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  • Capture wild microbes and turn them into bread – for science! This is a project you could do with your students in the classroom or they can do at home.

    Microbes are found in every environment on Earth and the majority are completely harmless, but microbes associated with our food often have a bad reputation due to their link to food poisoning. While some can make us ill and others cause food to spoil (for example, some moulds), without the activities of microbes, there would be no bread, cheese, beer or even chocolate! Friend or foe – without microorganisms we wouldn’t survive.

    Microorganisms are an important part of the production of food, including in the fermentation process, and they help determine flavour and texture.

    The microbial communities in sourdough are comparatively easy to grow and study, so understanding sourdough can help us untangle some of the mysteries of the microbial world.

    URL: https://robdunnlab.com/projects/wildsourdough

    Reach: Worldwide

    Nature of science focus: Online citizen science (OCS) projects can be used to develop any of the Nature of Science (NoS) substrands. Identify aspects of NoS that your students need to get better at or understand more fully and then frame your unit to be very clear about these things when you do them.

    Science capability focus: Gather and interpret data, Use evidence, Engage with science

    Science focus: Microorganisms, food science

    Some suggested science concepts:

    • Microorganisms live in, on and around us.
    • How do microorganisms interact?
    • Food safety.
    • Good versus bad microbes.

    Many concepts could be learned – focusing on a few can often be more powerful. Develop your learning outcomes and success criteria from these concepts as well as the Nature of Science strand and the science capabilities.

    Some examples of learning outcomes:

    Students can:

    • model ecosystems to study microbial ecology
    • explore the science involved in baking and other everyday activities
    • learn about a variety of microbes and their interactions with food.

    About sourdough

    Explore the science involved in baking. Sourdough and other food fermentations such as those that give us cheese, ginger beer and kimchi can provide relatively simple, easy-to-handle model ecosystems for studying microbial ecology.

    Fermentation is one of the earliest examples of biotechnology, and sourdough bread is one of the oldest types of bread. Sourdough is a slow-fermented bread and is unique because it does not require commercial yeast in order to rise. The preparation of sourdough begins with a pre-ferment called a starter – a fermented mixture of flour and water containing a colony of microorganisms including wild yeast and lactobacilli.

    About the Wild Sourdough project

    This project is run by a group of scientists from North Carolina State University who want citizen scientists from around the world to help them.

    Background

    This project came about from the Global Sourdough Project, which studied hundreds of existing sourdough starters from all over the world looking to understand more about the underlying biology of starter species. The question ‘How does the type of flour you use and where you live affect the success or failure of a wild sourdough starter?’ couldn’t be deciphered from this project’s data. The Wild Sourdough project aims to reveal how these communities form over time and understand how factors such as flour type or geography impact these communities.

    What to do

    This project will guide you through creating a wild sourdough starter using only water and flour and following a 10-day protocol. Once the starter has been made, you need to observe it and record some observations about its aroma and how fast it rises. There is a short online questionnaire to submit your data. Questions on how you characterise your data are based on the rise time, height and aroma of your starter. You will also need to send in two photos of the starter.

    Extension ideas: Make more than one starter using different flour types or use the same flour type but set one starter outside and one inside.

    The data will be compared with others from all over the world who have concurrently created wild starters. This data will be used to learn how geography and different flours affect microbial growth over time and how those microbes affect the taste and texture of bread.

    Resources

    The project has lots of helpful information with videos, recipes, tips, information on how to maintain your starter, a sourdough aroma wheel diagram and more.

    Before you start this project:

    • Check for student allergies – for example, are there any students with coeliac disease or wheat allergies? Search for safe alternative recipes for these students – a comparison of the impact of different ingredients could be incorporated as part of the lesson.
    • As this is US based, you may need to convert measurements to metric (or get your students to).
    • Ensure you have enough time for the starter and also arrange the weekend maintenance for it. This could be a project some students might like to do over the school holidays.
    • Plan what you will do after submitting the data – baking and maintaining your starter.

    Parāoa rēwena

    Parāoa rēwena is Māori sourdough potato bread. It uses a potato starter that ferments, causing the bread to rise and giving it a unique flavour.

    Visit these sites to find recipes for making the starting 'bug', maintaining the starter and making loaves of bread:

    These articles take a closer look at rēwena starters and whakapapa.

    Related content

    Here are some planning tips for when you intend to use a citizen science project with your students. See these helpful webinars: Getting started with citizen science and Online citizen science.

    Use our introductory article on microorganisms to see the range of resources we have about these tiny living organisms. Start with getting students to research facts about bacteria and explore the role of good and bad bacteria in yoghurt and cheese.

    In this recorded webinar, learn how kitchen science can be used to deepen students’ understanding of science in everyday contexts and demonstrate how simple kitchen ingredients and equipment can be utilised to excite and engage students in science learning.

    Activity ideas

    We have a range of other kitchen science activities – see a few examples:

    Investigate the process of making ice cream and explore the concept of states of matter through simple investigations.

    Useful links

    Scientists at North Carolina State University used DNA sequencing to identify the microbes in starters sent to them by over 500 participants in their Global Sourdough Project.

    Learn about other sourdough science projects from The Public Science Lab.

    Colorado State University has a list of sourdough starter best practices – ways to keep your starter growing well and safe to use.

    A selection of resources around kitchen science can be viewed on our Pinterest board.

    This visual guide from Berries.com website provides simplified explanations for how and why the most common baking ingredients do what they do.

    The Microbiology Information Portal website is full of useful and interesting microbiology resources.

      Published 6 July 2022, Updated 31 August 2022 Referencing Hub articles
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