[chefjohnpaul]

Nice thoughts Chris. I had a conversation with Harold McGee on this and it just coinsides with what's happening at the molecular level, as you so eloquently stated. There are also schools of thought that when making stock, like chicken, to not rinse the bones first thus washing away excess albumen, but start process very cold and allow the albumen that is present to clarify the stock as it slowly comes to the simmer and carries particles with it to the surface for depouillage.

 

[chrislehrer]

Clever! So if you do very cold and raise the temp slowly, you're using chicken albumen for the same purpose as egg white (also albumen) in the raft for clarification. Makes sense: I should have thought of that.

 

[dc sunshine]

I'm not sure that I should involve myself in this thread, as I am far from an expert and not qualified to debate in such matters.

But, I would like to report, I decided to make a lamb and chicken stock this week. (Ok couldn't sleep needed something to do!) The weather here is cold at the moment, so the temp of the water from my filter would be about 3 deg C which I started the stock in. It was a bit of an experiment I had the chicken carcasses and the trimmed lamb chop bones by themselves in the cold water for about an hour, slowly heating till it came to a slow boil.

The albumen came to the surface in nice "solid" pieces - easy to skim, didn't have to repeat the process very often.

Then added the veg etc etc, cooked overnight barely simmering, strained, chilled, took off the fat cap. It was lovely and clear -no need for an egg raft. I would recommend starting very cold anytime. I don't know the technical reasons for it - this thread seemed timely - if my reply has helped anyone I'm happy.

I'll start cold every time now.

 

[siduri]

Hi Ellohn. I live in Rome too - first time i encounter someone else from here on this site. (I can empathize with your coming up against nonna's prejudices all the time - even the doctors will tell you you got a draft (colpo di freddo)! ) Anyway, I have a very off-topic question. Seeing as it's almost impossible to get ice anywhere here, no less in any restaurant i've ever been in, where do they find all the ice???

 

[ellohn]

Mcdonalds?! :lol:

 

[ed buchanan]

I never recall starting a stock with ice. I was however, always instructed and always did start the clarrification of a consomme from stock to its completion with ice.
The reasons being the same that everyone have already mentioned. It lets the albumin in the bones start to come out later at a more congeeled level so it traps many of the particles extruded by other ingredients, and rises to the top of the consomme pot. :blush:

 

[kuan]

So I guess if you are doing lobster stock it would be consider shellshocked?

 

[ed buchanan]

That answer is a little fishy!!!:lol::lol:

 

[breton beats]

Yes you should use the coldest water possible for making stock for all the reason listed above, to drive out impurites, also to draw out the.

But the reason many professional chefs add ice to the stock is maybe because that is what they learned in their restaurants. Many restaurants put their stocks on to cook very slowly overnight. The closing shift puts in on, and the opeing shift takes it off. All night it goes at very low heat.

When you have stocks on for too long you run the risk of the vegetables breaking down and imparting bitterness to the stock. So one trick is to start with all ice so that the cooking temperature is delayed, along with the slow heat, and the bones, meat, and vegetables aren't getting too over cooked. (not that it does that too well)

At home I use ice water. That way I know that I am getting the coldest water possible.

 

[ellohn]

Would the same thing (coldest water possible) go for all types of stocks?
Meat stocks as well as fish stocks or maybe lobster?

 

[davidturner]

I've never heard of that particular use of use of ice although when I make gravy using pan drippings I add homemade stock that I have frozen. When I add the frozen stock it immediately attracts and solidifies the fat making it easier to remove.

 

[chrislehrer]

Yes, it should apply to anything with significant protein content. The point is that as the temperature rises, the proteins will tend to coagulate in little clumps. If you start cold and raise the temperature slowly, a great deal of this will stick to the sides of the pot and the chunks of stuff in the water, so it won't float around and cloud your stock or need to be skimmed. This is also why clarification with egg whites works: the egg whites coagulate slowly. Only the thing is, egg whites are almost pure albumen, and you're putting in a fair bit, so they float and coagulate in a mass (the raft), taking all the other coagulated bits with them.

The truly cool trick with lobster, though, is to make crustacean butter. Chop up cooked or raw shells coarsely, heave them in a big stand mixer, and add a lot of sweet butter. Run the machine slowly until everything is stuck together, and then turn up the speed a bit and leave it running for half an hour, by which point the butter will be salmon-colored. Now scrape everything into a big saucepan and add a whole lot of water, like several inches over the top. Bring very gently almost to a boil, then shut off the heat, let cool, and chill. The butter will freeze solid on the top. Remove it in a block, then heat it gently until it starts to sizzle just a little bit and strain it very fine. You now have pure crustacean butter, which freezes in an ice cube tray and keeps for a month or so.

Now make lobster risotto and finish with a cube of this stuff. Heaven!

 

[chefhf]

I realize this is extremely late, googled ice and saw this.

Some chefs say its because it hardens fat solubles to clean the stock better. Stories for days. I worked with a chef that seriously added 1, a single, all by itself, ice cube to a simmer stock. 

The reason I start a stock with ice doesn't have to do with any nonsensical crap wives/chefs - tale. It's simple.

Ice machines filter water very well. You get all the crap out of the tap water. You're making a stock, if you're reducing that stock in say a pork jus, you may taste the chlorine, the fluoride, etc. If you melt ice and drink it, it will taste better than tap water drawn from the same restaurant. I'm not going to buy bottled water to make 20 gallons of chicken stock, but i may use 160# of ice. Depending on the day of the week I can empty my ice machine. Cheaper, cleaner, tastier.

BOOM

 

[rpooley]

I've read Thomas Keller adding ice to the stock once it comes to the simmer, this "shocks" the fat (solidifies) and catches some impurities, making skimming at this stage somewhat more efficient and improving the final clarity.

From the cookbook "Bouchon":

"Place all the bones and the feet, if using, in a 14- to 16-quart stockpot. Cover with the cold water. Slowly bring the liquid to a simmer, beginning to skim as soon as any impurities rise to the top. (It is important to keep skimming, because as the stock comes to a simmer, impurities could otherwise be pulled back into the liquid and emulsify and cloud the finished stock.

Once the liquid is at a simmer, add the ice and then remove the fat. (The ice will chill and thicken the fat and turn it opaque, making it easier to remove.) Skim off as much of the impurities as possible. (Once the vegetables are added, skimming will be more difficult.)"

 

[foodpump]

Mmmm... Thomas Keller or not,  fat doesn't "solidify" at simmering temperatures --say, 75-90 C. 

Oils remain liquid at room temperature, and fats remain solid at room temperatures, was how my gr. 9 science teacher explained it.    And it goes without saying that oil or liquid fat will always float to the top of any liquid--provided it isn't emulsified.

On the other hand, proteins start to coagulate at the mid 60's regardless if they are dead proteins or live proteins.  Scum is nothing more than dead protein, has nothing to offer in terms of nutrition, flavor, or mouthfeel.  The classic theory goes something along the lines of: If you can keep the stock at 65-ish for prolonged periods of time, the dead protein will clump together in larger bits of foam, making it easier to skim off.  Once the temp goes above 90 the dead protein breaks down quickly into tiny bits, making it almost impossible to skim off, and clouding your stock and lending a stale and gritty flavor to it.  

 

[rpooley]

I don't shock my stocks, it tends to annoy them and they end up in the therapist's office.  

I was just posting T.K. view of it.  I find that most of the fat comes off with skimming, as long as the liquid is at or just below the simmer.  The rest comes off after chilling in the fridge.

I have found truth in what you say about prolonging the temp at about 65-70 C - those stocks are usually beautifully clear and skimming is a snap.

 

[John Con]

I've heard another technique of making consomme by freezing stock and them letting it defrost in the fridge, held over a chinois line with cheesecloth. Apparently it makes a product equal to the raft method. anybody tried?

Yep. Saw Heston do it first. Can't remember if he rafted slightly first, but, definitely works. These days, I just raft since I have less need for my stocks to be crystal clear. Also, fridging makes fat solidify, and so no need to raft the fat. I used to see top chef ls chuck the fat, and so, did it for years. But the fat is reused, depending on the fat!

 

[french fries]

I've only heard of using ice later on in the process as an aid to getting the surface fat to firm up so it can be more easily removed.

Same here. The only reason I've heard of to put ice cubes in a stock is to make it easier to remove the fat.