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The effect of different Click to edit Master subtitle style stabilizers aAgricultural University of Athens, Dept. Food Science & Technology, Athens, Greece bAgroParisTech, Unit for Food Process Engineering, on the Paris,France

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SLIDE 1

Click to edit Master subtitle style

The effect

  • f different

stabilizers

  • n the

aAgricultural University of Athens,

  • Dept. Food Science & Technology,

Athens, Greece bAgroParisTech, Unit for Food Process Engineering, Paris,France

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SLIDE 2

Ultrasonic emulsification

  • Basics
  • Advantages (+) Vs

Conventional methods

  • First reported by

Wood & Loomis (1927)

  • 16–100

kHzCavitation phenomenon

  • Minimum droplet

size 0.1–0.2 μm

  • More stable

emulsions (Smaller

droplet sizes within a narrow size distribution)

  • Requires little or no

surfactant

  • Less processing

time

  • Power saving

scale-up for in-line processing

(Lab to Plant)

slide-3
SLIDE 3

Objective

  • -Reduce
  • il droplet

& production

  • f fine

model emulsions (<1μm)

  • Use of different

commercial stabilizers

  • Influence of ultrasound

parameters (time, intensity) on stability

slide-4
SLIDE 4

Materials & formulation

  • O/W

emulsions (pH~7)

slide-5
SLIDE 5

Emulsion preparation

  • Primary or coarse o/w emulsion

(Ultra-Turrax 6.500 RPM/4+4min)

  • Ultrasonication

(20kHz, 200W)

Method A 70% Intensity/2min Method B 70%Intensity/3min+90%Intensity/1min

WPC + Oil + Gums Coarse emulsion

6.500 RPM 4min 6.500 RPM 4min

Ultrasonication Final emulsion

slide-6
SLIDE 6

Experimental

  • Microscopic observationpolysaccharide

texture

  • Viscosityrheology behaviour
  • Diffusion NMR Spectrometryoil droplet

sizing

  • Turbidity (Multiple Light Scattering) 

syneresis or coallesence

  • Differential Scanning Calorimetry (DSC,

cool-heat cycles -40 to 40 oC)effect on crystallization of water

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SLIDE 7

Microstructure of emulsions

XG 0.25 GG 0.1 LBG 0.1 XG 0.1 GG 0.25 GG 0.5 GG 0.5 XG 0.5 XG 0.5 LBG 0.25 LBG 0.5 LBG 0.5

Method A Method B

§0.5%better filling

properties, stronger network, fewer gaps, methods A&B similar structure

§0.1& 0.25%weak

structure, induce depletion flocculation

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SLIDE 8

Oil droplet size

Gum (% w/w ) Method A D50 (μm) Method B D50 (μm)

Xanthan

0.25

1.107a 0.832a

0.5

1.325b 0.786a Guar

0.25

1.093a 0.843a

0.5

1.330b 0.771a Locust bean

0.25

1.018c 0.876a

0.5

1.077a 0.615b

  • Gum concentration affects droplet size (method A)
  • Sub-micrometer emulsions method B
  • LBGmost effective in reducing droplet size

XG 0.5% (A)

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SLIDE 9

Emulsion viscosity

  • Emulsion rheology=ƒ(gum)

shear thinning

  • Viscosity:

XG>LBG>GG

  • Increase of sonication time and intensity

(method B) reduces viscosity

Stability

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SLIDE 10

Stability during cold storage- Clarification

  • Clarification

Serum Index (SI)

  • 0.1%,destabilized

within a few hours

Stability of 0.1% emulsions during storage at 5oC

SI (%)= Serum height Sample height

XG , GG & LBG 0.1% (A)

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SLIDE 11

Stability during cold storage- Clarification

  • Xanthan, more stable

emulsions

  • SI  XG<LBG<GG
  • Increase of time and

intensity decreased stability (XG)

Stability of 0.25% emulsions during storage at 5oC

XG 0.25%

A B

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SLIDE 12

Stability during cold storage- Coalescence

  • XG 0.5% (method A)
  • XG 0.5% (method B)

Back Scattering 0mm 50mm 0% 20% 40% 60% 80% 100%

0d 1d 2d 3d 3d 4d 6d 7d 8d 10d

Back Scattering 0mm 50mm 0% 20% 40% 60% 80% 100%

0d 1d 2d 2d 3d 4d 5d 5d 5d 6d 7d 7d 8d 9d 10d

BS10=78.8% BS0=79.9% BS10=78.9% BS0=79.5%

Back Scattering, (BS) ~ƒ(droplet size) -1 (Mie Theory) XG, stable during 10-day storage

time (days)

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SLIDE 13

Stability during cold storage- Coalescence

Back Scattering 0mm 50mm 0% 20% 40% 60% 80% 100%

0d 0d 2d 2d 4d 4d 6d 6d 8d 9d 9d

Back Scattering 0mm 50mm 0% 20% 40% 60% 80% 100%

0d 0d 1d 2d 3d 4d 5d 6d 7d 7d 8d 9d

BS0=83.1% BS10=74.5% BS10=75.6% BS0=83.5%

  • GG 0.5% (method A)

LBG 0.5% (method A)

Back Scattering, (BS) ~ƒ(droplet size) -1 (Mie Theory) GG & LBG, increased coalescence, less stable

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SLIDE 14

DSC cool-heat cycles (-40 to 40oC)

T max (o C) ΔΗ (J/g) Cycle 1 Cycle 2 Cycle 3 Cycle 1 Cycle 2 Cycle 3

Method A

XG 0.25%

  • 16.93 (0.16) -17.10 (1.93) -15.62 (0.57) 252.9 (35.78) 253.95 (37.41) 253.95 (36.56)

XG 0.5%

  • 15.34 (0.05) -17.00 (0.04) -16.53 (0.09) 294.40 (0.71) 291.30 (0.28) 292.10 (0.00)

Method B

XG 0.25%

  • 12.63 (1.93) -14.23 (1.19) -14.25 (2.31) 240.00 (0.57) 240.65 (0.07) 240.45 (0.07)

XG 0.5%

  • 12.97 (0.95) -13.07 (0.44) -14.21 (0.58) 237.80 (1.71) 237.97 (1.62) 237.77 (2.03)

Water crystallization parameters of emulsions containing XG (*)

*Results presented as average out of two measurements, in parenthesis standard deviation values.
  • Samples (B) crystallized in higher temperatures
  • ΔH values remain stable during heat-cool cycles
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SLIDE 15

Conclusions-future aspects

  • Ultrasonication time & intensity affected

droplet size, viscosity & stability of samples

  • Xanthan, more effective than guar and locust

bean gum.

  • Elucidate effect of crystallization on emulsion

stability

  • Explore effect of sonication on gum chains
  • Incorporate new gums (fenugreek & mastic

gum)

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SLIDE 16

Acknowledgements

  • This research has been co-financed by the European Union

(European Social Fund – ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: Heracleitus II. Investing in knowledge society through the European Social Fund.