The effect of different Click to edit Master subtitle style - PowerPoint PPT Presentation

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

Ultrasonic emulsification  Advantages (+) Vs  First reported by  Basics  More stable Conventional emulsions ( Smaller Wood & Loomis methods droplet sizes within a (1927) narrow size distribution)  16–100  Requires little or no kHzCavitation surfactant phenomenon  Less processing  Minimum droplet time size 0.1–0.2 μm  Power saving scale-up for in-line processing (Lab to Plant)

Objective  -Reduce oil droplet & production of fine model emulsions -Use of different commercial (<1μm) stabilizers -Influence of ultrasound parameters (time, intensity) on stability

Materials & formulation  O/W emulsions (pH~7)

Emulsion preparation  Primary or coarse o/w emulsion (Ultra-Turrax 6.500 RPM/4+4min) Method A 70% Intensity/2min  Ultrasonication (20kHz, 200W) Method B 70%Intensity/3min+90%Intensity/1min Coarse Final WPC + Oil + Gums emulsion emulsion Ultrasonication 6.500 RPM 6.500 RPM 4min 4min

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

Microstructure of emulsions § 0.1& 0.25%weak structure, induce depletion flocculation XG 0.1 GG 0.1 LBG 0.1 Method A XG 0.25 GG 0.25 LBG 0.25 § 0.5%better filling properties, stronger network, fewer gaps, methods A&B similar XG 0.5 GG 0.5 LBG 0.5 structure Method B XG 0.5 GG 0.5 LBG 0.5

Oil droplet size Gum (% w/w ) Method A Method B  Gum concentration affects droplet size (method A) D50 (μm) D50 (μm)  Sub-micrometer emulsions method B 1.107a Xanthan 0.25  LBGmost effective in reducing droplet size 0.832a 1.325b 0.5 0.786a 1.093a Guar 0.25 0.843a 1.330b 0.5 0.771a 1.018c Locust 0.25 0.876a bean 1.077a 0.615b 0.5 XG 0.5% (A)

Emulsion viscosity  Emulsion rheology=ƒ(gum) shear thinning  Viscosity: XG>LBG>GG  Increase of sonication time and intensity (method B) reduces viscosity Stability

Stability during cold storage- Clarification  Clarification Serum Index (SI) Serum height SI (%)= Sample height XG , GG & LBG  0.1%,destabilized 0.1% (A) within a few hours Stability of 0.1% emulsions during storage at 5oC

Stability during cold storage- Clarification  Xanthan, more stable emulsions A B  SI  XG<LBG<GG  Increase of time and XG 0.25% intensity decreased stability (XG) Stability of 0.25% emulsions during storage at 5oC

Stability during cold storage- Coalescence Back Scattering, (BS) ~ƒ(droplet size) -1 (Mie time (days) Theory) Back Scattering 0d Back Scattering 0d XG, stable during 10-day storage BS0=79.5% BS0=79.9% 1d 100% 100% 1d 2d 2d 2d 80% 80% 3d 3d 4d 60% 60% 5d 3d BS10=78.8% BS10=78.9% 5d 4d 5d 40% 40% 6d 6d 7d 20% 20% 7d 7d 8d 8d 0% 0% 9d 10d 10d 0mm 50mm 0mm 50mm   XG 0.5% (method A) XG 0.5% (method B)

Stability during cold storage- Coalescence Back Scattering, (BS) ~ƒ(droplet size) -1 (Mie Theory) Back Scattering 0d Back Scattering 0d GG & LBG, increased coalescence, less stable 100% BS0=83.1% 100% BS0=83.5% 0d 0d 1d 2d 80% 80% 2d 2d 3d 4d 60% 60% 4d 4d BS10=74.5% BS10=75.6% 5d 40% 40% 6d 6d 6d 7d 20% 20% 8d 7d 0% 9d 0% 8d 9d 9d 0mm 50mm 0mm 50mm  GG 0.5% (method A) LBG 0.5% (method A)

DSC cool-heat cycles (-40 to 40oC) -Samples (B) crystallized in higher temperatures - ΔH values remain stable during heat-cool cycles T max (o C) ΔΗ (J/g) Cycle 1 Cycle 2 Cycle 3 Cycle 1 Cycle 2 Cycle 3 Method A -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 0.25% -15.34 (0.05) -17.00 (0.04) -16.53 (0.09) 294.40 (0.71) 291.30 (0.28) 292.10 (0.00) XG 0.5% Method B -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 0.25% -12.97 (0.95) -13.07 (0.44) -14.21 (0.58) 237.80 (1.71) 237.97 (1.62) 237.77 (2.03) XG 0.5% Water crystallization parameters of emulsions containing XG (*) *Results presented as average out of two measurements, in parenthesis standard deviation values.

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)

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.