Food structure from the inside with neutron scattering

Wim G. Bouwman

• Neutrons• Small angle neutron

scattering (SANS)• Spin-echo small-angle

neutron scattering (SESANS)

• Margarine• Milk, yoghurt• Tuneable colloids• Water holding proteins• Plant protein meat

has a magnetic moment – magnetic fields to detect path

no electric charge - penetrates deep into specimen (easy sample environment)

Interaction element and isotopic sensitive – contrast variation

N

S

Why neutrons for food?

Contrast matching to make parts structure (in)visible

Morna Fisken, Britlabhttps://youtu.be/OZxtwIc3ieM

https://youtu.be/OZxtwIc3ieM

Small angle scattering(neutrons, X-rays or light same principle)

Brian Pauwhttps://youtu.be/n-8Y2p4kN4M

https://youtu.be/n-8Y2p4kN4M

γ-oryzanol

The phytosterol compoundsstructure oils without solid fats

β-sitosterol

Me

Me

Me

H

H

H

HO

Me

H Me

Me H

O

HO

MeO

O

Me Me

A. Bot (Unilever), et al.Faraday Discuss. 158, 223-238 (2012)

β-sitosterol and γ-oryzanol in d-decane

10-2

10-1

10-1

100

101

102

103

104

Q [A-1]

I [cm

-1]

Me

H Me

Me H

OHO

Me OO

MeMe

2.0 nm7.8 nm

Double walled helical ribbon

r2

r1rsolv

ρ2 ρ1 ρsolv

0.8 nm

7.2 nm

rin routrc

0.8 nm 2.3 nm

9.5 nm

SANS vs SESANS

• Sensitivity: 1 nm – 500 nm

• Length instrument:12 – 80 m

• Reciprocal space

• Sensitivity: 30 nm – 20 µm

• Length instrument:5 m

• Real space

SESANS = Fourier transform scattering ⇒projected density correlation function

0 100 200 300 400 5000.50.60.70.80.91.0

z [nm]

Pd

Sterically stabilised silica particles d=298 nm in deuterated cyclohexaneφv=0.05

sam

ple

θ0θ

Casein micelle in milk polydisperse: 50 - 200 nm

Structure determined of dairy products

Hans TrompNIZO food researchthe Netherlands

Size distribution is visible in measurementsLog-normal distribution

0.9

0.92

0.94

0.96

0.98

1

1.02

0 100 200 300 400 500

spin echo length [nm]

P/P0

0.E+005.E-061.E-052.E-052.E-053.E-053.E-054.E-054.E-055.E-05

0 50 100 150 200 250 300

radius [nm]

size

dis

t. [

nm-1

] SESANS

sedimentation fieldflow

SESANS measures size distribution of milk (casein micelles)

0.7

0.8

0.9

1

0 1 2 3 4spin echo length [um]

pola

risat

ion

milk

0.7

0.8

0.9

1

0 1 2 3 4 5spin echo length [um]

pola

risat

ion

milk yogurt

0.7

0.8

0.9

1

0 1 2 3 4 5

pola

risat

ion

spin echo length [um]

milk

yogurt

curd

Tromp et al. Food Hydrocolloids 21, 154-158 (2007)

Single casein micelle

50-200nm

From milk to yogurt and curd

Depletion interactions in charged, aqueous colloid-polymer mixtures (model for e.g. milk)

Kitty van Gruijthuijsen Peter Schurtenberger, Anna Stradner - Lund University

Adolphe Merkle Institute, Université de Fribourg

++ ++

polymer depletion

zone

salt reduces repulsion

polymers give attraction

+

-

+

-+ -+

-

+

-

+

-

+

-

+

-

+

-

+

-+ -+

-

+

-

+

-

+

-

+

-

Colloids

-140

-120

-100

-80

-60

-40

-20

00 0.2 0.4 0.6 0.8

z [µm]

ln P

(z) / t

32 wt% in 2mM

26 wt% in 1.5mM

26 wt% in 3mM

20 wt% in 50mM

Attr

actio

ns

cp

φspheres

[NaCl]

-- --

------

- -

--+

+ +

++ +

-- --

------

- -

-- +

+

+

Gels

-1000

-900

-800

-700

-600

-500

-400

-300

-200

-100

00 0.5 1 1.5 2 2.5 3

z [µm]

ln P

(z) /

t

+ 3.3 wt% polymer

+ 3.5 wt% polymer

+ 3.8 wt% polymer

+ 4.6 wt% polymer

-1000

-900

-800

-700

-600

-500

-400

-300

-200

-100

00 0.5 1 1.5 2 2.5 3

z [µm]

ln P

(z) /

t

+ 0.7 wt% polymer

+ 0.9 wt% polymer

+ 1.0 wt% polymer

+ 1.4 wt% polymer

Attr

actio

ns

cp

φspheres

[NaCl]

In 1.5 mM

In 50 mM

Water holding of ovalbumin gelsJuiciness, release tastants

Maaike Nieuwland, TNO & TI Food and Nutrition

Acid reduces water holding

Vegetarian steakMechanism of fibre formation of sheared plant proteins?

George Krintiras

Neutron refraction: # layers + orientation

36 ± 4 layers / 5 mm± 35o orientation

Food and neutrons are a tasty combination

Wim G. Bouwman

• Bulk• Texture micrometre• Quantitative• In principle in-situ

• Interaction• Aggregation• Water holding• Alignment

Acknowledgements

Delft: Chris Duif, Jeroen Plomp, Theo Rekveldt, Jurrian Bakker, Bei Tian & EvgeniiVelichko

Relating water holding of ovalbumin gels to aggregate structure, M. Nieuwland, W.G. Bouwman, L. Pouvreau, A.H. Martin, H.H.J. de Jongh, Food Hydrocolloids 52 87-94 (2016)

On characterization of anisotropic plant protein structures, G.A. Krintiras, J. Göbel, W.G. Bouwman, A.J. van der Goot and G.D. Stefanidis, Food & Function 5 3233-3240 (2014)

Direct comparison of SESANS and SAXS to measure colloidal interactions, K. van Gruijthuijsen, W.G. Bouwman, P. Schurtenberger and A. Stradner, EPL 106 28002 (2014)

A. Bot, E.P. Gilbert, W.G. Bouwman, H. Sawalha, R. den Adel, V.M. Garamus, P. Venema, E. van der Linden and E. Flöter, Faraday Discuss. 158, 223-238 (2012)

Milk Gelation Studied with Small Angle Neutron Scattering Techniques and Monte Carlo Simulations, L.F. van Heijkamp, I.M. de Schepper, M. Strobl, R.H. Tromp, J.R. Heringa, W.G. Bouwman, J. Phys. Chem. A 114 2412-2426 (2010)

Effect of processing on droplet cluster structure in emulsion gels, A. Bot, F.P. Duval, and, W.G. Bouwman, Food Hydrocolloids 21 844–854 (2007)

Food structure from the inside with neutron scatteringWhy neutrons for food?Contrast matching to make parts structure (in)visibleSmall angle scattering�(neutrons, X-rays or light same principle)Slide Number 5The phytosterol compounds�structure oils without solid fatsβ-sitosterol and γ-oryzanol in d-decaneDouble walled helical ribbonSANS vs SESANSSESANS = Fourier transform scattering projected density correlation functionStructure determined of dairy productsSESANS measures size distribution of milk (casein micelles)From milk to yogurt and curdDepletion interactions in charged, aqueous colloid-polymer mixtures (model for e.g. milk) ColloidsGelsWater holding of ovalbumin gels�Juiciness, release tastantsAcid reduces water holdingVegetarian steak�Mechanism of fibre formation of sheared plant proteins?Neutron refraction: # layers + orientationFood and neutrons are a tasty combinationAcknowledgements