Monday, 11 January 2010

Clarifying Stock - Ice/Gelatin Filtration Part 2

So I explained in part 1 yesterday the process of Ice/Gelatin Filtration in this post, today I will show you how I got on when I put the theory into practice.

Lightly colouring veg for the stock

I started by making brown chicken stock using some chicken wings, an onion (skin left on to aid the colour of the stock), a diced carrot, few bay leaves, garlic cloves and whole peppercorns. I roasted the chicken wings first to help with the flavour and colour of the stock, and brown the veg in a saucepan for the same reason.

Lightly roasted chicken wings, I could have gone for more colour if I wanted

I added the chicken to the veg, making sure to scrape the sticky 'juicy bits' from the tray and added water to just cover everything, then set it over a moderate until it boiled, then turned it down to a simmer for about an hour. I made the point of not skimming any impurities and fat from the stock as I wanted to really test how well this method would 'clean' my stock.

 Un-skimmed stock being brought to the boil

After an hour a drained the stock and passed it through a sieve to remove any large particles.  It is CRITICAL that the stock is well seasoned  at this point to how you want the final product to taste, any seasoning added after the stock is clarified will cloud the stock. Allow the stock to cool completely and freeze overnight.  

Sieving the stock
The following afternoon I removed the stock from the freezer and placed it on some muslin that had been folded three times and set that in a sieve. I place the sieve on a large pan and place it all in the fridge to slowly defrost for the next 24hrs. Remember that defrosting in the fridge is crucial to ensure gelatin remains solid so it can filter the melting liquid, and the fat stays solid so it doesn't re-emulsify back into the liquid and leave us with a greasy stock.
Frozen stock on muslin - the white stuff is frozen fat. Tasty

All we need now is time... time and patience. Fortunately I had a day at Tante Marie to complete allowing me to be distracted by other matters before returning home to see the results... and here they are....

The stock had nearly all melted leaving a nasty looking residue on the muslin

Spot the difference... no prizes will be awarded.

I had the foresight to save some of the original stock for comparison purposes, and as you can see the experiment was a resounding success and I am very very happy with the outcome. Even the smell of the cold stocks vary considerably, with the clarified stock smelling fresher, or maybe crisper would be a better description!
So what are your thoughts on this technique?  do you think as I do that it could be a valuable tool in the kitchen or a waste of time?  Let me know below in the comments section....



  1. Fascinating Dylan, though I remember seeing Heston using this technique, and extremely effective you have shown it to be. I'm not sure if it is practical for anything but a commercial kitchen though as it is a little long winded for domestic use. Apart from anything else I'd never find enough space in my fridge to sit a large bowl filtering all day! I make a lot of stock at this time of year, either ham from a ham hock or bacon bones, or chicken from chicken carcases or remnants of a roast chicken, but it is immediately used to make some variation of soup so the clarification is unimportant. If I need clarified stock I buy it at the supermarket!

  2. I do have a qualm about this filtration method. Since the gelatin is what is being used to prevent the transfer of impurities into the clarified stock, I assume that there is also no gelatin in said stock, whereas a traditionally clarified stock/consomme using a clearmeat raft would retain most of the gelatin.

    Did you find that the Ice Filtered stock had an inferior texture to a traditionally clarified stock?

  3. Anonymous...

    It appears great minds think alike.

    This method from what I have read is usually used for consomes for the very reason you have mentioned.

    Removing teh impurites from a stock will give a cleaner, fresher taste, however without teh gelatin, if one was to reduce it, I am sure it would suffer in the manner you describe.

    Next week I am planning on repeating this experiment, but this time I will add some Agar to the stock. The idea is that it can be defrosted in around 8hrs on the kitchen side rather than 2 days in the fridge.

    It should also mean that the gelatin can turn into liquid and be present in teh clarified stock.

    Will it work? I have no idea. The technique is used to make fruit consomm├ęs which obviously have no naturally occurring gelatins. Will be interesting to see if it works and how well it reduces afterwards.

  4. Did it work????!!???? Love the progressive thinking...

  5. Did the agar trick work Dylan?

  6. The agar trick did indeed work. Infact it works a little better and a lot faster! With the agar you can brake the mixture down with a whisk, place it between 2-3 layers of muslin and gently squeeze. The gel will gently weep a beautifully clear liquid in no time at all... just don't squeeze too hard!


I look forward to reading your comments whether they are good, bad or indifferent!