When you think of caviar, unfertilized fish eggs probably comes to your mind. But in the world of molecular gastronomy, things are not what they seem. Today, we are going to make your favorite fruit juice into little jelly pearls, or fruit caviar.
Molecular gastronomy is a subdiscipline of food science that focuses on the physical and chemical processes that occur in cooking. If you are a fan of boba tea, you may have tried popping boba, or a small type of boba made out of fruit juice, and bursts in your mouth. Popping boba is a great example of molecular gastronomy.
A common molecular gastronomy technique is spherification, or the process of creating soft, squishy balls that resemble caviar. Your kids will love how spherification transforms their favorite fruit juice into little balls that they can pick up and eat.
Edible Spheres Experiment for Kids
Materials:
- 2 cups of vegetable oil
- 1 tablespoon of unflavored gelatin
- Warm water
- 2 tablespoon plus ¼ cup of fruit juice, measured separately
- Ice
- Bowls
- Squeeze bottle or dropper
- Fine-mesh strainer
Directions:
- Fill a tall container or mason jar with 2 cups of vegetable oil.
- Place the oil in the refrigerator for 4 hours or overnight. It’s crucial to make sure that your oil is cold enough to form the spheres.
- Pour 2 tablespoons of fruit juice in a bowl. Slowly sprinkle in 1 tablespoon of unflavored gelatin a little at a time. Whisk until there are no more lumps.
- Pour ¼ cup of fruit juice in a separate container. Microwave until steaming, about 30 seconds.
- Pour the ¼ cup of fruit juice with the fruit juice and gelatin mixture. Mix until all the gelatin has dissolved.
- Pour the mixture into a squeeze bottle and let it cool in the fridge for 10 minutes. If you are not using a squeeze bottle, you can pour the mixture into a bowl instead. Note: Set a timer so you don’t forget to take it out of the fridge. If you leave the mixture in the fridge for too long, it will solidify and you will have jello in a bottle.
- Fill a large bowl about halfway with ice.
- Take the oil out of the fridge and place it in the bowl with ice.
- Put more ice around the container of oil to ensure the oil stays cold while you are forming your spheres.
- If you are using a squeeze bottle, gently squeeze the bottle and watch the droplets fall in the oil. They should form a sphere and sink to the bottom. If you are using a dropper, suction up some of the gelatin liquid in the bowl and make little droplets into the oil.
- To make larger spheres, keep dropping liquid in the same spot.
- Continue until you use up all the gelatin liquid.
- Pour the oil and spheres into a fine-mesh strainer set on top of another bowl. You can save the oil if you wish.
- Rinse the spheres in the strainer with cold water to wash off the oil.
- Enjoy the fruit caviar!
My kids thought the little balls of fruit juice was so amusing. It’s such a fun way to “eat” the fruit juice rather than drinking it!
The Science Behind the Fruit Caviar
If you have done the ocean in a bottle or DIY lava lamp experiments, spherification might look familiar. We are using the same concept of oil and water don’t mix, and adding gelatin to the water-based liquid to make the droplets solid.
The long, stringlike protein molecules of the gelatin are loose and wiggle around in hot water. Think of a person’s long hair blowing in the wind. As the gelatin mixture cools, the protein strands slow down and get tangled. So imagine the long hair now gets into knots that are really difficult to detangle. The protein strands bond together and trap the liquid inside.
When you drop the gelatin liquid into cold oil, the gelatin molecules almost immediately turns from liquid to a semisolid gel. That’s why it’s so important to ensure the oil is cold. If the oil is not cold enough, you won’t get nice spheres, but more like little tadpoles or blobs.
Science Extensions
- Any water-based flavorful liquid will work with spherification. Try making caviar from different juices, hot sauce, ketchup, chocolate milk, etc. Just add a little more water for thicker ingredients like ketchup or BBQ sauce.
- Heat up the fruit spheres you made in the microwave. What happens to the gel balls?
- Make the biggest sphere you can!
Storage Tips
If you made too much, you can store the spheres in a closed container in the fridge. You just want to pour a little bit of the vegetable oil in the container so that the spheres don’t stick to each other. Just rinse off the oil before you eat the fruit caviar.
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