Emulsifiers 2012
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Transcript of Emulsifiers 2012
SURFACTANTS - EMULSIFIERSSURFACTANTS EMULSIFIERS
An emulsion is a mixture of two or more immiscible (un-blendable) liquids. Emulsions are part of a more general class of two-phase systems q p g p yof matter called colloids.
Although the terms colloid and emulsion are sometimes usedAlthough the terms colloid and emulsion are sometimes used interchangeably, emulsion tends to imply that both the dispersed and the continuous phase are liquid. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase)dispersed phase) is dispersed in the other (the continuous phase)
A. Two immiscible liquids, not yet emulsifiedemulsified.
B. An emulsion of Phase II dispersed in Phase I.
C. The unstable emulsion progressively separates.
D Th f t t ( l tli dD. The surfactant (purple outline around particles) positions itself on the interfaces between Phase II andinterfaces between Phase II and Phase I, stabilizing the emulsion
Emulsions are made up of a dispersed and a continuous phase; the boundary between these phases is called the interface.the boundary between these phases is called the interface. Emulsions tend to have a cloudy appearance, because the many phase interfaces scatter light that passes through the emulsion. Emulsions are unstable and, thus, do not form spontaneously.
The basic color of emulsions is white. If the emulsion is dilute, the Tyndall effect will scatter the light and distort the color to blue; if y da e ect scatte t e g t a d d sto t t e co o to b ue;it is concentrated, the color will be distorted toward yellow.
Microemulsions and nanoemulsions tend to appear clear due to the small size of the disperse phase.
Energy input through shaking, stirring, homogenizing, or spray processes is needed to initially form an emulsion.
Over time, emulsions tend to revert to the stable state of the phases comprising the emulsion, an unstable emulsion that will quickly separate unless p g , q y pshaken continuously.
Whether an emulsion turns into a water-in-oil emulsion or an oil-in-waterWhether an emulsion turns into a water in oil emulsion or an oil in water emulsion depends on the volume fraction of both phases and on the type of emulsifier.
In general, the Bancroft rule applies: Emulsifiers and emulsifying particles tend to promote dispersion of the phase in which they do not dissolve very well; for
l t i di l b tt i t th i il d t d t f il iexample, proteins dissolve better in water than in oil and so tend to form oil-in-water emulsions (that is they promote the dispersion of oil droplets throughout a continuous phase of water).
There are three types of instability:flocculation, creaming, and coalescence.
Flocculation describes the process by which the dispersed phase comes out of suspension in flakes.
Coalescence is another form of instability, which describes when small droplets combine to form progressively larger ones. E l i l d i th i ti f f th b tEmulsions can also undergo creaming, the migration of one of the substances to the top (or the bottom, depending on the relative densities of the two phases) of the emulsion under the influence of buoyancy orcentripetal force when a centrifuge is used.
a b c
Orijinal Emülsiyon Flokulasyon Koalesens
a b c
e d
Kremleşme Kırılma
Surface active substances (surfactants) can increase the kinetic stability of emulsions greatly so that, once formed, the emulsion does not change significantly over years of storage.
Surfactants are compounds that lower the surface tension ofSurfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid. Surfactants may act asbetween a liquid and a solid. Surfactants may act as
detergents,wetting agents,emulsifiers,foaming agentsfoaming agents, and dispersants.
A micelle the lipophilic tails of theA micelle—the lipophilic tails of the surfactant molecules remain on the inside of the micelle due to unfavourable interactions The polar "heads" of the
Surfactants reduce the surface tension of water by adsorbing at the liquid-gas interface They interactions. The polar heads of the
micelle, due to favourable interactions with water, form a hydrophilic outer layer that in effect protects the hydrophobic core of the
the liquid gas interface. They also reduce the interfacial tension between oil and water by adsorbing at the liquid liquid effect protects the hydrophobic core of the
micelle. The compounds that make up a micelle are typically amphiphilic in nature, meaning that not only are micelles soluble
adsorbing at the liquid-liquid interface.
meaning that not only are micelles soluble in protic solvents such as water but also in aprotic solvents as a reverse micelle.
Surfactant classificationSurfactant classification according to the composition of their head: nonionic, anionic, cationic, Amphoteric (pH dependent).
Uses Of Surfactants 1. Emulsifiers
W I Oil L Hlb Water In Oil - Low Hlb Oil In Water - High Hlb
2 F St bili 2. Foam Stabilizers 3. Lipid Crystal Modifiers 4. Wetting Agents 5. Solubilizers 6. Starch Complexers 7. Protein Modifierso od 8. Detergents
I i Of S f A i A Wi hInteraction Of Surface Active Agents With Food Components
1. Lipids 2. Water
3 Starch 3. Starch 4. Protein 5. Air
6 I 6. Ions
MOST SURFACTANTS INVOLVE INTERACTONSINVOLVE INTERACTONS
WITH LIPIDSWITH LIPIDS
Why do we add surfactants toWhy do we add surfactants to foods ?
Orange DrinkSolublizer for colors Stabilize orange oil Possible cloudPossible cloud
Bread Loaf volume Entrap gas,
Soften Soften, Reduces stalingg
CSL, PS 60, DATEM
EMULSIFIERS IN BREADEMULSIFIERS IN BREAD BAKING During mixing
Improves wetability Improves distribution of shortening Interacts with starch, protein and fat
Results in: Decreased mixing time Decreased shortening usageg g Improved mixing tolerance Improved physical characteristics of the doughImproved physical characteristics of the dough
EMULSIFIERS IN BREADEMULSIFIERS IN BREAD BAKING During fermentation
R l i b i Results in better gas retention During baking
d Improved gas retention Improved loaf volume
D d t l Decreased water loss Finer, more uniform texture
During Storage During Storage Increased softness
Less staling Less staling
Pudding Emulsification Wetting agent in powder
Texture modifier Texture modifier
Ice cream Emulsion stability and destability, Foam stability,
Candy Bar Lecithin to stabilize fat crystals "bloom",
control viscosity and thus coating
Cookie Control spread
protein and fat interaction
Note: altering sugar may be a bigger Note: altering sugar may be a bigger factor
Surfactants 172 Listed Under Multipurpose Additives
Dioctyl Sodium Sulfosuccinate Glyceryl Tristearate Hydroxylated Lecithin Methylglucoside- Coconut Oil Ester Oxystearin Sodium Lauryl Sulfate Sodium Stearyl Fumarate
Surface Active Agents Acetylated Monoglycerides Succinylated Monoglycerides Ethoxylated Mono And Diglycerides Polysorbate 60 Polyoxyethylene (20) Sorbitan
Monostearate Aka Tween 60P l b t 65 P l th l (20) S bit Polysorbate 65 Polyoxyethylene (20) Sorbitan TristearatePolysorbate 80 Polyoxyethylene (20) Sorbitan Polysorbate 80 Polyoxyethylene (20) Sorbitan Monooleate
Surface Active Agents
Sorbitan Monostearate Aka Span Calcium Stearoyl-2- Lactylate Sodium Stearoyl-2-Lactylate Lactylic Esters Of Fatty Acidsy y Lactylated Fatty Acid Esters Of Glycerol And
Propyleneglycolpy g y Glyceryl-Lacto Esters Of Fatty Acids Polyglycerol Esters Of Fatty Acids Polyglycerol Esters Of Fatty Acids
Surface Active Agents
Propylene Glycol Mono- And Diesters Of Fats And Fatty AcidsFats And Fatty Acids
Propylene Glycol Alginate Sucrose Fatty Acid Esters Fatty Acids Fatty Acids
Affirmed GRAS Emulsifiers Diacetyl tartaric acid esters of mono- and
diglyceridesdiglycerides. Glyceryl monooleate.
l l Glyceryl monostearate. Glyceryl behenate. Lecithin Mono- and diglycerides.g y Monosodium phosphate derivatives of mono-
and diglyceridesg y
Mono & diglycerides Most commonly used
Generally as mono & di Generally as mono & di Highly lipophilic with HLB values range from 1 to 10 produced by transesterification of glycerol and triacylcerides p y g y y used in bakery products, frozen desserts, icings,
toppings, and peanut butter
Sources
Mono and diglycerides occur naturally as food fat constituents and areMono- and diglycerides occur naturally as food fat constituents, and are also formed from triglycerides, being normal products of fat metabolism, during the digestion and absorption of food.
As such, they are always found in conjunction with triglycerides, glycerol and some free fatty acids subject to the manner in which they have been roduced.
They are produced commercially by a) heating triglyceride fats with an y p y y ) g g yexcess of glycerol, or b) direct esterification of glycerol with fatty acids.
The resulting composition is dependent upon the proportion of glycerolThe resulting composition is dependent upon the proportion of glycerol and temperature conditions used. The mono-ester is usually in the range 30–60%. The composition of the product will vary according to conditions butThe composition of the product will vary according to conditions, but glyceryl monostearate and glyceryl distearate are often major components.
Function in FoodEmulsifiers are used to disperse fat droplets in water or water droplets in fat. B h h f b h f d h h lBecause they act at the surface between the fat and the water, they are also known as surface-active agents or surfactants.
Monoglycerides and mixtures of mono- and diglycerides are by far the most important commercially of all the food surfactants known; in Europe, they represent no less than 50% of the total food emulsifier market and, in addition, p , ,the monoglycerides are important intermediates in the manufacture of DATEMs (diacetyl tartaric acid esters of monoglycerides) and other emulsifiers.
Mono- and diglycerides are used widely in a great many products and are the surfactant type most used in bread. Performance characteristics are controlled by the skilful combining of alpha mono beta mono di and tri glyceryl estersby the skilful combining of alpha-mono-, beta-mono-, di- and tri-glyceryl esters of mixtures of fatty acids. In bread, the effectiveness of the emulsifier is dependent upon its total monoester content as, in this application, the
f f th l h d b t f ti i il d i t ithperformance of the alpha- and betafractions are similar and superior to either the di- or triglycerides.
BenefitsIn the production of bread, the contribution made by the surfactant is to enable the gluten in the dough to remain plastic and pliable so that duringenable the gluten in the dough to remain plastic and pliable so that, during the kneading process, the strands of gluten can form a smooth extensible film, ensuring that the correct texture is produced in the finished product.
As a general rule, volume and texture are of the utmost importance in baking. For example, it can be shown that, in cake making, the air bubbles in the batter that contribute to volume are enclosed in films of protein in which the fat is dispersed.
The action of the surfactant is to improve the production of the initial air bubbles, ensuring their uniformity and thereby an improved texture of thefinished baked product.finished baked product.Typical ProductsBread, cakes and other baked goods; cereals, puddings; fresh pasta, instant (mashed) potatoes; frozen desserts ice cream and soft-serve;instant (mashed) potatoes; frozen desserts, ice cream and soft-serve; confectionery, e.g. chewing gums, toffees, caramels; and fats, e.g. margarines and shortenings.
Polysorbates Polyoxyenthyene esters of sorbitan monoesters
Polysorbate 60 Polysorbate 60 polyoxyethylene sorbitan monostearate or TWEEN 60 - HLB =
14.9
oil toppings, cake mixes, and cake icing Polysorbate 65
polyoxyethylene sorbitan tristearate polyoxyethylene sorbitan tristearate Permitted in ice cream, frozen custard
Polysorbate 80 polyoxyethylene sorbitan tristearate Special dietetic foods, fat soluble vitamine Special dietetic foods, fat soluble vitamine
Sorbitan monostearate- sorbitan monostearate approved for food use- HLB = 4.7 - used in conjunction with polysorbates in oil
t i k i ttoppings, cake mixes, etc.
Stearoyl Lactylates an ionic, hyddophylic emulsifier lactic acid ester of monoglyceride with sodium
or calciumf t l ith l t i t h d form strong complex with gluten in starch and especially valuable in baked products
Lecithin A mixture of phospholipids including phosphatidyl
cholines phosphatidyl ethanolamines inositolcholines, phosphatidyl ethanolamines, inositol phosphatides, etc
Can be chemically modified by provide a wide range of HLB l f i li tiHLB values for various applications
widely used in baked goods, low-fat baked goods, chocolate, instant foods, confectionery products, and cooking spray , y p , g p y
SourcesLecithin is a mixture or fraction of phospholipids, which are obtained from
i l bl f d ff ( i l d ) b h i lanimal or vegetable foodstuffs (mainly soya and egg) by physical processes.
They also include hydrolysed substances obtained by the use of enzymes.
The finished product must not show any residual enzyme activity. A number of different lecithins or lecithin fractions are available.
Function in Food
Phospholipids are the active ingredients of lecithin and have a two-part molecular structure. One part is lipophilic (high affinity to fat/non-polar phase) and the other is hydrophilic (high affinity to water/polar phase)and the other is hydrophilic (high affinity to water/polar phase).
The phospholipids tend to dissolve in fat and disperse in water. This surface ti it i th b i f th j it f l ithi li ti d ll thactivity is the basis for the majority of lecithin applications and allows the
formation of both water-in-oil and oil-in-water emulsions.
Besides nutritional benefits, phospholipids have the following functional properties in food products: emulsification and stabilisation of oil-in-water or water-in-oil emulsions; release and anti-spattering effects; adjustment of the ; p g ; jflow properties in chocolate masses; improvement of the wettability of instant products; as well as optimisation of the gluten network of baked goods.
BenefitsLecithin allows the production of fine stable emulsions with littleLecithin allows the production of fine, stable emulsions with little aggregation or coalescence. It is also used in chocolate manufacture to modify the flow characteristics of liquid chocolate y qfor both blocks and coating. Lecithin is used on the surface of powders to improve “instant” properties. In bakery applications, l ithi i d t i th t ibilit f th l t i b dlecithin is used to increase the extensibility of the gluten in bread making, and in batters to improve the overall distribution of ingredients in cakes and to assist the release of wafers from hotingredients in cakes and to assist the release of wafers from hot iron moulds.
Typical ProductsMargarines, dressings, chocolate and confectionery items, instantpo de s and bake goodspowders and bakery goods.
Emulsifier Usage in U.S.Emulsifier Usage in U.S. (millions of pounds) Emulsifier Bread Cake mix M,SD,S * Total
Mono&Di 116 23 30.5 200 Lecithins 1 10 42.5 MG 13.2 0.5 2.5 25 Polysorb. 1.5 1 .75 8 CSL/SSL 27 .75 .25 30CSL/SSL 27 .75 .25 30 SorbMS .1 2 PG ester 10 1.8 14.3
*Margarine, salad dressings, shortenings
Sorbitan Monostearate Calcium Stearoyl-2- Lactylate Sodium Stearoyl-2-Lactylate
Emulsifier UsageEmulsifier Usage
Product % of total US Bread and Rolls 49 Cake Mixes 11 Cookies and crackers 7 Sweet goods and icings 3g g Margarine, dressings, shortenings 14 Confectionaries 6 Confectionaries 6 Deserts and toppings 3 Dairy products 3 Dairy products 3
The Hydrophilic-lipophilic balance of a surfactant is a measure of the degree to which it is hydrophilic or lipophilic determinedof the degree to which it is hydrophilic or lipophilic, determined by calculating values for the different regions of the molecule
All surfactants must have an oil loving portion and a water loving portion or they would not have surface activityloving portion or they would not have surface activity
•The ratio of the oil loving portion to the water loving portion g p g pis what we call its balance
W thi b l b d l l i ht•We measure this balance based on molecular weight
•“HLB” stands for• HLB stands for
–HYDROPHILE / LIPOPHILE / BALANCE
Hydrophillic-Lipophillic BalanceHydrophillic Lipophillic Balance (HLB) This is a concept for choosing
emulsifiers. The value of HLB ranges from 1-20 The value of HLB ranges from 1-20. Low HLB emulsifiers are soluble in oil
while high HLB emulsifiers are soluble in water..
Bancroft's RuleThe type of emulsion (i.e. oil in water or
water in oil) is dictated by the emulsifier and that the emulsifier should beand that the emulsifier should be soluble in the continuous phase.
Low HLB emulsifier's are soluble in oil andLow HLB emulsifier s are soluble in oil and give rise to water in oil emulsions
Wh i h H B “ ”What is the HLB “system” story
•The “system” was created as a tool to make it easier to use•The system was created as a tool to make it easier to use nonionic surfactants•In general it applies to nonionic surfactants onlyg pp y•The basic principle of the system is:
–Surfactants have an HLB valueA li ti f f t t h HLB i t–Applications for surfactants have an HLB requirement
–Matching the requirement with the value saves time and moneymoney
What is the chemistry of a nonionic surfactant ?What is the chemistry of a nonionic surfactant ?
•Each surfactant has a hydrophilic group and a lipophilic y p g p p pgroup
–must have both or it would not be surface activeth h d hili i ll l h d i * l h l•the hydrophilic group is usually a polyhydric* alcohol or
ethylene oxide•the lipophilic group is usually a fatty acid or a fatty•the lipophilic group is usually a fatty acid or a fatty alcohol–* polyhydric-an alcohol with OH’s attachedp y y
The relationship ( or balance ) between the hydrophilic portion of the nonionic surfactant to the lipophilic portion p p p pis what we callHLB•All nonionic surfactants have an HLB Value
How do we determine the HLB “value” of a surfactant ?
•We calculate the water loving portion of thesurfactant on a l l i ht b i d th di id th t b b 5molecular weight basis and then divide that number by 5
•this keeps the HLB scale smaller and more manageable–the working scale is from 0 5 to 19 5–the working scale is from 0.5 to 19.5
•this number is then assigned to the nonionic surfactant
HLB VALUES OF SOME FOODHLB VALUES OF SOME FOOD EMULSIFIERS EMULSIFIER HLB VALUE Oleic acid * 1.0 Acetylated monoglycerides 1.5 Sorbitan trioleate 1.8 Glycerol dioleate 1.8y Sorbitan tristearate 2.1 Propyleneglycol monostearate 3.4 Propyleneglycol monostearate 3.4 Glycerol Monoleate 3.4 Glycerol monostearate 3 8 Glycerol monostearate 3.8
HLB VALUES OF SOME FOODHLB VALUES OF SOME FOOD EMULSIFIERS EMULSIFIER HLB VALUE
Acetylated monoglycerides (stearate) 3 8 Acetylated monoglycerides (stearate) 3.8 Sorbitan monooleate 4.3 Propylene glycol monolaurate 4 5 Propylene glycol monolaurate 4.5 Sorbitan monostearate 4.7 Calcium stearoxyl-2-lactylate * 5 1 Calcium stearoxyl 2 lactylate 5.1 Glycerol monolaurate 5.2 Sorbitan monopalmitate 6.7Sorbitan monopalmitate 6.7 Soy lecithin 8.0 Diacetylated tartaric acid estersy of monoglycerides 8.0
HLB VALUES OF SOME FOOD EMULSIFIERSEMULSIFIERS
HLB VALUEEMULSIFIER HLB VALUE Sodium Stearoyl lactylate * 8.3
Sorbitan monolaurate ) 8 6 Sorbitan monolaurate ) 8.6 Polyoxyethylene (20) sorbitan tristearate 10 5 sorbitan tristearate 10.5 Polyoxyethylene (20) sorbitan trioleate 11.0 sorbitan trioleate 11.0 Polyoxyethylene (20) sorbitan monostearate 14.9 Sucrose monolaurate 15.0 Polyoxyethylene (20) sorbitan monooleate 15.0
HLB VALUES OF SOME FOODHLB VALUES OF SOME FOOD EMULSIFIERS EMULSIFIER HLB VALUE Sodium Stearoyl lactylate * 8 3 Sodium Stearoyl lactylate 8.3 Sorbitan monolaurate ) 8.6 Polyoxyethylene (20) sorbitan tristearate 10.5 Polyoxyethylene (20) sorbitan trioleate 11.0 Polyoxyethylene (20) sorbitan monostearate 14.9 Sucrose monolaurate 15.0 Sucrose monolaurate 15.0 Polyoxyethylene (20) sorbitan monooleate 15.0 Polyoxyethylene (20) sorbitan monopalmitate 15.6
Stokes' Law Creaming or sedimentation is
i lproportional to: 1. Diameter of the particle squared 2. Difference in density between the
particle and the continuous phase And inversely proportional to:
3 Viscosity of the continuous phase 3. Viscosity of the continuous phase
Stokes’ Law Rate = [Diameter squared x density
difference x g] / [16 x viscosity] How can we change diameter? How can we change diameter? How can we change density difference? How can we change viscosity?
Amylose Complexing Index Distilled Monoglycerides
From hydrogenated lard (65% MS, 30% MP) 92 From hydrogenated soy oil (85%Mono Stearate) 87 From unhydrogenated lard 45% Mono olein 35 From soy oil (55% mono olein) 28
Acetylated mono glycerides 0 Saturated Mono and Di glycerides (50% mono) 42 Steroyl-2-lactylate 79 Sodium Steroyl-2-lactylate 72 Calcium Steroyl-2-lactylate 65
Lactylated monoglycerides 22y g y Diacetyltartaric esters of monoglycerides 49
Basic Rules1. For emulsions, if you don't have A clue,
use At 5% Of The fat.2 Use unsaturated emulsifiers with2. Use unsaturated emulsifiers with
unsaturated fats.3. Mixtures work better than a single
emulsifier when stabilizing foams And gemulsions.
Basic Rules4. Bancroft's Rule
E l i S bili I F d B S l bili I ThEmulsion Stability Is Favored By Solubility In The Continuous Phase i.e. High HLB----> oil/water
Low HLB-----> water/oilLow HLB-----> water/oil5. HLB and most other rules go out the window
when protein and (sometimes)when protein and (sometimes) polysaccharides enter the system.
6 Only saturated monoglycerides complex with6. Only saturated monoglycerides complex with starch.
Basic Rules 4. Bancroft's Rule
E l i S bili I F d B S l bili I Th Emulsion Stability Is Favored By Solubility In The Continuous Phase i.e. High HLB----> oil/water
Low HLB-----> water/oil Low HLB-----> water/oil 5. HLB and most other rules go out the
window when protein and (sometimes)window when protein and (sometimes) polysaccharides enter the system.
6 Only saturated monoglycerides complex 6. Only saturated monoglycerides complex with starch.
Basic Rules 7. Emulsifier forms affect functionality.
fl k d h d l flakes vs powder vs hydrates vs gels 8. Many functions are due to affects on
l hipolymorphism. 9. Emulsifier preparations frequently contain
nsat ation and ma be an impo tantunsaturation and may be an important contributor to off flavors.10 Emulsifier preparations are seldom pure 10. Emulsifier preparations are seldom pure and thus variation from manufacturer to manufacturer may be substantialmanufacturer may be substantial.
Basic Rules11. When you find a non-obvious usage of
emulsifiers the function is often related toemulsifiers, the function is often related to interaction with starch or protein.
12 Order of addition may be very important12. Order of addition may be very important.13. Processing steps like homogenization may
substantially change the function ofsubstantially change the function of emulsifiers.