yeast carbon dioxide balloon experiment

• 1 packet of active dry yeast
• A 0.5 L (16.9 fl oz) or smaller plastic bottle
• 1 teaspoon measuring spoon (5 mL)

Short explanation

Long explanation.

• How does the water temperature affect how much carbon dioxide is formed?
• How does the amount of sugar affect how much carbon dioxide is formed?
• What type of yeast (find them in your grocery store) results in the most carbon dioxide?

Homemade yogurt

Strawberry DNA

Screaming dry ice

Dry ice in a balloon

Special: Dry ice color change

Dry ice smoking soap bubble snake

Dry ice giant crystal ball bubble

Dry ice in water

Rainbow milk

Gummy bear osmosis

Floating ping pong ball

Rotating Earth

Special: Colored fire

Special: Fire bubbles

Water cycle in a jar

Egg drop challenge

Taking the pulse

Orange candle

Glass bottle xylophone

Warped spacetime

Homemade rainbow

Water implosion

Warm and cold plates

Plastic bag kite

Tamed lightning

Yeast and a balloon

Forever boiling bottle

Moon on a pen

Moon in a box

Inexhaustible bottle

Crystal egg geode

Magic ice cut

Leaf pigments chromatography

Heavy smoke

Popsicle stick bridge

Micrometeorites

Special: Fire tornado

Special: Whoosh bottle

Dancing water marbles

Brownian motion

Flying static ring

Water thermometer

String telephone

Special: Dust explosion

Disappearing styrofoam

Special: Burning money

Special: Burning towel

Salt water purifier

Fish dissection

Hovering soap bubble

Homemade sailboat

Water mass meeting

Plastic bag and pencils

Water sucking bottle

Water sucking glass

Mentos and coke

Aristotle's illusion

Spinning spiral snake

Imploding soda can

Carbon dioxide extuingisher

Plastic bag parachute

Dental impression

Impact craters

Rolling static soda can

Static paper ghost

Color changing flower

Upside down glass

Shrinking chip bag

Solar system model

Electric motor

Flashy electric motor

Bouncing soap bubbles

Toilet paper roll maraca

Cloud in a bottle 1

Cloud in a bottle 2

Balloon rocket

Water whistle

Special: Screaming gummy bear

Homemade compass

Trash airplane

Wind-up spinner toy

Tea bag rocket

Balancing soda can

Lung volume test

Fireproof balloon

Baking powder popper

Expanding space

Straw propeller

Wooden cutlery

Levitating match

Human reflexes

Electromagnet

Soil layers

Straw potato

Straw rocket launcher

Traveling flame

Water bowls

Straw duck call

Solar eclipse

Silo of salt

Balloon skewer

Newspaper tower

Microwave light bulb

Heavy paper

Rubber chicken bone

Homemade marble run

Drops on a coin

Cartesian diver

Content of website.

• ScHOOL Sign Up
• Scientist Sign Up
• Our Scientists
• Our Research
• Give us Feedback!
• In the News
• Fermentation, or how to blow up a balloon with yeast!

image bt Ingenza Ltd

If you have ever baked bread, you probably have encountered yeast and used it to make the dough rise. But how does it work? The yeast you can buy in a shop is called Saccharomyces cerevisiae , or just baker’s yeast. Yeasts break down sugars and produce alcohol, which is used in alcoholic beverages, and carbon dioxide, which is a gas that makes bread dough rise.

You can see the fermentation process in a very easy way at home, by mixing some active dry yeast, sugar and warm water in an empty bottle and fit a balloon over the bottle top. Watch the balloon blow up magically!

Here is how you can do it: 

• Packet of yeast
• Empty Water Bottle
• Funnel 

Use the funnel  to put a couple of spoonfuls of sugar in an empty water bottle. 

Fill half of the bottle with warm water.

Add a package of yeast. Yeast is activated when it gets wet. So, put the top on and shake the bottle. Open the bottle again and place the ballon over the bottle opening. 

Finally you wait for the magic to happen. It will take more than an hour to get the balloon really good and inflated.

But how does this work? Yeast  is a microscopic fungus. As the yeast eats the sugar, it releases a gas called carbon dioxide. The gas fills the bottle and then fills the balloon as more gas is created.

Tips for the experiment and food for thought:

• Try to use clear bottles, so you can see the liquid bubbling!
• Try repeating the experiment with cold water. Or, putting the bottles in a warm place like a sunny window sill. Does the temperature influence the activity of the yeast?
• Try adding different amounts of sugar (or no sugar!) to the mixture. Which bottles grow the balloon most?
• Can yeast use other sugars than sucrose (which is the sugar in household sugar)? How about using some fruit juice (with a lot of fructose) or milk (with lactose)?
• When the balloons are all blown up, don’t forget to take a whiff before throwing it away! What does the smell remind you of? How do different bottles differ in their smell?

If you want to see a video with the experiment click here . 

The same process happens when we are making bread. Check this video to find out more.

By Daniel Sachs

•     [email protected]

Cool Science Experiments Headquarters

Making Science Fun, Easy to Teach and Exciting to Learn!

Science Experiments

Balloon Blow-up Science Experiment

Can you blow up a balloon without using your mouth? In this simple science experiment, we’re going to show you how to do it with only a few everyday items you probably already have in your home. It makes a great experiment for young children because the set-up is simple and it only takes a few minutes to get to the exciting finale.

In addition to a video demonstration and detailed printable instructions, we also have the scientific explanation of how this simple chemical reaction works making it perfect for older scientists too.

JUMP TO SECTION: Instructions | Video Tutorial | How it Works

Supplies Needed

• Small Soda Bottle
• Baking Soda

Balloon Blow-up Science Lab Kit – Only $5

Use our easy Balloon Blow-up Science Lab Kit to grab your students’ attention without the stress of planning!

It’s everything you need to  make science easy for teachers and fun for students  — using inexpensive materials you probably already have in your storage closet!

Balloon Blow Up Science Experiment Instructions

Step 1 – Start with some questions: How do you blow up a balloon? What if I told you that you couldn’t blow air into it, do you think you could still inflate (blow-up) the balloon? Then observe the supplies for the experiments. Do you think they can be use to blow up the balloon? If so how? Write down your hypothesis (prediction).

Step 2 – Using a funnel, pour about a third of a cup of vinegar into the bottle. We used Apple Cider Vinegar, but any type of vinegar will work.

Step 3 – Then insert another funnel into the mouth of the balloon. We recommend using two different funnels. One funnel for filling the bottle with vinegar and one for the balloon. However, you can do the experiment with only one funnel. Just make sure you completely wash and dry the funnel after you add the vinegar and before you put it into the balloon. This is very important.

Step 4 – Place two teaspoons of baking soda into the funnel so it falls into the balloon. When the balloon is filled with the baking soda, carefully remove it from the funnel. 

Step 5 – Next, secure the mouth of the balloon over the mouth of the bottle. Take your time doing this and don’t let any of the baking soda fall out of the balloon and into the bottom of the bottle. Take a moment to make some observations. What will happen if we lift up the balloon? Write down your hypothesis (prediction) and then test to see if you were right!

Step 6 – While holding the bottle, lift the end of the balloon and allow the baking soda to drop into the bottle. 

Step 7 – What happens to the balloon? Was your hypothesis correct? Wondering what caused the balloon to inflate? Find out the answer in the how does this experiment work section below.

Video Tutorial

How Does the Science Experiment Work?

When baking soda (a base) and vinegar (an acid) are mixed together they create a chemical reaction that results in the formation of carbon dioxide gas. Gases do not have a specific shape or volume, rather they expand rapidly filling their container. Gases expand rapidly because their particles move at high speeds in all directions. As the carbon dioxide gas fills the bottle, it has nowhere else to go so it begins to fill the balloon. As the carbon dioxide gas fills the balloon, the balloon inflates. The more gas that is created, the larger the balloon will inflate.

The baking soda and vinegar chemical reaction will continue to inflate the balloon as long as there is still baking soda and vinegar to react. Once the reaction between baking soda and vinegar has stopped, the balloon will slowly begin to deflate.

An acid is a substance that tastes bitter, reacts with metals and carbonates, and turns blue litmus paper red. A base is a substance that tastes bitter, feels slippery, and turns red litmus paper blue.

Other Ideas to Try

Does changing the amount of baking soda and vinegar change the size of the balloon when it inflates? What would happen if you used another acid like lemon juice instead of the vinegar? Would it react the same with the baking soda?

I hope you enjoyed the experiment. Here are some printable instructions:

Instructions

• Using a funnel, pour about a third of a cup of vinegar into the bottle. Tip: I used Apple Cider Vinegar, but any kind of vinegar will work.
• Then insert another funnel into the mouth of the balloon. Tip: It is best to have two funnels, one for filling the bottle with vinegar and one for the balloon. If you only have one funnel, it is important that you completely wash and dry the funnel after you add the vinegar and before you put it into the balloon.
• Place two teaspoons of baking soda into the funnel so it falls into the balloon. Then remove the balloon from the funnel.
• Next, secure the the mouth of the balloon over the top of the bottle. Tip: Don’t let any of the baking soda drop into the bottle…yet!
• While holding the bottle, lift the end of the balloon allowing the baking soda to drop into the bottle.
• Watch in amazement as the balloon magically inflates!

Reader Interactions

November 2, 2017 at 11:00 am

Yeah but don’t just eyeball the measurements of things because if you use to much baking soda it will make the baloon spring a leak and all sorts of stuff will fly out and make a big mess.

I speak form experience

Seriously, don’t do this

April 21, 2018 at 10:26 am

I did this experiment and it is perfect!

You need to hold properly the bottle when you mix the baking soda into vinegar.

May 22, 2019 at 8:57 am

We’re doing science experiments at school and this one is brilliant! I loved it a lot.

June 22, 2020 at 11:15 am

I love this experiment! My balloon grew 6 inches!

June 19, 2023 at 11:17 pm

I tried and it worked well – Exited to do such experiment

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

• Privacy Policy
• Disclosure Policy

Copyright © 2024 · Cool Science Experiments HQ

Yeast-Inflated Balloons

Activity length, 30-40 mins., chemical reactions fungi, bacteria & viruses states of matter, activity type, exploration.

Students use yeast to explore CO 2  production by living organisms.

This is an excellent opportunity for students to design their own experiments to determine which variables affect the yeast’s ability to produce CO 2 .

Yeast is a fungal microorganism that feeds on sugar and produces carbon dioxide (CO 2 ) plus ethanol. As the yeast feeds on the sugar, it produces carbon dioxide gas. This process is known as fermentation. The trapped CO 2  accumulates inside the balloon, slowly inflating it.

A very similar process happens as bread rises. Carbon dioxide from yeast fills thousands of balloon-like bubbles in the dough. This is what gives baked bread its airy texture.

Since yeast also produces alcohol as it feeds, it is an important ingredient in beer & wine production.

Determine variables used in an experiment of their own design.

Create a hypothesis

Describe one of the by products of respiration.

Describe the properties of gases.

Per Pair of Students: 1 tbsp (15 ml) active dry yeast (not fast-acting) 1 teaspoon (5 ml) sugar 1 cup (250 ml) very warm water (41–46°C or 105–115°F ) funnel balloon measuring tape (flexible kind) spot near a heat source (like a radiator or a sunny window)

Key Questions

• What special characteristic of yeast made the balloon inflate?
• Why was the sugar added?
• Why did we need to put the balloon in a warm place?
• Would you get the same results if the balloon was untied?
• Measure the length and circumference of your balloon. Record the results.

• Pour 1 tablespoon of yeast and 1 teaspoon of sugar into the balloon using the funnel.
• Slowly add the cup of very warm water.
• Remove the funnel from the balloon and tie it closed.
• Place the balloon in a warm place.
• Measure the length and circumference of the balloon every 15 minutes for an hour. Record the results.

​Teacher Tip: Try fast-acting yeast if you need the yeast to work within a shorter period of time.

• Design an experiment to explore one of the following questions:
• Which sugar/food combination helps the yeast produce the most gas?
• Try different foods for the yeast to ferment, e.g. brown sugar, syrup, honey, candy, salt. At what temperature is the yeast most active? At what temperatures is it unable to blow up the balloon?
• Try varying the water temperature, using a thermometer to measure the temperature of the water.

Other Resources

Science World Resources | Ballon gonflé par les levures | French version of this resource

About the sticker

Artist: Jeff Kulak

Jeff is a senior graphic designer at Science World. His illustration work has been published in the Walrus, The National Post, Reader’s Digest and Chickadee Magazine. He loves to make music, ride bikes, and spend time in the forest.

Comet Crisp

T-Rex and Baby

Artist: Michelle Yong

Michelle is a designer with a focus on creating joyful digital experiences! She enjoys exploring the potential forms that an idea can express itself in and helping then take shape.

Buddy the T-Rex

Science Buddies

Artist: Ty Dale

From Canada, Ty was born in Vancouver, British Columbia in 1993. From his chaotic workspace he draws in several different illustrative styles with thick outlines, bold colours and quirky-child like drawings. Ty distils the world around him into its basic geometry, prompting us to look at the mundane in a different way.

Western Dinosaur

Time-Travel T-Rex

Related Resources

Ballon gonflé par les levures, dans cette expérience, les étudiants utiliseront la levure pour étudier la production du gaz carbonique (co2) par des organismes vivants., balloon hovercraft, students explore newton’s third law of motion (“for every action there is an equal and opposite reaction”) by building a hovercraft., balloon rockets, in this activity, students learn about newton’s third law by making balloon rockets. using a balloon, we can create a…, in these activities students explore the impressive force of air and learn how air pressure affects their daily lives., in the activities that follow, students explore balloon properties and their use in demonstrating various scientific concepts. list of activities…, related school offerings.

Tinkering with Air Machines

Visit Eureka! Gallery

We believe that now, more than ever, the world needs people who care about science. help us fund the future and next generation of problem solvers, wonder seekers, world changers and nerds..

Playing With Rain

Explore the World Around You

in Instagram Feed · Kids Science Experiments

Yeast Balloon Experiment

Share with your friends!

Check out this super cool experiment that uses the expanding power of yeast to inflate a balloon! You and your kids will love doing this Yeast Balloon Experiment together.

Get more amazing Balloon Science Experiments here!

This is a mind-blowing (and balloon blowing) way to learn about the common reaction of yeast, sugar, and water!

Table of Contents

This post may contain affiliate links. As an Amazon Associate, I earn from qualifying purchases.

Supplies Needed:

• A Plastic Bottle

How to Inflate a Balloon With Yeast

• Fill a plastic bottle with about 1 inch of warm water.
• Pour in about 1 tablespoon of yeast and gently shake the bottle up a little bit.
• Add a teaspoon of sugar and swirl the bottle around a little more.
• Slide the neck of the balloon over the opening of the bottle.
• Let the yeast work its magic for about 15-20 minutes. The balloon should slowly start to inflate!

Step 1: Pour Warm Water Into a Plastic Bottle

I prefer to use a clear plastic bottle for this so that you can see the reaction of the rising yeast inside, but you really can use any type of small empty water bottle for this.

The important part is to pour enough warm water into the bottle so that that the water is about an inch deep inside the bottle.

If you bake with yeast often, then you will already know that the water needs to be warm, but not too warm or it will kill the yeast (I had to learn this from my wife who does the baking in our family).

Step 2: Add Some Yeast Into The Bottle

If you have the small little packets of yeast, you can dump one of those into the bottle, or you can measure and pour about 1 tablespoon of yeast from a large packet of yeast.

Using a funnel will make this a little easier and a little less messy to get the yeast inside the bottle.

Step 3: Add Some Sugar

Measure and pour about 1 teaspoon of sugar into your bottle of yeast and warm water. Again, using a funnel will help you get less sugar on the counter and more sugar into the bottle.

Step 4: Attach The Balloon to The Bottle

Quickly, but carefully connect a large balloon to the opening of the bottle. It may help to inflate and then deflate the balloon first just to stretch it out a little bit.

Then slide the mouth of the balloon over the opening of the bottle. Make sure the balloon is snug and sealed onto the bottle to prevent any air from escaping between the bottle and the balloon.

Give the bottle a little swirl or shake to mix the warm water, yeast, and sugar together. This should start the classic yeast reaction that we need for this experiment!

Step 5: Wait Patiently For The Reaction to Inflate The Balloon

The hardest part of this experiment is waiting 15-20 minutes for the reaction to happen and inflate the balloon…but I promise it will be worth it!

So set the balloon and bottle in a safe and secure place, go grab a snack and come back in a few minutes to check on it.

You can also try doing what I did and setting up your phone or camera for a time-lapse video of the reaction. It’s super fun to go back and watch the reaction inflate the balloon with the time-lapse.

After a good 15 or 20 minutes, the yeast, water and sugar should have reacted and expanded inside the bottle, and the balloon will inflated too!

Yeast Balloon Experiment Conclusion

The science behind this yeast balloon experiment is related to the same reason yeast is used in many bread, dough, and baking recipes!

Yeast is a single-celled organism described as a “sugar-eating fungus”. Yeast needs food, warmth, and moisture to thrive and grow.

As the yeast grows and converts the sugar into energy, it releases Carbon Dioxide gas in a process called fermentation .

The tiny little carbon dioxide (CO2) gas bubbles get trapped in bread dough as it bakes and is what makes bread so soft and spongy!

Now in our experiment, the warm water in the bottle provides warmth and moisture for the yeast, while the sugar provides the food for the yeast to grow and expand.

The addition of carbon dioxide in the bottle increases the air pressure in the bottle, which pushes air into the balloon and inflates it!

This Baking Soda and Vinegar Balloon Experiment is also another fun way to inflate a balloon if can’t find any yeast in your kitchen cabinets!

PIN THIS EXPERIMENT FOR LATER

More Fun Experiments For Kids:

• Dancing Grapes Experiment
• How to Make a Bottle Gun
• Cloud in a Bottle Experiment With Rubbing Alcohol

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

MORE ABOUT PLAYING WITH RAIN

LET’S CONNECT

Search for more ideas, create at your own risk.

All content on this blog was created for inspiration and entertainment purposes. Creating anything with the suggested tools, products or methods, is under your own risk!

Sugar & Yeast Balloon Experiment

By: Author Sara McClure

Posted on Published: February 5, 2018  - Last updated: May 31, 2018

Categories Homeschool , Kids Activities , Science

Sharing is caring!

Did you know that you can blow up a balloon without using your mouth or a helium tank? You totally can. This super fun Sugar & Yeast Balloon Experiment will have kids wondering how it works. Much like our magic light bulb balloon experiment , this balloon experiment is easy to do. This is one of those experiments where the kids can do most if not all of the work. The only thing they might need help with is putting the balloon over the bottle opening. Everything else is easy-peasy. This is a great preschool or kindergarten science experiment and would even be a good balloon science fair project.

*Affiliate links are present.*

• Packet of yeast (We used Rapid Rise Yeast, but it doesn't matter.)
• Empty Water Bottle

How To Blow Up a Balloon with Yeast

For the yeast balloon experiment, put a couple of spoonfuls of sugar in the bottom of the empty water bottle . You can use the funnel to make this a little easier.

Fill the bottle  about half full with warm water.

Add a package of yeast .

Swirl the bottle  around or put the top on and shake the bottle to get the yeast wet to activate it.

Place the balloon over the bottle opening.

Now you wait for the magic to happen. This will take a while. I'd say we left ours for over an hour to let our balloon get really good and inflated.

It will slowly get bigger...

and bigger...

How does the yeast balloon experiment work?

Yeast is a microscopic fungus. As the yeast eats the sugar , it releases a gas called carbon dioxide. The gas fills the bottle and then fills the balloon as more gas is created.

More fun science experiments for kids you might like:

Moon Crater Experiment Simple Science: Observing Worms Simple Science: How to Make a Volcano with Kids Balloon Rocket STEM Activity

100 Screen-free Summer Activities for Kids | Happy Brown House

Thursday 31st of May 2018

[…] 26. Blow up a balloon with sugar and yeast […]

Vinegar and Baking Soda Balloon Experiment | Happy Brown House

Monday 12th of February 2018

[…] excitement. Trust me, they’ll want to do this experiment over and over again! Much like our Yeast Balloon Science Experiment, kids will learn how to blow up a balloon with vinegar and baking soda and learn a little chemistry […]

Blow-up balloon

If a chemical reaction produces a gas, you might not notice it, unless the gas has a colour or a smell. This activity will show how you can capture the gas produced in a chemical reaction in a visually exciting way.

Printable downloads

Follow these steps….

Think and talk about…

• What can you see happening in the bottle?
• What is making the balloon inflate?
• Is it blowing up faster or slower than when you use your mouth??

Investigate…

• What happens if you use more baking soda? Or more vinegar?
• Time how long it takes to inflate and then repeat the experiment. Were the times similar?
• Try using a different size balloon and see what effect it has.
• What happens if you use a bigger or smaller bottle?

Did you know?

Carbon dioxide is a greenhouse gas that contributes to global warming. Natural sources include volcanoes, decomposing vegetation and respiration from living organisms. Human sources include the burning of fossil fuels and deforestation.

What’s the science?

Because the balloon forms a seal around the bottle, the gas produced cannot escape, so it fills up the balloon.

Science in your world

Related resources

Oozing oobleck

Oobleck: solid or liquid?

Can you make milk move without touching it?

Can you make an egg bounce?

Instant Ice Cream

Explore states of matter in the tastiest way – by turning milk into ice cream instantly!

• CONTACT & OPENING TIMES
• WEEKEND ACTIVITIES
• FOR SCHOOLS & GROUPS
• For the Little Ones
• BIOTOPIA Festival
• Rewatch past events
• Video series
• Virtual Tours
• School class offers
• Teacher training
• Kindergarten & After school
• Join-in offers
• Bavaria-wide network
• Natural History in Bavaria
• Touring Exhibitions
• Support BIOTOPIA
• Friends of Biotopia
• Success Stories

Blow up a balloon using yeast

Do it yourself.

Imagine baker’s yeast would occasionally go to parties with other types of fungi. Maybe the porcini mushroom, the stinkhorn and the mold might find themselves on the guest list for such a fungal get-together. Before the party starts, the yeast would have to prepare a few things for its guests, of course. As you might already know, baking pizza and cakes is not a problem for yeast. But can it also blow up balloons?

Sure, fungi rarely celebrate parties (except maybe the mold in the lunch box that was forgotten in your backpack over the summer holidays), but a yeast cube from the grocery store can actually inflate balloons! Don't believe us? With the following experiment you can easily put this to the test. Also, find out why fungi don’t belong to the kingdom of plants.

What are mushrooms and what else can you do with yeast?

What happens during our little experiment? How can yeast be used in the kitchen and is it still alive after baking? And why are mushrooms no plants? Here you can go directly to our background knowledge and learn more about these topics!

Suitable for age group: children at the age of 6 to 12 under adult supervision

Especially interesting for : friends of fungi, young researchers and budding chefs

Duration: 1 hour

A cube of yeast or two 2 packets of dried yeast

A party balloon

A glass bottle (250 - 500ml) with a narrow neck

One teaspoon of sugar

A funnel (optional)

Step 1: Prepare the balloon

Blow up the balloon once and let the air out again so that the balloon is stretched a little.

Step 2: Put yeast and sugar into the bottle

If you have a cube of yeast, crumble it with your fingers and put the yeast crumbs into the bottle. If you have packets of dried yeast you can simply pour it from the sachet into the bottle.

Now add a teaspoon of sugar to the yeast. Using a funnel makes it easier to fill the bottle.

Step 3: Add warm water and swirl

Next, add lukewarm water into the bottle until it is filled to one third of its height. Yeast doesn't like hot water. As a rule of thumb, the water should be about the same temperature that you would use when bathing or washing your hands. Carefully swirl the bottle with the lid open in order to dissolve the yeast and sugar.

Step 4: Put the balloon on the bottle

Now all you have to do is to pull the balloon over the bottleneck. The balloon opening should tightly cover the opening.

Step 5: Wait and watch

From now on you just have to wait a little while (approx. 30 - 45 minutes) until the balloon fills up.

The yeast will feel particularly comfortable and speed up the process if you put it close to a heater.

Have fun experimenting!

Learn more!

It is exciting to see how the yeast manages to inflate the balloon. But how does it do that anyway? We explain it to you here! In addition we have some interesting facts about fungi and yeast!

What is going on?

The yeast digests the sugar and creates a gas as waste product. This gas is called carbon dioxide (CO2) - it’s the same gas that is responsible for the fizzy bubbles in your lemonade. Since the gas carbon dioxide takes up more space in the bottle than the solid sugar, the balloon expands.

You might be wondering where this carbon dioxide is coming from. The gas originated from the sugar and parts of the oxygen. Oxygen is in the air around you and every human needs it to breathe.

However, since there was only little oxygen in the bottle, the yeast formed carbon dioxide mainly by fermentation instead of forming it by respiration. Yeast is pretty good at fermentation - much better than us humans. This special ability of yeast is used in the process of brewing beer, as alcohol is a waste product of fermentation.

Yeast has two survival strategies: either it lives with oxygen (aerobic) or without oxygen through fermentation (anaerobic). Carbon dioxide is produced during both processes.

Fungi don’t belong to the kingdom of plants

Plants need carbon dioxide, water, nutrients and sunlight (energy) to grow. So they use the gas, which humans, animals and also fungi constantly emit, as food. This creates a cycle consisting of plants producing oxygen and animals and fungi producing carbon dioxide. Therefore, the diet of fungi is more comparable to that of animals. Fungi  are neither animals nor plants and form their own incredibly diverse kingdom in nature.

Perhaps it’s easier to realize if you think of the following: Plants are mostly green as they harvest solar energy with the help of the green pigment chlorophyll. Green fungi are rare as fungi don't have the ability to use sunlight as a source of energy. Plants have to do this job for them - just like for animals, too. However, one should not exclusively  rely on the characteristic “green color” as a criteria for the ability of using sunlight as a source of energy. There are for example green animals (tree frogs, grasshoppers ...), which -despite of their green color -  do not belong to the kingdom of plants.

Research questions:

• Under which conditions is baker’s yeast particularly active?
• Take a look at a recipe for dough made with yeast and think about the purpose of the single steps. What’s the balloon envelope in a yeast dough? Why is it important to knead the dough for quite a while and why should it become elastic? Why do you always add a little sugar to the dough? And why is it important to place the kneaded dough at a warm place?
• Is the yeast still alive after he baking process?
• How could you prove that carbon dioxide was produced  during the experimet- and not for example oxygen?A little hint: not only organisms need oxygen ...

Related Links

Fungi for Future

Peter and the killer fungi

Checker Tobi: The Mushroom Check

Checker Tobi tracks down mushrooms. These very special creatures are found in thousands of colors and shapes. Some look like a giant ball, others look like black ink dripping out of them. They grow in the forest, under trees - and even on food, as molds. [In German]

© CHECKER WELT

Klexikon: Mushrooms

Fungi are living beings. They consist of individual cells with a cell nucleus. In biology they form their own realm next to animals and plants. They are more similar to plants, because they cannot move themselves. In contrast to plants, however, fungi do not need the light of the sun to live. [In German]

Book recommendations

From the fungi we see on supermarket shelves to fungi like penicillium that have shaped human history, this is the definitive introduction to what fungi are and just how vital they are to the world's ecosystem. Created in collaboration with the Royal Botanic Gardens, Kew.

© Templar Publishing , 2020

Fantastic Fungi

Viewed in over 100 countries and selling hundreds of thousands of tickets on the way to finishing 2019 with a rare 100% Tomato meter rating on Rotten Tomatoes, Schwartzberg’s documentary Fantastic Fungi has brought the mycological revolution to the world stage. This is the film’s official companion book, that expands on the documentary’s message: that mushrooms and fungi will change your life– and save the planet. 

© Earth Aware Editions, 2020

Entangled Life: How Fungi Make Our Worlds, Change Our Minds & Shape Our Futures

Created by our Lab Pilot Monika

Naturkundemuseum Bayern Botanisches Institut Menzinger Str. 67 80638 München, Germany

BIOTOPIA Lab :

Pressekontakt:

Sonstige Anfragen:

• Museum man and Nature
• Digital barrier-free accessibility
• Data Protection

April 3, 2014

Single-Celled Science: Yeasty Beasties

A fun fungal activity from Science Buddies 

By Science Buddies

Key concepts Biology Microorganisms Microscopic Metabolism Carbon dioxide   Introduction Did you know that dry yeast is actually alive ? Add the right ingredients, and presto, the mixture becomes a bubbly, oozing mess of life. But just what are the conditions required for this to happen? What does that yeast need to become active and thrive? Try this science activity to find out for yourself!     Background Yeasts are tiny, microscopic organisms—or microorganisms—that are actually a type of fungus. This means that they are more closely related to a mushroom than to plants and animals or bacteria (the latter of which are also microorganisms). These little critters might sound strange and different, but people have been using them for thousands of years to make bread rise. How does this work? It has to do with the metabolism of the yeasts, or, in other words, what they eat and what they turn that food into.   Like us, yeasts must get their food from their surrounding environment to grow and reproduce—that is, to make more yeast. What do they eat? Yeasts feed on sugars and starches, which are abundant in bread dough! They turn this food into energy and release carbon dioxide gas as a result. This process is known as fermentation. The carbon dioxide gas made during fermentation is what makes a slice of bread so soft and spongy. The pockets of gas are produced by yeasts when the dough is allowed to rise before baking. Materials

Three plastic two-liter bottles

Measuring tablespoon

White table sugar

Salt, baking soda or vinegar

Permanent marker (optional)

Measuring cups

Warm tap water

One medium-sized pot or bowl, at least two quarts in size

Six packets of dry yeast or an equivalent amount from a jar

Three standard-sized latex balloons

Clock or timer

  Preparation

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

Rinse each bottle thoroughly with water and remove any labels.

Add two tablespoons of sugar to two of the three bottles. How do you think the sugar will affect the activity of the yeast?

To one of the bottles that you added sugar to, also add two tablespoons of salt, baking soda or vinegar. How do you think adding salt, baking soda or vinegar will affect the activity of the yeast?

Throughout the experiment, keep track of what you added to each bottle. If needed, you can label the bottles with a permanent marker.

  Procedure

Fill the medium-sized pot or bowl with at least eight cups of very warm tap water. Adjust the temperature of the hot water coming from the tap until it is almost too hot to hold your hands under. Use this temperature of water to fill the pot.

Using the warm water from the pot, fill each bottle with about two and one-half cups (or about one-third full). Put the lid back on to each bottle and shake them each thoroughly to dissolve all of the ingredients.

To each bottle, add two packets of dry yeast (or an equivalent amount from a jar). Put the lid back on to each bottle and shake each one gently to mix in the yeast.

Remove each lid and stretch a balloon completely over the opening of the bottle (over all of the ridges). Why do you think it is important to form a tight seal with the balloon on the bottle’s opening?

Leave the bottles to rest in a warm location for 45 minutes. Keep the balloons out of direct sunlight. How do the balloons change over time?

After 45 minutes, examine the bottles and the balloons. Which balloons have become inflated? How big are they compared to each other? Do you notice any differences in the contents of the bottles?

In which environment did the yeast make the most carbon dioxide? What does this tell you about the conditions needed for yeast fermentation to take place? 

Extra: You could quantify your results from this activity by using a water displacement test. To do this, you could fill a large pot completely full with water, place it in a larger tray, pan, or pot. Quickly tie off the balloon you would like to measure without letting gas escape, and then submerge the balloon in the water. You can measure how much water overflowed from the pot into the tray to determine how much water the balloon displaced, and consequently the volume of the carbon dioxide gas inside the balloon. If you quantify your results, exactly how different are the sizes of the balloons?

Extra: Another environmental condition that can affect the activity of yeast and the process of fermentation is temperature. You could explore this by preparing several bottles using the same conditions, and then placing each bottle in a different place with a different temperature. After 45 minutes, how do the balloons vary in size?

Extra: You could try this activity again, but next time just focus on how using different types and sources of sugars affect the carbon dioxide production. How do the sugars from different juices or other sources affect how much carbon dioxide is produced ?

  Observations and results Did the balloon on the bottle with only yeast and water remain un-inflated? Did the balloon on the bottle with only sugar added inflate the most?   When yeasts eat sugar and turn it into energy, they also produce carbon dioxide. This process is known as fermentation. In this activity, the balloons on the bottles should have captured carbon dioxide produced by the yeasts during fermentation. In the bottle that contained yeasts but not sugar, the yeasts did not have food (i.e., sugar) so the balloon should not have inflated. In the bottle that contained yeasts and sugar (but not salt, baking soda or vinegar), the yeasts should have thrived and made a lot of carbon dioxide, clearly inflating the balloon. When salt, baking soda or vinegar was added, the yeasts should have made less carbon dioxide, inflating the balloon less than when only sugar was used. This is because the addition of these substances changed the environment and made it less ideal for the yeasts. Specifically, adding salt increased the salinity of the environment, and adding baking soda or vinegar changed the pH of the environment, making it more basic or acidic, respectively, compared to the neutral environment provided by the plain water.   Cleanup When you are done with this activity, dispose of the yeasts by composting them or (with permission) dumping them outside somewhere. Do not pour the yeasts down the drain without diluting them with water, as they may damage pipes when they expand.   More to explore Fun Facts About Fungi: Fermentation , from Utah State University Experiments with Acids and Bases , from Fun Science Gallery Fun, Science Activities for You and Your Family , from Science Buddies Yeasty Beasties , from Science Buddies  

This activity brought to you in partnership with Science Buddies

Incorporate STEM journalism in your classroom

• Exercise type: Activity
• Topic: Microbes

Fermentation and Pasteurization in the classroom

• Download Student Worksheet

Purpose: Students will learn about pasteurization by performing an experiment that involves calculating and interpreting results.

Procedural overview: Students will annotate and analyze “ Louis Pasteur’s devotion to truth transformed what we know about health and disease ” from Science News online. After learning about Pasteur’s discoveries and how he developed the pasteurization process, students will do a hands-on experiment. In this experiment, yeast solutions will be prepared at different temperatures and then monitored for gas production. Students will collect data on gas production by measuring how big the gas makes a balloon and will approximate the volume of gas produced. The data will be graphed and interpreted by students to identify the temperature that pasteurization occurs. As an optional activity, students will further study the importance of pasteurization in food production and in the prevention of foodborne illness.

Approximate class time: 2 class periods

Bunsen burner

Thermometer

Whiteboard/chalkboard

Yeast (Make all packets the same brand)

Scale (Alternative: tablespoon or disposable plastic spoon)

Stopwatches

Plastic bottles of the same size, (1 liter or 1.25-liter bottles recommended)

Round balloons

Tape measures (Alternative: rulers and string/yarn)

Student worksheet

Directions for teachers:

Before the start of class, set up the experiment. Around the lab, set up stations with a Bunsen burner, a beaker to heat water, a funnel, a bottle, a thermometer, a yeast packet, a stopwatch, a tape measure and a balloon. Have one or two weighing stations where students can weigh sugar and yeast.

In class, have students read the introduction and the section call “How Pasteur developed pasteurization” in “ Louis Pasteur’s devotion to truth transformed what we know about health and disease .” This article appeared in the November 19, 2022, print edition of Science News with the title “Louis Pasteur’s Long Legacy.” Ask students to annotate the article as they read and identify any new vocabulary and concepts.

Article analysis

After students have read and done their annotations, have them answer the following questions.

1. Who was Louis Pasteur?

Louis Pasteur was a French chemist and biologist, who was born in 1822.

2. How was tartaric acid important to Pasteur’s career?

Pasteur’s work on tartaric acid and wine got him started on work that eventually led to discoveries about microbes and diseases.

3. Why was it important that Pasteur showed yeast are living things?

Until Pasteur’s work, most scientists thought that fermentation was a “natural nonbiological chemical process.” Demonstrating that yeast are living organisms changed how scientists thought about fermentation.

4. Microorganisms are living things too small to see with the naked eye and include fungi and bacteria. What kind of microbe is a yeast?

Pasteur thought yeast was a “small plant,” but it really is a kind of microscopic fungus.

5. What do yeast do with sugar, and what is the process called?

Yeast can convert sugar to alcohol in a process called fermentation.

6. Why do yeast ferment?

Fermentation is how yeast meet their nutritional (energy) needs.

7. People use fermentation to make wine, beer and other products. But sometimes those products can become spoiled or get contaminated with microbes that are harmful. What method of food and beverage protection did Pasteur develop, and how does it work?

Pasteur created pasteurization, a method of heating that kills microorganisms that can spoil food items or cause disease.

8. What questions do you have about the fermentation process? What might you want to investigate about pasteurization?

Student answers will vary. When you make yogurt, how much can you change the flavor by changing the bacteria you add to the milk? I would like to do an experiment with raw milk. My question: If you start with raw milk, and it starts to sour because of the microbes that are present, can you reverse or minimize the souring by pasteurizing the sour milk?

Preparing to do the experiment

Review fermentation and introduce the chemistry behind it. Include any of the following information that you find useful.

Pasteur thought yeast was a “small plant,” but today we know that it is really a microscopic fungus. However, Pasteur was right in thinking that yeast metabolizes sugar in a process called fermentation. In this process, yeast consumes sugar to produce carbon dioxide, ethanol and energy (in the form of ATP).

C 6 H 12 O 6 –> 2C 2 H 5 OH + 2CO 2 + 2ATP

Sugar –> ethanol (alcohol) + carbon dioxide + energy

Humans have used yeast to ferment food items for thousands of years. Because yeast creates ethanol, a type of alcohol, it is used to make alcoholic beverages like beer and wine. Yeast is also important in breadmaking. When the yeast in bread dough ferments, carbon dioxide is produced. The carbon dioxide helps the bread rise.

In this experiment, students will determine the temperature at which pasteurization occurs for a yeast solution. Pasteurization occurs when the yeast have died. Ideally, you should not give the students hints about the temperature at which pasteurization occurs.

Before starting the experiment, discuss the concept of a control in a science experiment and what might be possible options for a control in this study. Remind students of the importance of multiple trials; ask that each group test at the control temperature and one of the other nine temperatures. Also, they should do at least two trials at each of their temperatures, if there are enough materials and time. Two separate student groups could also test at the same temperature.

Cover lab safety. At the highest temperatures, the students could burn themselves if they do not pour carefully.

After mixing yeast, water and sugar together in a bottle, the students will top the bottle’s opening with a balloon to capture any gas produced. The water used in the bottles will be varied in temperature so students can find out for themselves at what temperature yeast cells die and pasteurization occurs.

Students will need it to calculate the volume of gas produced during fermentation. Review this volume formula, where c is circumference, V=(c 3 )/(6π 2 )  and note that the unit students will use is cubic centimeters cm 3 .

The amount of information you give students can vary depending on the time available. However, students will feel more ownership over their experiment and their findings if they help decide how to set up the experiment.

Use the following questions to guide students in setting up the lab and determining experimental variables.

1. Yeast produces carbon dioxide, a gas, as it ferments sugar. What do you expect will happen to the balloons?

The balloons will inflate with carbon dioxide as the yeast cells break down the sugar into carbon dioxide, alcohol and energy.

2. How do you think the water temperature will affect gas production?

Initially, as the temperature increases, the amount of gas produced will also increase. Once the temperature is hot enough for pasteurization to occur, gas production will begin to decrease or will stop entirely as the yeast cells die.

3. The data you collect in this experiment will be graphed. What units will you use on the x axis and the y axis?

The x axis will show temperature in degrees C. Depending on how students are measuring the gas produced, the y axis will show the amount of carbon dioxide, indicated by either the circumference or volume of the balloon.

4. What temperatures should the class test (starting at room temperature, approximately 22° C)? (Note that each group should run trials at the control temperature and one other temperature.)

Student answers will vary. We should test at 22° C, 28° C, 34° C, 40° C, 46° C, 52° C, 58 ° C, 64° C,  70° C and 76° C.

5. What should the control group be in this experiment?

A bottle with water, sugar and no yeast at room temperature; a bottle with water, no sugar and no yeast at room temperature; or a bottle with water, yeast and no sugar at room temperature.

6. What should be the length of time for each trial? Twenty minutes.

7. If time permits, how many trials should ideally be run at each temperature?

Two or three trials.

8. How can we measure the amount of gas produced, and what scientific unit could we use?

Student answers will vary. We could figure out the amount of gas produced after measuring the balloon’s volume. To get to volume, we will need to know the circumference of the balloon to put into the volume formula. The unit to use is cubic centimeters (cm 3 ).

Fermentation experiment

Ask the class to decide what temperatures they want to test. Try to have the students evenly space the temperatures. For example, temperatures could increase in 6-degree increments: 22° C, 28° C, 34° C, 40° C, 46° C, 52° C, 58° C, 64° C, 70° C and 76° C. Temperatures should not go above 80° C.

The students also must agree on how much sugar, yeast and water they want to use in their bottles and in what order they want to combine their materials, or you could suggest 250 ml of water, 40 grams (3 tablespoons) of sugar and the contents of one yeast packet. All yeast packets should be the same brand and at room temperature. Whatever the students decide, please emphasize that each group should use the same amount of sugar, yeast and water. Only the control will have different amounts of sugar and/or yeast.

Have the students form groups. Each group would ideally do multiple trials on the control temperature and one other temperature. In setting up, each group should put the sugar and yeast in the bottle, and then heat their water beaker over the Bunsen burner. As the water heats, carefully check the temperature. When the water reaches the group’s study temperature, students should carefully pour 250 ml of water through a funnel into their bottle, screw on the bottle’s lid and shake the bottle to mix the water, yeast and sugar. The temperature of the water might cool during its transfer into the bottle. This could result in some experimental groups showing carbon dioxide production when the yeast should have been killed by pasteurization.

Once the bottle’s contents are combined, students should unscrew the bottle, place a balloon on the top of the bottle and start a 20-minute timer. As each group’s timer ends, the group should measure the circumference of their balloon at the widest point using a tape measure and record the circumference on their worksheet and on the board. Then use the formula V=(c 3 )/(6π 2 ) , to calculate the volume of carbon dioxide produced and graph the volume of gas produced using metric units for the volume and degrees Celsius for the temperature.

Ask the students to answer the following questions about their experimental results.

1. Measure the circumference of your group’s balloon and record it in your chart and on the board. Calculate the volume of your group’s balloon and add the data to the chart using the formula: V=(c 3 )/(6π 2 ) , where c represents the circumference. Continue to fill in the chart as other groups add their data to the board. (Students will use the chart in the student worksheet.)

Student answers will vary, but should follow this trend: Circumference and volume should go up for 28 ° C and 34° C. For high temperatures, circumference and volume should trend downward.

2. Graph the volumes from each group. Remember to label your graph and axes. (The graph is available in the student worksheet.)

Graphs will vary. The x axis should be for temperature in degrees Celsius; the y axis is for volume of carbon dioxide in cubic centimeters. Temperature should be marked every six spaces; the line on the graph climbs until about 34 degrees or a little higher, and then moves steadily downward until the volume of carbon dioxide tapers to zero. A possible label for the chart could be “Volume of Carbon Dioxide Produced from Yeast Fermentation.”

3. Why is it important to record what happens with the control group?

If the control group shows that gas has been produced, then there might be other microorganisms that could skew the data.

4. What is the relationship between gas volume and temperature?

Initially, the volume of carbon dioxide produced increases as temperature increases. However, eventually the volume of carbon dioxide produced begins to decrease.

5. At what temperature did the most fermentation occur? How could you tell?

Student answers will vary. For example, the temperature at which most fermentation occurred was 34 ° C because the largest volume of carbon dioxide was produced at 34 ° C.

6. At what temperature did yeast stop fermentation and gas production? How could you tell?

Student answers will vary. I think fermentation started slowing down when temperatures got into the 60s. As temperatures went higher and higher, there was less carbon dioxide produced. The highest temperatures killed the yeast, preventing them from fermenting the sugar and producing carbon dioxide. There was less carbon dioxide in the balloons at higher temperatures.

7. How might we know that the yeast died due to pasteurization?

Student answers will vary. We know that carbon dioxide is produced during fermentation. As temperatures rise, there will come a point when fermentation slows as yeast cells die. If the balloon does not inflate much, it suggests that carbon dioxide production is declining and that yeast are likely dying. Assuming nothing went wrong with the experiment, pasteurization probably occurred if the balloon does not inflate at all.

8. How has learning about Pasteur’s discoveries influenced your views about what you eat?

Student answers will vary. I am more aware of how important pasteurization is for protecting our food supply.

9. What other question would you like to answer about microorganisms in food?

Student answers will vary. Do different microorganisms get killed through pasteurization at different temperatures?

Activity extension: After students perform the experiment, you can ask them to learn about foodborne illnesses that can be prevented by pasteurization and to create a poster explaining how pasteurization protects people from these illnesses.

The following questions can serve as prompts. If students want to, they can ask their own questions.

1. What is a foodborne illness?

A foodborne illness is a disease that is spread by the consumption of contaminated food.

2. Name a foodborne illness that can be caused by drinking contaminated milk.

Student answers will vary. Listeriosis and tuberculosis are two diseases that can be spread in unpasteurized milk.

3. What are the symptoms of this disease?

Student answers will vary. Listeriosis can cause fever, muscle aches, loss of balance and seizures.

4. Have there been any recent outbreaks of this disease? If so, what food products caused this outbreak?

Student answers will vary. In 2022, people developed listeriosis after eating deli meats and cheeses and ice cream contaminated with Listeria .

5. Even pasteurized food can cause foodborne illnesses. Why is this the case?

Microorganisms could be introduced after the food was pasteurized or the disease was caused by a microorganism that was not killed by pasteurization.

6. Create a poster that shows how pasteurization protects people from your foodborne illness.

Student products will vary but should all mention pasteurization.

• Share full article

buying time

This Scientist Has a Risky Plan to Cool Earth. There’s Growing Interest.

David Keith wants to spray a pollutant into the sky to block some sunlight. He says the benefits would outweigh the danger.

David Keith leads the Climate Systems Engineering Initiative at the University of Chicago. Credit... Mustafa Hussain for The New York Times

Supported by

By David Gelles

Gelles reported this article from Chicago and Cambridge, Mass.

• Published Aug. 1, 2024 Updated Aug. 2, 2024

David Keith was a graduate student in 1991 when a volcano erupted in the Philippines, sending a cloud of ash toward the edge of space.

Listen to this article with reporter commentary

Seventeen million tons of sulfur dioxide released from Mount Pinatubo spread across the stratosphere, reflecting some of the sun’s energy away from Earth. The result was a drop in average temperatures in the Northern Hemisphere by roughly one degree Fahrenheit in the year that followed.

Today, Dr. Keith cites that event as validation of an idea that has become his life’s work: He believes that by intentionally releasing sulfur dioxide into the stratosphere, it would be possible to lower temperatures worldwide, blunting global warming.

Such radical interventions are increasingly being taken seriously as the effects of climate change grow more intense. Global temperatures have hit record highs for 13 months in a row, unleashing violent weather, deadly heat waves and raising sea levels. Scientists expect the heat to keep climbing for decades. The main driver of the warming, the burning of fossil fuels, continues more or less unabated.

Against this backdrop, there is growing interest in efforts to intentionally alter the Earth’s climate, a field known as geoengineering.

We are having trouble retrieving the article content.

Please enable JavaScript in your browser settings.

Thank you for your patience while we verify access. If you are in Reader mode please exit and  log into  your Times account, or  subscribe  for all of The Times.

Thank you for your patience while we verify access.

Already a subscriber?  Log in .

Want all of The Times?  Subscribe .

Advertisement