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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