Understanding Physical Attributes of Biological Materials

1. Lecture 4 – Physical Attributes BAE2023 Physical Properties of Biological Materials Lecture 4

2. Lecture 4: Physical AttributesChpt 2, Pages 11-20 For grain, seeds, fruits, vegetables Size described by 3 dimensions Major diameter: longest dimension of the max projected area (fat part) Intermediate diameter: min. diameter on the max projected area, assumed to be equal to the longest diameter of the min projected area (thickness) Minor diameter: shortest dimension of the minimum projected area (skinny part) May be referred to differently in industry Usually called length, width, and depth BAE2023 Physical Properties of Biological Materials Lecture 4

3. Lecture 4: Physical AttributesChpt 2, Pages 11-20 Shape: used to describe unprocessed foods Example: carrots = cones Style: used to describe processed foods Example: carrot coins, french cut beans, apple wedges, banana chips Shape: use geometric solids…sphere, truncated cone (see appendix C) BAE2023 Physical Properties of Biological Materials Lecture 4

4. Lecture 4: Physical AttributesChpt 2, Pages 11-20 Sphericity: Ratio of volume of triaxial ellipsoid to a circumscribed sphere (show correction in book for 2a, 2b, 2c, page 13 and pg 14 example) Blueberry example BAE2023 Physical Properties of Biological Materials Lecture 4

5. Lecture 4: Physical AttributesChpt 2, Pages 11-20 Sphericity, Sc: Aspect ratio, Ra = (b/a)*100 Ra >50%...tends to slide Sc >50%...tends to roll Both > 50%, will tend to roll with some sliding BAE2023 Physical Properties of Biological Materials Lecture 4

6. Lecture 4: Physical AttributesChpt 2, Pages 11-20 Volume Volume determined by liquid or gas displacement Pycnometers or graduated burettes Weight of fluid displaced by solids divided by the density of the fluid = volume of the solid particles Buoyant force of water on object, page 16, 2.3 Platform balance Optical method BAE2023 Physical Properties of Biological Materials Lecture 4

7. Lecture 4: Physical AttributesChpt 2, Pages 11-20 Volume Volume determined by gas displacement Page 17 Fig.2.2 Gas penetrates grains and seeds Coat with wax BAE2023 Physical Properties of Biological Materials Lecture 4

8. Lecture 4: Physical AttributesChpt 2, Pages 11-20 Volume Estimation through calculation Use Appendix C for equations of similar geometries Error determination, %: [(Your calculation – test value)/(test value)]*100 Example: calculated volume using equation…48.7 mm3 Gas pyncnometer measure 50.1 mm3 BAE2023 Physical Properties of Biological Materials Lecture 4

9. Lecture 4: Physical AttributesChpt 2, Pages 11-20 Surface Area Peel Coating and peeling Bread loaf estimation example Estimate Surface Area Similarity to geometric solids Appendix C (not A!!!) Example 2.3 page 19 BAE2023 Physical Properties of Biological Materials Lecture 4

10. HW#4 AssignmentDue 1/25 Problem 1: A) Calculate the sphericity of a blueberry, a Red Haven peach, and a Norchip potato. B) Which one is more spherical? Problem 2: Calculate the volume of a Bart 46 Wheat kernel Reference data What is the percentage error when compared to the volume determined by testing? Problem 3: Using a piece of fruit or vegetable of your choice, and example 2.3 in Chpt 2, determine the volume and surface area. BAE2023 Physical Properties of Biological Materials Lecture 4

11. HW#4 Part AssignmentDue 1/25 Problem 4: #2.6 in book Problem 5: #2.12 in book BAE2023 Physical Properties of Biological Materials Lecture 4