[PPT] - Structural organization of casein mic icelle les concentrated la PowerPoint Presentation

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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

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Water, lactose…

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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) Soluble proteins Ions Casein micelle 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)

SLIDE 3

Formation of fouling gel layer:

limitation of the filtration performance

reduces permeate flux, decreases permeate quality (low transmisson 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

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Transmembrane pressure ≈ 1 bar Membrane Cross-flow Permeate Gel with high concentration

f casein micelles

Increase

f micelles

concentration Bouchoux et al., Biophys. J., 2009

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Th The structural l organiz izatio ion and behavi viour

f

f concentrated case sein in mice icelle lles in in fouli ling la layer duri ring cross ss-fl flow ultr ltrafil iltratio ion

to analyse fouling layer development during filtration step

and redispersion during pressure relaxation step

to focus on the effect of temperature
to perform in situ Small-Angle X-ray Scattering (SAXS)

cross-flow filtration Objective

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SLIDE 5

In-situ SAXS cross-flow filtration

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

0.001 0.01 0.1 1 10 100 1000 0.01 0.1 1 10 Scattered beam intensity, I (a.u.)

Scattering vector, q (nm−1)

Spatial resolution 20 µm

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SLIDE 6

0.0001 0.001 0.01 0.1 1 10 100 1000 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)

I(q=1nm-1) = 0.0132×C (g/L)

SAXS by y cas asein mice icelle les in in static

Scattered beam intensity, I (a.u.) Scattering vector, q (nm−1) 06

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100 200 300

SAXS an anal alysis of

f fou
ulin

ling la layer

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

2000µm Distance to membrane 20 µm

103 101 10−1 10− 3

Scattered beam intensity, I (a.u.) Casein concentration, C (g/l) Initial suspension Fouling layer Calibration curve

1 0.1

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

0 100 200 300

x y z

Membrane ΔP Filtration channel (side view) Retentate Permeate Concentration polarization layer X-ray Distance z (µm)

Scattered intensity

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SLIDE 8

100 200 300

Quantification of

f fou
uli

ling la layer

Accumulated mass

f casein micelles

in fouling layer

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

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)

Csol-gel Gel thickness

Mass (g/m²) or gel thickness (µm) Time (min) 08

SLIDE 9

Relaxation 55 min Filtration 150 min

Filt Filtration protocol

Suspension: 50 g/L of casein micelles in milk ultrafiltrate Temperature: 12, 25 or 42°C Filtration cycle: 2 steps TMP, crossflow rate Time TMP = 1,1 bar Crossflow rate, v = 3 cm/s TMP = 0,1 bar Crossflow rate, v = 10 cm/s

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SLIDE 10

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

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

Casein concentration (g/L) Distance to membrane z (µm) t0 25°C 42°C 12°C

Filt Filtration step

Filtration 150 min Accumulated mass and gel thickness rise over time At 42°C, accumulation is faster and more important, gel is more concentrated and thicker than at 12 or 25°C

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TMP = 1.1 bar v = 3cm/s

50 100 150 200 50 100 150 Gel thickness (µm) Time (min) 12°C 25°C 42°C

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Filt Filtration kin kinetics

5 10 15 20 25 50 100 150

Time (min) 42°C 12°C 25°C 25 20 15 10 15 00 Flux (L∙m−2∙h−1)

Permeate flux decreases over time for each temperature With temperature decreasing, fouling layer less permeable Fouling rate and intensity due to the lower filtrate viscosity and higher filtrate flux

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TMP = 1.1 bar v = 3cm/s

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Relaxation step allowed to remove a part of polarized layer without using chemical products, ultrasound… But, relaxation time is comparable with accumulation time, relatively slow Removed mass rises with temperature

Pressure rela laxation step

5 10 15 20 25 10 20 30 40 50

Removed mass (g/m2) Relaxation time (min)

Relaxation Filtration

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TMP = 0.1 bar v = 3cm/s and 10cm/s

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

SLIDE 13

50 100 150 200 250 100 200 Gel thickness (µm)

Time (min)

12°C 25°C 42°C

Rela laxation

Gel removal follows same trend as total accumulated matter removal: starts simultaneously with pressure decrease, at the very beginning of relaxation step At 12°C, less accumulation than at 42°C but it is removed with difficulty Relaxation Filtration

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TMP = 0.1 bar v = 3cm/s and 10cm/s

SLIDE 14

Ge Gel l behaviour after pressure rele lease

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) Example 25°C

Time Csol-gel Concentration Osmotic pressure Gel Sol Retentate

Strong pressure gradient

Liquid flux Concentration Gel swelling Re-dispersion of sufficiently swelled part with C below Csol-gel Simultaneous decreasing of gel thickness and concentration from beginning of relaxation Fouling removal via gel swelling and re-dispersion of external swelled part

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SLIDE 15

0.4 0.6 0.8 1 20 40 60 12°C 25°C 42°C

Relative gel thickness Relaxation time, min

Limited gel removal at 12°C?

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, g/L Distance, µm

12°C 25°C 42°C

Distance, µm Distance, µm

Concentration profiles during relaxation at different temperatures (same Y-axis scale)

Im Impact of

f temperature on
n gel

l rela laxation

Casein Concentration, g/L Casein Concentration, g/L 15

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Schematic presentation of fouling layer Gel that swells but doesn't re-disperse Gel that re-disperses after swelling Sol Observed at moderate gel concentration (12°C) Not observed at highest concentration (42°C) → Nature of fouling (repulsive gel/attractive gel) depends on temperature

Lower steric barrier density – more open surface for interactions (gelling)?

Three typ types of

f fou
uli

ling

Cooling 16

− Calcium phosphate + Water Gaucheron, Reprod. Nutr. Dev., 2005 Hydrophilic brush Hydrophobic core

Cooling

SLIDE 17

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

Fouling rate and fouling intensity (quantity of accumulated micelles and gel thickness)

increase with temperature due to the lower filtrate viscosity and higher filtrate flux

Important part of fouling can be reduced by simple pressure relaxation
The fouling by casein micelles is removed through the swelling-dissolution mechanism
A limited efficiency of pressure relaxation at 12°C can be explained by transformation of

repulsive gel (swells and dissolves) into attractive gel (swells but does not dissolve)

In the future:

1) local microstructure 2) rheological characterization of gels at different temperatures 3) study of cross-flow, time and transmembrane pressure effects on gel properties in fouling layer

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SLIDE 18

Thank you for your attention!

SLIDE 19

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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) = 0.0132×C (g/L) 2) Calibration in static

SLIDE 20

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Cali alibration at t dif ifferent sc scatterin ing vectors

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

SLIDE 21

Filt Filtration kin kinetics

5 10 15 20 25 50 100 150

Time (min) 42°C 12°C 25°C 25 20 15 10 15 00 Flux (L∙m−2∙h−1)

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

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

Mass (g/m2) 12°C 25°C 42°C 11 00 Flux∙viscosity (10−10 Pa∙m) 12 14 13

Permeate flux decreases over time for each temperature Accumulation mass impacts permeate flux Viscosity corrects difference

f flux observed for

different temperatures

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