Freeze-thaw clarified stock or juice

A modern route to a clear liquid

Freeze-thaw clarification uses a small amount of gelatin to hold a stock or juice in a loose gel. When the frozen block is thawed slowly through several layers of cheesecloth, the clear liquid drips out while the cloudy matter stays in the cloth.

Dave Arnold described the method on Cooking Issues in 2010. He calls it the first non-traditional clarification technique chefs adopted, and credits Wylie Dufresne with applying it to juices. The older clarification route for stock is the egg raft, which this record does not describe.

The procedure and what goes wrong

The liquid is hydrated with 5 g of gelatin per kilogram. Stock with its own natural gelatin needs none. The mix rests in the refrigerator, is frozen solid, and is then cracked out of its pan without a torch and set in cheesecloth in a perforated hotel pan, which sits in a larger pan to catch the drip.

The thaw is slow. Arnold's refrigerator at 32 to 34 °F (0 to 1 °C) thawed too slowly to be practical, and a warm kitchen melts the gelatin into the drip. The first liquid from a thaw is richer in sugar, acid and colour than the last, so the drip is combined to one batch. A stock that already holds much gelatin yields poorly, and the source advises a weaker stock reduced after clarifying.

The agar variant

Agar replaces gelatin at 2 g per kilogram. It is boiled for several minutes, and the mix is kept above about 35 to 40 °C until it is in the pan, because it sets early otherwise. After it gels, the block is frozen and thawed as above. Agar does not melt, so Arnold notes that it can thaw at room temperature.