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Yeast Fermentation Experiment

Fermentation is a fascinating process that kids can easily explore through a simple experiment using yeast and sugar. This hands-on activity teaches students about fermentation and introduces them to the scientific method, data collection, and analysis.

Investigate how different types of sugar (white, brown, and honey) affect the rate of yeast fermentation by measuring the amount of carbon dioxide (CO₂) produced.

Example Hypothesis: If yeast is added to different types of sugar, then the type of sugar will affect the amount of carbon dioxide produced, with white sugar producing more CO₂ than the others.

💡 Learn more about using the scientific method [here] and choosing variables .

Watch the Video:

• Active dry yeast
• White sugar
• Brown sugar
• Measuring spoons and measuring cups
• Small bottles or test tubes
• Rubber bands
• Ruler or measuring tape
• Notebook and pen for recording data ( grab free journal sheets here )
• Printable Experiment Page (see below)

Instructions:

STEP 1. Prepare a yeast solution by dissolving a packet of active dry yeast in warm water according to the package instructions.

STEP 2. Label 3 bottles and add 1 tablespoon of white sugar to the “White Sugar” bottle. Add 1 tablespoon of brown sugar to the “Brown Sugar” bottle. Measure 1 tablespoon of honey and add it to the “Honey” bottle.

STEP 3. Measure and pour an equal amount of the yeast solution into each bottle, ensuring the yeast is well mixed with the sugar.

STEP 4. Quickly stretch a balloon over the mouth of each bottle. Secure the balloons with rubber bands if needed. Ensure the balloons are sealed tightly to prevent CO₂ from escaping.

STEP 5. Place the bottles in a warm, consistent environment to promote fermentation.

STEP 6. Observe and record the size of the balloons at regular intervals (e.g., every 15 minutes) for 1-2 hours. Use a ruler or measuring tape to measure the circumference of each balloon.

TIP: Note the time it takes for the balloons to start inflating and the differences in balloon size over time for each type of sugar.

STEP 7: Analyze the data by comparing the amount of CO₂ produced (balloon size) for each type of sugar. Create a graph showing the balloon size over time for each sugar type.

STEP 8. Determine which sugar type resulted in the most and least CO₂ production. Discuss possible reasons for the differences, considering what each sugar is made of. Think about whether the results support or disprove the hypothesis. Can you come up with further experiments or variations to explore other factors affecting yeast fermentation?

Free Printable Yeast and Sugar Experiment Project

Grab the free fermentation experiment worksheet here. Join our STEM club for a printable version of the video!

The Science Behind Yeast Fermentation

For Our Younger Scientists: Yeast is a type of fungus that feeds on sugars. When you mix yeast with sugar and water, it starts to eat the sugar and convert it into alcohol and carbon dioxide gas. The gas gets trapped in the balloon, causing it to inflate. This shows that fermentation is happening!

Yeast fermentation is a biological process where yeast converts sugars into alcohol and carbon dioxide (CO₂) in the absence of oxygen. This process is used in baking, brewing, wine making and biofuel production. How much fermentation occurs can vary depending on the type of sugar used.

Yeast contains enzymes that break down sugar molecules through a series of chemical reactions . Here’s how it works:

Enzymes are molecules, usually proteins, that act as catalysts to speed up chemical reactions within living organisms.

First the yeast is mixed with warm water, and it becomes activated. The warm environment “wakes up” the yeast cells, preparing them to consume sugars.

Yeast cells produce enzymes that break down sugar molecules (sucrose, glucose, and fructose) into simpler molecules. This process is called glycolysis. During glycolysis, sugar molecules are converted into pyruvate, releasing a small amount of energy.

In the absence of oxygen (anaerobic conditions), yeast cells convert pyruvate into ethanol (alcohol) and carbon dioxide gas (CO₂). The carbon dioxide produced during fermentation is what inflates the balloons in the experiment.

Different Sugars & Fermentation

Different sugars can affect the rate of fermentation. This is how:

• White Sugar (Sucrose): Composed of glucose and fructose and is easily broken down by yeast, leading to efficient CO₂ production.
• Brown Sugar: Contains sucrose along with molasses, which includes minerals and additional nutrients. May result in a slightly different fermentation rate due to its composition.
• Honey: Contains a mixture of glucose, fructose, and other components. The additional components can influence the fermentation process, potentially leading to different CO₂ production rates compared to pure sucrose.

The amount of CO₂ produced depends on how easily the yeast can break down the sugar molecules and convert them into ethanol and CO₂. Sugars that are more readily broken down by yeast will typically produce more CO₂ faster.

More Fun Science Experiments

Explore chemistry , biology and more, including…

• Bread Mold Experiment
• Baking Soda Balloon Experiment
• Bread In A Bag
• Elephant Toothpaste
• Mentos and Soda

Helpful Science Resources To Get You Started

Here are a few resources that will help you introduce science more effectively to your kiddos or students and feel confident presenting materials. You’ll find helpful free printables throughout.

• Best Science Practices (as it relates to the scientific method)
• Science Vocabulary
• All About Scientists
• Free Science Worksheets
• DIY Science Kits
• Science Tools for Kids
• Scientific Method for Kids
• Citizen Science Guide
• Join us in the Club

Printable Science Projects For Kids

If you’re looking to grab all of our printable science projects in one convenient place plus exclusive worksheets and bonuses like a STEAM Project pack, our Science Project Pack is what you need! Over 300+ Pages!

• 90+ classic science activities  with journal pages, supply lists, set up and process, and science information.  NEW! Activity-specific observation pages!
• Best science practices posters  and our original science method process folders for extra alternatives!
• Be a Collector activities pack  introduces kids to the world of making collections through the eyes of a scientist. What will they collect first?
• Know the Words Science vocabulary pack  includes flashcards, crosswords, and word searches that illuminate keywords in the experiments!
• My science journal writing prompts  explore what it means to be a scientist!!
• Bonus STEAM Project Pack:  Art meets science with doable projects!
• Bonus Quick Grab Packs for Biology, Earth Science, Chemistry, and Physics

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~ projects to try now ~.

Easy Peasy All-in-One High School

An extension of easy peasy all-in-one homeschool.

Problem : What effect does sugar have on the growth rate of yeast?

• measuring spoons/cups and funnel
• Four clean, dry glass or plastic bottles (Ex: 16oz water bottles)
• Four packets (or 9 teaspoons) of active dry yeast – not quick-rising
• Six teaspoons of sugar
• Four cups warm water
• Four balloons

Key Terms Fermentation – A metabolic process that converts sugars to acid, gasses, and/or alcohol. It occurs in yeast, bacteria, and other microorganisms as well as oxygen-starved muscle cells.

• Add one packet (or 2 1/4 teaspoons) of yeast to each bottle.
• Label your bottles 1-4.
• Bottle 1 – no sugar
• Bottle 2 – 1 teaspoon
• Bottle 3 – 2 teaspoons
• Bottle 4 – 3 teaspoons
• Add one cup of warm water to each bottle.
• Gently mix each bottle. (Cover the bottle with your thumb or put the lid back on.)
• Uncover the bottles and stretch a balloon over the mouth of each bottle.
• Leave the bottles some place warm to sit for an hour.
• Create a table to record your data: the diameter of the balloon, the time passed, and any observations. Starting at one hour after the balloons are placed onto the bottles, measure every 12 hours for two days (4 entries of data).
• Create a graph to compare your results.

Watch this video for more discussion. https://www.youtube.com/watch?v=FYClCHVT00M

Write a conclusion. State your question, your findings, and your answer  to the question – how did you see sugar affecting the growth rate of yeast?