5/15/2015BAE2023 Physical Properties of Biological Materials Lecture 5 1 Quick Review –Describe size, shape, style –Sphericity –Determining volume, equipment

04/18/23 BAE2023 Physical Properties of Biological Materials Lecture 5

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•Quick Review–Describe size, shape, style–Sphericity–Determining volume, equipment–Surface area–Electronic method for estimation

Lecture 5 – Physical AttributesChapter 2, pgs. 21-48


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–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


http://en.wikipedia.org/wiki/Image:Hydrometer6455.png


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• Hydrometer– Brix: sucrose– Lactometers: milk

density– Oleometers: veg.

oil


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– 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: 30-40%• Sherbet: 50-80%• Cream: 100-120%

100%foam liquid

liquid

V VOR x

V



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– 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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• For water and solids:

• BOOK CORRECTION ex. 2.4

1

1solids n

i

i i

m

ker

11.0nel

water solids

M M



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–“particle density is highly dependent on moisture content”

• EX: suppose the soybean moisture content were 0.16 and the kernel density were 1.232 g/cm3



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–Density of fruits and vegetables:• Determined by water displacement method.• Example 2.5 • Table


http://www.thermexcel.com/english/tables/eau_atm.htm


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–Bulk density• Determined by pouring a sample into a container with

known dimensions.• Variables: method of filling and striking surface• Conversion: 1 bushel = 1.244 ft^3 or 0.035239 m^3



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–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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–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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–Sieve analysis–Sized by the 64th



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–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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–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


04/18/23 16

HW#4 Part 2 AssignmentDue 1/31

• 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 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

Chpt 2, determine the volume and surface area.

BAE2023 Physical Properties of Biological Materials Lecture 5

04/18/23 17

HW#4 Part 2 AssignmentDue 1/31

• Problem 4: #2.6 in book

• Problem 5:• #2.10 in book

BAE2023 Physical Properties of Biological Materials Lecture 5

Documents

5/15/2015BAE2023 Physical Properties of Biological Materials Lecture 5 1 Quick Review –Describe size, shape, style –Sphericity –Determining volume, equipment