Oct 03: Experiment - Clarifying Stock with Gelatin

When I was researching methods to clarify stocks with egg whites, I came across another method of clarify stock using gelatin.

To me, this was intriguing... How does gelatin work to clarify stock? Does it really work?

How does it work?
The stock is frozen solid. Afterwards, the stock is wrapped in cheese cloth and allowed to thaw into a clean bowl while in the refrigerator. The gelatin forms a microscopic matrix that traps impurities, but he water is able to pass through.

Does it work?
That's the objective of this experiment to find out. :-)

I have 4 cups of broth that I divided into 2-two cup portions.
One portion will be the control (as is, nothing added) and the other portion will have gelatin added to the liquid.

Amount of gelatin?
0.5% per weight of the liquid.
The 2 cup portion of stock weighed 460 grams... so I added 460*.5% = 2.3 grams. My scale is not that accurate so I added a 1/2 teaspoon.

The gelatin was added to 1 cup of warm broth to soften for about 5 minutes. Afterwards, I added to the rest of the broth and brought to a boil.


The two portions of broth were placed in separate bowls. Covered with saran wrap and placed in the freezer for two days.

This is the basic broth - no addictions. Instead of cheesecloth, I used a coffee filter. This was placed in the refrigerator to thaw slowly.


After 36 hours, the only stuff left is a slimy puddle. Looks like the stock did contain gelatin from the chicken bones.


This is the broth with the added gelatin. Interesting thing to point out in both pictures, the little mound near the center of the stock-sicle. Water is one of the few compounds that actually expand when it freezes. (Typically, materials shrink as they get colder). You can tell the stock froze from the outside towards the center. As the stock expanded, it pushed the slushy center into a mound.


After 36 hours in the refrigerator, there's more slimy junk.


Surprisingly, both stocks were clarified. The little gelatin in the basic stock was able to filter out the impurities. The stock with the added gelatin was clear and seemed a little lighter in color. However, both had the clarity of a glass of white wine.

Both samples started with 16 fluid ounces.
Remaining stock (Control - no gelatin added): 13 fluid ounces
Remaining stock (0.5% gelatin added): 11.7 fluid ounces
I did not try squeezing any out of the coffee filter. The broth had 36 hours to drain. I figured what was still on the filter was trash.


Bowl of stock before clarification.


Bowl of stock after clarification.


The gelatin worked at clarifying the stock. Typically, meat stocks made by boiling bones contain natural gelatin and additional gelatin isn't needed. However, the batch I made did not gel in the refrigerator so I figured I needed to added a little.

Based upon the results, I could have clarified the stock without adding the extra gelatin. However, adding the extra gelatin is just insurance.

Tasting
Currently, I have a cold so I can't taste much of anything.
The clarified stock was warm and soothing for my sore throat.
Other than that, I'd have to wait to get over my cold to get a real taste.

One of the pros of this method, you can use it to clarify almost any stock or juice.

One of the cons of this method is the gelatin in the stock and the fat are filtered out so you end up with a flavorful "water". Some people miss the mouth feel of the gelatin and fat in their stock.

Further Discussion and Information can be found at this link: Clarifying broth and juices with gelatin