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Answering the Challenge:
Label-friendly Emulsifiers and
Surfactants for Food Systems
Prof. Pete Wilde
2nd annual Clean Label Conference
March 31-April 1, 2015, Westin Hotel, Itasca, Ill.
Making Emulsions
(and foams)
Oil droplets
How to make a solid
from 2 liquids
Oil droplets
Dilute emulsion
Droplets free to move,
behaves like a liquid.
Viscosity c(1 + 2.5 Vd)
(Einstein, 1906)
Concentrated emulsion
Vd 0.6, droplets trapped
Liquid motion arrested
behaves as a “solid”
Small droplets m “rigid” spheres
Role of Emulsifiers
Aid breakup of droplets by reducing interfacial tension
Droplet shape during emulsification
High interfacial tension
Applies to both emulsions and foams
Low interfacial tension Stabilise droplets against coalescence
Unstable
Stable
Interfacial tension
Force acting around
the droplet to
minimise surface free
energy, and keep
droplet spherical
F F
Properties of emulsifiers
Hydrophobic
Hydrophilic
HLB = Hydrophilic:Lipophilic Balance
HydrophobicLow HLB
(oil soluble)
HydrophilicHigh HLB
(water soluble)
Size, structure, charge
Oil
Oil
Water
Preferred Interfacial curvature
High HLBFoams,
Oil – in – water emulsions
Low HLBWater in oil emulsions
HLB Use
4-6 W/O emulsifiers
7-9 Wetting agents
8-18 O/W emulsifiers
13-15 Detergents
10-18 Solubilizers
Interfacial StabilityThe importance of curvature
Hydrophobic
Hydrophilic
HLB = Hydrophilic:Lipophilic Balance
HydrophobicLow HLB
HydrophilicHigh HLB
o/w
w/o
High HLB Low HLB
Stable Unstable
StableUnstable
Size, structure, charge
Food Emulsifiers & Surfactants
Ancient Greeks used beeswax in cosmetic products
Egg yolk traditionally used as an emulsifier - rich in phospholipids
Replaced by phospholipids (lecithin) extracted from soy in 1920’s
More effective, synthetic emulsifiers developed based on fatty acid derivatives
Mono- and di-glycerides of fatty acids
Lecithins
Naturally occurring molecules, but mass produced by chemical
modification. Refined / enriched to control HLB and functionality
Tend to be extracted from plant sources or egg. Can be further
refined/enriched to give better control over HLB, and functionality.
(Poly)sorbates and sucrose estersSynthetic emulsifiers with highly controlled range of HLB and
functionalities .
Esters of monoglycerides (Lactylate, citrate, polyglycerol)
Chemically modified esters of monoglycerides with specific
functionalities.
Emulsifiers Uses & Functions
Mayonnaise, sauces, soups – Emulsify and stabilise fat by
adsorbing and reducing interfacial tension and providing stable
interfacial layer
Margarines & Spreads – Emulsify and stabilise water phase.
Prevent splattering, stabilise and control fat crystal network
structure.
Chocolate – Emulsify and stabilise different phases, stabilise
fat and sugar. Improve consistency during filling and moulding,
reduce bloom formation.
Fat
Sugar
Protein
Cocoa
Emulsifiers Uses & Functions
Bread & Baked products – Emulsify and stabilise
shortenings, stabilise gas cells. Control starch – gluten
interactions. Controls dough strength, loaf volume, crumb
structure and shelf life.
Meat products – Emulsify and stabilise water and
fat phases, particularly in reduced fat products.
Improves texture and taste.
Ice cream and whipping cream– Emulsify and
stabilise fat droplets. Destabilise interfaces to
promote partial coalescence to develop
structure formation. Stabilise ice crystals to
maintain texture.
Air bubble
Thin aqueous film
Gluten/StarchMatrixFat
Clean label solutions
• Direct Replacements – “Natural” alternatives
• Additional or Alternative Functionalities
• Modifications & Processing Aids
“Natural” Emulsifiers
Quillaja extract - from inner
bark of the soapbark (Quillaja
saponaria, Molina). Rich in
saponin – natural surfactant
Bile salts – derived from
cholesterol, secreted by gall
bladder, excellent emulsifiers,
aid digestion of fats. Used a
supplement in bile deficiency.
Potential Food Emulsifier ?
“Natural” Emulsifiers
Lipoproteins, Nature’s own emulsions. Energy store
Egg yolk, soy, sunflower etc…
Oil bodies in plants and animal tissues.
Highly stable, energy efficient.
Phosholipids, surface active proteins (oleosins, apo-
lipoproteins, hydrophobins etc)
Assembled on an individual basis, slow manufacture.
Tend to be locked into structures, eg fat globule
membranes – poor solubility
Hence, purification / refinement required
no longer clean label?
Oil body
Iipoprotein
Chloroplast
“Natural” Emulsifiers
Chloroplasts, thylakoid membranes packed with
galactolipids.
Bound up in structure, but free galactolipids linked with
improved functionality in breadmaking (see enzyme
section).
Galactolipids may also modulate fat digestion and may
help reduce appetite.
Need targeted processing to help develop as a “natural”
ingredient.
MonoGalactosylDiacylGlycerol
(MGDG)
MonoGalactosylMonoacylGlycerol
(MGMG)
“Natural” Emulsifiers
Hydrophobins – secreted by filamentous
fungi to help hyphae break through water
surface
Froghopper – cuckoospit froth.
Natural, but not tasty
Excellent long term
stability of bubbles in
ice cream, and
responsible for
“gushing” in beer.
But……
Food or Additive?
Grape seed and apple tannins: Emulsifying and antioxidant
properties.
Figueroa-Espinoza, Maria Cruz; Zafimahova, Andrea;
Alvarado, Pedro G Maldonado; et al.
Food chemistry Volume: 178 (2015) Pages: 38-44
Emulsions stabilised by
grape and apple tannins
Optimization of extraction conditions and fatty acid
characterization of Lactobacillus pentosus cell-bound
biosurfactant/bioemulsifier
Vecino, Xanel; Barbosa-Pereira, Letricia; Devesa-Rey,
Rosa; et al.
Journal of the Science of Food and Agriculture Volume:
95 (2015) Issue: 2 Pages: 313-320
Using biosurfactants produced
by lactic acid bacteria. Efficient
as surfactants, but clean label?
Production of exopolysaccharides by Lactobacillus
helveticus MB2-1 and its functional characteristics in
vitro
Li, Wei; Ji, Juan; Rui, Xin; et al.
LWT- Food Science and Technology Volume: 59
(2014) Issue: 2 Pages: 732-739
Exopolysaccharides
produced by lactic acid
bacteria with emulsifying
properties. Interesting
properties but clean label?
Emerging Research
Proteins and Polymeric Emulsifiers
Hydrophobic
groups at core of
molecule
Oil / Air Phase
Aqueous Phase
InteractionsUnfolding to expose
hydrophobic groups to
surface
Proteins vs Surfactants
Strong interactions High mobilityWeak interactions
Restricted mobility
Protein Mixed Surfactants
Foam & Emulsion Stability
Short range
Thin film
Polymers and Emulsion Stability
Proteins and polymers can confer excellent long term stability
Some proteins, eg hydrophobins create strong,
elastic interfaces which prolong stability and
can improve texture and mouthfeel.Protein
1
2
3
4
5
6
7
0 10 20 30 40 50
Fat Content (vol %)
Per
ceiv
ed F
at C
on
ten
t (S
core
)
Sensory perception
Surfactant
Natural carbohydrate – protein complexes (eg
gum arabic, sugar beet pectins) form thick,
bulky structures at surface, conferring excellent
long term steric stabilisation.
Protein
Carbohydrate
However, high molecular
weight, not efficient
during emulsification, so
high concentrations /
high energy required
Pickering Stabilisation
Emulsions stabilised by particles with
defined surface hydrophobicity.
Some small starch granules (quinoa,
rice) can form stable emulsions.
Fat crystals can also be used, but
sensitive to heat treatment.
Large size warrants high energy required
to form emulsions initially.
Surface modification
improves functionality
Modification & Processing Aids
There are many natural, clean label emulsifiers, but often not in a functional form
Adams et al.
Extraction, isolation and characterisation of oil bodies
from pumpkin seeds for therapeutic use.
Food Chemistry 2012 Volume 134, Issue 4, Pages
1919–1925
Oil bodies are already in an emulsified form
Could their natural
emulsifying properties be
exploited by in situ use of
oil bodies
Modification & Processing Aids
Lipases in breadmaking
Gas cell in bread are stabilised primarily be
polar lipids.
Lipid composition of bread affects loaf volume
and quality
Addition of emulsifiers such as DATEM and
SSL improve baking quality.
Flour polar lipids
C16:0 - FA
C14:0 - FA
C18:2 - FA
Flour non-polar lipids
Flour total lipids
Loaf
volu
me (
ml)
Gas cell development
Gluten starch matrix Gas cells
Lamellae
Coalescence “Sponge” transition
• CO2 production – bubble expansion during proofing and
oven spring
• Bubbles in contact rely on interfacial stability
• Early coalescence – loss of loaf volume
Mixing Proofing Baking
Type of Lipids
Polar Lipids TAG FFA DAG
%m
ol T
ota
l L
ipid
s
0
10
20
30
40
50
60
70
Flour Dough Liquor Foam
Dough liquor foam and lipid composition
Fatty acids concentrate in foam
TAG do not accumulate in foam, but some present
which may cause instability
Using lipase to alter lipid profile
Gerits LR. et al. Food Chemistry 156 (2014) 190–196
40424446485052545658
Control YieldMAX Lipolase Lecitase Lipopan
Loaf
Vo
lum
e (
ml)
Lipase
FFA
DGDG DGMG
MGDG MGMG
PC LPC
Conversion of polar lipids
from di-Acyl to Mono-Acyl
Strong correlation with
loaf volume
Summary
Emulsifiers and surfactants have been developed and optimised for
functional performance – adsorption, emulsification, stabilisation,
texture modification etc.
Natural, clean label alternatives becoming will probably never match
bespoke emulsifiers for performance.
Understanding the structure – function – performance relationships of
conventional ingredients is key to developing viable replacements.
Emerging research is revealing new sources of active ingredients, but
not all will be clean label.
Process modification and addition functionalities of some clean label
solutions do make them viable alternatives.