Adventures with sodium alginate

[Jonathan M. Guberman]

Much to my delight the sodium alginate and calcium chloride that I ordered in the mail arrived yesterday. I've been waiting to make my first eGullet post a good one, and this seemed like the perfect topic.

First, a little personal background. (Feel free to skip this paragraph. You won't miss anything.) I've been a life-long kitchen-phobe: when I started working on my PhD and no longer had parents or dormitory food I relied mostly on take-out and the occasional hand-out to sustain me. Recently, however, I realized that if I can manage in the laboratory at work, then I should be able to manage in the kitchen at home. Hence, I've been teaching myself to cook and, though I'm still a novice, I've been happy with my progress. My tastebuds (and my friends') have been reaping the benefits. I find that I now spend most of my free time reading about cooking or playing around in the kitchen. (Incidentally, if there are any people within a reasonable radius of Princeton, NJ who feel like showing a novice a thing or two in the kitchen, PM me! I'm always looking to learn.)

When I read about "fruit caviar" and "liquid ravioli" I was dying to taste them. As I read more, it seemed like something that wouldn't be too hard to do at home. Thanks to this thread, I learned that Will Goldfarb's Room 4 Dessert in New York was selling both sodium alginate and calcium chloride. I called the restaurant on Monday, and the packets arrived on Wednesday.

(Apologies for the blurry photo; either I was shaking with excitement or I'm just a terrible photographer.) The powders came in nice re-sealable packages and are labelled www.willpowder.net. It's just a "coming soon" page as of this writing, but I look forward to seeing what other goodies they will offer.

I was eager to play around with my new toys, and so I rushed to make something. I was somewhat worried about acidity since I don't have any calcium citrate to balance the pH, so I decided to do a simpler variation on the tea ravioli recipe from the Texturas web site (the simplification being the omission of the lemon ice centres). I also used this post about liquid pea ravioli from the Hungry in Hogtown as a reference.

In my zeal I made at least one silly mistake. I added all of the alginate that the recipe called for to the water at once and then attempted to blend it in, rather than adding a little powder at a time and then blending, which led to gooey chunks that were difficult to dissolve (which you can sort of see in the picture.)

I probably could have dissolved these chunks by heating, but I was doing this for fun, not for serving, and I was eager to get some mixture into the calcium chloride bath.

And that's exactly what I did.

Here you can see a couple of tea balls floating in the calcium chloride bath. You can see the remains of an unsuccessful one on the right side in the middle. I definitely got better at forming the spheres as time went by, but I can't say I got a perfect shape every time. Still, even the deformed looking ones at the top look much more spherical once they're out of the bath.

Finally, here's a picture of the finished product. It's not much for presentation, and certainly wasn't the nicest one of the batch, but it's the only one that I took a picture of.

What did they taste like? Well, not to be glib, but it tasted exactly like iced tea. The texture was pure liquid. I experimented with leaving the balls in the bath for shorter and longer amounts of time. If I didn't leave it in long enough, they were very delicate. The longer they were left in the more durable they were, because they had a thicker skin. However, the skin has a bit of an odd feeling in your mouth and isn't nearly as flavourful. It seems to me that the goal of this particular preparation is to make the skin as thin as possible while still holding together.

The whole thing was definitely a lot of fun, and I can see what it delights people so much. I'm looking forward to experimenting further, and am curious to hear what others have done with this. In particular, I'm wondering if I can use baking soda rather than calcium chloride to change the pH of fruit juices without compromising flavour. If anyone has recipes for alginate dishes (other than the ones linked to in this post and the ones on starchef.com) I'd love to know about them, and any tips would be much appreciated. If I can, I'd be happy to answer any questions people might have (although I've put most of what I know in this post!).

Cheers!

Jonathan

[BryanZ]

Bad ass. Please continue doing this and update. It's about time home cooks started getting "molecular," so to speak. I plan to be doing much of the same in coming weeks.

[Malaclypse]

very cool, I'm just waiting on some CaCl and then I'll be doing some experiments of my own.

[johnder]

awesome work! Looking forward to your further experiments!

j

[MelissaH]

very cool, I'm just waiting on some CaCl and then I'll be doing some experiments of my own. 

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[soapbox]

Not to be nit-picky, but I taught this to my students not long ago: the correct formula for calcium chloride is CaCl2. Because calcium forms cations with a charge of 2+ and because the chloride anion has a charge of -1, in order to make a neutral formula you need to use 2 Cl anions for every 1 Ca cation.

[/soapbox]

MelissaH the chemist

[Malaclypse]

very cool, I'm just waiting on some CaCl and then I'll be doing some experiments of my own. 

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[soapbox]

Not to be nit-picky, but I taught this to my students not long ago: the correct formula for calcium chloride is CaCl2. Because calcium forms cations with a charge of 2+ and because the chloride anion has a charge of -1, in order to make a neutral formula you need to use 2 Cl anions for every 1 Ca cation.

[/soapbox]

MelissaH the chemist

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I stand corrected

[Mussina]

Great post. Thanks for sharing. Quick question -- I ordered some sodium alginate from Dharma Trading. When it arrived there was a warning on the package that ingesting it could cause diarrhea or runny stools (charming, eh?). As you might imagine, i haven;t dived in yet.

Are there specific food versions of sodium alginate or is this always a risk?

[Patrick S]

Great post.  Thanks for sharing.  Quick question -- I ordered some sodium alginate from Dharma Trading.  When it arrived there was a warning on the package that ingesting it could cause diarrhea or runny stools (charming, eh?). As you might imagine, i haven;t dived in yet.

  Are there specific food versions of sodium alginate or is this always a risk?

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The MSDS for sodium alginate lists these as possible symptoms of ingestion, so this is an effect probably inherent to sodium alginate. However, I doubt this a common side effect, because sodium alginate is one of the main ingredients in Gaviscon, a drug used to treat heartburn -- once ingested, the alginate forms a gel "raft" on the top of the stomach contents, so that if gastric reflux occurs, it is the less-irritating alginate raft that contacts the esophagus rather than the acidic stomach contents.

[Digijam]

Great post. Been doing similar experiments myself since getting hold of some alginate, calcium chloride and sodium citrate. Getting the ravioli shapes right is a bit tricky, but El Bulli style caviar is a cinch if you try using a dropper or syringe.

[Jonathan M. Guberman]

Great post. Been doing similar experiments myself since getting hold of some alginate, calcium chloride and sodium citrate. Getting the ravioli shapes right is a bit tricky, but El Bulli style caviar is a cinch if you try using a dropper or syringe.

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Thanks, Digijam. I definitely made some accidental caviar just from having drops fall off the spoon I was using to make ravioli. I'd like to try a dropper or syringe; any ideas on where I can find one, and what size I can get? I imagine the type used medically is too small, but maybe I'm wrong.

Edited April 28, 2006 by Jonathan M. Guberman (log)

[Patrick S]

Great post. Been doing similar experiments myself since getting hold of some alginate, calcium chloride and sodium citrate. Getting the ravioli shapes right is a bit tricky, but El Bulli style caviar is a cinch if you try using a dropper or syringe.

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Thanks, Digijam. I definitely made some accidental caviar just from having drops fall off the spoon I was using to make ravioli. I'd like to try a dropper or syringe; any ideas on where I can find one, and what size I can get? I imagine the type used medically is too small, but maybe I'm wrong.

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I think you can buy syringes OTC at drug stores in most states.

[Lee Ratliff]

Very interesting thread. I'm sure some creative types will come up with some very innovative applications for this technique.

Not sure if this is true, but I've been told that Burger King uses this technique to make onion rings. They make a paste of shredded onions and sodium alginate, extrude it through a ring shaped die, cut it off, and the "onion ring" drops into a calcium chloride bath where it firms up. Then bread, freeze, ship, deep fry, and serve. They reduce labor costs, can use the entire onion, can use damaged onions, and achieve the uniformity that franchises love. Can anybody confirm this?

Lee

[Patrick S]

Very interesting thread.  I'm sure some creative types will come up with some very innovative applications for this technique.

Not sure if this is true, but I've been told that Burger King uses this technique to make onion rings.  They make a paste of shredded onions and sodium alginate, extrude it through a ring shaped die, cut it off, and the "onion ring" drops into a calcium chloride bath where it firms up.  Then bread, freeze, ship, deep fry, and serve.  They reduce labor costs, can use the entire onion, can use damaged onions, and achieve the uniformity that franchises love.  Can anybody confirm this?

Lee

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Well, I don't know if the onion rings are extruded or not, but both sodium alginate and calcium chloride are listed as ingredients in the onion rings. BK nutrition infor (PDF format)

[Patrick S]

Check out this image of BK onion rings. They are remarkably uniform in size.

ETA: So either 1) BK has discovered a variety of onion that grows in a perfectlycylindrical shape of consistent diameter from plant to plant, 2) is spectacularly wasteful and uses only onion slices of a given diameter , or 3) they are extruded.

Edited April 28, 2006 by Patrick S (log)

[Kerry Beal]

The syringe that I see in the 'kit' from the Texturas web site appears to be what is called a catheter syringe. I has a larger opening than the typical luer lok syringe that you attach to a needle. I suspect you might be able to vary the size of the caviar you make depending on the syringe.

The one thing I couldn't tell from that site was how you make the large shapes of the ravioli using the spoons they show. Do you just lay the spoon in the CaCl2 solution and slowly turn the spoon over to release the liquid?

One other question, is the other ingredient 'Citras' sodium citrate or citric acid, because it says 'made from sodium citrate'?

I'm just waiting for a shipment to arrive from Xenex in Vancouver, they are a Canadian source of food grade CaCl2 and Na Alginate.

Can't wait to start playing.

Do you think the resulting products could be dried off then dipped in tempered chocolate? This could be the start of the ultimate liquor chocolate.

[Jonathan M. Guberman]

Check out this image of BK onion rings. They are remarkably uniform in size.

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It could also be that the onion rings they use for photography are either fake or are chosen for their uniformity. On the other hand, it wouldn't surprise me if they were indeed extruded.

The syringe that I see in the 'kit' from the Texturas web site appears to be what is called a catheter syringe.  I has a larger opening than the typical luer lok syringe that you attach to a needle.  I suspect you might be able to vary the size of the caviar you make depending on the syringe. 

The one thing I couldn't tell from that site was how you make the large shapes of the ravioli using the spoons they show.  Do you just lay the spoon in the CaCl2 solution and slowly turn the spoon over to release the liquid?

One other question, is the other ingredient 'Citras' sodium citrate or citric acid, because it says 'made from sodium citrate'?

...

Do you think the resulting products could be dried off then dipped in tempered chocolate?  This could be the start of the ultimate liquor chocolate.

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Thanks for the syringe info.

For making ravioli, I did exactly what you described, using a hemispherical measuring spoon. A regular spoon, of course, wouldn't work. There's actually a video clip of this being done at El Bulli which can be found at this link.

I forget where I saw it, but some other site mentioned using sodium citrate, so that's what I assume the 'citras' is. The whole point is to lower the pH of the solution, so I don't think adding citric acid would work.

Regarding dipping in chocolate, I recall reading somewhere that the product is thermally stable. However, I did try a couple times to heat up the tea balls they burst or deflated pretty quickly. I'd like to try it again with a little more alginate. Also, remember that the solidification continues even after you remove the balls from the water bath, so you want to eat it pretty soon after you take them out. Now, if you could use the calcium in milk chocolate to perform the reaction, you might be able to do something interesting...

[Patrick S]

Check out this image of BK onion rings. They are remarkably uniform in size.

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It could also be that the onion rings they use for photography are either fake or are chosen for their uniformity.

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Possible, but I don't think so. Here's a picture of 3 BK onion rings on someone's blog, and they appear to be similarly uniform.

[BryanZ]

I'd love to hear if Chef Goldfarb's powders have suggested ratios on the package. If not, I'd love to hear what proportions you're using and also the effects of changing pH using sodium citrate.

Great find on the Bourdain clip, btw. He looked genuniely giddy.

[Digijam]

I'd love to hear if Chef Goldfarb's powders have suggested ratios on the package.  If not, I'd love to hear what proportions you're using and also the effects of changing pH using sodium citrate.

Great find on the Bourdain clip, btw.  He looked genuniely giddy.

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For ratios it's worth visiting that Texturas website, which has three key recipes - including one that's likely the same as for Chef Goldfarb's mango caviar, and another that uses citrate to balance out an acid ingredient. Adria does mention using baking soda to do the same ph-balancing job in this recipe at Starchefs, but I'm guessing that by doing it this way there's a greater chance of getting a bitter flavour if the balance isn't exactly right.

The Texturas syringe has a surprisingly wide opening (about 4mm), so any non-hyperdermic drug store model should do the trick.

Jonathan: The ravioli should be stable enough to heat - there's another Adria recipe at Starchefs here, where he melts caramel wafers onto the ravioli -

so I'd suggest adding a little more alginate and/or increasing the bath time.

[Jonathan M. Guberman]

Jonathan: The ravioli should be stable enough to heat - there's another Adria recipe at Starchefs here, where he melts caramel wafers onto the ravioli -

so I'd suggest adding a little more alginate and/or increasing the bath time.

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I think you're right, the problem was most likely the amount of alginate. As I showed in my original post, I had trouble getting all the alginate to dissolve, and when you're dealing with such small amounts to begin with that amount is probably significant. On my next run-through I'll definitely be more careful.

BryanZ, from what I understand (from the Texturas website) the alginate/calcium reaction doesn't work properly at a pH lower than 4, so the reason for adding sodium citrate or something else is simply to allow the solidification to occur. I think I'm going to borrow a few pH indicator strips from the lab and try to do some real experiments sometime. If and when I do I will, of course, post the results here.

Has anyone found a source for sodium citrate? I'd love to be able to use it rather than baking soda.

[Digijam]

I think you're right, the problem was most likely the amount of alginate. As I showed in my original post, I had trouble getting all the alginate to dissolve, and when you're dealing with such small amounts to begin with that amount is probably significant. On my next run-through I'll definitely be more careful.

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I had the same problem first time round. Some of the recipes call for heating, so maybe you're right about it helping the alginate to fully dissolve.

Has anyone found a source for sodium citrate? I'd love to be able to use it rather than baking soda.

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It's available at Chemistry Store, but I can't vouch for them. Alternatively, the Texturas one is available from German supplier Buchgourmet.

[Kerry Beal]

Has anyone found a source for sodium citrate? I'd love to be able to use it rather than baking soda.

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In Canada www.xenexlabs.com

they may ship to the states, would have to ask them. They also have alginate and CaCl2

Edited April 29, 2006 by Kerry Beal (log)

[alanamoana]

according the the texturas web site, PCB Creation

is the distributor of their products in France. I've ordered from them before and they are very reputable. I think they also carry the "kit" for working with alginate and calcium chloride. They also carry all the other fun things like licithin, gellan, xantham gum, etc.

thanks for posting your demo, it was fun to see how someone can do this easily in the home.

edited to add: and darn you for making me order some from w. goldfarb! i've been avoiding this but you made it seem so accessible that i had to give it a try. there aren't many people on the west coast doing this stuff, so it should be fun.

Edited April 29, 2006 by alanamoana (log)

[Jonathan M. Guberman]

My concern with all of those North American sodium citrate distributors is that none of them are marked as food grade chemicals; that means that, essentially, there is no guarantee that there isn't a contaminant that will make you sick. Of course, the Texturas stuff doesn't have that problem, so I may have to look into getting some from Europe. That said, there's plenty to experiment with even without sodium citrate; I'm going to try to experiment some more later this week.

[Kouign Aman]

If you use the pH indicator strips, please dont dip them in your working stock. They arent made with good eatin' in mind. Remove a bit of stock and drip it on the indicator strip instead.

If you get really into this, Fisher Scientific sells reasonably priced pH meters. Just what every well-stocked kitchen needs!