From jiggly cakes to fluffy marshmallows, here's how to use gelatin

Jell-O is, inexplicably, back.  

The wiggly, wobbly, neon dessert that many of us encountered in our youth — for me, it was at Sunday lunches at the cafeteria by my grandmother’s in Charleston, where bowls of red Jell-O cubes swayed softly in the buffet line — has resurfaced alongside other old-is-new trends like low-rise jeans and Sex and the City. Dayana Lanuza, who makes stunning floral gelatin desserts at Honey Flower Sweets, says that for some customers, "the gelatin reminds them of when they were little and [they] get nostalgic."

Colorful gelatin desserts are cropping up on Instagram, at restaurants, and in home kitchens alike, bringing retro flair to our feeds. Such desserts range from boozy delights (a far cry from Jell-O shots) to classic Mexican desserts to edible art pieces, all of which call for gelatin to achieve a texture and consistency that’s wholly unique.  

This small but mighty ingredient is essential for a variety of treats beyond Jell-O-inspired desserts, but despite its prominence, it’s not always the easiest to use. To help you unlock this fun and fabulous genre of baking, read on for our guide to all things gelatin.  

Rossi Anastopoulo

What is gelatin? 

Gelatin is a flavorless, colorless substance that’s added to desserts and other dishes as a thickening agent. It’s derived from the collagen found in the bones, skin, and connective tissue of animals, and sold in processed form for use in baking and cooking.  

What kind of recipes is gelatin used in? 

Gelatin is key to giving some desserts their distinct texture — mainly anything that’s soft and creamy, but still stable enough to hold its shape. It’s responsible for the bouncy chewiness of marshmallows, the fluffy-yet-firm texture of chiffon pie filling, the transparent appearance and characteristic jiggle of jelly cakes, and even the cloud-like mousse in this Strawberry-Filled Angel Food Cake.  

(Knox Gelatine, the most common brand on American grocery shelves, also has some more, ahem, unexpected uses for gelatin. They claim it can be used for gardening, skincare, shampoo, and more.) 

Rick Holbrook

How gelatin works in desserts and sweets 

To use gelatin (both in powdered and sheet form, more on that below), you first need to hydrate or “bloom” it in cold water, then add to your recipe. If you just sprinkle a packet straight into your mixture, it will clump and remain grainy.  

According to pastry chef Stella Parks in her article for Serious Eats, the bloomed gelatin is then “melted and incorporated into a dessert, dispersing little molecules of protein throughout. As the gelatin cools to below 100°F, those molecules begin to interlink, reorganizing themselves into a three-dimensional net, with water caught inside. That reduces a dessert's ability to flow, giving mousse or panna cotta a relatively firm texture despite a high proportion of liquid ingredients.” 

So basically, gelatin is bloomed, then dissolved and stirred into a mixture like pie filling or mousse, and finally left alone to set and solidify into its final form.  

It can take a little time for the gelatin to set. And by a little, I mean a lot: anywhere from a few hours to a whole day. Desserts are often chilled in the fridge or left on the counter to wait while the gelatin finishes working its magic and firms up, at which point it’s time to serve your pie or cut your marshmallows.  

John Sherman

Sheet gelatin vs. powdered gelatin 

Gelatin typically comes in two forms: powdered and sheet (or “leaf”). In the United States, we most often use powdered gelatin. That’s the kind that Knox sells in little packets. (You’ll even see some recipes, like our Homemade Marshmallows, call for “3 packages unflavored gelatin.”) 1 pouch or envelope is about 2 1/2 teaspoons (7g) gelatin. 

However, gelatin can also come in the form of thin, transparent sheets. They essentially function the same way in a recipe (though strength can differ across brands and styles) but each are used slightly differently.  

How to use powdered gelatin  

Most powdered gelatin recipes will clearly outline steps along the lines of: Sprinkle the gelatin in an even layer over cold water (or whatever liquid is used in the recipe). Make sure to evenly disperse, rather than dumping in a single pile, or else you’ll have some gelatin in the middle of the pile that never touches liquid and remains dry and un-bloomed.  

Let the gelatin stand until it starts to solidify. This takes about 5 to 10 minutes.  

Dissolve the solidified gelatin by heating it or adding hot liquid. The gelatin should “melt” to become thick, clear, and syrupy.   

As a general rule of thumb, David Lebovitz outlines the gelatin to liquid ratio in this blog post: “1 envelope of gelatin will firmly set 2 cups of liquid, enough to unmold a dessert. 1 envelope of gelatin will softly set 3 cups of liquid. You will not be able to unmold this type of dessert.” 

Rossi Anastopoulo

How to use sheet gelatin  

Similar to powdered gelatin, a recipe designed for sheet gelatin will tell you how to use it. Here’s the basic approach: Soak the sheet in a bowl of cold water until soft, about 5 to 10 minutes. Remove from the water and shake off excess liquid. Either dissolve the sheet in hot liquid, as called for in a recipe, or heat gently to melt, then stir into the recipe.  

Substituting sheet gelatin for powdered, and vice versa 

Most American recipes call for gelatin in powdered form, but you might find a recipe that calls for sheet gelatin when you only have powdered in your pantry, or vice versa. There isn’t a consensus on the exact conversion between the two forms, and different brands have different strengths, so unfortunately there’s not a perfect recommendation. That said, according to the Knox website, one pouch of gelatin has the same gelling strength as 5 sheets (2-7/8" x 8-1/2") sheet gelatin.  

So as an example, to make our Strawberry Cream Shortbread — which calls for “two 1/4-ounce packages unflavored gelatin” — you could sub 10 gelatin sheets.

Erica Allen

Vegan and vegetarian substitutes for gelatin  

Something that many people don’t realize: Gelatin is an animal product! Since it’s made from animal collagen, bakers avoiding these kinds of products need to use plant-based replacements.  

One of the most popular vegan- and vegetarian-friendly substitutes for gelatin is agar, a powdered substance common in many Asian cuisines — you may recognize it in Japanese anmitsu or Vietnamese thạch — that’s derived from algae and sets similarly to gelatin. There’s also carrageenan, which is derived from seaweed and can be found in some stores under the brand name Bakol Natural Foods Unflavored Jel Dessert. 

I tried substituting agar and the Unflavored Jel Dessert into a few recipes using gelatin: Chocolate Panna Cotta, Homemade Marshmallows, and the filling for Strawberry-Filled Angel Food Cake. They worked fairly well in the panna cotta and strawberry filling, as there’s a little more “wiggle room” (no pun intended) in these desserts: If your panna cotta or mousse are a little softer than intended, for instance, they’ll still be scoopable and delicious. The marshmallows were trickier, as there’s less margin for error. If you don’t get the texture right, you’ll be left with a soupy sugar syrup or rubbery candy. I haven’t nailed the right approach for marshmallows, but stay tuned for more insight (and a follow-up blog post!) once I crack the code to these vegan substitutes.  

One final note: the Unflavored Jel Dessert had a very noticeable aftertaste, especially in the panna cotta, that I found somewhat unpleasant. While you get a fairly good texture, the added flavor made this an ingredient I wouldn’t choose to use again.  

Rossi Anastopoulo

Tips for baking with gelatin 

Finally, a few things to remember when baking with gelatin for maximum success:  

Know how long to chill: According to David Lebovitz on his blog, “Desserts made with gelatin should chill for at least eight hours, but twenty-four hours is best. After twenty-four hours, gelatin will not set any further.” 

Things can get too hot to handle: Though heat is used to dissolve gelatin, there’s a limit to just how hot. Once gelatin hits boiling temperatures (212°F), it can start to lose strength — meaning it won’t enable marshmallows or molds to hold their shape well.  

Use exact measurements: Gelatin can be a balancing act. Too little and your dessert will be a liquid mess; too much and it will be stiff and rubbery. So, as with all baking, follow the recipe! And be careful while measuring to ensure you’re using the exact amount called for.  

Make sure the gelatin dissolves: Once it’s bloomed, gelatin is dissolved into a mixture with heat. When you use it this way, make sure that it dissolves completely; otherwise the mixture may have a grainy texture, instead of the smooth, silky result you’re going for.   

Beware of tropical fruits: Some tropical fruits — including figs, kiwi, papaya, and pineapple — contain certain enzymes that prevent gelatin from gelling properly. You can avoid this by boiling the peeled, cut-up fruit (except kiwi) for around 5 minutes to deactivate the enzymes, making them suitable for gelatin recipes. 

Ready to bake with gelatin? Some delicious recipes to start with include Cranberry Chiffon Pie, Strawberry Cream Shortbread, Chocolate Coconut Panna Cotta, and Homemade Marshmallows.     

Cover photo of Keto-Friendly Marshmallows by Rick Holbrook.