Homemade Marshmallows


During the summertime, when surrounded by a fire, a common food found alongside a box of graham crackers and a Hershey chocolate bar is marshmallows. This gooey and essential ingredient of s’mores originated as early as the 1300s; however, a lot uncertainty remains in what exactly a marshmallow is made of (“Science Buddies”). Surprisingly, marshmallows must undergo several chemical processes before they can emerge as the white spongy product seen on store shelves. The steps to make marshmallows are rather simple and can be easily made at home with a couple of ingredients.

Step 1: Denaturing Proteins

The first step in making marshmallows involves simply adding two ingredients into a saucepan—water and gelatin (i.e. collagen; protein). Once these two ingredients are stirred slowly on low heat, the powdered gelatin will dissolve.  The water causes the special protein bonds in gelatin to expand and “dissolve.”  This is an example of denaturation at work, where the use of physical surface change and heat caused the breakage of protein bonds in the gelatin.

Step 2: Boiling Point Elevation & Caramelization

The second step involves two chemical processes: boiling point elevation and caramelization. By adding sugar to water, sugar ion interfere with lattice formation causing the boiling point of the water to be higher than the normal 212 degrees Fahrenheit. Boiling point elevation is key for the next step in making marshmallows—caramelization. Caramelization is one form of non-enzymatic browning that is crucial in the making of marshmallows. This chemical process takes place once the sugar solution reaches the temperature of 240 degrees Fahrenheit and the sugars are oxidized. This temperature is the prime window for browning to occur, causing the liquid sugar mix to turn into a thick sauce.

Step 3: Coagulation

Once caramelization has occurred, the thick sauce is then poured into a mixing bowl with the gelatin mixture where a third chemical process takes place. Coagulation occurs while mixing the ingredients with a blender allowing breaks and the integration of air into protein bonds. This chemical process is responsible for the marshmallow’s fluffy and foam-like texture. When the mix is poured in the bowl, granulated sugar is gradually added and as the entire liquid is mixed. However, while stirring the mix another chemical process is taking place with the help of sugar.

Step 3: Preventing Crystal Formation

Throughout the course we have learned that sugars play an important role in cooking and baking in general.  They are also essential in marshmallow formation.  If granulated sugars were not accompanied by corn syrup when added to the mix of dissolved gelatin, the final product would be hard.  However, when glucose is added, it blocks crystal formation, preventing the marshmallows from turning into a hard candy-like substance.

Step 4: Drying Agent

The last step according to the recipe is to pour the thickened sauce into a baking pan covered in vegetable oil and cornstarch.  Not only does the starch give the marshmallows their signature texture, but it also acts as a drying agent. Cornstarch helps speed up the drying process of the liquid by absorbing additional moisture, creating semi-soft shell while leaving the inside nice and gooey.

In conclusion, once these steps are complete and the chemical reactions have taken place, the marshmallows must sit for four hours. Afterwards the marshmallows can be enjoyed and used for s’mores or Rice Krispy Treats, which are also great chemistry-related snacks.  The ability to make these snacks using marshmallows is the result of a unique relationship between the evolution of food and chemistry.


  • 2 envelopes of plain, unflavored gelatin
  • ½ cup cold water
  • 1 cup light corn syrup
  • ½ cup granulated sugar
  • 1/3 cup cornstarch
  • ½ teaspoon vanilla
  • 1/3 cup confectioner’s sugar


  1. In a small bowl, combine the cornstarch and confectioner’s sugar. Grease the sides of a 9” square baking pan, and place a sheet of parchment paper or wax paper, cut to size, along the bottom and then grease that, too. Use a bit of the cornstarch mixture to dust the bottom and sides of the greased pan.
  2. Place the contents of the two packets of gelatin into a small saucepan, and mix in the ½ cup of cold water. Let it stand for one minute, and then cook and stir over low heat until the gelatin is fully dissolved.
  3. Now pull out a mixing bowl, and blend the granulated sugar, corn syrup, and vanilla. Add the gelatin mixture, and beat the whole mixture thoroughly—for up to 12-15 minutes—with an electric mixer. Watch the mix become thick and creamy. Pour it into the greased baking pan, and let it stand at room temperature for at least 4 hours.
  4. Afterwards, use a greased knife to cut and enjoy!


http://www.popsci.com/diy/article/2008-11/anatomy-marshmallow http://www.sciencebuddies.org/science-fair-projects/project_ideas/FoodSci_p065.shtml#background http://www.education.com/activity/article/marshmallow_science/ http://www.popularmechanics.com/science/environment/a7802/the-reason-you-can-walk-on-water-and-cornstarch-10555366/

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