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Food Physics

Food Physics. 李良彬 中国科学技术大学合肥国家同步辐射实验室软物质研究组负责人 中国科学技术大学高分子科学与工程系教授. Where does Food marry Physics?. Physics Food Atomic and Molecular Physics Food Chemistry Plasma Physics Food Biotechnology

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Food Physics

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  1. Food Physics 李良彬 中国科学技术大学合肥国家同步辐射实验室软物质研究组负责人 中国科学技术大学高分子科学与工程系教授

  2. Where does Food marry Physics? Physics Food Atomic and Molecular Physics Food Chemistry Plasma Physics Food Biotechnology Optic Physics Food microbiology Solid state Physics Food Engineering ………….PhysicsFood……………. Soft Matter Physics

  3. Soft Matter In Europe: Soft Matter Physics De Gennes: Nobel Lecture In US: Complex Fluid Most people were from Exxon Mobile Including: Polymer (melt, gel, solution etc) Liquid crystals Colloid (micelle, emulsion) Other biomaterials such as tissue etc

  4. Food Stuff Starch Food: Rice, noodle, bread, chip, fry etc Gel Food: Tofu, cooked egg, yoghurt, Jelly etc Frozen Food: Ice cream, frozen fruit bar etc. Candy: Chocolate Drink: beer, tea, milk, coffee etc.

  5. Chocolate: food of the gods 只熔于口不熔于手

  6. How does tempering influence the quality of chocolate? Appearance. Solidity. Mouth Feel.

  7. Tempering • Four steps • complete melting of the chocolate to about 50 oC, which removes most or all of the crystalline material • cooling to the point of crystallization • maintaining a holding temperature for crystallization for about a minute • reheating to melt out unstable crystals. • During this process, temperature control is very critical, and the shear applied within the process is also a crucial parameter. Fryer, P et al. MRS BULLETIN/DECEMBER 2000, 25-29

  8. Chocolate Three triglycerides (~85% fat): POP (20%), POS (40%), and SOS (25%), palmitic (P), oleic (O), and stearic (S) acids Fryer, P et al. MRS BULLETIN/DECEMBER 2000, 25-29

  9. Sato K, et al. Progress in Lipid Research 38 (1999) 91-116

  10. Cocoa butter crystallized at 5 oC for 7 days (A), at 15 oC for 28 days (B), at 20 oC for 7 days (C), 21 days (D), 35 days (E and F), and at 24 oCfor 7 days (G and H). Brunello N. et al. Lebensm.-Wiss. u.-Technol. 36 (2003) 525–532

  11. Chocolate Fryer, P et al. MRS BULLETIN/DECEMBER 2000, 25-29

  12. Melting point influenced by cooling rate and shear rate Marangoni, A. G., & McGauley, S. E. (2003). Relationship between crystallization behavior and structure in cocoa butter. CrystalGrowth and Design, 3, 95–108.

  13. (a) Temperature variation profile and (b) SR-XRD spectra of the -melt-mediated crystallization of SOS with annealing . (a) Temperature variation profile and (b) SR-XRD spectra of the -melt-mediated crystallization of SOS without annealing .

  14. Phase diagrams of the binary mixtures of POP/PPO and POP/OPO; the most stable forms in (a) POP/PPO and (b) POP/OPO and (c) a kinetic phase diagram of POP/PPO.

  15. How to influence consumer requirements by the N-line Solids 40 30 More ambient stable Better spreadable 10 10 10 10 Better oral melt and taste 20 10 20 30 35 10 Temperature

  16. 生米煮成熟饭

  17. Starch

  18. The ratio between amylose and amylopectin: How to cook? The taste and sensory, Stability Starch gelatinization

  19. 35 105 Starch gelatinization studied with SAXS (Donald et al

  20. Starch gelatinization studied with DSC

  21. Starch gelatinization studied with POM

  22. Effect of sugar and salt Bello-Pbrez LA, Food Chemistry 53 (1995) 243-247

  23. 生米煮成熟饭

  24. ToFu—protein gel

  25. Soybean (4000—5000 years from China) 40% protein 10% Albumins, extracted by water 90% Globulins, extracted by dilute salt solutions) Block copolymer Acidic polypeptide (38 kDa) Basic polypeptide (20 kDa) PH=3.8 PH=7.6 Schematic presentation of a glycinin molecule and its trimeric and hexameric complexes. A and B denote the acidic and basic polypeptides, respectively. The small bar connecting A and B represents the disulphide bond.

  26. ToFu—protein gel

  27. Native hydrophilic hydrophobic Unfolded hydrophilic hydrophobic

  28. 表面自由能和静电排斥势的平衡 PH~4-5 for soy protein

  29. A combination of short-range attraction (surface free energy) and long-range repulsion (electrostatic) results in the formation of small equilibrium clusters. Equilibrium cluster formation in concentrated protein solutions and colloids Anna Stradner et al. Nature, 2004, 432, 492.

  30. Photonic crystal and gel A colloidal model system with an interaction tunable from hard sphere to soft and dipolar Anand Yethiraj & Alfons van Blaaderen, Nature, 2003, 421, 513

  31. Insights into phase transition kinetics from colloid science Valerie Anderson & Henk Lekkerkerker, Nature, 2002, 416, 811.

  32. Beer

  33. Beer foam

  34. The physics of beer foam 1) Bubble formation 2) Creaming (bubble rise) 3) Disproportionation (Ostwald ripening) 4) Drainage

  35. The physics of beer foam Bubble formation is heterogeneous nucleation: a particle, scratch on the glass or a pre-formed micro bubble. The size of bubble: Where Rm = radius of nucleation site (m) γ = surface tension (mN m–1) ρ = relative density of the beer (kg m–3) g = acceleration due to gravity (9.8 m s–2) Test flow-induced nucleation: Shake beer, more bubbles

  36. The physics of beer foam Bubble rising: Stokes’ equation v = rising velocity (m s–1) g = acceleration due to gravity ρ = mass density of the beer r = radius of the bubble η = viscosity of the beer (Pa s)

  37. Disproportionation (Ostwald ripening) Understanding foods as soft materials MEZZENGA et al. Nature Materials, 2005, 4, 729.

  38. The physics of beer foam Foaming is in conflict with surface tension

  39. ice Continuous phase Fat globule Air bubble

  40. Ice nucleation

  41. Smoothness vs size of ice crystals

  42. Biopolymer retarding ice re-crystallization Antifreeze glycoproteins and antifreeze proteins comprise several structurally diverse classes of molecules that have in common the ability to inhibit the growth of ice. The antifreeze glycoproteins are carbohydrate rich 2.6-34 kDa proteins containing an (Ala-Ala-Thr)n repeat with a disaccharide attached to threonine. Four classes: Type I, alanine-rich, a-helical 3.3 to 4.5-kDa proteins; Type II, cysteine rich globular proteins that contain five disulfide bonds; Type III, approximately 6 kDa globular proteins Type IV, glutamate- and glutamine-rich proteins that contain a-helices but appear to be unrelated to other proteins. Haring et al. Eur. J. Biochem. 264, 653-665 (1999)

  43. Worrall, et al. Science, 1998, 282, 115

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