Cocktails - egg white foam vs gelatin

[Libationgoddess]

Hi Mr. McGee,

Thank you for being here this week. I can't tell you what a priviledge it is to be able to pose a question to you directly.

I work with beverages, and try to devote as much of my time as possible experimenting on the "liquid side" of things. It's difficult as there is not that much scientific work and support devoted to beverage as there is to food.

So here it is, and I'm hoping you can help me with my question. We are seeing a lot of experimentation with gelatin-based foams in cocktails these days. Classically, egg whites have been used in the past to create a froth---for some reason, egg white foam seems to be a lot more stable than gelatin-based ones.

I did a side-by-side comparison of both, utilizing a classic gin sour (gin, lemon juice, simple syrup) as the base. When I prepared drink #1 with the addition of an eggwhite, the foam maintained it's texture and stability for a long period of time; after the drink settled, the foam rose to it's rightful place at the top of the drink, and remained in the glass long after the drink was finished. I then prepared drink #2 and topped it with gelatin foam; the foam began to deteriorate after approximately 8 minutes.

I thought that perhaps it was the gelatin foam in contact with the alcohol that accelerated it's deterioration, so I went a step further. I shook up a gin sour with an egg white, and allowed it to settle---the eggwhite foam properly rose to the top of the drink---at that point I applied gelatin foam on top of that.

My idea was that the eggwhite layer would act as a buffer between the alcohol and the gelatin in drink #3, but to no avail. The gelatin still collapsed on top of the eggwhite layer. I have attempted different versions of the gelatin foam; increasing the number of sheets to give it more stamina, but it doesn't seem to make a difference. What are your thoughts here? Are eggwhites stronger in the presence of alcohol? Why?

Thank you for any help you can offer here. I greatly appreciate it!

Audrey

[Harold McGee]

Excellent experiments, Audrey! As you’ve discovered, egg whites are better foam stabilizers than gelatin, alcohol or no alcohol. There are several reasons for this. The egg proteins are relatively small and move easily into place in the bubble walls, and bubbles denature them and cause them to bond permanently to each other. Gelatin molecules are long and tangly and not as mobile, and don’t bond permanently to each other—that’s why jellies can be repeatedly melted and resolidified. Gelatin can be made into a better stabilizer by cutting its molecules into smaller, more mobile pieces (“hydrolyzed” gelatin)—something you could do by holding the gelatin for a short period with fresh pineapple, then heating it to kill the pineapple enzyme—but it still won’t match egg whites.