Health and sustainability: Fundamental aspects of oil structuring - - PowerPoint PPT Presentation

Health and sustainability: Fundamental aspects of oil structuring for different applications

Elke Scholten

Physics and Physical Chemistry of Foods Wageningen University, the Netherlands

PhD thesis (FS002)

PhD thesis:

Auke de Vries

(graduated March 2017)

• De Vries, A., Hendriks, J., van der Linden, E., Scholten, E. Langmuir 2015, 31, 13850.
• De Vries, A., Wesseling, A., van der Linden, E., Scholten, E. Journal of Colloid and

Interface Science 2017, 486, 75.

• de Vries, A., Lopez Gomez, Y., van der Linden, E., Scholten, E. RSC Advances 2017, 7,

11803-11812.

• de Vries, A., Lopez Gomez, Y., Jansen, B., van der Linden, E., Scholten, E. Applied

Materials and Interfaces 2017, 9, 10136-10147.

http://edepot.wur.nl/403635

Functionality of (solid) fat: Texture:

• Layered phase

Hardness Crispiness

• Dispersed phase

Hardness Creaminess Flavour:

• Hydrophobic flavours

Fat Functionality

Bakery products Yogurt Dressings/ sauces Sausages Cheese

Health: Saturated fatty acids are assumed to have negative health affects (debated): WHO  reduction in solid fats: use of unsaturated fats (oil) is encouraged Sustainability Solid fats: Palm oil, Shea butter, Cocoa butter, Milk fat Need for alternatives for hard fats

How to make oil act as a solid fat?

Liquid Solid

Gelation of oil using structuring agents: Oleogels

?

Oil composition Unsaturated fatty acids  No detrimental health benefits Functionality Provides solid-like characteristics Controls textural properties such as creaminess, hardness Still contains fat flavour characteristics (compared to other fat replacers)

Resemble fat characteristics:

Solid at small deformation Yield at larger deformation (break-down) Melting behavior

Oil Gelation

Oleogel / organogel

• Continuous phase of oil
• Network of fillers

Known Categories

Particle Networks (fats..) Polymers (polysaccharides) Network formation Entanglements

• Ethyl cellulose
• chitin

Low molecular weight surfactants Self assembly behavior:

• Lecithin
• sterols
• waxes

New Category

Protein oleogels Proteins hydrogels Yogurt Cheese Eggs Desserts Tofu

?

• Not healthy
• Not efficient
• Too expensive
• No legal status
• Etc..

Requirements for foods:

• Natural origin
• Cheap
• Widely-available

Protein based oleogels

Air Liquid

Water Oil

Proteins well-known for ability to create hydrogels in aqueous environments How to get them in the oil phase ?

Sedimentation of proteins

Modification : heat treatment (denaturation) create initial building block

increased hydrophobicity

2 4 6 8 0.01 1 100 Volume [%] Size [μm]

~ 200 nm

Protein based oleogels

Air Liquid

Water Oil Intermediate solvent

Proteins well-known for ability to create hydrogels in aqueous environments How to get them in the oil phase ?

~ 200 nm

2 4 6 8 0.01 0.1 1 10 100 1000 Volume [%] Size [μm]

Modification : heat treatment (denaturation) create initial building block

increased hydrophobicity

Protein oleogels – from hydrogel (mm – cm)

Water Oil Intermediate solvent Hydrogel Oleogel ~ 5% Protein ~ 91% Oil < 1% Water

Microstructure design pH, salt, type of protein Fine - stranded Transparent Coarse Opaque

• leogels

5mm

Protein content Oil content Fine - stranded Transparent Coarse Opaque

Cm scale

Protein oleogels – from protein aggregates (nm)

Water Oil Intermediate solvent Protein aggregates Oleogel ~ 5% Protein ~ 91% Oil < 1% Water

• leogels

Microstructure design pH Salt Protein type (plant-based) Size Density Hydrophobicity Protein content Oil content Network Concentration

nm scale

Mechanical properties

50 100 150 200 1 2 True Stress [kPa] Strain εH [-] Fine Coarse

1 10 100 1,000 10,000 100,000

Modulus [kPa] Hydrogel Oleogel

Characteristics (from hydrogels)

91% - 80% Oil 5% - 16% Protein

5mm

5 mm

4μm

4μm

Microstructure Oil holding 0.0 0.5 1.0 1.5 2.0 2.5

Qoil

Self standing gels No oil-leakage

Fine Coarse

Oil binding depends on the microstructure

Characteristics (from aggregates)

5 mm

Varying protein content

4μm

Microstructure

25 μm

In Water

25 μm

In Oil Mechanical properties

0.1 1 10 100 1000 10000 0.001 0.01 0.1 1 10 100

G’, G” [Pa] Strain [%] G’, G” [

A

No oil leakage Show solid-like behavior Show yield behavior  spreadable

G’ = Gel strength Tan δ = solid-like behavior Limit of linearity

Network formation Protein network same as in water

Characteristics (from aggregates)

5 mm

Varying protein content

4μm

Microstructure

25 μm

In Water

25 μm

In Oil

0.01 0.1 1 1 10

Limit of linearity γ0 [-] cP [wt%]

1 10 100 1000 10000 1 10

G’ [Pa] cP [wt%]

B C

Slope: 5.3 Slope: - 2.7

Fractal gel model: “Strong-link network”

𝐻′~𝜒(𝑒+𝑦)/(𝑒−𝑒𝑔)

𝛿0~𝜒−(1+𝑦)/(𝑒−𝑒𝑔)

Shih et al. Phys Rev A, 1990

df ~ 2.2

Network formation - Rheological properties

Control network  gel strength, yield stress, plastic deformation

Water removal Hydrogen bonding Van der Waals interactions Heat treatment hydrogen bonding capillary interaction Rearrangements in the network Water addition: hydrogen bonding capillary interactions

Upscaling ??- Drying from different solvents

Air Liquid

Water Hexane Acetone

30 μm 30 μm 30 μm

Solvents prevent agglomeration (hydrophobicity, interfacial tension)  Better dispersibility in oil How to accomplish ??

• Drying from organic

solvents

• Optimization in freeze

drying process

• CO2 drying ?

 Dry protein aggregates powder

Protein aggregates

Applications

Protein hydrogel Fracture properties Gel strength Spreadable properties Yield behavior Sausages

Fat Fat Oil Aggregates Pieces

Cookies

Margarine Aggregates Aggregates Oil

Protein oleogels have potential as a fat replacer

Conclusion

New type of protein functionality: Oil gelation

Hydrogels Emulsifier Oleogels

Gelation of oil with proteins:

Healthy composition with solid character Tunable oleogel characteristics/properties (applications) Interactions can be controlled by:

• Aggregregate properties (size, hydrophobicity, source, density)
• Interactions: water addition and heat treatment

 Can be used as alternative for solid fats (palm oil, shear butter, milk fat)