Principles of Food Science, 3rd Edition Page 727 (749 of 864)

727
Chapter 23 Separation Techniques: Mechanical and Chemical Methods
Purpose
Eggs have a membrane that separates the shell from the egg
white. This membrane is similar in structure to cell walls. In this
experiment, you will observe the movement of solutions through
the membrane of the egg. To achieve this, the shell must fi rst be
removed. The shell is composed largely of calcium carbonate,
which will slowly dissolve in vinegar.
Equipment
1000-mL beaker
1 250-mL beaker per student
100-mL graduated cylinder
wax pencil
Supplies
1 egg per student
1 to 2 L white vinegar
100 mL corn syrup
100 mL cider or red wine vinegar
100 mL 1 M NaCl solution
100 mL distilled water with food coloring added
plastic wrap
Experiment 23C
Osmosis and Egg Membranes
Safety
• Do not taste any of the food samples.

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727
Chapter 23 Separation Techniques: Mechanical and Chemical Methods
Purpose
Eggs have a membrane that separates the shell from the egg
white. This membrane is similar in structure to cell walls. In this
experiment, you will observe the movement of solutions through
the membrane of the egg. To achieve this, the shell must fi rst be
removed. The shell is composed largely of calcium carbonate,
which will slowly dissolve in vinegar.
Equipment
1000-mL beaker
1 250-mL beaker per student
100-mL graduated cylinder
wax pencil
Supplies
1 egg per student
1 to 2 L white vinegar
100 mL corn syrup
100 mL cider or red wine vinegar
100 mL 1 M NaCl solution
100 mL distilled water with food coloring added
plastic wrap
Experiment 23C
Osmosis and Egg Membranes
Safety
• Do not taste any of the food samples.

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726
Unit 7 Working with Complex Food Systems
Calculations
1. Calculate the total mass lost from the chicken wings during
cooking.
2. Calculate the total percentage of mass lost from the chicken.
3. Calculate the percentage of mass lost from the chicken in the
form of fat.
4. Calculate the mass lost from the chicken in the form of substances
other than fat.
5. Calculate the percentage of mass lost from the chicken in the
form of substances other than fat.
Data
Record the results of your calculations on a class data chart. Copy
the data from the other lab groups into your data table.
Questions
1. Which solution was the most effective for extracting gelatin?
How did you determine this?
2. Were other compounds extracted during the simmering process?
How do you know?
3. What principles made it possible to extract fat during simmering?
4. How does the percentage of mass lost in the form of substances
other than fat compare among the three variations?
5. How can this information be applied to food preparation?

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728
Unit 7 Working with Complex Food Systems
Procedure
Day 1
1. Place one egg per lab group member in a 1000-mL beaker.
2. Cover the eggs with white vinegar.
3. Wait 5 minutes and record your observations.
Days 2 and 3
1. Turn any eggs that have risen above the surface of the vinegar.
If necessary, add more vinegar to keep the eggs covered. Record
your observations.
Day 4
1. Under cool running tap water, gently rub your egg in a circular
pattern. The eggshell will slowly dissolve in the water and be
lifted off the egg. Be very patient with this step. It takes as
much as 10 minutes to remove all the shell. If your hands are
callused, cover them with plastic gloves. The egg membrane
will rupture easily.
2. Place your egg in a 250-mL beaker. Record your observations
regarding the egg’s size in comparison to the beaker.
3. Cover your egg with 100 mL of the assigned liquid.
Student 1: corn syrup
Student 2: cider or red wine vinegar
Student 3: 1 M NaCl solution
Student 4: distilled water with food coloring added
4. Use a wax pencil to label the beaker with your name and assigned
liquid. Cover the beaker with plastic wrap.
Day 5
1. Record your observations regarding changes in the egg’s size in
a data table. Also note any other changes in the egg.
2. Copy the data from the other lab group members into your
data table.

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Page 25Unit 1 The Science of Food click to expand contents

Page 111Unit 2 Basic Chemistry click to expand contents

Page 231Unit 3 Organic Chemistry: The Macronutrients click to expand contents

Page 389Unit 4 Food Chemistry: The Microcomponents click to expand contents

Page 513Unit 5 Food Microbiology: Living Organisms in Food click to expand contents

Page 593Unit 6 Food Preservation and Packaging click to expand contents

Page 691Unit 7 Working with Complex Food Systems click to expand contents

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