The Quest for Clarity

If you’ve ever made vegetable stock, slow cooked a bunch of vegetables then strained off the liquid to use as a soup base or flavoring agent, then you are probably familiar with some of the issues in this article. For instance, you are probably aware that if you use certain vegetable combinations you will end up with different flavor profiles that vary on a metaphorical range between chicken and beef. Caramelizing or sweating the vegetables can also vary the taste or color in pursuing your goal.

In classic French cuisine a consommé is a clarified soup broth or stock that has been strained and then treated to a fining process to remove any remaining impurities. The finished product should resemble a steeped tea in clarity, varying between golden and a dark amber tint depending on whether it was made from poultry or beef. A consommé is made from a meat base and turns into jelly when refrigerated because of the high gelatin content. This is the basis for aspic which is usually made from a reduced consommé for a stronger flavor when paired with meat.

Any soup stock, whether from animal or vegetable, will have particulate matter that is not easily filtered away. Solids may fall out of suspension and settle to the bottom of the container or oils may congeal under refrigeration and be skimmed off the surface even after any filtration. And after all this work the broth is still cloudy. So what do you do?

The classic method of clarification is to use egg albumin to remove this cloudiness. This cloudiness is matter that is so tiny that it stays in solution and must be absorbed in some way because it seems to defy filtration. Stirring the stock while heating causes the floating matter to be absorbed by a ‘raft’ of egg whites floating on the surface of a boiling soup stock. This albumin is then strained off to produce the clear consommé that is pale gold for poultry and amber for beef. This method could not be used with a vegetable stock if one wanted this stock to remain vegan.

An alternative method to eliminate this cloudiness is to allow the strained stock to freeze then strain through cheesecloth as the gelatin in the stock will absorb the particulate then the freezing will expel the water with flavors still intact. Although it works and saves eggs, it is a costly method on account of the time and effort that goes into it.

Someone with knowledge of this tried the gelatin method using vegetable stock and agar agar, a dried transparent seaweed that absorbs many times its weight in liquid when boiled. Cooling the agar treated liquid causes it to jell similar to gelatin. When using an amount of agar agar equal to .02 % of the total weight of the liquid, the result will be a jellied substance that is easy to make slushy with a whisk. This concentration will cause a mixture loose enough to dispel most of the liquid trapped in the seaweed.

Strain the vegetable stock, then reheat and mix in the .02% agar. An easier way to estimate this proportion is to use 2-3 tablespoons agar to a pound of liquid. Bring this to a boil and simmer, stirring for a few more minutes. Remove from heat and cool down in an ice bath then freeze, removing it now and then to whisk and keep it from becoming solid. Once it becomes a partially frozen slushy mess transfer to a strainer lined with several sheets of cheesecloth.

Carefully strain off the liquid using the weight of the jelly to force the liquid out. Use only a small amount of pressure as you squeeze the cheesecloth ball to extract the last amount of liquid before the jelly starts to ooze out of the cheesecloth.

Now what I did was to conduct a test using half the original strained stock and apply the method described above. The other half I used as a control, subjecting it only to finer and repetitive filtration. Once the agar jelled amount was strained off with the cheesecloth I filtered the agar batch twice and the non-agar fined test batch eight more times through a coffee filter. The results are shown. In the photo below the glass on the right is the finished consomme using the agar method. The other glass is the result of multiple filtration only. As you can see, the batch with agar became very clear and presented a soup brilliantly whereas the batch filtered conventionally remained cloudy.

In conclusion, I would say that the experiment worked and I was able to create a perfectly clear consommé from vegetable stock that retained its flavor nuances and displayed a beautiful color. I wish the method was easier and I would not recommend doing this every day, but making up a batch and freezing it for special occasions is a great idea.