Stabilization of Omega-3 Fatty

Acids with Emulsification

Technologies

D. Julian McClements & Eric A. Decker

Department of Food Science

University of Massachusetts , Amherst

Incorporation of Bioactive Lipids

as Emulsion Delivery Systems

Extract

oil

Incorporate

as ingredient

Emulsion

Delivery System

Oil Final

Product

Homogenize

Oil

Source

Oxidation

Preparation of ωωωω-3 Emulsion

Delivery System

Oil

Water

Homogenization

Emulsion

Droplet

+ Emulsifier

Homogenizers: Mixers, HPVH, Colloid Mills etc

Emulsifiers: Surfactants, Proteins, Polysaccharides etc

Desired Properties of ωωωω-3

Emulsion Delivery System

• Stability

– Droplet aggregation

– Creaming

– Lipid oxidation

• Physicochemical Properties

– Easy to store & transport

– Easy to incorporate into foods

• Commercial Attributes

– Food grade ingredients

– Economical

Optimization of Physical Stability

of ωωωω-3 Emulsion Delivery System

• Droplet Concentration

– 30-40%

– High lipid, Low viscosity

• Droplet Diameter

– < 1 µm

– Good creaming stability

• Compatibility

– Incorporation into products

1

10

100

1000

0 20 40 60

φφφφ (wt %)V

isco

sity

(m

Pa s

)

Optimization of Oxidative Stability

of ωωωω-3 Emulsion Delivery System

• Shelf-Life

– 1 to 12 months

– No detectable rancidity

– Depends on product

Challenge: How to retard lipid oxidation?

Reactants

(Unsaturated Lipids + O2)

Primary Reaction Products

(Peroxides and Conjugated Dienes)

Secondary Reaction Products

(Aldehydes, Ketones, Alcohols, Hydrocarbons)

Lipid Oxidation Reaction

Lipid oxidation is a complex series of chemical reactions that is

initiated when oxygen interacts with unsaturated lipids.

0

0.2

0.4

0.6

0.8

1

1.2

0 5 10 15 20

Storage Time

Co

nc

en

tra

tio

n

R

1º 2º

Proposed Lipid Oxidation Mechanism

in Oil-in-Water Emulsions

ROOH

ROOH = Fatty Acid Peroxide

Fe2+

RO•Attack

Lipid

RO• = Alkoxyl Radical

PUFA

Move to

interface

PUFA = Polyunsaturated Fatty AcidWater-Soluble

2º Products

Move from

interface

Evidence for Hydroperoxides role

0

100

200

300

400

500

600

700

0 1 2 3 4 5 6 7 8

Time (days)

Hexan

al

(uM

)

Control

Control +

TAG Hydroperoxides

Strategies to Retard Lipid

Oxidation in Emulsions

• Retard Oxidation Reaction

– e.g., Add antioxidants

• Inactive Iron

– e.g., Chelation, Binding

• Prevent Iron Reaching Interface

– e.g., Electrostatic or Steric Repulsion

Emulsion Preparation and

Characterization

Emulsion

Characterization

• Particle Size

• ζζζζ-Potential

• Creaming

• Oxidation

Emulsion

Preparation

HPVH

Retard Oxidation Reaction: Add Antioxidants

Salmon Oil-in-Water Emulsions

0

100

200

300

400

500

600

700

0 20 40 60 80 100 120

Hours

Pro

pa

na

l (u

M) Control

a-Toc

Mix Toc

Antioxidant Effectiveness Depends

on Partitioning

Site of Action is Important !

• Antioxidants appropriate for bulk oils may

not work in emulsions !

Non-Polar

Amphiphilic

Polar

Inactivation of Iron:

Sequestration

ROOHFe2+

Sequestering Agent

Inactive Iron by Sequestration

• Chelating agents (EDTA, organic acids, polyphosphates)

• Proteins (Transferrin, Phosvitin, Lactoferrin, Ferritin)

• Polysaccharides (xanthan)

0

5

10

15

20

25

30

0 14 28 42 56 70 84 98 112 126 140

Hours

Pro

pa

na

l (m

mo

l/k

g l

ipid

)

Control

EDTA

Transferrin

Inactivation of Iron: Chelation

Influence of EDTA on Fe-Promoted Lipid

Oxidation and Zeta Potential of SDS-

Stabilized Salmon Oil Emulsions

0

2

4

6

8

10

12

14T

BA

RS

or

Zet

a

0 50 200 500 1000 2000

EDTA Conc.

TBARS

Zeta____

Fe2+

____

Fe2+

Prevent Iron Reaching Interface: Electrostatic Repulsion

ROOHFe2+

Electrostatic

Repulsion+ +

+++

+

+

+

++ +

+

+

Prevent Iron Reaching Interface

• Use Cationic Emulsifier (e.g., Protein below IEP)

Prevent Iron Reaching Interface: Electrostatic Repulsion

0

5

10

15

20

25

30

0 14 28 42 56 70 84 98 112 126 140

Hours

Pro

pa

na

l (m

mo

l/k

g o

il)

SDS

Tween 20

DTAB

Salmon Oil-in-Water Emulsions

−−−−

+

Prevent Iron Reaching Interface:

Electrostatic Repulsion

0

0.5

1

1.5

3 4 6 7

pH

TB

AR

S

(m

M k

g-1

oil

)

WPI Stabilized Salmon Oil-in-Water Emulsions

+

−

Prevent Iron Reaching Interface: Thick Interfacial Membrane

ROOHFe2+

Steric

Hindrance

Prevent Iron Reaching Interface

• Use Emulsifier That Forms Thick Membrane

Prevent Iron Reaching Interface: Thick Interfacial Membrane

0

5

10

15

0 50 100 150

Time (hr)

Pr

op

an

al

(u

mo

l/k

g o

il)

Brij 76

Brij 700

Salmon Oil-in-Water Emulsions

Utilize Pure Ingredients: Hydroperoxide Concentrations of

Commercial Surfactants

Brij 10 4.0 uM/g

Brij 35 13.7 uM/g

Tween 20 16.8 uM/g

Tween 40 11.6 uM/g

SDS 0.6 uM/g

DTAB 0.4 uM/g

Lecithin 13.0 uM/g

0

500

1000

1500

2000

0 20 40 60 80 100

Time (hours)

Pro

pa

na

l (m

M)

Low

ROOH

High

ROOH

Impact of Tween 20 Hydroperoxides on

Oxidation of Salmon Oil

Interfacial Engineering:Traditional One-Step Emulsion

Formation

Oil

Water

Homogenization

Emulsion

Droplet

+ Emulsifier

HomogenizeAdd Biopolymer

Separate Oil

and Water Phases

Single Layer Two Layers

Primary Emulsion Secondary Emulsion

Interfacial Engineering:Multi-Step Emulsion Formation

+ Emulsifier

Control of Interfacial

Characteristics

• Control of Interfacial Properties

– Charge Density

– Thickness

– Packing

• Control of Emulsion Properties

– Stability

– Rheology

– Oxidation Stability

Improvement of Emulsion Stability to

Environmental Stress: Lipid Oxidation

0

200

400

600

800

1000

1200

1400

3 4 5 6 7 8

Time (Days)

TB

AR

S (

mM

)

1º

2º

3º

1º 2º 3º

Fe2+

−−−− + + + + −−−−

Conclusions

Omega-3 fatty acids

can be incorporated into

stable emulsion delivery

systems, which offer

advantages over direct oil

incorporation into foods

• Easier Handling and

Utilization

• Additional Protective Strategies

Strategies to Retard Lipid

Oxidation in Emulsions

• Control Interfacial Characteristics

– Charge, Thickness, Composition, Rheology

• Control Droplet Characteristics

– Size (Surface Area), Concentration, Physical State, Composition

• Control Aqueous Phase Characteristics

– pH, Ionic strength, Chelating Agents

• Add Antioxidants

– Oil, Water or Interfacial