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Kids’ Science Challenge - Make Your Own Yogurt 1
Make Your Own Yogurt
Saucepan
Captions
YOGURTPOWDERED
MILK
ALUMINUM FOIL
SODA
Kitchen Thermometer
Water
Find What You Need... • Ameasuringcup• Water• Amarker• Plasticcups• Wholemilk• Asaucepan• Akitchenthermometer
• Plainyogurtfromthegrocerystore(make sureitsays“activeculture”)• Powderedmilk• Aluminumfoil• Acooler• 4smallplasticsodabottles• 3cupshotwater
Marker Whole MilkYOGURT
POWDEREDMILK
ALUMINUM FOIL
SODA
YOGURTPOWDERED
MILK
ALUMINUM FOIL
SODA
Plain Yogurt Active Culture
YOGURTPOWDERED
MILK
ALUMINUM FOIL
SODA
Powder Milk
YOGURTPOWDERED
MILK
ALUMINUM FOIL
SODA
YOGURTPOWDERED
MILK
ALUMINUM FOIL
SODAAluminum Foil
Cooler
YOGURTPOWDERED
MILK
ALUMINUM FOIL
SODA
Plastic Cups
Small Plastic Soda Bottles
YOGURTPOWDERED
MILK
ALUMINUM FOIL
SODA
YOGURTPOWDERED
MILK
ALUMINUM FOIL
SODA
YOGURTPOWDERED
MILK
ALUMINUM FOIL
SODA
YOGURTPOWDERED
MILK
ALUMINUM FOIL
SODA
3 Cups Hot Water
We recommend that an adult
help lead this activity.
Kids’ Science Challenge - Make Your Own Yogurt 2
*Are your hands really clean after you wash
them? Design an experiment to test how many microbes live on your hands when they’re really
dirty, compared to after they’re cleaned in different ways. For example, you could test the difference between using cold and warm water, and between regular soap and anti-bacterial
soap, for example.
Brain Buster:
Kids’ Science Challenge ScienceProjectsarepresentedbytheaward-winningradioseries,PulseofthePlanet
Made possible by theNationalScienceFoundation
©2010JimMetznerProductions.Allrightsreserved.
FromChampionship Science Fair Projects,adaptedwithpermission,©2004SudiptaBardhan-Quallen,www.sudipta.compublishedbySterlingPublishingCo.,Inc.
1. Usingthemeasuringcup,pour1cupofwaterintoaplasticcupandmarktheleveloftheliquidwiththemarker.Repeatsothatyouhavethreeplasticcupsmarkedatthe1-cupmark.
2. Heat3cupsofmilkinasaucepanonthestovetopuntilthemilkreachesatemperatureof175ºF.Checkthetemperatureusingthekitchenthermometer.Letthemilkcooluntilitis120ºFsothatitiseasiertoworkwith.
3. Pourthemilkintoeachofthethreeplasticcups,stoppingatthemarkerlines.
4. Microwaveafewtablespoonsofyogurtfor10secondstoheatitup.
5. Labelonecup“MilkOnly”andsetitaside.
6. Labelanothercup“MilkandYogurt.”Add1tablespoonofyogurttothiscupandmixwell.Setitaside.
7. Labelthelastcup“Milk,PowderedMilk,andYogurt.”Add1tablespoonofpowderedmilkand1tablespoonofyogurttothiscupandmixwell.Setitaside.
8. Coverallthreecupswithaluminumfoilandplacetheminsidethecooler.
9. Fillthefourplasticsodabottleswithveryhotwaterandsealthemtight.Placetheseinsidethecooleraswell.
10.Usethethermometertomonitorthetemperatureofthecooler,whichneedstostayatabout110ºFfortheentiretimeyouculturetheyogurt.Ifitstartstocooldown,refillthewaterbottleswithhotwater.
11.Aftersixhours,checkonthecups.Recordanychangesinappearance,texture,andodor.
12.After12hours(orovernight),checkonthecups.Recordanychangesinappearance,texture,orodor.
Things to Notice:• Thecuplabeled“MilkOnly”willlookandsmell
moreandmorelikerottenmilkastimepasses.
• Thecupslabeled“MilkandYogurt”and“Milk,PowderedMilk,andYogurt”won’tlookorsmellrotten;instead,theywillappearyogurt-y.
• Thecuplabeled“Milk,PowderedMilk,andYogurt”willhaveathickerconsistency,morelikeyogurt,thanthecuplabeled“MilkandYogurt.”
Things to Try:• Tryusingstarterculturesfromflavoredyogurts
ordifferentbrandsofyogurt.Doesthismakeadifference?
• Tryusingmilksubstitutes(heavycream,infantformula)insteadofmilk.Howdoesthisaffecttheyogurt-makingprocess?
• Whathappensifyouuselactose-freemilkinthisexperiment?
