Gelatin is one of the wonders of the world. It is an enigma shrouded in anonymity. However, in true Batman-like fashion I think I am on its tail. I hope I can help answer many questions that loom about what gelatin is, how it works, and when to use it.
Before I go too deep into gelatin, let me back out and cover collagen. I’ve been in medical school for about a month now, and I’ll be darned if it doesn’t feel like I’ve been beat over the head with facts about collagen. I can rattle a variety of facts off memory like it is the most abundant protein in the human body, it is created and excreted by fibroblasts in connective tissue, and it consists of the amino acid repeat glycine-proline- hydroxyproline, but what is most important in the context of cooking is collagen hydrolysis. Gelatin is collagen that has been hydrolyzed or separated from the main collagen source. The best way to imagine this is to visualize hard candy. If we drop hard candy into hot water, eventually it will break apart into sugar. This is the same concept.
Now that we have separated our gelatin from collagen, it is time to use it. But how does it work? When heated gelatin proteins are denatured or unfolded. When the liquid that gelatin is added to cools down, gelatin proteins wrap around liquid and trap it. This is what forms the gel. This might seem bizarre, but it is important to understand that gelatin proteins are thousands of times larger than water molecules. Imagine that gelatin is a wound up rope, that when pulled apart (denatured) stretches out 20 feet. In it wound form it wouldn’t be long enough to wrap around one person, but when stretched it wraps around 10 people easily (water molecules). The same goes for gelatin and water. This process is very similar to the method that starches use to thicken puddings and sauces.
Generally, standard gelatin violates rules of kosher and hallal because of the variance of animal bones used to create the gelatin. There are some gelatins that are very tightly regulated that do not contain pig byproducts. These gelatins work exactly the same as non-kosher/hallal gelatins because they are made of the same proteins. There are a few substitution options for vegans including pectin, agar, and carrageenan. These are different chemically so they are not a 1:1 replacement, but they act very similarly to gelatin.
When writing for this website, I take on the view that I am, above all else, a researcher. My goal isn’t to discover new things, but rather to search for knowledge that is already shown and apply it to cooking/baking in a way that makes it learnable and usable to the home cook. That stated, often I run into questions that are not explained or given a cursory look. There’s always a pattern of websites stating the exact same information as other websites over and over again. This same phenomenon goes for the question of why do we hydrate gelatin (blooming)? I’ll use my background in chemistry and physics to come up with an explanation, since there isn’t much written on the subject.
Before use, most recipes require that we soak gelatin in cold water. This is a step known as “blooming” gelatin. I believe that the main reason for this is to insert water inside the gelatin micelles (particles), so that upon heating there is rapid interchanges of hydrogen bonds between the gelatin and the water, in addition to some hydrophobic interactions. This leads to the dissociation of the gelatin proteins and separation of strands, internally and externally. That might have been a bit too technical (sorry, I’m in exam mode), but the gist of what I am saying is that the water, when heated, breaks apart the gelatin protein bonds. This causes the individual gelatin proteins to enter the liquid and is the driving force behind gel formation.
Here’s how to use gelatin. First, allow gelatin to bloom in cold water for 5 to 10 minutes. Then add the gelatin to the already cooked/heated solution that we are forming into a gel. (We can add the gelatin directly to the heating step, but there is a greater risk of damaging the gelatin proteins). Finally, we allow the liquid-gelatin to cool to close to room temperature before putting it into the refrigerator. It is important to let it cool slowly or else there is a risk of getting strands or clumps of gelatin in the food. Trust me, gelatin clumps are not very tasty at all.
In general, one tablespoon of gelatin can be used to gel two cups of water. There are a few fruits like pineapple, papaya, and kiwi that contain an enzyme that breaks down gelatin, so do not use these fruits with gelatin. In addition, two much sugar can disrupt gel formation. Usually, recipes account for this, but if you are modifying a recipe be weary of too much sugar.
There really is no limit to the possibilities for using gelatin. I primarily use it to stabilize mixtures and to form gels, but it can be used as a slight thickener (if very little is used), to stabilize alcohol based ice creams, and to make marshmallows. The most important thing is to be creative. There’s no telling how many cool ideas you’ll think of that include gelatin.