Open access

Introductory Chapter: The Perspective of Emulsion Systems

Written By

Selcan Karakuş

Published: 22 August 2018

DOI: 10.5772/intechopen.75727

From the Edited Volume

Science and Technology Behind Nanoemulsions

Edited by Selcan Karakuş

Chapter metrics overview

1,256 Chapter Downloads

View Full Metrics

1. Introduction

Emulsions (0.1–100 mm) are metastable systems and commonly used in our daily life. They are extensively preferred on many industrial processes in the food, beverage, dye, detergent, drug, cosmetic, coating, technological areas, agricultural, and petroleum production due to their special rheological (yield stress, viscosity and storage or loss modulus) and antibacterial properties [1, 2, 3]. Generally, synthesis methods for emulsion systems are stirring, colloid mills, and high-pressure homogenizers [4, 5].


2. Emulsion: Types anproperties

Emulsions are thermodynamically unstable (coalescence, sedimentation/creaming, flocculation, Ostwald ripening, and phase inversion) and are provided with kinetic stability by surfactant molecules for weeks, months, or years. The average particle size and its distribution are crucial factors for stability of emulsion which depends on the rate of coalescence and also other important factors are the aggregation of the droplets, ionic strength, concentration, temperature, pH, energy, osmotic pressure, viscosity, interfacial tension and dynamically the addition of emulsifying agent (emulsifier), and stabilizer. The stability of emulsion depends on the steric hindrance and electrostatic interactions and the viscosity of the continuous phase (gelation) [6, 7]. The stability of the system is related to the empirical hydrophile–lipophile balance (HLB) number of the emulsion. [8]. Emulsifiers are small surface-active molecules and contain hydrophilic and hydrophobic areas, so they change the structure of the interface. They enhance its stability by reducing the interfacial tensions of dispersed phase-continuous phase (oil–water), and the van der Waals’ steric and electrostatic repulsion have significant roles in stabilization [9]. Emulsifiers create special area for preventing them from aggregation and having low HLB value. Stabilizers are largely biopolymers (proteins, polysaccharides, phospholipids, plant-based emulsifiers) [10] and are amphiphilic molecules which contain hydrophobic and hydrophilic parts. Stabilizers decrease interfacial tension and conversely increase the surface area of immiscible phases. Synthetic surfactants and biosurfactants are two basic groups [11].

Emulsions can be classified according to the structure of the phases as single, multiple emulsions (a size range 0.1–5 μm), micellar emulsions, or micro-emulsions (a size range of 5–50 nm) and nano-emulsions (a size range of 10–500 nm). The single emulsion is a colloidal dispersion of two immiscible liquids (water and oil) and is simply divided into two systems as oil-in-water (O/W) or water-in-oil systems (W/O) depending on the dispersed phase (oil) or continuous phase (water) [12]. In W/O emulsions, simple steric effect is the key role for stabilizing the system, owing to the low electrical conductivity of the water (continuous phase) and their products can be in the solid or semi-solid and liquid forms. Studies about W/O emulsions investigate the interaction mechanisms of water, oil, and emulsifier (polarity, layer thickness, lipophilic bioactive compounds, and the charged molecules) and the emulsion stability for the development of new products and applications [13, 14, 15, 16, 17]. Sato et al. showed enhanced oxidation and pH stability as compared to systems produced with only one biopolymer in alginate-gelatin-mixed emulsions, and they explained the emulsifying properties of gelatin with the high pH resistance of alginate as a delivery system [18]. Roldan-Cruz et al. investigated the stability of O/W emulsion using Tween-80 as emulsifying agent [19]. Capitani et al. explained that in the O/W emulsion, polysaccharides (hydrophilic structure) increase the viscosity of the continuous phase, thereby decreasing the mobility of the oil droplets [20]. Nasrabadi et al. showed that the stability of emulsion improved by using linoleic acid (CLA), acacia gum (AG), and xanthan gum (XG) in oil-in-water emulsion. The experimental results discovered that a stable CLA emulsion can be used in beverage products [21]. Felix et al. focused on the preparation and stabilization of high-oleic O/W emulsions by using Xanthan Gum (XG) (0.06, 0.12, 0.25, and 0.50 wt.%) at different pH values (3.0, 5.0, and 8.0) [22]. Zhang et al. found that the droplet size and size distribution did not change throughout the storage by using the novel peptide-based nanoparticles as bifunctional and effective emulsifiers in O/W emulsion systems and the most important factors are well-controlled droplet size and composition [23]. Chang et al. also addressed a remarkable improvement in Fish oil-in-water emulsion stability due to the combined effect of thiol-modified β-lactoglobulin (β-LG) fibrils, chitosan, and maltodextrin by using a high-energy method [24].

Water-in-water (W/W) emulsions are much less known than classic oil-in-water emulsions and can be synthesized into two immiscible hydrophilic structures which are thermodynamically incompatible in solution. And also, the kinetic stability of W/W emulsions are mostly hard to control because amphiphilic molecules do not adsorb on emulsion interfaces. Nowdays, highly kinetically stable W/W emulsions can be prepared by using biocompatible and biodegradable ingredients [25].

Multiple emulsions are emulsions of emulsions and complicated polydispersed systems, which own extremely regular internal macromolecules and thus both oil-in-water-in-oil (O/W/O) and water-in-oil-in-water (W/O/W) emulsions exist simultaneously. The multiple emulsion is a complicated system such as water-in-oil-in water (W/O/W) or (O/W/O). Multiple emulsions are made up of small oil droplets dispersed in continuous phase (W) and are generally used in the different industrial sectors. (in food—slow release, in drug—the carrier, in cream—encapsulated compounds) [26]. W/O/W multiple emulsions occur in small water droplets intercepted within larger oil droplets that are themselves dispersed in a continuous phase [27]. Multiple emulsions have a potent for droplet coalescence and for this reason alipophilic emulsifier (to stabilize the inner water in oil emulsion) and a hydrophilic emulsifier (to stabilize the outer oil in water emulsion) have key roles to disperse from one interface to the other [28, 29, 30, 31].


3. Nano-emulsion systems

Nano-emulsion systems have smaller droplet sizes in the nanometric scale (mean droplet diameter ranges between 10 and 500 nm). Due to their small droplet size, they have different physicochemical properties and are thermodynamically unstable. Nano-emulsions are transparent and commonly prepared by using sonochemistry to produce smaller droplet sizes [32, 33, 34, 35]. Ma et al. achieved the application of curcumin/triglyceride oil nano-emulsions to help improve solubility and bioavailability in food industry [36].

Pickering emulsions are known to spontaneously disperse small droplets of two immiscible liquids stabilized by solid nano- and micro-particles (silica, triacylglycerols, soft polymers, or clay) adsorbed at the interface. Pickering emulsions show excellent properties as to encapsulate any substance, to regulate the emulsion consistency by changing the solid concentration, and to get porous materials and special rheological behavior [37, 38, 39, 40]. Dai et al. enhanced the stabilization of Pickering emulsion by using silica nanoparticles (SNP) in dimethyldodecylamine oxide (OA-12) and explained the dynamic behaviors of interface and the hydrophilic-lipophilic balance of particle surfaces [41]. Thus, from the information obtained in the literature, the necessary calculations for use in emulsion studies are given in Table 1.

Table 1.

The necessary calculations.


  1. 1. García MC, Alfaro MC, José M˜n. Influence of the ratio of amphiphilic copolymers used as emulsifierson the microstructure, physical stability and rheology of pinene emulsions stabilized with gellan gum. Colloids and Surfaces B: Biointerfaces. 2015;135:465-471
  2. 2. Pal J, Duo W, Hakkarainen M, Srivastav RK. The viscoelastic interaction between dispersed and continuous phase of PCL/HA-PVA oil-in-water emulsion uncovers the theoretical and experimental basis for fiber formation during emulsion electrospinning. European Polymer Journal. 2017;96:44-54
  3. 3. Kole S, Bikkina P. A parametric study on the application of microfluidics for emulsion characterization. Journal of Petroleum Science and Engineering. 2017;158:152-159
  4. 4. Sosa N, Schebor C, Pérez OE. Encapsulation of citral in formulations containing sucrose ortrehalose: Emulsions properties and stability. Food and Bioproducts Processing. 2014;92:266-274
  5. 5. Shao Y, Tang C-H. Characteristics and oxidative stability of soy protein-stabilized oil-inwater emulsions: Influence of ionic strength and heat pretreatment. Food Hydrocolloids. 2014;37:149-158
  6. 6. Kowalska M, Krzton-Maziopa A. Viscoelastic effects in carrot oil emulsions thickened withcarboxymethylcellulose. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2015;464:121-128
  7. 7. Romero A, Felix M, Perez-Puyana V, Choplin L, Guerrero A. Use of a mixer-type rheometer for predicting the stability of O/W protein-based emulsions. LWT- Food Science and Technology. 2017;85:75-81
  8. 8. Kundu P, Agrawal A, Mateen H, Mishra IM. Stability of oil-in-water macro-emulsion with anionic surfactant: Effect of electrolytes and temperature. Chemical Engineering Science. 2013;102:176-185
  9. 9. Desplanques S, Renou F, Grisel M, Malhiac C. Impact of chemical composition of xanthan and acacia gums on the emulsification and stability of oil-in-water emulsions. Food Hydrocolloids. 2012;27:401-410
  10. 10. Doki L, Krstonosi V, Nikoli I. Physicochemical characteristics and stability of oil-in-water emulsions stabilized by OSA starch. Food Hydrocolloids. 2012;29:185e192
  11. 11. Lovaglio RB, dos Santos FJ, Junior MJ, Contiero J. Rhamnolipid emulsifying activity and emulsion stability: pH rules. Colloids and Surfaces B: Biointerfaces. 2011;85:301-305
  12. 12. Ushikubo FY, Cunha RL. Stability mechanisms of liquid water-in-oil emulsions. Food Hydrocolloids. 2014;34:145-153
  13. 13. Abdolmaleki K, Mohammadifar MA, Mohammadi R, Fadavi G, Meybodi NM. The effect of pH and salt on the stability and physicochemical properties of oil-in-water emulsions prepared with gum tragacanth. Carbohydrate Polymers. 2016;140:342-348
  14. 14. Gomes A, Costa ALR, Cunha RL. Impact of oil type and WPI/tween 80 ratio at the oil-water interface: Adsorption, interfacial rheology and emulsion features. Colloids and Surfaces B: Biointerfaces. 2018;164:272-280
  15. 15. Shao P, Qiu Q, Chen H, Zhu J, Sun P. Physicochemical stability of curcumin emulsions stabilized by Ulvafasciata polysaccharide under different metallic ions. International Journal of Biological Macromolecules. 2017;105:154-162
  16. 16. Politova N, Tcholakova S, Denkov ND. Factors affecting the stability of water-oil-water emulsion films. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2017;522:608-620
  17. 17. Soukoulis C, Tsevdou M, Yonekura L, Cambier S, Taoukisb PS, Hoffmann L. Does kappa-carrageenan thermoreversible gelation affect-caroteneoxidative degradation and bioaccessibility in o/w emulsions? Carbohydrate Polymers. 2017;167:259-269
  18. 18. Sato ACK, Moraes KEFP, Cunha RL. Development of gelled emulsions with improved oxidative and pH stability. Food Hydrocolloids. 2014;34:184-192
  19. 19. Roldan-Cruz C, Vernon-Carter EJ, Alvarez-Ramirez J. Assessing the stability of Tween 80-based O/W emulsions with cyclicvoltammetry and electrical impedance spectroscopy. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2016;511:145-152
  20. 20. Capitani MI, Nolasco SM, Tom MC. Stability of oil-in-water (O/W) emulsions with chia (Salvia hispanica L.) mucilage. Food Hydrocolloids. 2016;61:537-546
  21. 21. Nasrabadi MN, Goli SAH, nasirpour A. Stability assessment of conjugated linoleic acid (CLA) oil-in-water beverage emulsion formulated with acacia and xanthan gums. Food Chemistry. 2016;199:258-264
  22. 22. Felix M, Romero A, Guerrero A. Influence of pH and xanthan gum on long-term stability of crayfish-based emulsions. Food Hydrocolloids. 2017;72:372-380
  23. 23. Zhang Y, Zhou F, Zhao M, Lin L, Ning Z, Sun B. Soy peptide nanoparticles by ultrasound-induced self-assembly of large peptide aggregates and their role on emulsion stability. Food Hydrocolloids. 2018;74:62-71
  24. 24. Chang HW, Tan TB, Tan PY, Abas F, Oi ML, Wang Y, Wang Y, Nehdi IA, Tan CP. Physical properties and stability evaluation of fish oil-in-water emulsions stabilized using thiol-modified β-lactoglobulin fibrils-chitosan complex. Food Research International. 2018;105:482-491
  25. 25. Esquena J. Water-in-water (W/W) emulsions. Current Opinion in Colloid & Interface Science. 2016;25:109-119
  26. 26. Li F, Zhang W. Stability and rheology of W/Si/W multiple emulsions withpolydimethylsiloxane. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2015;470:290-296
  27. 27. Matos M, Gutierrez G, Martínez-Rey L, Iglesias O, Pazos C. Encapsulation of resveratrol using food-grade concentrated double emulsions: Emulsion characterization and rheological behavior. Journal of Food Engineering. 2018;226:73-81
  28. 28. Panagopoulou E, Evageliou V, Kopsahelis N, Ladakis D, Koutinas A, Mandala I. Stability of double emulsions with PGPR, bacterial cellulose and wheyprotein isolate. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2017;522:445-452
  29. 29. Fernandez-Martín F, Freire M, Bou R, Cofrades S, Jim_enez-Colmenero F. Olive oil based edible W/O/W emulsions stability as affected by addition of some acylglycerides. Journal of Food Engineering. 2017;196:18-26
  30. 30. Neumann SM, Wittstock N, van der Schaaf US, Karbstein HP. Interactions in water in oil in water double emulsions: Systematical investigations on the interfacial properties and emulsion structure of the outer oil in water emulsion. Colloids and Surfaces, A: Physicochemical and Engineering Aspects. 2018;537:524-531
  31. 31. Gustafsson H, Holmberg K. Emulsion-based synthesis of porous silica. Advances in Colloid and Interface Science. 2017;247:426-434
  32. 32. El Kadri H, Virgina P, Devanthi P, Overton TW, Gkatzionis K. Do oil-in-water (O/W) nano-emulsions have an effect on survival and growth of bacteria? Food Research International. 2017;101:114-128
  33. 33. Katsouli M, Polychniatou V, Tzia C. Influence of surface-active phenolic acids and aqueous phase ratio on w/o nano-emulsions properties; model fitting and prediction of nanoemulsions oxidation stability. Journal of Food Engineering. 2017;214:40-46
  34. 34. Kaltsa O, Spiliopoulou N, Yanniotis S, Mandala I. Stability and physical properties of model macro- and nano/submicron emulsions containing fenugreek gum. Food Hydrocolloids. 2016;61:625-632
  35. 35. Homs M, Calderó G, Monge M, Morales D, Solans C. Influence of polymer concentration on the properties of nano-emulsions and nanoparticles obtained by a low-energy method. Colloids and Surfaces, A: Physicochemical and Engineering Aspects. 2018;536:204-212
  36. 36. Ma P, Zeng Q, Tai K, He X, Yao Y, Hong X, Yuan F. Preparation of curcumin-loaded emulsion using high pressure homogenization: Impact of oil phase and concentration on physicochemical stability. LWT - Food Science and Technology. 2017;84:34-46
  37. 37. Nushtaeva AV. Superstabilization of emulsions by solid particles. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2015;481:283-287
  38. 38. Szumała P, Luty N. Effect of different crystalline structures on W/O and O/W/O waxemulsion stability. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2016;499:131-140
  39. 39. Chen K, Gaobo Y, He F, Zhou Q, Xiao D, Li J, Feng Y. A pH-responsive emulsion stabilized by alginate-grafted anisotropicsilica and its application in the controlled release of λ-cyhalothrin. Carbohydrate Polymers. 2017;176:203-213
  40. 40. Björkegren S, Nordstierna L, Törncrona A, Palmqvist A. Hydrophilic and hydrophobic modifications of colloidal silica particles for Pickering emulsions. Journal of Colloid and Interface Science. 2017;487:250-257
  41. 41. Dai C, Li H, Zhao M, Wu Y, You Q, Sun Y, Zhao G, Xu K. Emulsion behavior control and stability study through decorating silica nano-particle with dimethyldodecylamine oxide at n-heptane/water interface. Chemical Engineering Science. 2018;179:73-82
  42. 42. Liu W-Y, Feng M-Q, Wang M, Wang P, Sun J. Influence of flaxseed gum and NaCl concentrations on the stability of oil-in-water emulsions. Food Hydrocolloids. 2018;79:371-381
  43. 43. Oppermann AKL, Renssen M, Schuch A, Stieger M, Scholten E. Effect of gelation of inner dispersed phase on stability of (w 1/o/w 2) multiple emulsions. Food Hydrocolloids. 2015;48:17-26
  44. 44. Xiang S, Yao X, Zhang W, Ke Z, Fang Y, Nishinari K, Phillips GO, Jiang F. Gum arabic-stabilized conjugated linoleic acid emulsions: Emulsion properties in relation to interfacial adsorption behaviors. Food Hydrocolloids. 2015;48:110-116
  45. 45. Cano-Medina A, Jiménez-Islas H, Dendooven L, Herrera RP, González-Alatorre G, Escamilla-Silva EM. Emulsifying and foaming capacity and emulsion and foam stability of sesame protein concentrates. Food Research International. 2011;44:684-692
  46. 46. Veverka M, Dubaj T, Veverková E, Šimon P. Natural oil emulsions stabilized by β-glucan gel. Colloids and Surfaces, A: Physicochemical and Engineering Aspects. 2018;537:390-398
  47. 47. Jurgelane I, Sevjakova V, Dzene L. Influence on illitic clay addition on the stability of sunflower oil in water emulsion. Colloids and Surfaces, A: Physicochemical and Engineering Aspects. 2017;529:178-184
  48. 48. Mikulcova V, Bordes R, Kasparkova V. On the preparation and antibacterial activity of emulsions stabilized with nanocellulose particles. Food Hydrocolloids. 2016;61:780-792
  49. 49. Sui X, Bi S, Qi B, Wang Z, Zhang M, Li Y, Jiang L. Impact of ultrasonic treatment on an emulsion system stabilized with soybean protein isolate and lecithin: Its emulsifying property and emulsion stability. Food Hydrocolloids. 2017;63:727-734

Written By

Selcan Karakuş

Published: 22 August 2018