Influence of emulsifiers on double emulsion stability

Transcription

1 Influence of emulsifiers on double emulsion stability Muschiolik, G. 1), Knoth, A. 2), Bindrich U. 3) 1) Food Innovation Consultant, Potsdam 2) Gutena Nahrungsmittel GmbH, Apolda 3) DIL e.v., Quakenbrück 1

2 Agenda What are double (multiple) emulsions? Emulsion preparation, influence of homogenization method Influences of emulsifiers - W/O emulsifier - O/W emulsifier Summary 2

3 What are double (multiple) emulsions? 3

4 Double emulsions Definition: Droplets of a dispersed phase (Oil or Water) contain small droplets of another phase W 2 -Phase Oildroplets Waterdroplets O 2 - Phase W 1 /O/W 2 O 1 /W/O 2 Special multiple types: O/W/O/W/O and W/O/W/O/W 4

5 Advantages of double emulsions Controlled aroma release Encapsulation of bioactive components Reduction of fat content without changing the mouthfeeling Problem: - Finding the optimal ingredient composition to - realize a long time stability Important: Selection of emulsifier type and emulsifier combination 5

6 Structure of confectionery W/O/W W 2 primary surface Sucrose/glucose e.g % sucrose/glucose e.g % Thickener Osmotic agent O/W emulsifier Fat or Oil W 1 Healthy additives Secondary surface W/O emulsifier 6

7 Emulsion preparation, influence of homogenization method 7

8 Principle of formation multiple emulsions 1. W 1 /O- Emulsion Emulsifying high energy W 1 -phase water + sugar and hydrocolloid, osmotic pressure regulated Oil-phase + W/O emulsifier fat composition tailored W 1 /Oemulsion particle size of primary water droplets ~ 1 µm 8

9 Principle of multiple emulsion preparation 2. W 1 /O/W 2 - Emulsion Emulsifying low energy W 1 /O- Emulsion W 2 -phase + water + sugar O/W emulsifier W 1 /O/W 2 - Emulsion Particle size of filled oil droplets with W 1 ~ 5 7 µm 9

10 Methods for emulsion preparation (emulsification of W 1 /O in W 2 ) Avoid: Disruption of internal emulsion droplets (W 1 ) and fusion with the external phase (W 2 ) Emulsification methods for multiple systems are described by: Muschiolik and Bunjes, 2007 (Behr s Verlag, 2007) 10

11 Stability of W/O/W is influenced by: Size of inner water droplets (W 1 ) Oil droplet size Water (W 2 ) Osmotic gradient between W 1 and W 2 Laplace curvature pressure Water flow between W 1 and W 2 (influenced by osmotic gradient) Viscosity of the emulsion phases Interaction between W/O Lipid Agents, aroma Water (W 1 ) and O/W-emulsifier Hindrance between different emulsifiers should be prevented! 11

12 Influence of emulsifiers 12

13 low molecular ZDS Solingen Fats & Emulsifiers, Sept , 2008 W/O emulsifier lecithin PC depleted and PE enriched < 5% > 11 % Hydrophobic lecithin with higher PE content as W/O emulsifier 13

14 W/O-Premix prepared with different lecithins Partial aggregated W-particles Improved W/O stability with higher PE content *Phase separation W/O : 30/70; O-phase: sunflower oil, emulsion preparation at 3000 rpm, 2 min; 50 C; Homogenizer MPW-302 (Metronex, Poland) 14

15 Cumulative fraction ZDS Solingen Fats & Emulsifiers, Sept , 2008 Lecithin-screening - W/O emulsions with 0.75 % Lecithin (2.5 % in O) h d! Standard deoiled PC 0, W-droplet diameter (µm) , W-droplet diameter (µm) Cumulative particle-size distribution for W-droplets 15

16 effective viscosity (Pa s) ZDS Solingen Fats & Emulsifiers, Sept , 2008 Flow behaviour of W/O-Emulsionen prepared with lecithin 10 PGPR; Sunflower oil 1 PC ; Sunflower oil 0,1 0, Shear rate (s -1 ) Due to aggregation of water particles W/O emulsions with lecithin are higher viscous 16

17 d 32 of w-droplets (µm) ZDS Solingen Fats & Emulsifiers, Sept , 2008 Influences of emulsification methods - W/O with lecithin h 7 d MPa 4 MPa 20 MPa 50 MPa 100 MPa A B Ball valve Combi orifice High pressure Ultrasonic Rotor- Stator A: 10 ml, 240 s ultrasonic, 60 % amplitude; B: 30 ml, 240 s ultrasonic, 60 % amplitude 0.2 % XPS and 1.5 % whey protein in W; 2.5 % PC in O; 50 C 17

18 W/O with lecithin W/O phases prepared with lecithin are more viscous than w/o phases with PGPR and the stability depends strongly on the emulsifying methods 18

19 W/O emulsifier PGPR Polyglycerol-Polyricinoleate E476 ZZulV, , appendix 7 max. 4 g/kg in spreads with less than 41 % fat, spreads with < 10 % fat and salat dressings max. 5 g/kg in sweets with cacao 19

20 d 32 of w-droplets (µm) ZDS Solingen Fats & Emulsifiers, Sept , 2008 d 32 of w-droplets (µm) Lecithin or PGPR in O - Influence of NaCl and WPI in W 1 -phase h 7 d h 7 d !! 3 2 1!! NaCl (%) +1.5% WPI +1.5% WPI +1.5% WPI 2.5 % PC + 3.0% Gelatine + 0.2% Xanthan % WPI +1.5% WPI 4.0 % PGPR + 3 % Gelatine 20

21 Influence of other emulsion components: - Electrolytes (NaCl) are essential to achieve coalescence-stable emulsions prepared with PGPR. - Electrolytes (NaCl) in emulsions containing lecithin contribute more to coalescence of water droplets and phase separation (other components are necessary to regulate the osmotic pressure, e.g. glucose). - Combination of lower surface active whey protein with xanthan in W-phase (1.5 % protein % XPS in W) reduces the W-droplets additionally when W/O emulsions are prepared with PC depleted lecithin (2.5 % in O). 21

22 d 32 of w-droplets (µm) ZDS Solingen Fats & Emulsifiers, Sept , 2008 Influence of emulsification method - W/O with PGPR h 7 d Rotor- Stator 4 MPa Combi orifice 8 MPa Ball valve Rotor- Stator 4 MPa 8 MPa Combi orifice Ball valve without additives with gelatine and NaCl 4 % PGPR Rotor-stator-system is effective! 22

23 W/O emulsifier sucrose esters Sucrose erucate ER-190, HLB 1 Sucrose erucate ER-290, HLB 2 Sucrose esters, which are allowed in the European Union have to contain at least 80 % mono-, di-, and tri-esters At the present time the tested sucrose esters with HLB 1 and 2 are not permitted RYOTO SUGAR ESTER Technical Information 23

24 d 32 of w-droplets (µm) ZDS Solingen Fats & Emulsifiers, Sept , 2008 Particle size of W/O Sugar esters with HLB 1 and HLB 2 (2, 4 and 6 % emulsifier in O; 0.6 % NaCl in W) HLB 1 HLB MCT; 2% MCT; 4% MCT; 6% Oil; 2% Oil; 4% Oil; 6% MCT: Medium-chain triglyceride (Miglyol 812), Oil: Vegetable oil (BISKIN) 24

25 d 32 of w-droplets (µm) ZDS Solingen Fats & Emulsifiers, Sept , 2008 Particle size of W/O Sugar ester with HLB 1 and HLB 2 (2, 4 and 6 % emulsifier in O) HLB 1 HLB MCT; 2% MCT; 4% MCT; 6% Oil; 2% Oil; 4% Oil; 6% MCT: Medium-chain triglyceride (Miglyol 812), Oil: Vegetable oil (BISKIN) 25

26 Surface area of O (m²/g) ZDS Solingen Fats & Emulsifiers, Sept , 2008 Surface area of O-droplets (W/O in W) depending on storage (Particle size between µm) 1 day 7 days 35 days 0,5 0,45 0,4 0,35 0,3 0,25 0,2 0,15 0,1 0,05 0 ER 290 MTC+BF ER 290 Oil+BF ER 290 BF PGPR MTC+BF PGPR Oil+BF PGPR BF W 2 : 25 % dry matter (sugar, milk protein, starch, maltodextrin) 4 % sugar ester (ER 290, HLB 2); PGPR: 4 %; BF: butter fat; MCT: Miglyol 812; Oil: vegetable oil W 1 /O = 20:80, (W 1 /O) : W 2 = 20:80 26

27 Summarised effects of sugar esters Esters with HLB 2 are more effective in forming small W 1 particles than esters with HLB 1 Application of NaCl in W 1 supports the formation of small water droplets W/O are stable with 4 % sugar ester in O (HLB 2) and 0.6 % NaCl in W 1 The size of O-droplets (surface area) in W/O/W is comparable to emulsions with PGPR 27

28 Emulsifiers for W 1 /O in W 2 28

29 Emphasized O/W emulsifiers for double emulsions Native proteins (whey, vegetable) Protein-ionic polysaccharide mixtures (a high zeta-potential is advantageous) Protein-polysaccharide conjugates Combination of proteins with ionic polysacharides in W 2 increases the barrier function! Structural compatibility between W/O- and O/W-emulsifiers is of importance! 29

30 Protein-polysaccharide conjugate at O/W-surfaces O-phase Polysaccharides with different molecule weight are coupled with protein according to Dunlap u. Côté, 2005 Available space for adsorbing at oil surfaces depends on the polysaccharides molecule weight 30

31 Milk protein and protein-pectin-conjugate as O/W-emulsifier in W/O/W W/OW were heated for 10 min at 90 C, and stored for 6 weeks W/O/W W/O/W Milk protein concentrate in W 2 Conjugate in W 2 Double emulsions with conjugate in W 2 are heat stable! No aggregation of O-droplets! 31

32 Influence of O-phase on W/O/W stability The stability can be improved by using O-phases with a high degree of saturated fatty acids, i.e. by fat phases with a low polarity (promotion of a close packed condensed interfacial film) 32

33 Conclusions Stable W/O/W can be prepared by using W/O emulsifiers in O: 4 % PGPR (0.6 % NaCl in W 1 ) or % PE enriched lecithin (without NaCl) or (4 % sucrose ester; HLB 2; 0.6 % NaCl) O/W emulsifiers in W 2 : Whey or vegetable protein or Protein-ionic polysaccharide conjugates Low molecular weight W/O emulsifier + high molecular weight O/W emulsifier = better compatibility and no negative interactions! 33

34 Conclusions The stability of multiple systems depends on: osmotic balance, electrolyte and ionic status and fat phase composition (saturation degree, polarity) The selection of emulsifiers for double emulsions has to consider the electrolyte and ionic status. 34

35 Acknowledgement This research project was supported by the German Ministry of Economics and Technology (via AiF) and the FEI (Forschungskreis der Ernährungsindustrie e.v., Bonn). Project AiF BG 35

36 Main publications Muschiolik/Bunjes, Multiple Emulsionen Behr s Verlag, 2007 Muschiolik, G. Multiple emulsions for food use, Current Opinion in Colloid & Interface Science 12 (2007) Preissler, P. Süßwarenfüllmassen auf Emulsionsbasis Logos Verlag Berlin, 2006 Weiss, J. and Muschiolik, G. Factors affecting the droplet size of water-in-oil emulsions (W/O) and the oil globule size in water-in-oil-in-water emulsions (W/O/W), J. Dispersion Sci. and Technol. 28 (2007)