1. Lecture 4 – Physical Attributes Announcements
HW #3 due Jan. 23rd
Laboratory 1, Physical Characteristics, due 2/6 (choose 2 products)
Instructions for lab reports
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BAE2023 Physical Properties of Biological Materials Lecture 4

2. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Quick Review
Describe size, shape, style
Sphericity
Determining volume, equipment
Surface area
Electronic method for estimation
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BAE2023 Physical Properties of Biological Materials Lecture 4

3. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Density:
Definition: weight per unit volume
Liquid density determined by pycnometer, hydrometer
Common liquid food product in Table B.1 in Appendix B
May change significantly with temperature
Specific Gravity:
Definition: ratio of density of liquid to density of water
Change due to temperature is small
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BAE2023 Physical Properties of Biological Materials Lecture 4

4. BAE2023 Physical Properties of Biological Materials Lecture 4
Hydrometer
Brix: sucrose
Lactometers: milk density
Oleometers: veg. oil
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BAE2023 Physical Properties of Biological Materials Lecture 4

5. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Foams: products with large amounts of air incorporated during processing
Whipped cream, sherbet, ice cream
Describe using “overrun”: % increase in volume attributed to air
Icemilk: %
Sherbet: %
Cream: %
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BAE2023 Physical Properties of Biological Materials Lecture 4

6. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Particulate Materials
Solid Density: weight per unit volume excluding interior pores
Particle Density: weight per unit volume of individual kernel
Bulk Density: weight per total volume occupied by large quantity of kernels
Density of water is different than other components…we can distinguish solid density and water density
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BAE2023 Physical Properties of Biological Materials Lecture 4

7. For water and solids: BOOK CORRECTION ex. 2.4
Lecture 4 – Physical Attributes Chapter 2, pgs
For water and solids:
BOOK CORRECTION ex. 2.4
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BAE2023 Physical Properties of Biological Materials Lecture 4

8. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
“particle density is highly dependent on moisture content”
EX: suppose the soybean moisture content were 0.16 and the kernel density were g/cm3
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BAE2023 Physical Properties of Biological Materials Lecture 4

9. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Density of fruits and vegetables:
Determined by water displacement method.
Example 2.5
Table
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BAE2023 Physical Properties of Biological Materials Lecture 4

10. BAE2023 Physical Properties of Biological Materials Lecture 4
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BAE2023 Physical Properties of Biological Materials Lecture 4

11. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Bulk density
Determined by pouring a sample into a container with known dimensions.
Variables: method of filling and striking surface
Conversion: 1 bushel = ft^3 or m^3
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BAE2023 Physical Properties of Biological Materials Lecture 4

12. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Test Weight
Factors affecting test weight…moisture content, broken kernels, fines, variety/hybrid, growing conditions
Bulk density
Table 2.3 (you will need this table later on!!!)
Porosity: space between particles, not within particles
Calculated from bulk density and particle density
Example 2.6
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BAE2023 Physical Properties of Biological Materials Lecture 4

13. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Regression and Statistical Distribution
Equation 2.6
What is this business about logs?
Mean and standard deviation (measure of variability)
r^2
Normal distribution
Influences how we design equipment to handle particles
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BAE2023 Physical Properties of Biological Materials Lecture 4

14. Sieve analysis Sized by the 64th
Lecture 4 – Physical Attributes Chapter 2, pgs
Sieve analysis
Sized by the 64th
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BAE2023 Physical Properties of Biological Materials Lecture 4

15. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Radius of Curvature
Sharpness of curvature will determine how readily an object will roll
Determined by radius of curvature
Figure 2.6
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BAE2023 Physical Properties of Biological Materials Lecture 4

16. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Applications
Separate foreign material
Proper singulation during planting
Separate germs, pericarps, hulls from endosperm or cotyledon
Size grades and shape
Density separation (milk separator)
Watermelon sorting by shape and weight
Sorting by shape…orientation is a problem
Optical sorting
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BAE2023 Physical Properties of Biological Materials Lecture 4

17. Lecture 4 – Physical Attributes Chapter 2, pgs. 21-48
Homework #3 Part 3 Due 1/23
Problem 1: Using the formula for density versus solids content for salt solutions given in Appendix B, calculate the minimum concentration of a salt solution in which apples of average density will float.
Problem 2: #2.17 in book
Problem 3: #2.18 in book
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BAE2023 Physical Properties of Biological Materials Lecture 4