and Technology

Kasetsart University, Chatuchak

Parinda Penroj

Wunwiboon Ganjanagoonchorn

John Mitchell and Sandra Hill Division of Food Sciences, University of Nottingham, England

Konjak:Carrageenan Mixed Gels

The Influence of Alkaline pH

Konjak Glucomannan

Glucose:mannose ratio~1:1.5. 5-10% of sugar residues

acetylated

Rationale of Work

• Konjak mannan interacts synergistically

with carrageenan and xanthan in a similar

way to locust bean gum (Morris, ER in Biopolymer Mixtures (1995) edited Harding,

S et al, Nottingham University Press)

• What happpens to this interaction when

konjak mannan deacetylates?

Series of Mars patents

claiming

thermoirreversible gels

prepared from heated

glucomannan/carrageenan

blends.

Inventors: Vernon, Cheney

and Stares

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

1.00E+05

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

1.00E+05

Sto

rag

e m

od

ulu

s (

Pa

)

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

1.00E+05

10 20 30 40 50 60 70 80 90

Temperature (C)

10 20 30 40 50 60 70 80 90

Temperature (C)

pH10

before holding after holding

10 20 30 40 50 60 70 80 90 Temperature (C)

Heating Curves in Oscillation for 0.3%/0.3% Carr +

KM before and after two hours holding at 90OC

pH 6

pH 8

pH 10

Before holding

After holding

Protocol:Cool>

Heat>Hold

>Cool> Reheat

1OC /min

Critical gelling concentration (cO) for alkali gelation

of konjak mannan has been reported as 0.4% (Case

et al, 1992).

In our work we found it impossible to prepare

homogenous gels with 0.3% konjak mannan alone

under any of the conditions used yet in the presence

of carrageeenan after alkali deacetylation dynamic

rheology suggest strong gels can be prepared in the

presence of 0.3% carrageenan above the melting

point of the carrageenan helices.

WHY?

Phase Separation Model

Carrageenan

rich

Konjak

mannan rich

If modulus of konjak phase (Gk)>> modulus of carrageenan phase then

modulus of gel = Φ Gk . To achieve the observed modulus of

2x103Pa konjak phase volume has to be reduced to about 0.1

Conclusions

• On deacetylation, in the presence of carrageenan,

konjak mannan forms gels at lower concentrations

than normal.

• This may be explained on the basis of an

excluded volume effect.

• Deacetylation would be expected to occur at less

alkaline pHs on severe heat treatment (could

explain thermal irreversible gels in patent

examples)

Xanthan Gum

O

OOO

O

O

O

OO

HO

O

O

HOH2C

HOOH

HOH2C

OH

AcOH2C

HOHO

+M

-OOC

OH

HO

H3C

COO-M

+

OH M+=Na

+, K

+, ½Ca

2+

Mw ~ 4.106 D

“Hydrocolloid of choice for long term

future…. Excellent opportunities both for

new products and for process improvement

on the production of existing products”

Dennis Seisun In Gums and Stabiliser for

the Food Industry 11. (2002)

Xanthan Gum Price Trend

Average price US$ per kg

year

Adapted from “Food stabilisers, thickeners and gelling agents” ed: A Imeson, chpt 1 Introduction D. Seisun (2010)

Stiff worm like chain

Persistence lengths

Xanthan ~120 nm

DNA ~50 nm

Alginate 5-17 nm

Chitosan 6-12 nm

Maurstad , G. et al (2003) 107, .8172

Secondary Structure

• Dihelical

• Not clear whether coaxial or side by side helices

• Denaturation temperature increases

strongly with salt content

• Because of heat treatment during recovery

process most commercial material has been

denatured and renatured .

Effect of salt concentration on xanthan isotropic:anisotropic transition

sato slide.pdf

Isotropic

Anisotropic

Biphasic

Xanthan

concentration

Salt concentration

Sato, T and Teramoto , A (1991) Physica A 176, 72-86

Liquid Crystalline Polymers, Donald A et al Cambridge University Press

Change in viscosity across the transition (solvent 1M NaCl)

C1 C11

Xanthan concentration %

Viscosity

(Poise)

Lee H-C and Brant D.A. (2002) Macromolecules 35, 2223

Why should phase changes at xanthan

concentrations > 1% be relevant for food

applications?

0

10

20

30

40

0 1 2 3 4 5

% (w/w) added alginate

G', G

" at

1.0

2 H

z (

Pa)

0

0.5

1

1.5

2

Tan

Delta

G'

G"

Tan Delta

Xanthan 1%

Effect of adding Alginate Viscoelasticity at 1.02 Hz

Phase separation visible

(Mean ± SD, n=3)

Crossed Polarised Light Microscopy

1% Xanthan 5% Alginate

Phase Diagram

Concentrating xanthan by exclusion from

swelling starch granule

Lad, M.D. et al (2010) Gums and Stabilisers for the Food Industry 15, 126

0

1000

2000

3000

4000

5000

6000

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Hydrocolloid concentration / %

Fin

al vis

co

sity /

cP

Viscosity of 10% starch in the presence of varying hydrocolloid concentration

10% starch plus 2% Xanthan

80 um

10% starch only

Guar

xanthan

low viscosity

anisotropic

xanthan phase

been swollen

starch granules?

Can positron annihilation spectroscopy provide new

insight into the role of water on polysaccharide

properties in the glassy state?

Ashraf Alam1, Javier Enrione2, Bill MacNaughtan3, John

Mitchell3 and Mina Roussenova1

1 H.H. Wills, Physics Laboratory, University of Bristol, UK

2 Food Structure Group, Universidad de Santiago de Chile

3 Division of Food Sciences, University of Nottingham, UK

Thermalisation and diffusion of e+

e+ + e- → Positronium (Ps)

22Na decay e+ production prompt emission of 1.28 MeV γ ray

o-Ps decay Two 511 keV γ rays

↑↓ p-Ps 0.12 - 0.2 ns Free e+ 0.35 - 0.5 ns ↑↑ o-Ps 1 - 4 ns (“pick-off”) ↓↓ (environment dependent)

Positron Annihilation Lifetime Spectroscopy (PALS)

4

T (K)

200 250 300 350 400 450

vh (

Å3)

70

80

90

100

110

120

130a

w = 0.11

aw = 0.22

aw = 0.33

aw = 0.44

aw = 0.68

Tg

Qw

0.0 0.1 0.2 1.0

vh (

Å3)

60

70

80

90

100

?

Glassystate

Rubbery/ Gel state

T = 298 K

T (K)

270 280 290 300 310 320 330 340 350 360 370

Endoth

erm

al heat flow

(m

Wg

-1)

25

30

35

40

45

50

321.2 K321.4 K

365.9 K365.7 K

Tg,DSC

(K)

260 280 300 320 340 360 380

Tg

, P

AL

S

(K

)

260

280

300

320

340

360

380

a b

T (K)

280 320 360 400 440

vh (

Å3)

75

80

85

90

95

100

Tm

Tg

Effect of water on molecular packing of gelatin matrices

Water has a complex effect on the molecular packing of the gelatin matrices. Depending on the level of hydration it can acts as a plasticiser or an anti-plasticiser.

Dependence of free volume hole size on water

content for amorphous maltodextrin(starch) and

gelatin

Mean free

volume hole

size (Å3)

Weight fraction of water

0

20

40

60

80

100

120

0 0.05 0.1 0.15 0.2

gelatin

maltodextrin

Starch antiplasticization by water

comparison with glycerol

water

glycerol

Sala, R. and Tomka, I. (1993) pp475-482 in the Glassy State in Foods edited

Blanshard, J., and Lillford, P. Nottingham. University Press.

Sereno, N., Hill, S.E and Mitchell,J.R.

Impact of the extrusion process on xanthan gum

behaviour.

Carbohydrate Research (2007), 342: 1333

Reference

Producing Particulate Xanthan By

Extrusion

H2O

Xanthan gum

Heaters

Sample

Die

Screw

Twin Screw Clextral BC21 Extruder

Drying and milling

Milling to particle size

125 to 250 µm

Fan assisted oven (90°C)

Vacuum oven (65°C) Freeze dryer (<0°C)

Dispersibility of xanthan gums

9

Non-processed xanthan gum

Processed xanthan gum

Solutions were briefly mixed with a spoon

Control

Processed

0

20

40

60

80

100

120

0

500

1000

1500

2000

2500

3000

3500

0 2 4 6 8 10 12 14 16 18 20

Tem

pera

ture

( C

)

Vis

co

sit

y (

Cp

)

Time (min)

Hydraxan Trial 1

Hydraxan Trial 2

Keltrol-T Control

Temp( C)

Solvent: 0.2%NaCl 2% xanthan

CoVA prTemperature dependence of viscosity of processed (Hydraxan ) and control (Keltrol T)

xanthan

Microscopy of xanthan particles on

water addition

0.16 mm 1.2 mm

0 seconds 1 minute 5 minutes 10 minutes

Non-processed xanthan gum

Extruded xanthan gum

0 seconds 1 minute 5 minutes 10 minutes

0.25 mm 2.8 mm

Swollen Volume of Particulate Phase Obtained After Mild

Centrifugation

Typically about 10% of total

xanthan is found in the

supernatant

Effect of salt concentration and temperature on

viscosity of 0.75% physically modified xanthan

gum

-500

0

500

1000

1500

2000

2500

3000

3500

4000

20 25 30 35 40 45 50 55 60 65 70 75 80 85 90Temperature (°C)

Vis

co

sit

y (

Cp

)

no NaCl

0.005%

0.01%

0.02%

0.03%

0.04%

0.05%

0.10%

0.50%

1.00%

Microcalorimetry at Different Salt

Contents (0.75% xanthan)

Temperature of Viscosity Peak and

Order Disorder Transition Agree

Process Produces a Particulate Xanthan

Structure. Kinetically Trapping

Renaturation??

Xanthan “particles” result of network

formed by intermolecular helices

Molecular solution Particle/microgel

Consequences of Particulate

Structure

• Excellent dispersibility

• Swelling of particles and hence viscosity

will be strongly salt dependent

• Above the “helix coil” transition of xanthan

particulate structure will be disrupted and

there will be a conversion to the “normal”

renatured xanthan structure.

QUESTIONS

• Is this new?

• Does the process degrade the material?

• Why does the process work?

• Why xanthan?

• What are the applications?

The Germans (Generally) Get There First

Starch (1989) 41 467-471

“Now it has been shown that cooperative linkage of

β-1,4 –D glucan chains of xanthan with α-1,4 D-

glucan chains of starch take also place under the

conditions of cooking extrusion

Effect of hydrocolloid concentration (% of maize starch) on water holding

capacity of extruded blends (Kuhn et al, Starch (1989) 41 467-471)

Typical extruder operating conditions water content ; 27% wwb;

Product temperature 140-150OC

Specific mechanical energy ~0.15 kWh/kg

Does the process degrade the

macromolecule?

0

20

40

60

80

100

120

0

500

1000

1500

2000

2500

3000

3500

0 2 4 6 8 10 12 14 16 18 20

Tem

pera

ture

( C

)

Vis

co

sit

y (

Cp

)

Time (min)

Hydraxan Trial 1

Hydraxan Trial 2

Keltrol-T Control

Temp( C)

Solvent: 0.2%NaCl 2% xanthan

CoVA prTemperature dependence of viscosity of processed (Hydraxan ) and control (Keltrol T)

xanthan

Zero shear intrinsic viscosity

Control 50.6 dl/g

Processed material 50.8 dl/g

0.2% NaCl Temperature 25 C

No evidence for degradation

Influence of Mechanical Energy on Molecular Weight of Wheat Starch

Meuser et al. 1992

Why does the process work?

Prism Extruder At Nottingham

Extruder layout

Die

Feed Port

Water

Heating Blocks

Screw length (cm)

79.52.515.57

Zones 2-7 (30°C)Zone 8 (50°C)Heating Blocks

Zone 9-10 (80°C)Die (90°C)

MotorShaft

Screw

Screw profile

Conveying elements

Half helix

elements

Reverse elements Conveying

elements

End extrusion

elements

Inside an extruder barrel

Zone 2 Zone 4

Zone 8 Zone 10

Zone 5 Zone 7

0

20

40

60

80

100

120

0

50

100

150

200

250

300

350

400

450

0 5 10 15 20

Tem

pe

ratu

re(°

C)

vis

cosi

ty (

cP)

Time (min)

Zone 2 Zone 5Zone 6 Zone 7Zone 8 Zone 9Zone 10 Before exit dieTemp(°C)

Zone 2

Zone 9

Zone 10

Why is the extruded material fundamentally

different from xanthan modified by heating

in other ways?

Difficult to melt out xanthan ordered structure by

heating at low water contents

High ionic strength because of counter ion concentration in

limited water

Reducing solvent concentration raises a polymer melting point

Hypothesis is that as with starch extrusion high

mechanical energy (~0.5 kWh/kg in our process)

plays a major role in disrupting the ordered structure

Could explain “weak” temperature dependence of the process

Why xanthan?

Observations More Consistent with Side By Side Helices Than Coaxial

Helices

•

Some Applications

• Powder can be added to liquids containing

very low levels of salts e.g. fruit juices to

provide very rapid thickening without

mechanical stirring

• In the presence of some salt xanthan will

disperse and swell on heating giving rise to

starch type viscosity profiles.

– Dairy, sauce and soup products developed based

on this principle

Comparison of Viscosity Development

During Cooking in Product Based on Semi-

skimmed Milk

Conclusions

• Extruding xanthan produces a material which in

water behaves like a polyelectrolyte particle

• In comparison to the unprocessed material the

new product shows:-

– Excellent dispersibility

– In salt solutions thickening on heating in a

similar way to starch

• A lot still to be understood but we are getting

there

Acknowledgements

• Tim Foster

• Sandra Hill

• Mitaben Lad

• Nuno Sereno

• Matt Boyd

• Nuno Sereno

• Val Street

• Colin Melia

• Sanyasi Gaddipati

• Rachael Abson

Thank you for listening