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Nano and Microstructure design
Anne-Marie Hermansson
• understand food structures • control food structures
• product development • process development
• new measurement tools • predictive science
Nano and Microstructure design
Structural levels
Molecules
Supermolecular
assemblies
Gels and
interfacial structures
Mixed structures
Anne-Marie Hermansson
Myosin molecules on a mica surface
0.2 mm
Hermansson and Jordansson
Myosin filaments
Head to head interactions of myosin molecules
Hermansson and Jordansson
Myosin gels
1 mm
pH 6.0 and 0.6M KCl pH 5.5 and 0.25M KCl
Hermannson and Langton 1986
Macroscopy 2x10-2-1x10-4m
bulk specimen
Light microscopy 2x10-3 - 5x10-7m
smears, cryosections, plastic sections
CLSM 2x10-3 - 5x10-7m
bulk specimen, cryosections, dynamic structures
Scanning electron microscopy
CSEM; LVSEM; ESEM 2x10-3 - 5x10-9m
critical point drying, cryo-SEM
uncoated wet samples, dynamic structures
Transmission electron microscopy 2x10-5 - 5x10-9m
thin-sectioning, negative staining,
freeze-etching, mica-technique, cryo-TEM
Microstructure characterisation
Biopolymer gels
structural aspects and properties
??
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Molecular properties
Junction zones
Gel properties
Network Morphology
Amylose Superabsorbent Sepharose
100 nm 200 nm 50 nm
Gels – length scales
Hermansson A.M. , Kidman S and Altskär A
Mass transport rate
1 10 100 1000
?
Design for diffusion and flow
Diffusion
Flow
Pore size / nm
Modification by aggregation
κ-carrageenan in 100 mM KCl
Gel formation by quenching Gel formation by slow cooling
Kidman and Hermansson
Lorén N, Nydén M, Hagman J and Hermansson A.M
Nano structure design of diffusion
Pressure drop as a function of pore size
100 nm 100 nm
The importance of structure related mass transport
properties
Nanoscaled 3D microstructure – Sepharose Gel
1000 nm
Mathematical identification of the 3D microstructure from TEM micrographs
Nisslert, Lorén, Kvarnström, Nydén, Rudemo (2007) J. Microscopy
A LATTICE-BOLZMANN FRAMEWORK FOR DIFFUSION AND
FLOW
Predictable mass transport in soft materials
and a detailed understanding of flows and
diffusion in heterogenous structures
Tobias Gebäck, Alexey Heintz, Jenny Jonasson, Marie Skepö,
Magnus Nydén
Compare diffusion and flow streamlines in a gel structure
Confinements – structure formation in restricted volumes
Mayonnaise Cream cheese
Phase separated biopolymer structures
25 μm
?
Sophia Wassén, Niklas Lorén and Anne-Marie Hermansson
Effect of confinement
Droplet size 4% Gelatin - 6% Maltod. Quenching to 20°C
25 µm 25 µm
(b) Diam. ~130 μm
Bulk Discontinuous
25 µm
(d) (d) Diam. ~10 and 15 μm
25 µm
(c) (c) Diam. ~20 μm
25 µm
Different microstructures in small droplets
Janus-like Core-shell
Decreasing diameter
(a)
Sophia Wassén, Niklas Lorén and Anne-Marie Hermansson
30 s at 40 °C
50 μm
(a)
100 s at 40 °C
(b)
Smaller droplets were seen to phase separate at higher temperatures
30 s at 20°C
(c)
100 s at 20°C
(d)
Effect of confinement
Initiation of phase separation 4% Gelatin - 6% Maltod. 5 min holding time at 40 °C
Time
Sophia Wassén, Niklas Lorén and Anne-Marie Hermansson
4% gelatin LH and 7.3% maltodextrin
90°C/min
55°C/min
5°C/min
S. Wassén, E.Rondeau, K. Sott, N. Lorén, P. Fischer and A.M. Hermansson. Food Hydrocolloids 2011
A faster cooling rate results in smaller domain sizes
Kinetics of structure formation
4 w/w% gelatin 7.3 w/w% maltodextrin
Quenched from 70°C to 20°C
4 w/w% gelatin 6 w/w% maltodextrin
Quenched from 70°C to 20°C
50μm 50μm
Heterogeneous systems
Hagman, Wassen, Lorén, Hermansson (2010).
• Development of new methods for controlled wetting
and swelling experiments during observation of SEM
cooled Cu cylinder with
condensed water
sample
Anna Jansson, Stefan Gustafsson, Anne-Marie Hermansson and Eva Olsson
Controlled wetting of individual cellulose
fibres
Water
droplet
Cu cylinder
(cooled)
Cellulose fibre
Nanomanipulator
Piezoelectric tube
Electron beam
10 µm
Phase separated biopolymer film
In situ ESEM studies of water transport in cellulose
films for controlled release of drugs
Anna Jansson, Stefan Gustafsson, Anne-Marie Hermansson and Eva Olsson
Structure management
Microstructure characterisation
• Different microscopy techniques (LM, CLSM, TEM))
• Length scales
• Time scales
• Image analysis
Measurements under dynamic conditions
• Structure formation
• Water uptake
• Structure break-down
Structure breakdown directly studied in the CLSM
Fresh cheese
0.1
0
F (N)
120 40 80 160 sec
500mm
0.6mm extension
Process control
Co
olin
g tu
be
Co
olin
g tu
be
Co
olin
g tu
be
Emulsification
(Mixing) HP
pump Pasteur Precooling Pin
mixer
Storage (after 2
weeks)
The art of Food Technology
Co
olin
g tu
be
Co
olin
g tu
be
Co
olin
g tu
be
Emulsification
(Mixing)
HP
pump Pasteur Pre-cooling Pin
mixer
Storage
(after 2
weeks)
1mm equals 13,5 m m 1mm equals 5 m m
Tillverkning av Lätt och Lagom
Variables
• Fat phase
- vegetable / milk fat
- crystallisation kinetics
• Water phase
- protein / starch
- pH
- holding time
- temperature
• Process
- flowrate
- temperatures
• Storage time
Ekstedt et al
-
- - - Safety
Expectations
Nutritional aspects Function
Product quality
What is healthy?
property control
Process
Raw materials
Consumer attitudes
Nano and Microstructure Design
Composition