Category:Biology Experiments’

Butter Candles and Biofuel

 - by KitchenPantryScientist

Biofuels are burnable energy sources produced by living organisms, like corn, algae, and even cows.   Microorganisms and plants gather carbon from the atmosphere and incorporate it into the organic compounds that make up things like leaves, fruit, stems and wood. When animals eat plants and microbes, they store some of the carbon energy they’ve gobbled up as fat, like the milk fat used to make butter. Scientists call carbon stored in plants, microbes and animals “new” carbon. Old carbon is carbon tied up in fossil fuels like coal and oil, that’s been underground for millions of years.

Butter Candles

We used broken-off skewers to attach our butter candles to an ear of corn.

Although butter isn’t usually burned as a fuel, a Pennsylvania farm show recently converted their thousand pound butter sculpture into 3 days-worth of power for a local farm, using a methane digester. The New York State Fair turned its butter sculptures into biodiesel fuel.  At home, you can make a stick of butter into a candle to see for yourself how an animal product can be used as a fuel.

To make butter candles you’ll need a stick of butter, a toothpick or skewer, some cotton kitchen twine and scissors.

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1. Cut the butter into the size candles you want. Place your candles on a fire-proof surface, like a metal plate.

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2. Cut pieces of string slightly longer than the height of your candles.

3. Use a skewer or toothpick to poke a hole from the top of your candle to near the bottom.

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4. Push your string into the hold using your skewer or toothpick. Leave 1/4 inch or so sticking out. This is your candle wick.

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5. Rub a little butter onto the wick. Light your candle. It may take a few tries, but soon it should burn like a wax candle.

*As with all candles, butter candles should never be left unattended. Be sure to place your candles on a surface like a candle holder that cannot catch fire.

What happens?  The lit cotton wick starts to burn and liquefies some of the butter fat. The wick then absorbs the melted butter and pulls it up,via capillary action, to the flame. The flame starts to burn the fat vapors rather than the wick, in a combustion reaction. This reaction produces heat, water vapor and carbon dioxide gas, putting the carbon is back in the atmosphere.

Since burning food isn’t an efficient use of energy or money (it takes lots of oil to raise and care for a cow,) scientists are coming up with ways to turn animal fats and byproducts that can’t be used as food into biofuels.  Some inedible plant foods can be reused as well. For example, some cars can run on used cooking oil. Can you imagine how much oil a fast food restaurant throws away each week?

Although butter will never replace candle wax, butter candles are a good way to introduce the carbon cycle and get kids thinking about how new fuels and cleaner-burning fuel will impact the future of our planet.

To make the corn candle at the top of this post, we attached the butter candles to an ear of corn with broken off wooden skewers.

Outdoor Science Lab

 - by KitchenPantryScientist

It’s hard to believe it’s already August. Other than reading, we don’t do much to fight summer brain drain at our house, but the end of summer is a great time to head to the back yard or driveway for some science experiments. They’re so much fun that kids won’t even realize they’re using their noggins! Just click on the experiment for how-to directions, photos and videos.

Learn physics by throwing eggs!

Got water? Make siphons, a water-purifier, water rockets, or fire-proof water balloons.

Hungry? Build a solar oven from a pizza box and bake s’mores.

Stand on eggs or throw them as hard as you can without breaking them. You can always clean up mistakes with your hose!

Play magician with the tablecloth trick, or make paper bag volcanoes erupt in your back yard.

Of course, there’s always the famous Mentos geyser, and film canister rockets are always a hit.

Nature walk bracelets add fun to any excursion, and you can collect water from trees or make water filters with grass and sand.

August is a great time to find Monarch caterpillars or study the earthworms in your back yard.

And no summer would be complete at our house without an epic marshmallow shooting competition. You’ll even learn some physics!

Photosynthesis Experiment

 - by KitchenPantryScientist

Plants are wonderful chemical reorganizers.  Using the sun’s energy and a process called photosynthesis, they can turn water and carbon dioxide into sugar (glucose) and oxygen.

Thanks to plants and other autotrophs like algae, Earth has an oxygen-containing atmosphere that can sustain animal and human life.

To watch plants make oxygen, all you need is a water plant like Elodea (available at pet stores), a large container, water and a few small clear glasses or test tubes.

Fill the large container with water and turn your small, clear containers on their sides underwater to remove all the air bubbles.

Cut a branch off of your plant, place it under water in the large container, shake off any air and put it under your small, clear container- stem side up. Invert the small container, allowing no air to enter it. Repeat the experiment with your other small clear container, but don’t add a plant. This is your control. If you’re using test tubes, you can put them in small cups or beakers so they don’t tip over. (See photo above.)


Place your experiment in bright sunlight or near a strong lamp and observe what happens. You should see oxygen bubbles form on the plant as it performs photosynthesis.  In a test tube, you will eventually see some water displaced by oxygen.

What happens if you duplicate the experiment in a room with no light?

Tap water contains some carbon dioxide. How do you think the experiment would work with lake or pond water?

 

Earth Day Science Experiments

 - by KitchenPantryScientist

Here are some of our favorite environmental science experiments. Click on the experiment name for directions and photos. I’ll post a new photosynthesis experiment on Monday!

Window Sprouts: Plant a bean in a plastic baggie with a damp paper towel to see how plants need only water and air to sprout roots and leaves.  Here’s a short video demonstrating how to make a window garden.

Homemade Solar Oven: Using a pizza box, aluminum foil, plastic wrap, and newspaper, you can harness the sun’s energy to cook your own S’mores!

Nature Walk Bracelets: Wrap some duct tape around your wrist (inside out) and take a walk, sticking interesting natural objects like leaves and flowers to your bracelet. It’s a great way to get outdoors and engage with nature!

Carbon Dioxide and Ocean Acidity: See for yourself how the carbon dioxide in your own breath can make a water-based solution more acidic. It’s the same reason too much carbon dioxide in Earth’s atmosphere can be bad for our oceans.

Plant Transpiration:  See how trees “sweat” in this survival science experiment.

Earthworm Experiment:  Do you know what kind of earthworms are living in your back yard?

Composting: Be a composting detective. Bury some things in your back yard (away from power cables) and dig them up in a few months to see how they look. Composting reduces methane gas emissions (a greenhouse gas) from dumps.

Diffusion and Osmosis: See for yourself how the chemicals we add to water, put on our streets to melt ice, and spray on our lawns and crops can move into our soil, ground water, rivers, lakes and oceans.

Solar Water Purification: This project illustrates the greenhouse effect and is a fun “survival science” experiment. Requires hot sun and some patience!

Citizen Science: Don’t forget about all the real environmental research projects you can participate in through Citizen Science programs all around the world!

For mores activities and games, check out NASA’s Climate Kids website, to see a kid-friendly diagram of the water cycle, click here or just get outside and enjoy the beautiful planet that sustains and nurtures us.

Joseph Priestly: Kitchen Sink Scientist

 - by KitchenPantryScientist

We kicked off a new experiment today in honor of upcoming Earth Day. Details and an Earth Day experiment “round-up” coming soon!

Joseph Priestly was an amateur scientist who started out doing experiments in his kitchen sink. Eventually, he was credited with being among the first scientists to isolate oxygen. He noticed that in a sealed container, fire burned something away that animals needed to survive (oxygen) and that plants could replace this mysterious element. This research inspired him to become one of the earliest natural philosophers to hypothesize about the science of ecosystems.

What sparked Priestly’s creative genius? Steven Johnson, the author of “The Invention of Air” guesses it might be the fact that he played with spiders in jars as a kid and always wondered why they couldn’t survive for long after the lid was sealed. It also didn’t hurt that Joseph Priestly had friends like Benjamin Franklin to toss his ideas around with.  In addition, he wrote a number of books, advised Thomas Jefferson and was a founder of the Unitarian church.

Finally, if you like soda, you have Priestly to thank for the invention of soda water.

What inspires you to be creative?

The Science of Hard-Boiled Eggs

 - by KitchenPantryScientist

You can’t judge an egg by its shell, but you can use science to figure out whether or not it’s fresh.

Imagine an egg. It can be white or brown, since they’re identical except for shell color. There are two membranes inside an eggshell, separating it from the inside of the egg and helping to keep it safe from microbial invaders.

Under the membranes is the egg white, made up of proteins and water, and the yolk, which also contains fat and is enclosed in a sac. Tiny rope-like structures anchor the yolk between either end of the egg. The egg white contains a substance called lysosyme, which is a potent antibacterial. Eleven percent of an egg’s weight is made up by shell, 58% by white and 31% by yolk.

When a hen first lays an egg, the raw egg white contains carbon dioxide, making it look cloudy, and the proteins in the egg white are freshly folded into their correct protein shapes, so it will hold a nice shape in a pan. However, egg shells contain thousands of tiny pores, some big enough to see with the naked eye, and as an egg sits, it changes.

The contents begin to slowly shrink, and a small air pocket forms between the two membranes, usually at the large end. The egg’s pH, about 7.6 when first laid, rises as the egg ages and loses carbon dioxide. In just a few days, the pH may reach 9.7, causing the egg white to look clear and spread out more in a pan when the egg is broken.

The nicer shape and centered yolk of fresh eggs is why they’re recommended for frying. But why are older eggs better for boiling, and why does the yolk turn green sometimes?

Fresh eggs are harder to peel. When you boil an egg, it cooks from the outside to the inside, and its proteins become unfolded, or denatured. The denatured proteins are more likely to stick to the membranes on the eggshell of a fresh egg because the pH is lower. According to “FOODS, A Scientific Approach” by Charley and Weaver, eggs are easier to peel if their pH is greater than 8.7. In other words, old eggs that have lost carbon dioxide have a higher pH (are less acidic) and are easier to peel.

Sometimes, when you boil eggs, you see a greenish/gray/blue layer on the outside of the yolk. It’s the harmless product of a chemical reaction between the iron in the egg yolk and sulfer-containing proteins in the white. You can try to avoid it by using fresh eggs, using hot (not boiling water) to cook the eggs, by plunging eggs into ice water immediately after cooking, and by promptly removing the shells.

If you’ve heard of candling eggs, it involves shining a strong light through a raw egg to look at yolk position, air sac size and white clarity. You can also tell that an egg is older if it floats in water, due to the enlarged air sac.

Ideally, to cook perfect hard boiled (large) eggs, you put them in cold water, bring the water to a boil, remove the heat and let the pan stand with the lid on for 17 minutes before removing the eggs and plunging them into cold water. Alternately, boil large eggs for eleven minutes and put them in ice water to stop the cooking. For perfect eggs, prick the large end of your eggs with a pin to release the air in the air sac.

Homemade Petri Plates Video

 - by KitchenPantryScientist

Does soap really get rid of germs? On Wed. morning, Feb.27th, I’ll stop by Kare11 Sunrise around 6:20 to demonstrate a cool hand-washing experiment and talk about Citizen Science, which lets you help real scientists with their research by collecting data on everything from microbes to dog behavior.

Here’s how to make petri plates for the hand-washing experiment, where you touch labeled sections of the plates with your fingertips before washing, after washing with water alone, and after scrubbing with soap. You can also use the plates to grow microbes from around your house or school!

Click here for a link to the written recipe and more science. I made this video for both the free and premium version of KidScience app, where it will appear on next week’s update, along with the recipe.  I’ll post details for the hand-washing experiment early next week.

Kitchen Science

 - by KitchenPantryScientist

“Are you a good cook?” was the first thing Dr. Tsneo Suzuki asked when I sat down in the office next to his cancer research lab at the University of Kansas. I stared at the picture of his wife, who I later learned had passed away from breast cancer, and wondered whether I should be offended.

After all, I was in my twenties and had five years of molecular biology experience under my belt. But I understood why he asked the question. Once you figure out how to test a hypothesis, most science experiments involve following recipes, which scientists call protocols. Generally, if you can read directions and mix things together in the correct order, in the right proportions, you can do things like amplify DNA and clone genes into bacteria.

So I truthfully answered “Yes, I’m a pretty good cook,” and got the job.

Food preparation is like a science experiment. If you can follow a recipe, you should get something close to what you set out to make, because often the ingredients will interact with each other to make something new. This is the very definition of a chemical reaction. Everything you cook with, from water to baking soda, is just a collection of molecules.

Here’s a collection of some food science experiments on my website. Since I love to cook, I hope to add more in the future! Leave a comment if you have other favorite kitchen science experiments, and I’ll try to add them to the list.

Testing Foods for Starch- Add a drop of iodine and watch for color change to detect starch.

Crock Pot Microbiology: Making yogurt from scratch is a delicious experiment

Yeast Experiment: Pyramids, Pasteur and Plastic Baggies- Grow yeast in a plastic bag to see how they make bread rise.

Emulsions: Mayonnaise and Vinaigrette- Mix the un-mixable using surfactants.

Curds and Whey: Make glue and plastic from milk and vinegar.

Gluten Ball- Explore the protein that makes bread chewy.

Red Cabbage Juice CO2 experiment- Use the pH-sensitive pigment in red cabbage to illustrate how CO2 can acidify liquids (and why soda is bad for your teeth.)

Homemade Petri Plates: test surfaces around your kitchen and house for microbes.  Use to test fingers before washing, after washing with water alone, after washing with soap, and after using hand sanitizer.

So remember, cooking can make you a better scientist, and doing science can make you a better cook.

 

 

Crock Pot Microbiology: Yogurt

 - by KitchenPantryScientist

Microbes are always fighting for space.

Bacteria and fungi try to outnumber other tiny competitors using chemical warfare, among other things.  That’s why many antibiotics (which kill certain bacteria) are actually produced by other bacteria. One reason foods like yogurt and cheese, which are made by beneficial bacteria like Lactobacillus acidopholis, don’t easily spoil is that these bacteria  can turn milk sugars into lactic acid. This makes their environment toxic to some of their competitors, like pathogenic bacteria.  Luckily, we humans aren’t harmed by lactic acid and can enjoy its tangy flavor.

To grow bacteria in labs, scientists have to take care of them the way you’d take care of a pet.  You have to give them the type of food they like, the right amount of oxygen and moisture, and keep them at their optimal temperature.

The same principles apply to growing the bacteria that make yogurt.  You prepare the bacteria’s food by heating some milk and letting it cool to a temperature that the bacteria can tolerate. Then, you add the bacteria and let them grow for about eight hours.  During that time, the bacteria will happily divide, multiply and eat milk sugar. In the process, they’ll produce lots of lactic acid which changes the way the proteins and fats in the milk interact, forming a more solid food product.

We made yogurt in our crock pot, which turned out to be a lovely bacterial incubator. The end product was a little runny, but putting it through cheese cloth (or a coffee filter in a plastic bag with the tip cut off) gives you thicker yogurt.  It is delicious!  Here’s how we made it, thanks to directions from Stephanie O’Dea:

Ingredients: 8 cups (half-gallon) of whole milk , 1/2 cup grocery store yogurt  (must contain live/active culture), thick bath towel, slow cooker

Turn crock pot on to low. Add an entire half gallon of milk. Cover and cook  for 2 hours and 30 minute. Unplug your crock pot, but leave the cover on. Let it sit for 3 hours so your bacteria will not be overheated when you add them.
After 3 hours, put 2 cups of your warm milk  in a bowl. Whisk in 1/2 cup of the live/active culture yogurt. Dump the bowl contents back into the crock pot and stir well. Wrap a heavy bath towel all the way around the unplugged crock pot as insulation and let your bacteria grow for 4-8 hours or until thickened.  Refrigerate and enjoy with fruit, honey, or granola.  As I mentioned, you can strain the yogurt if you prefer a thicker consistency, and your homemade yogurt will make a great starter culture for the next batch!

If you don’t have cheesecloth, you can strain your yogurt through a coffee filter in a plastic bag with a corner cut off.

Happy kitchen microbiology!