Rheology Solid and Liquids ·Rheology TXUT& [Greek rheos-“to flow"】is the study of deformation and Solids-Elastic:Materials that can flow of matter support a applied stress ·Name was coined by Dr. Liquids-Viscous:Materials that can Marcus Reiner instead of the more obscure not support an applied stress “continuum mechanics” (that is they flow under stress) Motto of the Society of Rheology:"Panta Rhei"or “everything flows'” after Heraclitus Pie Units of Measure ·Force (Newton) Distance (meter) ·Time(second) Liquid or derived measures Semi-Solid Stress(N/m2 or Pascals) olid ·Velocity(ml/s) Forces and Stresses Table 2.6 Forces Exerted Between Teeth (in Pounds)" Male Female Compression Tensile Subject Mean Maximum Mean Maximum 348 200 200 85 mencan (dentures) 60 "Data taken from Waugh (1937)and Klatsky (1942). Shear 1 pound=0.45 Kg 1
1 Rheology • Rheology [Greek rheos - “to flow”] is the study of deformation and flow of matter • Name was coined by Dr. Marcus Reiner instead of the more obscure “continuum mechanics” • Motto of the Society of Rheology:“Panta Rhei” or “everything flows” - after Heraclitus Solid and Liquids • Solids - Elastic: Materials that can support a applied stress • Liquids - Viscous: Materials that can not support an applied stress (that is they flow under stress) Pie Liquid Semi-Solid Solid Units of Measure • Force (Newton) • Distance (meter) • Time (second) or derived measures • Stress (N/m2 or Pascals) • Velocity (m/s) Forces and Stresses Compression Tensile Shear
Secondary parameters Table 2.3 Size Threshold Between Smooth and Grainy Texture Hardness Softfirm-hard wy-Ou Food Particle size(m) Chocolate 13 56cy+ac南→gooy Chocolate Chocolate Class Fondant(sugar crystals) 20-25 Ice cream (ice crystals) 55 Margarine(fat crystals) 22 Sweetened condensed milk(lactose crystals) 10-12 Secondary parameters Popular terms Tofu (soy particles) Dy→moi+w+wat Fat content 8 Stress Deformation-Strain Compression Compression Stress=Force/Area Ay Strain=△yy Deformation-Strain Ax Shear 门7 Shea Bcompression Shear Stress=△r/y 2
2 Stress Compression Stress = Force / Area Deformation - Strain Compression y Δy Strain = Δy/y Deformation - Strain Shear y Δx Shear Stress = Δx / y
Elastic Solids Force Measures of Texture Compression Shear Fundamental Tests-Rheology F- ·Imitative Tests ·Empirical Tests Stress=F/A=o Stress=F/A=o Strain=△y/y=8 Strain=△rIy=Y G=E8 0=GY E=Compressive Modulus G=Shear Modulus Texture Imitative Hands-on Gel Ridgelmeter Cone App山 Penetrometer Force apply force (gravit中 and (weight of cone) Measure Deformation and measure (sag of gel) deformation (distance of penetration) 3
3 Elastic Solids Δy Compression y Force Stress = F / A = σ Strain = Δ y/ y = ε σ= E ε E = Compressive Modulus Δx F Shear y Stress = F / A = σ Strain = Δx / y = γ σ= G γ G = Shear Modulus Measures of Texture • Fundamental Tests - Rheology • Imitative Tests • Empirical Tests Imitative Texture Hands-on Cone Penetrometer apply force (weight of cone) and measure deformation (distance of penetration) Gel Ridgelmeter Apply Force (gravity) and Measure Deformation (sag of gel)
Christel Warner Bratzeler Texturometer Applies Cutting Deformation and Measures Apply Forces Deformation And measure Force Armour Tenderometer Warner Bratzeler for meat tenderness General Foods Texturometer First attempt at a Imitative, General Empirical, Foods and Fundamental Texturo Test for Texture meter Evaluation ￥
4 Christel Texturometer Apply Deformation And measure Force Warner Bratzeler Applies Cutting Deformation and Measures Forces Warner Bratzeler Armour Tenderometer for meat tenderness General Foods Texturometer First attempt at a Imitative, Empirical, and Fundamental Test for Texture Evaluation General Foods Texturo meter
Use different Texturometer fixtures for either Imitative, Empirical, and Fundamental Tests Texture Profile Analysis Instron (TPA) Universal combination of Testing Imitative, Machine Empirical, and Fundamental Types of Rice Grains 6 Long Medium Short Waxy (N) 4 000 3 L-204 M-202 Koshihikari Calmochi-101 Increasing Amylose Content 2 DESPLAZAMIENTO (mm) 5
5 Texturometer Use different fixtures for either Imitative, Empirical, and Fundamental Tests Instron Universal Testing Machine Texture Profile Analysis (TPA) combination of Imitative, Empirical, and Fundamental L-204 M-202 Koshihikari Calmochi-101 Long Medium Short Waxy