Observations and results
Were the marshmallow pieces from recipe 1 fluffier, softer and less sweet than the pieces from recipe 2? Did the marshmallows from recipe 1 melt faster than the pieces from recipe 2?
In the sugar and corn syrup solutions you heated, the sugar made the solutions' boiling points higher than that of pure liquid water. The greater the concentration of sugar in the solution, the higher its boiling point. Consequently, marshmallow pieces from recipe 1 should have had a lower boiling point than pieces from recipe 2, making the former melt faster than the latter when placed in hot water. The final concentration of sugar in the syrup determines the structure of the candy that forms. Think about caramels and lollipops—the caramel is softer and chewier whereas the lollipop is hard and cracks when you bite it. The syrup used to make caramels is cooked until it has about an 87 percent concentration of sugar in solution, whereas the syrup used to make lollipops reaches about 99 percent concentration of sugar in solution. (As the syrup boils water evaporates, and the syrup becomes even more concentrated with sugar.) When making marshmallows, the syrup is cooked until an 85 percent concentration of sugar is in the syrup, and the corn syrup is added to help prevent crystals from forming in the cooled syrup. The marshmallow pieces from recipe 1 should have been fluffier, softer, less sweet and more like store-bought marshmallows than the pieces from recipe 2.
Gelatin is a protein that comes from collagen, the main protein in connective tissue in animals. It has the special quality of being able to coagulate (or come together) when it is beaten or whipped. When the hot concentrated syrup is beaten into gelatin with a mixer, bubbles form in the mixture and the gelatin coagulates around the bubbles, stabilizing their walls so they don't collapse.
Enjoy your tasty marshmallow treats! If stored in an airtight container, they should be good for a week. To clean up any marshmallow-making messes, try dissolving and washing them away with warm water.
More to explore
Monster Mallows from the Exploratorium
The Cold Water Candy Test from the Exploratorium
Test Recipes: Marshmallows from Michael Chu at Cooking for Engineers.
Mixing Your Own Marshmallows: Finding the Right Ratio of Sugar to Corn Syrup from Science Buddies
This activity brought to you in partnership with Science Buddies