Sodium alginate (Say it like you say algae!) is a substance found in the cell walls of brown algae, including seaweeds and kelp. Its rubbery, gel-like consistency may be important for the flexibility of seaweed, which gets tossed around on ocean waves.
Here on dry land, you can use sodium alginate to make edible balloon-like blobs that are liquid in the middle. We can thank scientists for this delicious project, since they discovered that a chemical reaction between sodium alginate and calcium causes the alginate to polymerize, or form a gel. In this experiment, the gel forms on the outside of a sodium alginate blob, where the chemical reaction is taking place. The inside of the blob remains liquid!
No heat is required for this experiment, making it safe and fun for all ages!
Sodium alginate and calcium lactate can be tricky to find at the grocery store, so you’ll probably have to order them online. But they’re not very expensive, and you’ll have lots of fun playing with them!
-a blender or hand blender (parental supervision required for small children)
-1/2 tsp sodium alginate
-2 tsp calcium lactate
-flavored drink drops, like Kool-Aid or Tang (optional)
You can try making these with juice, but if there is any calcium in the juice, you may end up with foam in your blender, since it may start to polymerize the sodium alginate when you blend it in.
- Add 1 and 1/2 cup water to the blender.
- To the water, add 1/2 tsp. sodium alginate.
- Blend for about a minute, and let rest for 15 or 20 minutes, until the bubbles are gone.
- If you want to add flavor, divide the sodium alginate solution into small containers and stir in the flavor, like a squirt of Kool-Aid liquid.
- Add 4 cups of water to a clean, clear glass bowl or container.
- To the water, add 2 tsp. calcium lactate and mix until completely dissolved. This is your calcium lactate “bath.”
- Fill a spoon, like a tablespoon, with the sodium alginate solution, and slowly lower it down into the calcium lactate bath. You’ll see a gel begin to form. Gently turn the spoon so the sodium alginate falls off the spoon and into the calcium lactate.
- After about 30 seconds, you’ll be able to see a pale blob in the water. Leave it there for three or four minutes. You can make several edible balloons at once.
- When the blobs are ready, use a spoon to carefully remove them from the bath and put them in a clean bowl of water for a few seconds to rinse them off.
- Put your edible balloons on a plate and taste them. What do you think?
Now that you know how to polymerize sodium alginate with calcium, what else could you try? Can you make a foam in the blender? Can you make gummy worms in the bath using the rest of your sodium alginate solution? Can you invent something entirely new??? Try it!
Thank you to Andrew Schloss’s book Amazing (Mostly) Edible Science for the experiment inspiration! Adding the Kool-Aid and Tang drops to add a little flavor and color was our idea!
“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.
Happy Earth Day! This weekend, we planted a garden. Few things make me happier than watching my kids digging in the dirt, planting things. Maybe it’s because I come from a long line of farmers, or maybe it’s the sun-warmed, homegrown tomato I can almost taste just by thinking about it.
One of the most interesting books I’ve read recently is Michael Pollan’s “Omnivore’s Dilemma,” which follows four meals from field to table (from McDonald’s to foraging for mushrooms and hunting a wild boar.) It reminds the reader of how disconnected we have become from the sources of our food. One of my favorite parts of the book talks about Joel Saletin, who is a seminal figure in the sustainable agriculture movement and probably the most famous farmer in America. His bio on the FRESH movie website says:
“Joel calls himself a grass-farmer, for it is the grass that transforms the sun into energy that his animals can then feed on. By closely observing nature, Joel created a rotational grazing system that not only allows the land to heal but also allows the animals to behave the way the were meant to – as in expressing their “chicken-ness” or “pig-ness”, as Joel would say.”
This week, Joel is in town with Ana Joanes, who has made a documentary called “FRESH” that celebrates the farmers, thinkers and business people across America who are re-inventing our food system. It’s about food, but it’s also about economics, community and social justice. Last weekend, I was lucky enough to meet both Ana and Joel while volunteering at one of Joel’s lectures and was impressed with their optimism and sense of humor. Ana recently told planetgreen.discovery.com “I just had a little girl. Her name is Maayan. And, as clichéd as it may sound, I just want to do right by her. I don’t know what reality she’ll face when she reaches adulthood, but I’m trying my best so she doesn’t have to pick up the pieces of our recklessness and inaction.”
I saw FRESH last night in Minneapolis and loved it! The movie is just 70 minutes long, but you will want to talk about it for two hours afterwards! Tonight’s the last night it’s showing, so if you’re in the Twin Cities, don’t miss it! You can order tickets here.
The movie brings up interesting points about monocultures, antibiotic resistance, high fructose corn syrup, the corn industry (which my grandparents’ farm in Iowa is a part of,) and beneficial bacteria. I’m planning to explore many of these issues on this blog by writing a weekly post about food science between science experiments! Stay tuned!