No, that’s not a Ziploc container of glomerular filtrate (you crazy wonk): it’s actually clarified quail broth, or what I like to refer to as “freshly-squeezed” quail juice.

Clarification of stock into consommé has been around since the Middle Ages, but the classic method involves using a raft of ground meat, mirepoix and egg whites. There’s considerable room for failure as the stock won’t clear if the raft doesn’t form well, and it’s expensive as the clarification also takes away a lot of the flavor from the stock unless you use a lot of meat for the raft.

Enter syneresis, the phenomenon of liquid leeching out from gel matrices and the chemist’s answer to classic clarification: the impurities that cloud the stock get trapped in the gel matrix, while the clear filtrate flows out. Syneresis is another one of those phenomena that people have seen for a long time (e.g. cheese production, blood clots), but no one has really paid close attention to. You can see this really easily at room temperature in the lab with acrylamide gels, but it’s impractical to use in the kitchen because of the tiny issue of neurotoxicity (that and the extra problem for Y-chromosome bearing individuals who happen to like fully functional little pals).

The specific application of syneresis in food preparation for clarification purposes was first presented by Professor Gerd Klöck at the 2004 Inicon conference, and further modified by Heston Blumenthal (who makes stocks with additional gelatin content) and Wylie Dufresne (who added gelatin to liquids which didn’t have any). A variant using agar instead of gelatin was posted in 2008 by “Maestro@ forero“, and has since replaced gelatin to become my favorite method for clarification.

The advantages of syneresis over classical raft clarification is that it’s easy, it works with any liquid (Dufresne’s first success was with carrot juice), and it doesn’t take away any flavor from the liquid. It’s also economical in that you don’t have to spend the extra $ for meat, eggs and mirepoix. The disadvantage? Mouth feel, but that is easily corrected by the selective re-introduction of gelatin or other thickener to the clarified liquid.

I haven’t decided on what to use the quail juice for, but it’ll either go to quail “tea” or be further reduced to become the basis for a quail jus.

Ingredients

• quail carcasses (I used 60 quail carcasses for this demonstration)
• gelatin sheets (if using)
• agar (if using)

Preparation

Make a quail broth with the quail carcasses and water (carcasses + water, 6 hours or so of simmering). Aromatics are optional depending on what the broth is being used for. In this demonstration, 60 carcasses made up 1.5 L of finished broth, and no aromatics were used.

If using gelatin, weigh out enough gelatin to make a 0.5 % gelatin solution with the available volume of broth (5 g gelatin for 1.0 L liquid). If using agar, weigh out enough gelatin to make a 0.18 % agar solution with the available volume of broth (1.8 g for 1.0 L liquid). If the broth already contains adequate gelatin to set when cool, skip both additives and proceed with clarification (FYI – quail bones on their own do not have enough collagen to do this).

Make the gel matrix. For gelatin, bloom gelatin and add to heated stock and mix well. For agar, heat agar and stock until agar dissolves (> 80ºC). Pour the gel mix into small containers (e.g. no more than 125 mL / 1 cup) and let cool. Once cooled and set, freeze portions until fully solid. Place a fine mesh strainer into a container and line strainer with a coffee filter. Place frozen block of gel matrix into filter and let melt. Clear liquid will filter through while a semi-solid matrix will remain in the filter.

Notes

Agar filtration will take approximately 8-12 hours per block to melt and filter, while gelatin filtration will take approximately 1.5-3 days per block to melt and filter. Due to the time required, it’s imperative for food safety reasons to melt the blocks in the refrigerator (and use a fresh bowl/filter/strainer between blocks!). The gel matrix percentages are the maximum that one should use, and I recommend lowering the percentages slightly if the starting liquid is viscous. A fine balance such as a Tanita 1579D mini-scale (what I use) is a requirement to accurately weight out the gelatin or agar.

There will never be 100% recovery (because there is material trapped in the gel matrix) but in terms of yield, I generally get more liquid per block with agar than I do with gelatin. This is something to consider if the available starting material is limited in volume.

Note that the resultant liquid from any meat broth (poultry, beef, veal, pork, rabbit, mixed meat etc) will be a pale to dark yellow color. It’s an inherent property of the broth as you will still get this color if you don’t add any vegetables when making the broth. In comparison, the resultant liquid from seafood based broths (fish, shellfish) will be almost devoid of color unless you’ve added something with a tint (e.g. kombu, aromatics). Fruit and vegetable juices will have varying colors depending on what they are in the first place (e.g. I’ve made a grey-green asparagus juice and a pale pink radish juice), and their clarification works better with gelatin than with agar.

If you’re doing pineapple or papaya, you need to use agar.

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