Food and Nutrition
Carbohydrate Test
FOSS food and Nutrition, TESLA Science Notebooks
BIG IDEA:
Foods contain specific materials such as fats, proteins, sugars,
and acid that work together to create healthy or unhealthy
eating choices.
Engaging Scenario
The nutritionist for the Lewiston School District was happy to receive
your results on the fat test. She will be studying your results and getting
back to you soon. In the meantime she has given us a bag of yeast (a
live organism) to help us investigate some different foods. The yeast
will be an indicator of which foods contain a mystery nutrient. After our
investigations we will be able to identify the mystery ingredient as well
as state claims and evidence as to which foods contain more of this
ingredient than others.
She is also asking that each group bring a small amount of breakfast
cereal to school tomorrow, so we can determine if this ingredient is
present in the cereal you eat.
What do we need to investigate?
What is the problem that needs to be solved?
Word Wall
Yeast: small organisms that are a type
of fungus, neither plant nor animal.
Indicator: an object, material, or
organism that tells you if a specific
substance is present.
Nutrient: Important chemicals found
in food that helps keep an organism
alive and active.
Focus Question:
“What does the school nutritionist want us to do?”
• Examine and test different types of food with yeast to determine if they contain
a mystery nutrient.
• Bring a small amount of breakfast cereal to school tomorrow
“Discuss with your group what we need to investigate and record it as the
FOCUS QUESTION. This is the problem we are going to investigate and
solve.”
How can we … use yeast as an indicator
to find the mystery ingredient in foods?
Background Knowledge:
In this bag is a small amount of yeast. Yeast are a single-celled type of
fungi. Yeast fungi are living, but they are not a plant or animal. The
yeast in the bag do not look alive because they are tiny organisms in a
dormant, or resting state.
“What do you think yeast will need to break out of their dormant state
and become active?”
Water, Warmth, and Food
Background Knowledge:
We are going to try to activate the yeast by placing them in a bag with
warm water and animal crackers. The warm water will supply the
yeast’s need for water and warmth and we will see if the animal
crackers will supply their need for food. To determine if the animal
crackers could be a food source for yeast we will also place the yeast in
a bag of warm water without animal crackers.
“What do you know about the ingredients found in cookies? Has
anyone ever made cookie dough before, what ingredients did you
use?”
“Has anyone ever read the ingredients on a cookie package before?”
Background Knowledge:
“What are the main ingredients found in
animal crackers?”
• Flour and Sugar
• The main ingredients (largest quantity) are always
listed first.
Prediction:
Before we complete this part of the investigation I would like you to
record a prediction in your science notebook. Discuss with your group
what you think will happen when we place yeast in a bag of warm water
and animal crackers. Will the yeast become active, how do you know? Be
ready to share your ideas with the class.
EXAMPLE Prediction:
I think that if we _______________________________________
because ______________________________________________
Part One: Activating Yeast
Materials per Test/Group:
•1 syringe (holds minimum 50ml)
•Two 1-liter zip bags
•Two 1-liter container half filled with hot water
•thermometer (Celsius)
•hot water (40-50* Celsius)
•Two 5-ml spoons of dry yeast per bag
•2-5 animal crackers
•Marking Pen
•Water greater than 50* C will kill
yeast.
•Use hot tap water supplemented
with your hot water.
1. Label one bag as cookie and the other no cookie, put two 5-ml spoons of yeast into each zip
bag.
2. Use a syringe to draw up 50ml of hot water from the 1-liter container (Water is 40-50* Celsius).
If water temperatures exceed 50* C the yeast will die. Squirt the water into the bag with the
yeast, spraying back and forth to wet all the yeast. Repeat with the second bag.
3. Put 2-5 animal crackers in the “cookie” bag and nothing in the other bag. Let the cookies soak
for a moment and then crush them.
4. Seal both bags most of the way across. Lay them flat on the table, holding the open corner up
slightly, and carefully press all of the air out of the bags. Seal the bags tightly.
5. Put the sealed bags in the 1-liter container half filled with hot water (called the warm-water
bath).
6. Maintain the warm-water bath at 40-50* C for approximately 10 minutes.
7. Remove the bags from the warm-water bath, lay them on a flat surface, and observe.
Animal Cracker Observations:
“What changes did you see?”
The “cookie bag” puffed up with gas; the other bag did not.
“Why do you think this happened?” “Why did the bag with no
cookies not react?”
The bubbles and gas in the bag with the food are evidence that the yeast is alive
and metabolizing. The gas that is produced during this process is carbon dioxide
or CO2 .
Metabolize: The process of
turning food into energy within a
living cell or organism.
Carbon Dioxide: a gas produced as
waste during cellular respiration
and metabolism.
Prediction/Quick Write:
If the carbon dioxide is produced because the yeast is turning food
into energy, can you think of a way to find out if one of the major
ingredients used to make animal crackers, flour or sugar, caused
the yeast to become active?
I think that if we ___________________ because _____________.
Part Two: Flour or Sugar
We could see if the yeast will metabolize flower or sugar as a food
source by running the test again using flour and sugar instead of
animal crackers. This time one bag will contain only sugar and the
other bag will contain only flour.
Which food source do you think the yeast will prefer? Justify
your prediction with a because statement.
I think that…
because…
The Volume Tube
The volume tube can be used to measure the volume of carbon dioxide
produced by the yeast. We know from our last activity that the bag
expands in size because a gas called carbon dioxide is produced as a waste
product when organisms are metabolizing their food. If the organism does
not have a food source to metabolize, carbon dioxide is not produced. This
happened in the bag that did not contain cookies.
If we place our bags in the volume tube we can compress the piston down
the cylinder and record the volume of carbon dioxide present in the bag in
millimeters. We need to apply enough pressure to compress the bag so
that we are filling the space with just carbon dioxide, but not enough to
pop the bag.
Flour or Sugar
We will follow the same procedure we used in the animal cracker test except this
time we will not add animal crackers to the bag. We will add sugar to one bag and
flour to the other (We need to label our bags). The variable we are testing in this
investigation is food source. All other materials and procedures are the same.
Materials per Test/Group:
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Two 1-liter zip bags, 1 syringe (holds minimum 50ml)
Two 1-liter container half filled with hot water
thermometer (Celsius)
hot water (40-50* Celsius), Thermos and Hot water Source (Coffee Pot, Insta Hot, etc)
Two 5-ml spoons of dry yeast per bag
•Water greater than 50* C will kill
1 spoon of sugar
yeast.
1 spoon of flour
•Use hot tap water supplemented with
Marking Pen
your hot water.
Recording our Results
Place the bags in a warm water bath for 10 minutes. You need to
quickly measure the volume of gas produced in the flour and sugar bags
and record the data in your science notebook.
Volume of CO2 in the bag (milliliters)
Flour
Sugar
Making Meaning of our
Results
“Based on your results, does yeast metabolize flour or sugar?”
“How do you know?”
The bag with sugar was the only bag that produced a significant amount of carbon
dioxide. Yeast uses sugar as a food source.
“So if yeast is placed in a bag with warm water and an unknown
material, and the mixture starts to bubble and produce gas, what can
we conclude?”
The material contains sugar as an ingredient
Making Meaning of our
Results
Yeast can be used as an indicator for the presence of sugar.
Indicator: an object, material, or
organism that tells you if a
specific substance is present.
Sugar: a simple carbohydrate,
which is a nutrient found in foods
Nutrient: Important chemicals
found in food that helps keep an
organism alive and active.
Quick Write
Our district nutritionist asked us to determine How we can use
yeast as an indicator to find the mystery ingredient in foods?
Please respond to her request by completing a claims and
evidence statement
I claim that yeast can be used as an indicator to identify ________
in mystery foods. I claim this because...
Part Three: Cereal
“What are some things we know about cereal? What nutrients
are found in cereal?”
Today we are going to use the cereal samples you brought to
determine which cereal will contain the most sugar. Since most
of you brought your samples in small containers or bags, we can’t
reference their food labels to determine sugar contents. How do
you think we can identify the cereals with the greatest or least
amounts of sugar without looking at food labels?
Prediction:
Before we complete this part of the investigation I would like you to
record a prediction in your science notebook. Discuss with your
group which cereals you think will contain the most sugar and why.
Be ready to share your ideas with the class.
I predict that _________________________ will contain the most
sugar, because…
I predict that _________________________ will contain the least
amount of sugar, because…
Sugar and Cereal Test:
We will conduct the same test as we did for animal crackers, flour
and sugar. This time we will use our cereal samples as a food
source for yeast.
“Since we are all testing a different cereal sample how can we make this
a fair test?”
“If one group is adding a spoonful of cereal and another group adds a ¼
cup of cereal, will the volume of CO2 produced reflect which cereal
contains the most sugar?
In order for this to be a fair test, each group will need to add the same volume of
cereal to their bags. We will do this by using a balance to weigh and measure
equal amounts of our cereal samples.
Sugar and Cereal Test:
In order for the results of this investigation to be fair and accurate, the
variables in the experiment must be controlled.
What are we going to change?
 The type of cereal we test
What are we going to keep the same?
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The amount of cereal we use
The amount of yeast added
The amount of warm water added
The temperature of the water
The time we allow for yeast to metabolize
Recording our Results
Which Cereals Contain the Most Sugar?
Cereal Type
Volume of CO2 in milliliters
After 10 minutes
After 20 Minutes
Sugar and Cereal Test
Materials per Test/Group:
• 1-liter zip bags, a syringe (holds minimum 50ml)
• 1-liter container half filled with hot water
• thermometer (Celsius)
•Water greater than 50* C will kill
• hot water (40-50* Celsius)
yeast.
•Use hot tap water supplemented with
• Two 5-ml spoons of dry yeast per bag
your hot water.
• Approx. 3 grams of cereal
• Balance from the measurement kit
• Marking Pen
Which cereals tested today contained the greatest and least amount
of sugar? How do you know?
Making Meaning:
How can we use yeast to indicate the presence of sugar in foods?
When yeast and warm water come in contact with sugar the mixture bubbles and a gas is
produced.
What caused carbon dioxide to become present in the bags?
The yeast was metabolizing the sugar. Carbon dioxide is produced as a waste material
when respiration and metabolism occur.
What is sugar?
A simple carbohydrate that is a nutrient found in foods.
Why did the yeast not metabolize the flour?
Flour is not an appropriate food source for yeast.
How did we determine which cereals contained the greatest amounts of sugar?
We used a yeast test and measured the amount of CO2 produced. Cereals with greater
concentrations of sugar produced more CO2.
Claims and Evidence:
Based on what you have learned from your investigation of
sugars, you need to record some claims and evidence
statements in your science notebook… Your evidence must be
based on your data!
I claim that…
I know this because…
Possible Example:
I claim that yeast can be used as an indicator for the presence of
sugar in foods. I know this because…
I claim that cereals with larger amounts of sugar produced greater
volumes of carbon dioxide. I know this because…
REFLECTION AND CONCLUSION
November
11/8
• What did you learn…?
• What really surprised you…?
• What new questions do you have…?
• What would you like to know more about…?
2011