Stock Clarification Techniques

I like to try out new techniques in the kitchen every once in a while to see how they might be useful in my repertoire. Cooking is a continual process of learning for me; if I’m not learning, why am I in the kitchen? Among the new techniques that I have tried is a method for clarifying stocks into consommés. I conducted a small series of experiments over the last year to compare the new technique to the standard technique.

Because my grounding is solidly classical, I have heretofore made my consommés using a protein fining technique, adding raw egg whites or raw chicken breast to cold stock and gently heating it. As the raw protein coagulates (cooks), it traps the impurities from the stock and with reasonable care, a clear consommé emerges after filtering the “raft” of solid protein from the liquid.

Some years ago, I learned of a technique called ice filtration (or gelatin clarification) via the famous British chef Heston Blumenthal. I doubt that he invented the technique, but he is certainly responsible for bringing it to my attention and that of chefs all over the world. The technique involves letting a stock gel (either from naturally occurring gelatin or by adding more gelatin), then freezing the gel, and then letting the gel melt very slowly such that the clear liquid separates from the gelatin matrix which holds the impurities in suspension. There is no doubt that this technique is high on cool factor; it is really quite amazing to see it in action.

Both techniques achieve the desired result of a clear liquid, but there are some significant procedural differences and clearly perceptible differences in the resulting consommé.

First the technical differences. The ice filtration technique takes almost no effort on the part of the cook, a clear win for the novel technique. But the process of chilling the stock, freezing it, and letting it thaw at refrigerator temperatures takes seemingly forever, a minimum of 48 hours for a reasonable amount of consommé. And getting the frozen stock to thaw in a reasonable amount of time involves freezing it in thin sheets; this takes a lot of both refrigerator and freezer space, space that many restaurants may not have. That’s two wins for the standard technique to one for the new technique.

Now for the qualitative factors. The ice filtration technique appears to clarify the stock slightly better than the standard method based on my observation in the kitchen. Done correctly, ice filtration gives crystal clear consommé every time; sometimes it is necessary to clarify a stock a second time using the standard technique. That’s two wins apiece, a draw so far.

My experiments concluded by tasting consommés made from the same stock using the two techniques, side-by-side and blind. The ice filtration consommé has a water-like body: all the gelatin is gone from the final product. The standard consommé has a weight to it, a silkiness that the gelatin imparts, not unlike the body that glycerin gives a wine made from ripe grapes. And I find that the ice filtration consommé tastes weaker than the standard consommé. It may be that the gelatin increases my perception of flavor; in any case, I clearly prefer the standard consommé over the ice filtration consommé every time during blind tasting. On my score card, that’s four wins for the old method to two for the new. Your mileage may vary.