The Use of the Ultra Small Angle X-ray Scattering Technique to study the Solid Structure of Edible Fat Systems

Transcription

1 The Use of the Ultra Small Angle X-ray Scattering Technique to study the Solid Structure of Edible Fat Systems Fernanda Peyronel Alejandro Marangoni & David Pink Session: Analytical and Quality Control September 14, 9:00-9:30 am

2 Motivation

3 Motivation Health: Food & Drug Admin. mandates trans-fat elimination Trans fats free Low in saturated fats problems -oil leaks out -less solid structure Research question Is it possible to make an educated prediction as to which edible fats to use as replacements while maintaining the same solid structure? What to study? The nano- to meso-scale solid structure Which Technique? Ultra small angle X-ray Scattering 3

4 Length Scale (001) face (100) face CNP Crystalline NanoPlatelet Aggregate 30 µm USAXS 4

5 CNPs as primary units FHCO in HOSO FHSO in SO SMS in HPKO stearin CB 5

6 What is this talk about? Molecular features ~ Å Atomic features ~ 1-5 Å USAXS length scale or d 2 π q 6

7 Facility

8 USAXS Facility 15 ID Dr. Jan Ilavsky Sector 9 ID-C Advanced Photon Source (APS), Argonne National Laboratory Illinois, USA 8

9 Storage Ring where electrons orbit at nearly the speed of light to produce high-energy x-ray beams for research APS Brochure 9

10 Instrument Beam Line 9 ID-C

11 Beam Line 9ID-C Ultra-small-angle X-ray scattering at the Advanced Photon Source. J. Ilavsky, P.R. Jemian, A.J. Allen, F. Zhang, L.E. Levine and G.G. Long. Journal of Applied Crystallography, 2009, 42 (3), p

12 Beam Line 9D-C Incoming Up stream Linkam for temperature control Down stream

13 Beam Line 9ID-C USAXS Analyzer Pin-SAXS: Pilatus detector USAXS photodiode detector WAXS detector Sample position 13

14 Beam Line 9ID-C USAXS Detector 14

15 Approach to study fat systems

16 Approach 1: Cryo TEM to see CNPS 2: USAXS Experiment Data Analysis Interpretation Little sample manippulation Must consider the scattering by the minority phase Models: Unified Fit 1 Guinier-Porod 1 Model CNPs Model grain boundaries & voids < 20% Solids 50% to 100% Solids Predictions of X-ray intensity to understand the internal structures of the aggregates and the hierarchy of their aggregation 1 Irena: tool suite for modeling and analysis of small-angle scattering", J. Ilavsky and P. R. Jemian, J. Appl. Cryst. (2009). 42(2),

17 % of solid material Minority phase does the scattering The simulations were carried with this in mind Less than 40% solids The solid is made by a fundamental unit, the CNPs Scattering done by CNPs and the structures they made when aggregating Pink et al Edible Oil Structures at Low and intermediate Concentrations: I. Modelling, Computer Simulation and Predictions for X-ray Scattering. Journal of Applied Physics. 114, More than 60% solids The solid is created as grains Scattering done by cavities (empty or filled with oil) Peyronel et al Edible Fat Structures at High Solid Fat Concentrations: Evidence for the Existence of Oil-filled Nanospaces. Applied Physics Letters. 106, 2,

18 Basic Theory

19 Scattering Limits Guinier: q 0 II qq = ( ρρ) 2 VV 2 (qq ee 2 RR 2 gg ) 3 RR gg Radius of gyration. Approximate size of object. Porod: q Fractal Interpretation of P II qq = ( ρρ) 22ππ qq 4 SS II qq qq PP ( ρρ) 22ππ SS qqpp ln II(qq) PP ln(qq) 1 PP < 3 DD mm = PP DD mm : mass fractal: DLCA? RLCA? DLA? 3 PP 4 DD ss = 6 PP DD ss : surface fractal PP > 4 Schaefer et al. J. Inorg. Organomet. Polym. Mater. 22, 617 (2012) the surface of the aggregating particles are diffuse 19

20 Results for low concentration of solids

21 d 2 TAGwood 60 nm 450 nm D = 3 CNP I(q) [cm -1 ] 1.9 < D m < 2.0 d 2, 800 nm nm d 1, 110 nm nm D s = 2 Pink et al J. Appl. Phys.. Peyronel et al J. Appl. Phys. q q[å -1 ] 3 Levels obtained using Unified Fit model 20% SSS in OOO slow cooling 21

22 Level 1 slope Nano-Size Slope to to to -3.4 Pure Solids Nano-voids -3.9 to -3.4 Pink et al. J Applied Physc Quinn et al. J Cond. Matt Peyronel et al. Appl. Phys. Lett

23 Level 2 slope Micro-Size Fast Cooling Slow Cooling Slope to to to -1.5 Deformed Cylinders Fractal aggregation DLCA : RLCA : Pink et al. J Applied Physc Quinn et al. J Cond. Matt Peyronel et al. Denver X-ray Conference

24 Level 3 slope Slope to -4.5 Aggregates uniformly distributed in space Diffused/ undefined surface. Multiheaded TAGwoods aggregation 24 Peyronel et al. Denver X-ray Conference 2016

25 Example

26 Example Complex Triacylglycerol (TAG) Systems less than 20% solid #1: 20% SSS, 16% shea and HOSO #2: 15% SSS, 51% cotton seed and OOO TAG #1 #2 S S 2 U 6 6 S 1 U U S 3 : 3 saturated hydrocarbon chains U 3: 3 unsaturated hydrocarbon chains

27 How are solid fats organized? How to figure out the right answer 1-Fit the data using either Unified Fit 1 or Guinier-Porod 2 models. This gives us P 1, P 2, P 3 2-We interpret results using a Fractal Interpretation. We looked at slopes values. 3-Use the predictions from the simulations and compare with the data Models and computer simulations Beaucage. J Appl. Crystallogr. 1995, Hammouda. J Appl Cryst Data: Peyronel et al. Cond Matt. 2014

28 48 hours after preparation 8 months after preparation Guinier-Porod suggests rod formation 28

29 Diffuse surface -4.3 Peyronel et al. Denver X-ray Conference 2016

30 Slope 1, R g1 Unified Fit SSS in Shea with High Oleic Sunflower Oil S=1.2 1 Guinier-Porod Slope 2, R g2 Unified Fit Slope 3 Unified Fit Smooth 2D surface 1 D Cylinders D m = 4.1 etanglement CNPs TAGwoods Aggregated TAGwoods, end to end Quinn et al. J App Cond Matter 2014 Peyronel et al. Denver X-ray Conf

31 Why use USAXS as an analytical technique? To learn about Length Scale Slope 1 Slope 2 Slope 3 Morphology of CNPS Mechanism of CNP aggregation Type of larger structures Less than 500 nm 500 nm < L < 2 µm 2 µm < L < 6 µm

32 More examples Milk Fat Cocoa Butter Palm Olein HPKO Peyronel et al. Lipid Technology 2014

33 20% SSS in OOO S 3 20 S 2 U - S 1 U 2 - U 3 80 Both in β Slow: 0.5 deg/min Fast: 30 deg/min No storage (Linkam) Peyronel et al. AOCS Salt Lake City Conference 2016

34 Preliminary Shear Experiments 15% SSS, 51% Cotton Seed Oil, 34% OOO Intensity log I(q) [cm -1 ] Slow: 0.5 C/min; 1w Slow: two steps Fast 1: 50 C/min Fast 2: two steps All in β S 3 15 S 2 U 6 S 1 U 2 25 U 3 49 q [Å -1 ] Peyronel et al. AOCS Salt Lake City Conference

35 Conclusions part 1 Static crystallization 60 µm TAGwoods Fractal structure DLCA/RLCA CNP average size depends on cooling rate and shearing protocol (none, low, high) - R g1 Fast cooling < R g1 Slow cooling CNP morphology Systems with similar Polymorphism can give rise to different USAXS Intensities The USAXS Intensities can be modified by manipulation of the processing conditions Matching USAXS Intensities might help identify fat replacers or compatibility 35

36 Food and soft material Laboratory Thank you for your attention Natural Sciences and Engineering Research Council of Canada

37 Instrument Set up qq = kk ss - kk ii kk ii Sample kk ss Pin SAXS Absolute WAXS Intensity Bonse-Hart Instrument APS Beam line 12 Multiple sample holder- room temperature Linkam: temperature control Ultra-small-angle X-ray scattering at the Advanced Photon Source. J. Ilavsky, P.R. Jemian, A.J. Allen, F. Zhang, L.E. Levine and G.G. Long. Journal of Applied Crystallography, 2009, 42 (3), p

38 What are we trying to find out? USAXS SAXS WAXS More aggregation? Aggregation? Fractal? size? Scatterer Shape? Size? length scale L=2π/q 6 µm 0.6 µm 60 nm 6 nm 0.6 nm 38

39 Unified Fit * (spheres) I i q =G ee 22 qq 22 RR ggii 33 +ee 22 qq 22 RR ggii B i q P erf 3P q Rg i P 3 R g3 set =10 10 P 2 R g2 R g1 P 1 set =4 Unified Level 3 Unified Level 2 Unified Level 1 q[å -1 ] 20% SSS - Unified Fit in IRENA *Beaucage G J. Appl. Crystallogr. 28: *Beaucage G J. Appl. Crystallogr. 29:

40 Guinier-Porod * II q = GG 11 qq ss ee 11 I q = BB qq PP qq 22 RR (33 ss 11 ) qq 22 qq qq 11 qq qq 11 : shape of scatterer 20% SSS R g1 P 1 Guinier-Porod Level 2 Guinier-Porod Level 1 one particulate system * Hammouda, J. Appl. Cryst. 43, 716 (2010) q 2 q 1 q [Å -1 ] 40

41 How to choose the best fit? All levels must converge Smaller errors for parameters of interest When necessary do an F-Test between two fits for : either 2 or 3 levels Choosing the right starting points for a level is crucial 41

42 Material stored over 8 months SSS in OOO Changed over time SSS + Shea Butter + HOSO no changes over time 42

43 mount of solids: between 50 and 100% Grain µm Grain log I(q) - log of fitted line log (q) q [Å -1 ] Sample Fractality Slopes Rough S Length scale L (Å) 50% SSS or PPP % SSS or PPP % PPP Peyronel et al Applied Physics Letter 43

44 Does the same USAXS imply the same polymorphism? Preliminaries 44