Structuring Foods with Polysaccharides

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1 Structuring Foods with Polysaccharides John Mitchell

2 Countries with most Carbohydrate Polymers downloads Usage % Usage % Usage % Country China United States Thailand Malaysia Iran, Islamic Republic Brazil Taiwan Korea, Republic France United Kingdom Japan Total

3 Hydrocolloid Materials & Function - Gelling Pectin Alginate Starch Agar Carrageenan Gellan Curdlan Celluosics Mixtures - Thickening - Emulsification Pectin Gum Arabic Alginate Propylene Glycol Alginate Starch Sugar Beet Pectin Guar Gum OSA starch Xanthan Konjak Glucomannan Xanthan Lamda Carrageenan

4 Structuring Foods with Polysaccharides Innovation A Couple of Eureka Moments Oranges

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6 Crude pectinaceous gelling material with a pectin degree of esterification preferably less than 10%

7 Why a pectin with a very low degree of esterification (DE)? Change in viscosity on autoclaving (120 O C 10mins) pectin solutions of different DEs as a function of ph. Pilnik, W. and MacDonald, R.A. (1968) Gordian, 68,531

8 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

9 Pectate pulp process Mitchell J. and Taylor, A (1983) pp in Upgrading Waster for Food and Feed; edited Ledward, DA et al, Butterworths, London

10 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 Some increased interest in material The future??

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12 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

13 Konjak:Carrageenan Mixed Gels The Influence of Alkaline ph Parinda Penroj Wunwiboon Ganjanagoonchorn Department of Food Science and Technology Kasetsart University, Chatuchak John Mitchell and Sandra Hill Division of Food Sciences, University of Nottingham, England

14 Konjak Glucomannan Glucose:mannose ratio~1: % of sugar residues acetylated

15 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?

16 Series of Mars patents claiming thermoirreversible gels prepared from heated glucomannan/carrageenan blends. Inventors: Vernon, Cheney and Stares

17 Storage modulus (Pa) Heating Curves in Oscillation for 0.3%/0.3% Carr + KM before and after two hours holding at 90 O C 1.00E E E E+02 ph E E E E E E E E E E E E E Temperature (C) Temperature (C) ph10 before holding after holding ph 8 ph 10 Before holding After holding Protocol:Cool> Heat>Hold >Cool> Reheat 1 O C /min 1.00E Temperature (C)

18 Critical gelling concentration (c O ) 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?

19 Phase Separation Model Carrageenan rich Konjak mannan rich If modulus of konjak phase (G k )>> modulus of carrageenan phase then modulus of gel = Φ G k. To achieve the observed modulus of 2x10 3 Pa konjak phase volume has to be reduced to about 0.1

20 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)

21 Xanthan Gum H 3 C COO - M + O O HO HOH 2 C HOH O 2 C O O HO OH O OH HO HO O O + M - OOC AcOH 2 C OH O O M + =Na +, K +, ½Ca 2+ HO O M w ~ D OH 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)

22 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)

23 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

24 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.

25 Liquid Crystalline Polymers, Donald A et al Cambridge University Press Effect of salt concentration on xanthan isotropic:anisotropic transition Anisotropic Xanthan concentration Biphasic sato slide.pdf Isotropic Salt concentration Sato, T and Teramoto, A (1991) Physica A 176, 72-86

26 Change in viscosity across the transition (solvent 1M NaCl) C 1 C 11 Viscosity (Poise) Xanthan concentration % Lee H-C and Brant D.A. (2002) Macromolecules 35, 2223

27 Why should phase changes at xanthan concentrations > 1% be relevant for food applications?

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29 G', G" at 1.02 Hz (Pa) Tan Delta Xanthan 1% Effect of adding Alginate Viscoelasticity at 1.02 Hz G' G" Tan Delta Phase separation visible % (w/w) added alginate 0 (Mean ± SD, n=3)

30 Crossed Polarised Light Microscopy 1% Xanthan 5% Alginate

31 Phase Diagram

32 Concentrating xanthan by exclusion from swelling starch granule Lad, M.D. et al (2010) Gums and Stabilisers for the Food Industry 15, 126

33 Final viscosity / cp Viscosity of 10% starch in the presence of varying hydrocolloid concentration Guar xanthan Hydrocolloid concentration / % 10% starch only 10% starch plus 2% Xanthan low viscosity anisotropic xanthan phase been swollen starch granules? 80 um

34 Can positron annihilation spectroscopy provide new insight into the role of water on polysaccharide properties in the glassy state? Ashraf Alam 1, Javier Enrione 2, Bill MacNaughtan 3, John Mitchell 3 and Mina Roussenova 1 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

35 Positron Annihilation Lifetime Spectroscopy (PALS) 22 Na decay e + production prompt emission of 1.28 MeV γ ray Thermalisation and diffusion of e + e + + e - Positronium (Ps) p-ps Free e + o-ps ns ns 1-4 ns ( pick-off ) (environment dependent) o-ps decay Two 511 kev γ rays 4

36 Effect of water on molecular packing of gelatin matrices v h ( Å 3 ) v h ( Å 3 ) Glassy state Q w T g? Rubbery/ Gel state Endothermal heat flow (mwg -1 ) T = 298 K v h (Å 3 ) 25 T (K) T (K) T (K) K T g K T m K K a w = 0.11 a w = 0.22 a w = 0.33 a w = 0.44 a w = 0.68 a T g, PALS (K) T g,dsc (K) b 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.

37 Dependence of free volume hole size on water content for amorphous maltodextrin(starch) and gelatin Mean free volume hole size (Å 3 ) gelatin maltodextrin Weight fraction of water

38 Starch antiplasticization by water comparison with glycerol water glycerol Sala, R. and Tomka, I. (1993) pp in the Glassy State in Foods edited Blanshard, J., and Lillford, P. Nottingham. University Press.

39 Reference Sereno, N., Hill, S.E and Mitchell,J.R. Impact of the extrusion process on xanthan gum behaviour. Carbohydrate Research (2007), 342: 1333

40 Producing Particulate Xanthan By Extrusion Xanthan gum H 2 O Heaters Die Screw Sample Twin Screw Clextral BC21 Extruder

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42 Drying and milling Vacuum oven (65 C) Freeze dryer (<0 C) Fan assisted oven (90 C) Milling to particle size 125 to 250 µm

43 Dispersibility of xanthan gums Non-processed xanthan gum Processed xanthan gum Solutions were briefly mixed with a spoon 9

44 Control

45 Processed

46 Viscosity (Cp) Temperature( C) 3500 CoVA prtemperature dependence of viscosity of processed (Hydraxan ) and control (Keltrol T) xanthan Hydraxan Trial 1 Hydraxan Trial 2 Keltrol-T Control Temp( C) Time (min) Solvent: 0.2%NaCl 2% xanthan

47 Microscopy of xanthan particles on water addition Non-processed xanthan gum 0 seconds 1 minute 5 minutes 10 minutes 0.16 mm 1.2 mm Extruded xanthan gum 0 seconds 1 minute 5 minutes 10 minutes 0.25 mm 2.8 mm

48 Swollen Volume of Particulate Phase Obtained After Mild Centrifugation Typically about 10% of total xanthan is found in the supernatant

49 Viscosity (Cp) Effect of salt concentration and temperature on viscosity of 0.75% physically modified xanthan gum no NaCl 0.005% 0.01% 0.02% 0.03% 0.04% 0.05% 0.10% 0.50% 1.00% Temperature ( C)

50 Microcalorimetry at Different Salt Contents (0.75% xanthan)

51 Temperature of Viscosity Peak and Order Disorder Transition Agree

52 Process Produces a Particulate Xanthan Structure. Kinetically Trapping Renaturation?? Xanthan particles result of network formed by intermolecular helices Molecular solution Particle/microgel

53 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.

54 QUESTIONS Is this new? Does the process degrade the material? Why does the process work? Why xanthan? What are the applications?

55 The Germans (Generally) Get There First 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 Starch (1989)

56 Effect of hydrocolloid concentration (% of maize starch) on water holding capacity of extruded blends (Kuhn et al, Starch (1989) ) Typical extruder operating conditions water content ; 27% wwb; Product temperature O C Specific mechanical energy ~0.15 kwh/kg

57 Does the process degrade the macromolecule?

58 Viscosity (Cp) Temperature( C) 3500 CoVA prtemperature dependence of viscosity of processed (Hydraxan ) and control (Keltrol T) xanthan Hydraxan Trial 1 Hydraxan Trial 2 Keltrol-T Control Temp( C) Time (min) Solvent: 0.2%NaCl 2% xanthan

59 Zero shear intrinsic viscosity Control Processed material 50.6 dl/g 50.8 dl/g 0.2% NaCl Temperature 25 C No evidence for degradation

60 Influence of Mechanical Energy on Molecular Weight of Wheat Starch Meuser et al. 1992

61 Why does the process work?

62 Prism Extruder At Nottingham

63 Extruder layout Die (90 C) Die Zone 9-10 (80 C) Zone 8 (50 C) Zones 2-7 (30 C) Heating Blocks Water Feed Port Screw Heating Blocks Screw length (cm) Motor Shaft

64 Screw profile Conveying elements End extrusion elements Conveying elements Reverse elements Half helix elements

65 Inside an extruder barrel Zone 4 Zone 2 Zone 7 Zone 5 Zone 10 Zone 8

66 viscosity (cp) Temperature( C) Zone 10 Zone 2 Zone 5 Zone 6 Zone 7 Zone 8 Zone 9 Zone 10 Before exit die Temp( C) Zone Zone Time (min)

67 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

68 Why xanthan?

69 Observations More Consistent with Side By Side Helices Than Coaxial Helices

70 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

71 Comparison of Viscosity Development During Cooking in Product Based on Semiskimmed Milk

72 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

73 Acknowledgements Tim Foster Sandra Hill Mitaben Lad Nuno Sereno Matt Boyd Nuno Sereno Val Street Colin Melia Sanyasi Gaddipati Rachael Abson

74 Thank you for listening