1. Lecture 4 – Physical Attributes Announcements
1/3/2019
BAE2023 Physical Properties of Biological Materials Lecture 3

2. Lecture 4: Physical Attributes Chpt 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
1/3/2019
BAE2023 Physical Properties of Biological Materials Lecture 3

3. Lecture 4: Physical Attributes Chpt 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)
1/3/2019
BAE2023 Physical Properties of Biological Materials Lecture 3

4. Lecture 4: Physical Attributes Chpt 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
1/3/2019
BAE2023 Physical Properties of Biological Materials Lecture 3

5. Lecture 4: Physical Attributes Chpt 2, Pages 11-20
Sphericity, Sc:
Palm fruit example…will it roll or slide???
research paper
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
1/3/2019
BAE2023 Physical Properties of Biological Materials Lecture 3

6. Lecture 4: Physical Attributes Chpt 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
1/3/2019
BAE2023 Physical Properties of Biological Materials Lecture 3

7. Lecture 4: Physical Attributes Chpt 2, Pages 11-20
Volume
Volume determined by gas displacement
Page 17 Fig.2.2
Gas penetrates grains and seeds
Coat with wax
1/3/2019
BAE2023 Physical Properties of Biological Materials Lecture 3

8. Lecture 4: Physical Attributes Chpt 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
1/3/2019
BAE2023 Physical Properties of Biological Materials Lecture 3

9. Lecture 4: Physical Attributes Chpt 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
1/3/2019
BAE2023 Physical Properties of Biological Materials Lecture 3

10. HW#4 Part 2 Assignment Due 1/29
Problem 1:
A) Calculate the sphericity of Plum and a Tomato.
B) Which one is more spherical?
Problem 2:
Calculate the volume of a Pacific Bluestem Seed
Reference class handout
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 your book, determine the volume and surface area.
1/3/2019
BAE2023 Physical Properties of Biological Materials Lecture 3