ult ltrafil iltration Floriane Doudis M. Loginov, N. Hengl, F. - - PowerPoint PPT Presentation

Structural organization of casein mic icelle les concentrated la layer durin ing cross-flow ult ltrafil iltration

Floriane Doudiès

• M. Loginov, N. Hengl, F. Pignon, N. Leconte, F. Garnier-Lambrouin, J. Pérez,
• L. Sharpnack, M. Granger-Delacroix, M. Belna, G. Gésan-Guiziou

FRANCE Rennes Grenoble Paris

UMR 1253 STLO INRA-Agrocampus Ouest Joint Research Unit on Science & Technology of Milk & Egg F-35000 Rennes, France 15 to 17 October 2018

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Water (91%wt)

Milk ilk filtr filtration

Casein micelles are large globular aggregates of caseins with calcium phosphate, they are porous, deformable, compressible and dynamic particles (50-500nm) Skimmed milk contains 26 g/L of casein micelles or 3%wt Soluble proteins (0.7%wt) Ions, lactose, minerals… (6%wt) Casein micelle (3%wt) Skimmed milk: Micro- and ultrafiltration of skimmed milk are largely used in the dairy sector (≈ 40% of the membrane area installed in food sector) ultrafiltration → proteins concentration (cheese manufacture, standardization) microfiltration → proteins fractionation (high added value ingredients)

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Formation of fouling gel layer:

• limitation of the filtration performance

reduces permeate flux, decreases permeate quality (low transmission of soluble proteins)

• difficulties of cleaning operation

large consumption of water, detergents and energy…

Membrane fou

• ulin

ing by y cas asein in mic icell lles

Bouchoux et al., Biophys. J., 2009

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Transmembrane pressure ≈ 1 bar Membrane Cross-flow Permeate Increase

• f micelles

concentration with time Gel with high concentration

• f casein micelles

Understand the structural organization and behaviour

• f concentrated casein micelles accumulated at the

membrane surface during cross-flow ultrafiltration

• Analyse fouling layer development during filtration

step and redispersion during pressure relaxation step

• Focus on the effect of temperature (12-45°C)

Objective & Str trategy

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Organic spiral membranes 8-12°C Mineral membranes 50-53°C

In In-sit itu SAXS cr cross-flow filt filtration

Scattered beam intensity, I (a.u.)

Scattering vector, q (nm−1)

Jin et al., J. Memb. Sci. (2014)

Typical SAXS «spectra» of casein micelles suspension

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0.0001 0.01 1 100 0.01 0.1 1 10

Concentration

0.2 0.4 0.6 0.8 1 1.2 100 200

I/Imax Casein concentration, C (g/l)

Calibration curve

12°C 25°C 44°C

SAXS an anal alysis of

• f fou
• ulin

ling la layer

100 200 300

100 200 300

1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 0.05 0.5

z = 2000µm Distance to membrane z = 20 µm

103 101 10−1 10− 3

Scattered beam intensity, I (a.u.) Casein concentration, C (g/l)

Initial suspension

Concentration distribution in fouling layer Calibration curve

1 0.1

Scattering vector, q (nm−1) Distance to membrane, z (µm)

0 100 200 300

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Membrane

z, µm

Fouling layer

0.01 0.1 1

Scattered intensity I(q)

mm-1

CCD detector Collimated X-ray beam

20 µm 250 µm

Accumulated mass

• f casein micelles

in fouling layer

Quantification of

• f fou
• uli

ling la layer

Casein concentration, C (g/L) Distance to membrane, z (µm) Predicted concentration of sol-gel transition: 12°C – 150 g/l 25°C – 174 g/l 42°C – 181 g/l

(from Nöbel et al., Int. Dairy J.(2016))

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Casein concentration, C (g/L) Distance to membrane, z (µm)

Csol-gel Gel thickness

Mass, m (g/m²) Filtration time, tf (min)

Filtration Relaxation

Mass, m (g/m²) Relaxation time, tr (min) Relaxation time, tr (min) Removed mass, mr (g/m²)

Relaxation 45 min Filtration 150 min

Filt Filtration protocol

Suspension: 50 g/L of casein micelles in milk ultrafiltrate Membrane: Polyethersulfone 100 kDa (Orelis, France) Filtration cycle: 2 steps Temperature: 12, 25 or 42°C TMP, crossflow velocity Time TMP = 1,1 bar Crossflow velocity, v = 3 cm/s TMP = 0,1 bar

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0.E+00 1.E-07 2.E-07 3.E-07 4.E-07 5.E-07 10 20 30 40 50

Mass, m (g/m2) 12 00 Flux, J (10−7 m∙s−1) 14

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Flux, J (L∙m−2∙h−1)

5 10 15 20 25 50 100 150

Filtration time, tf (min)

Filt Filtration kin kinetics

5 10 15 20 25 30 35 40 50 100 150

Mass, m (g/m2) Filtration time, tf (min)

Flux decrease over time linked to casein micelles accumulation

25°C TMP = 1.1 bar v = 3cm/s

50 100 150 200 250 300 350 200 400 Casein concentration (g/L) Distance to membrane z (µm) 7 min 150 min

Time

Initial suspension

At 150 min of filtration Distance 280 µm 20 µm

Im Impact of

• f temperature on
• n filt

filtration kin kinetics

10 20 30 40 50

Mass, m (g/m2) 12°C 25°C 42°C 11 00

• Flux. filtrate viscosity, J.µ (10−10 Pa∙m)

12 14 13 Flux, J (L∙m−2∙h−1)

5 10 15 20 25 50 100 150

Time, t (min) 12°C 25°C 42°C

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TMP = 1.1 bar v = 3cm/s

Darcy’s law: 𝐾 × 𝜈 =

𝑈𝑁𝑄 𝑆𝑛+𝑆𝑔

Flux is higher under higher temperature due to a lower filtrate viscosity

0.E+00 1.E-07 2.E-07 3.E-07 4.E-07 5.E-07 6.E-07 10 20 30 40 50

Mass, m (g/m2) 12°C 25°C 42°C 12 00 Flux, J (10−7 m∙s−1) 14 16

TMP = 1.1 bar v = 3cm/s

50 100 150 200 250 300 350 400 450 500 200 400

Casein concentration (g/L) Distance to membrane z (µm) 25°C 42°C 12°C

Im Impact of

• f temperature on
• n cas

asein in mic icell lles ac accumulation

At 150 min of filtration

10 20 30 40 50 60 50 100 150 Mass (g/m2) Time (min) 12°C 25°C 42°C 50 100 150 200 50 100 150 Gel thickness (µm) Time (min) 12°C 25°C 42°C

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At 42°C, accumulation is faster and more pronounced: gel is more concentrated and thicker than at 12 or 25°C

Initial suspension

TMP = 1.1 bar v = 3cm/s

Temperature impacts filtration performances: At 42°C:

• Flux is high
• Because of a lower filtrate viscosity
• And a high accumulation of casein micelles
• Concentration of casein micelles at membrane

surface is high

• Gel thickness is high

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Im Impact of

• f temperature on
• n cas

asein in mic icell lles acc accumulation

Pressure rela laxation

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Relaxation step allows to remove a part of accumulated casein micelles without using chemical products But, relaxation time is same order of magnitude with accumulation time

2 4 6 8 10 12 14 16 18 20 10 20 30 40 50

Removed mass, mr (g/m2) Relaxation time, tr (min) 5 10 15 20 25 30 35 40 100 200 Mass, m (g/m2) Time (min)

Relaxation Filtration

25°C TMP = 0.1 bar v = 3cm/s

Im Impact of

• f temperature on
• n pressure rela

laxation

Relaxation Filtration

5 10 15 20 25 10 20 30 40 50

Removed mass, mr (g/m2) Relaxation time, tr (min)

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Removed mass rises with temperature: likely due to the lower viscosity of accumulated casein micelles layers at high temperature

10 20 30 40 50 60 100 200 Mass, m (g/m2) Time (min) 12°C 25°C 42°C

TMP = 0.1 bar v = 3cm/s

Distance, z (µm)

0.4 0.6 0.8 1 20 40 60 12°C 25°C 42°C

Relative gel thickness Relaxation time, tr (min)

100 200 300 400 500 100 200 300 100 200 300 400 500 100 200 300 100 200 300 400 500 100 200 300

Casein concentration, C (g/L)

12°C 25°C 42°C

Distance, z (µm)

Concentration profiles during relaxation at different temperatures

Im Impact of

• f temperature on
• n gel

l rela laxation

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At 12 °C, gel removal seems limited even if the concentration is not the higher Gel is more cohesive at 12°C

Distance, z (µm) Casein concentration, C (g/L) Casein concentration, C (g/L)

TMP = 0.1 bar v = 3cm/s

Pressure rela laxation: gel l swelli lling

Osmotic pressure

Strong pressure gradient

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Gel swelling Filtration

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 100 200 300 100 200 300 000

Casein concentration, C (g/L) Distance to membrane, z (µm)

Time Csol-gel Accumulation of casein micelles is removed via gel swelling and re-dispersion of swelled part

TMP Cross-flow TMP

Relaxation

Cross-flow

1 min 41 min

25°C TMP = 0.1 bar v = 3cm/s

0.4 0.6 0.8 1 20 40 60 12°C 25°C 42°C

Relative gel thickness Relaxation time, tr (min)

Pressure rela laxation: im impact of

• f temperature

Gaucheron (2005); Wastra (1990); Creamer et al.(1977) − Calcium phosphate + Water

β-Casein migration from core to surface

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Cohesion of gel (repulsive gel or attractive gel) depends on temperature

Low temperature High temperature

Con

• nclusions
• In-situ SAXS cross-flow filtration allowed analysis of casein micelles fouling layer with

an unique resolution of 20µm during filtration step and relaxation step

• During filtration of casein micelles, temperature has a significative effect on filtration

performances:

• Increasing temperature implies:
• flux decrease because filtrate viscosity decrease
• casein micelles accumulation at membrane surface
• But during pressure relaxation, an easily removal of casein micelles and a gel

that is less cohesive

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Future work: 1) rheological characterization of gels at different temperatures 2) local strength force of fouling layer at different temperatures

Thank you for your attention!

Mohamed KARROUCH Michael Sztucki

25°C

Cali alibration

0.E+00 2.E-04 4.E-04 6.E-04 8.E-04 1.E-03 1.E-03 1.E-03 0.E+00 5.E-05 1.E-04 2.E-04 2.E-04 3.E-04 200 400 600 d(transmitted intensity)/dz

transmitted intensity (u.a.)

Distance to membrane z (µm)

Inox support Feed canal Membrane 120µm Width Slide view of cell 1) Zero membrane placement

1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E-02 1.E-01 1.E+00 1.E+01 Scattered beam intensity, I (a.u.)

Scattering vector, q (nm−1) 10 g/L 176 g/L Rise of concentration

0.2 0.4 0.6 0.8 1 1.2 100 200 I/Imax

Casein concentration (g/L)

I(q=1nm-1) = 0.0124×C (g/L) 2) Calibration in static

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Calibration at different scattering vectors q (𝑜𝑛−1)

y = 0.0053x R² = 0.9837 y = 0.0053x R² = 0.982 y = 0.0065x R² = 0.9219 y = 0.0057x R² = 0.9991 0.2 0.4 0.6 0.8 1 1.2 1.4 50 100 150 200

I/Imax

Concentration (g/L) q=0.08 q=0.1 q=0.3 q=1

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