Ever since reading Harold McGee’s article about a simple method for making incredibly clear consommés I’ve been wanting to try it but it’s only in the past few weeks that I’ve got a chance to do so. I say the last few weeks because I’ve done quite a few experiments over the course of the month trying several different clarification techniques.
The first was the gelatin filtration method detailed by McGee where you freeze your stock and put it in a cheesecloth and let it slowly thaw in your fridge. The problem with this is it takes two to three days for the process to complete and it takes up a lot of room that would otherwise be available for storing food. The good news is it really works: I got a lovely, clear consommé from the frozen block although I only ended up with about 450ml of liquid from a starting volume of 800ml.
Now, gelatin belongs to a class of molecules called hydrocolloids which form gels at particular temperatures when in solution: this is the reason why stock turns to jelly when you put it in the fridge; however, as gelatin has a very low melting point it’s also why it starts to liquefy at room temperature and without it remaining solid and acting like a mesh, the filtering won’t happen. Luckily there are other hydrocolloids with much higher melting points and they give the possibility of performing the clarification without the need for a fridge.
I’d read this post on Cooking Issues and it said that using agar you could clarify without the need for the freezing step: by allowing the liquid to gel lightly you could squeeze the clear juices out of the cheesecloth in a few minutes. Well in theory at least because when I tried it it just didn’t work, the end product was pretty much just as cloudy as when it started out. I tried several different concentrations of agar from almost runny to completely solid and it made no difference so I decided to try something else.
My next experiment involved another method which required adding agar to the stock, freezing it and then letting it defrost over the course of a few hours at room temperature. The thing I also liked was the promise that the gelatin in the stock would be preserved thus giving the resulting consommé more body. I thought I’d be quite clever too and take advantage of agar’s melting point being around 85°C by defrosting in my oven at 50°C and speeding the whole process up. Unfortunately, while it worked to a point the resulting liquid was still quite cloudy even if it did turn to jelly in my fridge afterwards. I then prepared another batch and allowed it to defrost on the kitchen worktop overnight: there was definitely an improvement on the oven defrost – in clarity at least, the resulting fluid didn’t gel in the fridge – but still not better than the McGee technique as you can see from the picture here.
So it turns out that the first method I tried was the best and I’m pretty sure I can account for this: on The Fat Duck website there’s a section on ice filtration and the reason why the higher temperature clarifications don’t work either at all or as well is because unlike defrosting in the fridge all the fat (the main cause of cloudiness) in the stock doesn’t stay solid and trapped in the hydrocolloid mesh. The only problem I find with the gelatin method is the yield (roughly around 50-60%); apparently this can be improved by reducing the concentration of gelatin but I guess you would have to make sure the stock was very flavoursome to cope with diluting it with water.
The initial flavour of the liquid to be clarified is especially important here, if it was made using only bones then it will not be good enough: the solution is to dice up a good quantity of meat and make a strong broth by simmering it in your stock for a few hours. Remember, if after clarification the end product is too strong you can always dilute it with spring water but if it’s too weak there’s no way to rectify this without adding impurities which will have to be removed by filtration again. Also, it’s often recommended to add some commercial gelatin back into the consommé to reinstate the lost body but for this recipe I liked the idea of using the crisper and lighter profile of the no-gelatin version. Finally, one tip is do not season before freezing, I did this during one of my experiments and because some of the water gets left behind during defrosting it was far too salty.
800g very good quality homemade stock
75g podded broad beans
- Freeze the stock and when frozen, break it up into large chunks.
- Line a sieve with cheesecloth or a large coffee filter and place the frozen stock in it.
- Hang the sieve over a pot in the fridge and allow to defrost for two to three days. (The resulting consommé will keep for a few days afterwards.)
- In a large pot of boiling salted water add the broad beans and cook for 2-3 minutes until bright green.
- Immediately remove from the water and put into a bowl of iced water to stop them cooking.
- Remove the outer skin from the beans as they cool.
- Repeat these steps for the peas although only cook for around one minute.
- Gently reheat the consommé and add the salt. It needs to be piping hot before going into the soup bowl.
- To plate, add a layer of peas and broad beans to the bowl and cover with the consommé. Drizzle a few drops of olive oil over the soup.
PS: There were also supposed to be some nasturtiums but unfortunately they hadn’t flowered by the time I was making this.