83 replies to this topic

[BryanZ]

Pathetic pun aside, can anyone clarify how one clarifies a broth using powdered gelatin. My understanding is that one adds a very small amount of gelatin to a liquid needing to be clarified. This gelatin then binds to the small particulate matter and can be filtered out.

Should the liquid be heated after the gelatin is added, how long does this process take, what do I filter through (cheesecloth, filter paper)?

I understand this a typical process in clarifying juices, wine, and beer, but I can't find step-by-step guide. Clarifying broths with egg does impart an eggy flavor, so I'd like to try this out.

I should note that, again, I first saw this idea on ideasinfood.

[jayt90]

I checked ideasinfood and couldn't find anything on this. Nor could I get their Google search device to work. I wonder if you mean alum, which will precipitate and clear wine, juice and broth. I don't think it is used much now because of aluminum content.

Egg whites are used as a wine clarifying agent in France. Some traditional first growth vineyards will not depart from this method, and still make rich omelets the next day for the staff with the yolks. I have never heard a critic describing a wine as eggy.

I have used beaten egg whites to clarify stock, or consomme, and found that it works well if there is no trace of fat on the surface. The whites coagulate and carry particles to the bottom. The clear broth can be poured off, and I have never detected an eggy flavour.

[xdrixn]

if you do a search for 'gelatin wine fining' you'll find your answer.

[wattacetti]

The juice part is relatively easy since it's similar to fining wine (add gelatin, stir, let sink to bottom, filter).

Couldn't find anything specific on clarifying broth, but I suspect that the technique would eventually be similar to clarifying a consommé with a protein cap. You'd be making the gelatin and not just adding the powdered stuff straight.

If you elect to go with eggs to do it, I don't think you're going to get an eggy taste if you use just the whites; the albumin should be relatively flavorless (I find most of the "egg" taste comes from the yolk).

You can drip-filter the results through filter paper or a coffee filter if you want to make absolutely certain. Or, if you have a friend who works in a lab with a vacuum line, a 0.2 micron filter takes care of any remaining bits pretty quickly.

[BryanZ]

if you do a search for 'gelatin wine fining' you'll find your answer.

Not a bad start, but not exactly what I'm looking for either. I'm off to class now, but I'll keep looking in that vein. Thanks.

Anyone else?

Edited by BryanZ, 18 October 2006 - 11:34 AM.

[Vadouvan]

can anyone clarify how one clarifies a broth using powdered gelatin. My understanding is that one adds a very small amount of gelatin to a liquid needing to be clarified. This gelatin then binds to the small particulate matter and can be filtered out.

Probably.....

1.Gelatinise by standard liason method.
2.Freeze Solid.
3.Defrost over colander lined with coffee filter.
4.Suspended particulates captured by gelatin.
5.Dripping clear liquid retains flavor of base ingredient with clarity.

I used this to improve yield of tomato water, makes a fantastic "no heat" dashi.

[BryanZ]

Okay, here's an example. This is publicly available information so I think I'm okay to post this. I'll cite my source accordingly, but if the publishing parties don't want me to divulge this I'll quickly take it down.

Buttermilk consomme: 300g agave, 30g sugar to make a caramel then deglaze with 3852g buttermilk and add 20g salt, cook strain and clarify with .5%  gelatin

Other consommes are made in a similar fashion, with nearly all of them including the .5% gelatin clarification step.

This process might be somewhat different than what Vadouvan outlined. Or not. The step in Vadouvan's process I don't quite understand is the freezing. Why do it?

Some might wonder why I just don't ask Ideas in Food directly for queries of this nature. I like the discussion and the collective problem-solving and the new ideas that can spring forth.

Source: Ideas in food. Innovation.pdf notebook.

[godito]

Bryan, you should try emailing them with your question. I've done so before (I wanted to know the brand of dinnerware they use) and they were pretty cool. Also, they sometimes participate on this forum (I know I've seen them, I'm just too lazy too look them up, though... maybe it was in one of the good food blogs forum) Anyway, if you find out, let us know, I'm curious about that buttermilk consomme

[BryanZ]

They are indeed very cool and helpful. I think we can figure it out though.

[s_sevilla]

have you tried their method yourself yet? All I know is that for buttermilk, you can get it pretty clear if you just heat it up and force the buttermilk to form curds, but looking at the foie-gras broth, potatoe broth and other things they are doing now, I think the gelatin is just acting as a flocculating agent.

[BryanZ]

I think you're right. It seems that they're adding enough gelatin to bind to the particulate matter without geling the liquid. Once you strain through filter paper the gelatin and particulate matter are removed.

I guess my questions now are do you have to chill (or freeze) the liquid or will hydrating the gelatin in the hot liquid and letting it sit at room temperature for an hour or something be enough?

And there's the whole freezing thing I don't quite get. Why freeze if it's just going to melt through filter paper anyway?

[alanamoana]

if you heat the liquid, doesn't the gelatin dissolve too much to be filtered out (becomes too much part of the mix)? it would seem that you'd add the gelatin to a cool liquid and strain it out.

[BryanZ]

But according that same logic the gelatin wouldn't be able to hydrate in the liquid and do it's "thing."

[Vadouvan]

if you heat the liquid, doesn't the gelatin dissolve too much to be filtered out (becomes too much part of the mix)? it would seem that you'd add the gelatin to a cool liquid and strain it out.

You hydrate the gelatin in cold water and then add it to the warm mixture.

And there's the whole freezing thing I don't quite get. Why freeze if it's just going to melt through filter paper anyway?

Zupon...

Gelatin captures particulates.

Freezing breaks down the strucure of gelatin.

Defrosting releases the liquid.

Remember.....the particulates have been captured by the gelatin.

End product....Clear Liquid.

[nathanm]

This method is being used by most everybody doing cutting edge cooking - Heston Blumenthal, Wylie at WD50 as well as Alex and Aki at ideasinfood.

I don't know who did it first - I first heard about it from Christopher Young, who works with Heston. Heston and Harold McGee (and I) call this technique freeze filtering.

It is as described - add gelatin as you would normally. Freeze, then allow to defrost in a colander with a coffee filter. It works VERY well! It is an incredible techinque.

For a chicken or beef stock, you don't need to add the gelatin as long as the stock is concentrated enough to gel. It makes fantastic consumme.

It works because the gelatin molecules cross-link and in effect create a "filter" that traps particles. Normally speaking when you freeze a gelatin gel and defrost it, it will weep liquid. This is called "syneresis". This is a bad thing if you want to freeez and then thaw an aspic or dessert gel, and there are ways to combat it - typically by using different gelling agents (hydrocolloid gums like agar for example). However, in freeze filtering you exploit syneresis to the maximum extent - you want the syneresis because the weeped liquid is the product.

This is very different that the wine clarification method discussed in posts above. In wine clarification you put a TINY amount of gelatine into the wine - usally 10 to 120 ppm - that's parts per million. 10 ppm = 1 gram gelatin in 100 liters. This is WAY too weak to form a gel. You add it to the wine (heated to 140F/60C) then you let it cool (without freezing) and sit 48 hours, then you filter it.

To put this in perspective, to get a gel you use .5% to 1% or even gelatin, (and often much more), which is 5,000 to 10,000 ppm.

Instead it just precipates out particulates. This sort of technique would also be possible, but it can only cope with fairly small amounts of particulate, and in any event is quite different than the freeze filtering.

[BryanZ]

nathanm, you're golden. I didn't quite account for syneresis effect before, but now it makes perfect sense. Thank you very much.

It appears that Vadouvan was right all along. Figures.

[Rocklobster]

I forgot to respond to this thread a while ago... I got the process to work beautifully with peanut butter. Peanut Butter consomme is fairly mind boggling, since there are few things more opaque than PB...But i got the process to work. The only complaint i have is that it is SLOOOOOOW... and you cant heat the liquid. So booo to that...but theres plenty of cold applications you could use it for.

500g PB
1500g Water
2ea Ancho Chilies
20g? Gelatin(I forgot to write it down haha it may be less)







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[skidude72]

Bryan your always one step (or many) ahead of me. I've been trying to figure out this clear broth concept since i started to see it at ideasinfood.

[BryanZ]

Apparently you can heat the liquid, though. At least ideas in food uses the consommes for poaching.

[Rocklobster]

Oh yes you certainly can. But i believe the clouding comes from bases that are very high in protein? Its something to do with that, because Alex admitted that the chocolate consomme could not be heated either. But his buttermilk and Brown butter consomme's are able to be heated.



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[MobyP]

can anyone clarify how one clarifies a broth using powdered gelatin. My understanding is that one adds a very small amount of gelatin to a liquid needing to be clarified. This gelatin then binds to the small particulate matter and can be filtered out.

Probably.....

1.Gelatinise by standard liason method.
2.Freeze Solid.
3.Defrost over colander lined with coffee filter.
4.Suspended particulates captured by gelatin.
5.Dripping clear liquid retains flavor of base ingredient with clarity.

I used this to improve yield of tomato water, makes a fantastic "no heat" dashi.

You don't need to add gelatin to use this method - as most stocks have natural quantities anyway. This is now the preferred method for clarification used by Heston Blumenthal. He thinks you get the same clarity as a raft, with much less flavour loss. He uses it for a lamb gelee with very nice results.

[s_sevilla]

Just a quick note to see if my understanding of the effect is correct: By freezing the gelatenized liquid, the water forms ice crystals, these crystals force the water to expand in volume and form sharp crystals that break out of the gelatin matrix. This causes the gel to swell. Upon thawing the water is no longer "trapped" by the gelatin matrix, and the subsequent ripping caused by the ice crystals leaves microscopic paths through which the latent water can leave the gelatin matrix, while the particulate matter (along with some liquid) is still maintained in the gelatin. Thumbing through McGee it seems like the gelatin strength/bond strength has a lot to do with the efficiency of this application, and salt and acid in moderation should be able to improve yield. note this is bond strength, and not an increased concentration of gelatin.

This makes sense to me....I'm not sure if it is entirely correct, if someone else out there could give me a little more insight it would be much appreciated.----thanks.

[s_sevilla]

I don't think that the clarity issues have anything to do with the protein content because both buttermilk and brown butter have casein (a protein molecule).

Looking at the results on testkitchen and ideasinfood, it looks like starch is more likely the culprit here because the chocolate, potatoe, and the peanut broths all have this problem, and it seems the most common component among them is starch.

[s_sevilla]

After some further reading It looks like osmotic pressure has a lot to do with this.

Edited by s_sevilla, 15 November 2006 - 01:32 AM.

[Rocklobster]

Interesting starch could be the answer, I really have no idea. I assumed it was protein because im fairly certain that that is what makes standard stock based consommes become cloudy after being reheated. Its been a while since Skills 1 though so I will have to go back to my notes.






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[s_sevilla]

I would have to play around with this more and read through McGee....I did, however, find a very interesting paper on the effect and causes of syneresis....let's just say it has a lot more science to it than most would need for any Molecular Gastronomy, but the short is, the effects of syneresis have a lot to do with micelles and dissolution of Gelatin molecules during swelling and shrinking, as well as the stretching and contraction of molecules and bonds (a little bit like a glutan matrix).

[skidude72]

I'm curious if anyone has done some more work on with this proccess, if so, do you repeat the process of clarifying with gelatin becuase my broths keep tasting very watered down and bland.

[Shalmanese]

a) Does the original stock taste bland? If so, you probably should reduce it before clarifying.
b) Did you salt correctly, stupid I know but it could be the cause.

[cookman]

I'm bumping this thread up following an interesting article written on this topic by Harold McGee in the NYT.

Click here

I read somewhere that the gelatin should be 0.5% by weight. Does anyone know if that amount holds true for both leaf and powdered gelatin?

[chefadamg]

OK...so 2 cups strained fresh carrot juice addded to .05% gelatine.....freeze...thaw in fridge w/ coffee filter will yield a clear carrot juice??
So .05% gelatine.... is by weight of the carrot juice?