Ingredient Functionality & Characterization David Julian McClements Biopolymers and Colloids Laboratory Department of Food Science

• Emulsifiers • Texture Modifiers – Thickening Agents – Gelling Agents • Weighting Agents Emulsifiers: Major Functions in Food Emulsions

Functional Properties • Emulsion Formation • Emulsion Stabilization • Modification of Interfacial Properties • Modification of Crystallization • Interaction with Biopolymers

Displacement – Crystal modification – Polymer interaction – ice cream manufacture margarine manufacture Bread manufacture Emulsifiers: Formation

Emulsifier Factors Affecting Formation: • Concentration and Surface Load Microfluidics – sufficient present to cover all surfaces formed • Adsorption Kinetics – adsorbs fast enough to form protective coating • Interfacial Tension – lower γ gives smaller droplets • Protective Coating – Emulsifier layer should protect against aggregation

Movement Incorporation Film Formation − to surface − In surface − − − − − − − − − − Emulsifiers: Stability

Emulsifier Factors Affecting Stability: • Colloidal Interactions - Interfacial Thickness, Charge & Hydrophobicity • Resistance of membrane to disruption - Interfacial rheology Hydrophobicity Charge + + + + Thickness Environmental Responsiveness: pH, I, T Common Food Emulsifiers Small Molecule Surfactants – Tweens, Spans, fatty acids, DATEM – Sucrose esters, polyglycerol esters, monoglycerides

Phospholipids – Egg, soybean, milk

− − Biopolymers − − − − − − − – whey, casein, egg, gelatin, soy – modified starch, gum arabic, modified cellulose Emulsifier Applications in Foods Salad Dressings – Tweens Soft Drinks – PGA – Gum Arabic – Proteins – Modified Starch Mayonnaise – Proteins Ice Cream – Phospholipids – Proteins – Yolk particles – Phospholipids Sauces & Dips – (Surfactants) – Mono/diglycerides

Milk & Cream Nutritional Beverages – Proteins – Proteins – Phospholipids – Phospholipids Specifying Emulsifier Functionality Choosing the most appropriate emulsifier Physicochemical Factors • Emulsion type (O/W or W/O)

• Minimum amount needed ( Cmin ) • Minimum droplet size achievable ( rmin ) • Ingredient compatibility • Sensitivity to environmental stresses (pH, I, T)

Practical Factors • Ease of utilization • Reliability/Consistency of source • Long term stability • Sensory properties Currently no standard method of Economic & Marketing Factors specifying • Cost emulsifier • Label friendliness functionality Surfactants: Molecular Structure

Head Group − + • Electrical charge (non-ionic/ionic) • Chemical groups • Length and cross-section Tail Group • Number of chains • Length of chains − − − • Saturation of chains Industrial Manufacture of Surfactants

Tween 20 Structure: ChemBlink

Commercial surfactants are actually a complex mixture of many different molecules

Danisco Self Assembly of Surfactants

Micelle Non-spherical Micelle Reverse Micelle

Vesicle

Surfactants can form a variety of structures, with different functional properties, depending on their molecular structure Classification of Surfactants

• Bancroft rule – The phase in which the surfactant is most soluble (dispersible) forms the continuous phase of emulsion • HLB number – The ability of a surfactant to stabilize an emulsion depends on balance of hydrophilic to lipophilic groups HLB Classification Scheme

Hydrophobic Group Hydrophilic Group Group Number Group Number − + -CH- 0.475 -SO 4 Na 38.7 -COO −H+ 21.2 -CH 2 - 0.475 Sorbitan ring 6.8 -CH 3 0.475 -COOH 2.1 O

− + CH 3(CH 2)11 -O-S-O Na O HLB = 7 + Σ(hydrophilic groups) - Σ(lipophilic groups) HLB Numbers of Some Food Surfactants

Surfactant Name HLB Number

Sodium lauryl sulfate 40 Hydrophilic Potassium Oleate 20 Tween 20 15 Decaglycerol monooleate 14 Ethoxylated monoglyceride 13 Tween 20 DATEM 8 Soy lecithin 8 Calcium stearoyl lactylate 5.1 Lipophilic Glycerol monoleate 3.4 Sorbitan trioleate 1.8 Oleic acid 1.0 Oleic acid HLB Classification Scheme

HLB Number Solubility Emulsion Type

Very Low (<3) Oil Unstable Low (3-6) Oil W/O Medium (6-8) Oil&Water Unstable High (8-18) Water O/W Very High (>18) Water Unstable Benefits and Limitations of Classification Schemes Benefits • Provide information on emulsion type (O/W or W/O) • Enable rational selection of mixed surfactant systems Limitations • Not applicable to biopolymers • No insight into: • Minimum droplet size that can be created • Amount of emulsifier needed • Stability of emulsion to environmental stresses Testing Emulsifier Efficiency: Fundamental Measurements • Surface Load ( ΓΓΓ) – mg/m 2 – Maximum surface area that can be covered per gram

• Binding Affinity (c 1/2 ) – Amount of emulsifier required to reach saturation www.dataphysics.de

• Maximum Surface Pressure ( ΠΠΠSat ) 40 35 )

– mN/m 2 30 – Minimum droplet size achievable 25 c 20 1/2 π 15 ∞ (mJ/m • Adsorption Kinetics 10 Π Π Π Π − ∆c /δ t (measured under dynamic conditions) 5 i 0 – Minimum droplet size achievable 0.0001 0.01 1 [Emulsifier] Testing Emulsifier Efficiency: Practical Tests for Emulsion Formation

5 C min = minimum amount of m) 4 µ µ µ µ emulsifier to homogenize fixed 3 C quantity of oil min r 2 min = minimum achievable droplet size 1 Mean( Radius 0 rmin 0 2 4 6 8 10 Emulsifier Concentration (wt%) Depends on: • Solution Conditions • Mechanical Device Factors Affecting Emulsion Formation

C r min & min Depend on: • Adsorption Rate • Interfacial Tension Reduction • Packing Efficiency • Membrane Protective Effect

High Cmin Low Cmin Testing Emulsifier Efficiency Practical Tests for Emulsion Stability

Emulsion Emulsion characterization preparation Test or

Initial • Droplet Size Emulsion • Droplet charge • Rheology • Creaming Long term storage, accelerated or environmental stress tests Testing Emulsifier Efficiency Stability to Environmental Stress Minerals and pH • pH 2 to 8

• NaCl 0 – 1 M, CaCl 2 0 – 100 mM Thermal Processing • 30-90 ºC for 30 minutes Freeze Thaw Cycling -20ºC / +20ºC Dehydration • Spray drying or Freeze drying Mechanical Agitation • Shaking, Stirring Stable Unstable Stability to Environmental Stress Influence of Emulsifier Type ------• Thickness - - - • Charge - - - - • Hydrophobicity - - - • Rigidity - - - - -

Emulsifier Type Stabilizing Environmental Mechanism Sensitivity Proteins Electrostatic, Steric pH, I, T

Polysaccharides Steric, Electrostatic -

Surfactants • Non-ionic Steric, (Electrostatic) T • Ionic Electrostatic, Steric pH, I, T Stability to Environmental Stress Influence of Emulsifier Type

6

5 WPI 4 GA MS

m) 3 µ µ µ µ ( 2

Mean Diameter 1

0 3 4 5 6 7 pH WPI stabilized emulsions are sensitive to pH, minerals, temperature Comparison of Physiochemical Properties of Emulsifiers

Emulsifier Natural Adsorption Interfacial Amount Environmental Type Rate Tension Needed Sensitivity Surfactant No Rapid Low Low Freezing, Drying - Non-ionic Heating Surfactant No Rapid Low Low Freezing, Drying - Ionic (Yes) Heating, I Protein Yes Medium Medium Low / Freezing, Drying Medium Heating, I, pH Polysaccharide Yes Slow High High (Freezing, Drying) (No)

The choice of an appropriate emulsifier depends on many factors Selecting an Emulsifier

• Establish Operating Environment – pH, I, T, Mechanical stress, Water content • Establish Labeling Requirements – Natural? Kosher? Vegan? GMO? etc • Establish Maximum Cost-in-Use of Emulsifier • Identify Available Emulsifiers – Surfactants, Phospholipids, Biopolymers • Carry Out Product Tests – Particle Size, Amount Needed, Stability, Ease of Use Texture Modifiers Functional Properties: • Texture – Modify the overall textural properties and mouthfeel of the system • Stability – Retard movement of droplets and other particulate matter

Mode of Operation: • Thickening Agents: – increase viscosity because of their large molecular dimensions • Gelling Agents – form gels because of their ability

to form intermolecular cross-links −−−S−−−S−−− Thickening & Gelling Agents Typical Food Ingredients Polysaccharides – Agar, Alginic acid, Alginate, Carrageenan, Guar gum, Gellan gum, Curdlan, Modified Celluloses, Modified starches, Pectins, Xanthan Proteins – Gelatin, Whey, Casein, Soy, Egg Sugars & Polyols – Glycerol, Sorbitol, Lactitol, Mannitol – Trehalose

Xanthan Gum: IFR, UK Thickening Agents Molecular Characteristics Conformation

Random Coil Globular Rigid Rod Charge Sign Molecular Weight −−− + + + −−− −−− −−− + −−− + Low −−− + High Negative Positive

Branching Charge Density + + + + + + + + Unbranched Branched Low High Biopolymer Solution Rheology Influence of Particle Concentration

No Biopolymer

Greater Energy Biopolymer Dissipation

• Biopolymers Increase Fluid Viscosity

η = η0 (1 + 2.5 φ) Thickening Agents Quantifying their Functionality

Trapped Water Rotating Polymer

η = η0 (1 + 2.5 Rvφ)

Factors Influencing RV: Volume Ratio: • Molecular Weight • Degree of Branching Vsphere • Electrical Charge Density RV = • Conformation V polymer • Interactions Thickening Agents Influence on Solution Rheology Semi-Dilute 10

Dilute Concentrated

Relative Viscosity c*

1 0.01 0.1 1 10 Concentration (kg m -3 ) -3 c* ≈ 530 / Rv (kg m ) Thickening Agents Influence of Structure on Rheology

10 Rv

1 100 1000 5000 Relative Viscosity

1 0.01 0.1 1 10 100 Concentration (kg m -3 ) Thickening Agents: Effective Volumes

Proteins

MW [η][η][η] RV (kDa) (g/mL) Lysozyme 14.1 2.7 1.7

Hemoglobin 68 3.6 2.3

Collagen 345 1270 810

Gelatin 383 69 44

-1 η Rv ≈ 0.64 × [η] (in g mL )

C * Adapted from Peter Wolf (2005) Thickening Agents: Effective Volumes Polysaccharides

MW [η][η][η] RV (kDa) (g/mL) Alginate 100 270 173 300 550 350 Guar 100 62 40 200 120 77 LBG 100 71 45 300 170 109 Pectin 50 110 70 Xanthan 100 193 124 300 780 500 1,000 2,400 1540 Amylose 500 99 64 1,000 245 157

* Adapted from Peter Wolf (2005) Thickening Agents

Influence of Molecular Properties on R V Effect of Chain Length

Effect of Salt (Charged Polymer) − −+ − + − − + − High MW: Low MW: − − + High R V Low R V Low Salt : High Salt :

High R V Low R V Effect of Branching

Linear: Branched:

High R V Low R V Thickening Agents Shear Thinning Behavior

More resistance • Entangled to flow • Extended 0.1

Decreasing • Elongated Concentration 0.01 • Aligned Viscosity

Less resistance to flow 0.001 0.001 0.01 0.1 1 10 100 1000 Shear Stress (Pa) Gelling Agents: Molecular Basis of Functionality

Why do some biopolymers form gels? What determines gel characteristics? Food Gels: Many Different Gel Mechanisms

Gell-O Pudding • Flexible Proteins • Starch • Cold-set • Cold/Heat-set • Reversible • Irreversible

Eggs Deserts • Globular Proteins • Polysaccharides • Heat-set • Ca 2+ -set • Irreversible • Irreversible Molecular Basis of Gelation

Understanding

Design

Molecular Microscopic behavior: Physical Properties: Characteristics: - Interactions, - Texture, Appearance, - MW, Conformation, Organization Stability, Flexibility, Charge Mouthfeel Gelling Agents: Gelation Mechanism

Covalent Salt bond bridge −−− Ca 2+ −−−OOC −−−S−−−S−−− −−−COO −−−

Hydrogen VDW Hydrophobic bonding attraction attraction Gel Structure and Properties Structural-unit dimensions Pore Size

Bond Bond number strength

Particulate gel Filament gel Key Properties: • Gel Strength • Reversibility • Gel Appearance • Setting Mechanism • Water Holding Capacity – Heat, Cold, Ions, pH etc • Environmental Responsiveness Thickening & Gelling Agents Selection Criteria Physicochemical Characteristics – Rheology: Viscosity Enhancement Capacity; Gel strength, Gelation Temperature, Reversibility, etc – Dispersion & Solubility Characteristics – Appearance (Transparent, Turbid, Opaque) – Environmental Sensitivity (pH, T, I) – Ingredient Compatibility Other Characteristics – Legal Status – Label Friendliness – Cost, Reliability of Supply Weighting Agents: Retardation of Creaming

StokesStokes Law:Law: 2 VV == --22rr ∆ρ∆ρ g/9g/9 ηη1

RoleRole ofof weightingweighting agentsagents :: •• IncorporationIncorporation ofof densedense oiloil --solublesoluble materialmaterial inin thethe oiloil phasephase reducesreduces thethe densitydensity differencedifference (( ∆ρ∆ρ ),), therebythereby slowingslowing gravitationalgravitational separation.separation. Weighting Agents Creaming Velocity of Oil Droplets

Creaming 0.5 Stable to Creaming ) -1

s 0.3 -1

(m 0.1 6

-100-0.1 0 100 200 x 10 2 -0.3 U/r -0.5 Sedimentation -3 ∆ρ∆ρ∆ρ (kg m ) Commonly Used Weighting Agents

Name Density Characteristics

BVO 1290 kg m -3 Viscous Liquid SAIB 1150 kg m -3 Viscous Liquid Ester Gum 1080 kg m -3 Solid Damar Gum 1060 kg m -3 Viscous Liquid

SAIB: sucrose acetate isobutyrate BVO: brominated vegetable oil

WeightingWeighting AgentAgent ContentContent :: φφWA == [[ ρρAQ -- ρρO]/]/ [[ ρρWA -- ρρO]]

Factors: Legal Limits, Ease of Utilization, Labeling, Reliability Alternative Strategies to Traditional Weighting Agents

Filled Solid Lipid Multilayer Hydrogel Particles Nanoparticles Emulsions

Make density of particle equal density of surrounding aqueous phase: • Density of oil < density of water • Density of biopolymers > density of water • Density of solid fat > density of liquid oil Importance of Ingredient Interactions

Interactions Change: • Charge • Conformation Interactions: Electrostatic, Hydrophobic, Hydrogen bonding • Hydrophobicity • Solubility • Association

Functional ingredients can interact with other components, which can either improve and adversely affect their performance Example of Ingredient Interactions : Emulsifier and Thickening Agent

15 +++ +++ 10 +++ − m) +++ µ µ µ µ − ( +++ 32 +++ −

d 5 pH 3 0 0 0.05 0.1 0.15 0.2 0.25

Emulsifier: βββ-Lg [Pectin] (wt%) Thickening Agent: Pectin Importance of Order of Ingredient Incorporation

The order of ingredient addition may have a large impact on product properties:

• Homogenization - viscosity, competitive adsorption • Thermal Processing - thermally labile substances • Ingredient interactions - pH, salt, surfactants, chelating agents Example of Importance of Order of Ingredient Addition: NaCl Addition &Thermal Stability 100 m) µ µ µ µ 10 Heat + 0mM 0 mM + Heat Heat + 150mM 1 150 mM + Heat Diameter (

0.1 30 50 70 90 Thermal Surface Temperature ( oC) Denaturation Denaturation

Thermal stability of β-Lg stabilized O/W emulsions (pH 7) Wrap Up

• Clearly establish functional characteristics of each component in product - Why is it there? - What role(s) does it play? - Is there a better alternative? - Is there a cheaper alternative? - Is there synergism/antagonism? Food Grade Surfactants

Chemical Name Abbreviation EU number US FDA ADI ( mg/kg ) Solubility IONIC Lecithin − E 322 184.1400 NL Oil/water Fatty acid salts FA E 470 172.863 NL Oil/water Sodium stearoyl lactylate SSL E 481 172.846 0-20 Water Calcium stearoyl lactylate CSL E 482 172.844 0-20 Oil Citric acid esters of MG CITREM E 472c 172.832 NL Water Diacetyl tartatric acid esters of MG DATEM E 472e 184.1101 0-50 Water NON-IONIC Monoglycerides MG E 471 184.1505 NL Oil Acetic acid esters of MG ACETEM E 472a 172.828 NL Oil Lactic acid esters of MG LACTEM E 472b 172.852 NL Oil Succinic acid esters of MG SMG - 172.830 - Polyglycerol esters of FA PGE E 475 172.854 0-25 Water Propylene glycol esters of FA PGMS E 477 172.856 0-25 Oil Sucrose esters of FA E 473 172.859 0-10 Oil/Water* Sorbitan monostearate SMS E 491 172.842 0-25 Water Sorbitan tristearate STS E 492 - 0-15 Oil Polyoxyethylene (20) sorbitan Polysorbate 60 E 435 172.836 0-25 Water monostearate Polyoxyethylene (20) sorbitan Polysorbate 65 E 436 172.838 0-25 Water tristearate Polyoxyethylene (20) sorbitan Polysorbate 80 E 433 172.840 0-25 Water monooleate