The main substance that gives marshmallows their stretchy texture is gelatin. Gelatin is a protein derived from collagen in animal bones, skins, and tissues. It has unique properties that allow it to form thermo-reversible gels when mixed with water. This means it liquefies when heated and solidifies when cooled, allowing marshmallows to soften and melt when hot but bounce back to a soft, pillowy texture at room temperature.
The Role of Gelatin in Marshmallows
In marshmallows, gelatin chains cross-link during cooling to create a three-dimensional protein network that traps air bubbles. This gives the marshmallow its foamy, aerated structure. The gelatin chains unravel when heated, allowing the marshmallow to melt, but then re-form on cooling to reset the marshmallow texture.
Gelatin makes up about 3-10% of a marshmallow’s ingredient composition. More gelatin leads to a firmer, chewier marshmallow texture. The exact gelatin concentration can be adjusted to create different textures, from soft and fluffy to dense and gummy.
Other Ingredients in Marshmallows
While gelatin is the key ingredient, marshmallows also contain:
- Sugar (sucrose) – Gives marshmallows their sweetness and helps retain moisture.
- Corn syrup – Adds moisture and flexibility.
- Water – Hydrates the gelatin to allow it to bloom.
- Air – Whipped into the starch mixture to give marshmallows their foamy aeration.
- Colors and flavors – For variety, e.g. vanilla extract.
The sugar and corn syrup give the gelatin a viscous medium to work in. Meanwhile, the water hydrates the protein chains so they can unravel and form new bonds during heating and cooling. Getting the sugar-to-water ratio right is important for achieving the ideal marshmallow texture.
The Gelatin Manufacturing Process
Gelatin is derived from collagen, the main structural protein in animal connective tissue. To make gelatin:
- Collagen-rich animal parts are cleaned and pre-treated.
- The collagen is extracted by boiling the materials in water.
- The broth is filtered and concentrated.
- The liquid is dried to sheet, granule or powdered gelatin.
Pig skins, cattle bones, and fish bones are common sources. The pre-treatment helps remove impurities and prepare the collagen for optimal extraction. The concentration and drying stages produce concentrated, commercially useful gelatin.
Gelatin Varieties
There are two main types of manufactured gelatin:
- Type A – Derived from pork skins and cattle bones. Has a rigid, brittle texture when gelled. Best for marshmallows.
- Type B – Derived from cattle hides and bones. Produces a more flexible, elastic gel. Sometimes added to marshmallows along with Type A for texture.
Within each type, the gel strength can be customized based on treatment conditions like extraction temperature. Gelatin makers tweak processing to produce grades optimal for products like confectionery versus yogurt.
Alternatives to Gelatin
For vegetarian marshmallows, gelatin alternatives include:
- Agar – Derived from seaweed. Can replicate gelatin gelling but gives a firmer, brittle texture.
- Pectin – Extracted from fruits. Gives a softer set than gelatin.
- Gums – Like guar gum or gum arabic. Can help mimic gelatin properties in combinations.
- Carrageenan – Sourced from seaweed. Provides some gelling ability.
These alternatives can produce suitable vegetarian marshmallows, but the texture is slightly different from gelatin-based versions. The protein network formed by gelatin is unique and hard to perfectly replicate with substitutes.
Conclusion
Gelatin is clearly the key ingredient that gives marshmallows their distinctive soft, stretchy, yet aerated texture. It forms a thermo-reversible protein network that traps air bubbles and provides marshmallow sponginess. Alternatives like fruit pectin and seaweed extracts can create similar effects for vegetarian marshmallows but do not quite match the melt-in-your-mouth texture achieved with animal-derived gelatin.