There’s Always Room for Gel…

2007.May.26 Saturday · 4 comments

in Food & Recipes, Life

 Animal jelly; glutinous material obtained from animal tissues by prolonged boiling. Specifically, a nitrogeneous colloid, not existing as such in the animal body, but formed by the hydrating action of boiling water on the collagen of various kinds of connective tissue (as tendons, bones, ligaments, etc.). Its distinguishing character is that of dissolving in hot water, and forming a jelly on cooling. It is an important ingredient of calf’s-foot jelly, isinglass, glue, etc. It is used as food, but its nutritious qualities are of a low order.”

– Definition of Gelatin(e)

Buenos Aires – Oh yum… doesn’t that just sound like what you want to eat? What would Bill Cosby say about room for a nitrogeneous colloid? That’s what I’d like to know. As one might surmise, this week’s class was on the world of gelificantes – gelatins, carrageenans, and alginates – to give the broad strokes. There are folks out there that are far more adept at expressing all the chemistry and physics stuff that goes into how these work – more or less by making molecules line up in lattices and expelling water – I’m going to try to just give a look at some of what can be done with them.

My guess is that most folks are pretty familiar with gelatin itself – most of us grew up with it in some sort of powdered form, either flavored or not. There’s also “sheet gelatin” which is much more commonly used in the professional cooking world – it’s easier to work with, measure, dissolve, and not make a mess. Less commonly known is the vegetable version of gelatin, agar-agar, which is derived from algae, but has much the same properties. Agar-agar gives a stiffer gel than gelatin does, so when the animal versus vegetable thing isn’t coming into play, the texture thing is. You can also mix them for an in-between texture, as was demonstrated for us in this “vegetable parrillada” – each rectangle is a gelified vegetable juice extraction: green and red peppers, carrot, celery, asparagus, onion, and turnip. The original recipe called for a carbon flavored oil to be drizzled over the top – easy enough to make, warm a briquet of wood charcoal in oil, or butter, until it picks up the flavor – or, as our instructors did, just add some liquid smoke to the oil. Either way, a slightly odd way of imparting the grilled flavor to these vegetable gels, which were tasty enough, but we’re back to, other than for the pretty presentation, would I want to eat these, or grilled vegetables? On the other hand, our instructors admitted that for the most part, these techniques wouldn’t normally be presented as entire dishes, but would be used as compliments to more traditional prepartions – now we’re moving in the right direction.

Gel Vegetable ParrilladaCloseup of red pepper gel

Passionfruit marshmallowsAnother interesting version was gelatin mixed with methylcellulose. Now, this is a plant derived product that has the interesting property of dissolving in cold water, but gelling, or thickening, when it gets hot. There are folks out there who are experimenting with all sorts of hot gelatins. It’s also a laxative, something to keep in mind if you’re playing around with all these chemicals. Here, they demonstrated making marshmallows out of taking some passionfruit pulp, heating and mixing a small part of it with gelatin and the larger portion mixed with methyl cellulose, then combining them – resulting in a compound that is thickened enough to form when cold, as here it is piped into three little hills, and then sets into a spongy texture when heated. What’s different from traditional marshmallows is not having the beaten egg white or sugar to give it the spongy texture – this is essentially pure fruit pulp – and the addition of the methylcellulose so you can heat it and serve it hot with the marshmallow texture.

Prosciutto and MelonCarrageenans are algae derived products, of which there are apparently a large number, and they’ve been used as gelling agents for centuries. There are three main classes of commercially produced carrageenans, kappa, which form strong, rigid gels; iota, which form soft gels; and lambda, which form gels out of proteins rather than water based liquids – e.g., used for thickening dairy products. I’m not sure why not much emphasis was put on this particular class of gelling agent, but only part of one recipe was demonstrated using it, a slightly gelled “broth” – made from boiling prosciutto in water, then straining and degreasing it, and then adding the iota carrageenan to it to form a sort of thick almost syrup constency gel in which could be suspended something else… in this case little melon caviar made by using the last class of gelling agents, the alginates, which I’ll get to in a moment. All well and good as an interesting “cocktail” – though I wouldn’t say it beats out fresh melon wrapped in just sliced prosciutto….

Closeup of melon caviarI’d guess the reason that we spent most of the evening on alginates is that first off, they’re the most unknown to most folks, and second off, we’re getting into the whole playing with chemistry set thing. In a nutshell, you need two compounds – one of sodium alginate, the substance that’s going to end up gelling, and the other a solution of calcium salts, usually calcium chloride, though, as we’ll see, not always. Now, the question is, does the sodium alginate go into the food product, or does the calcium… and they produce two quite different results. Let’s start with the most basic, probably most common – in this case the melon caviar used in the cocktail above, and shown off here in closeup – the alginate is mixed into fresh melon juice, then this is dripped (using a large syringe), a drop at a time into a water bath in which calcium chloride has been dissolved. The droplets immediately form up into little spheres that gel. The longer they sit, the firmer they get, and it just sort of comes down to how firm you want them. After they reach the point you want – usually about 2 minutes or so, they are scooped out, rinsed, and then can be presented as is, they can even be warmed. The texture’s not that far off of something like caviar, and the flavor is nice and concentrated – which brings up a point, neither the alginate nor the calcium salt add flavor.

GnocchiHaving just last week spent a fair amount of time hand forming potato gnocchi, you’d think I’d be thrilled to find a time saver version. But, I like the way gnocchi come out, and these are the same only in that they use potato and have a vaguely pillowy shape. The “gnocchi” themselves use the same technique as above – mixing a potato puree with sodium alginate – and combined it with the previous week’s foam method – putting the puree into a canister where it could be foamed using nitrous oxide – into long snakes in a bath of calcium chloride, then, as the snake starts to gel, using scissors to cut it quickly into individual bite sizes. Because they’re much bigger blobs, they’re just left in the bath long enough to form a gelled shell on them, the inside remains, well, foamed potatoes. Strangely, well maybe not given my take on most of this, the more interesting part of the dish was the broth – no gels or foams – it’s a broth made from potato skins that have been roasted until they’re dried out, then simmered in water, strained, and seasoned.

Now here’s where stuff gets a little on the cool side. Reverse gelling. In these cases, the calcium salt is mixed with the base ingredient, or… a calcium based food substance, for example, yogurt, is used, and the water bath is a solution of sodium alginate. Because the alginate is the thing that gels, the food stays essentially untouched – liquid – and a clear gel forms around it, which you let set until it is thick enough to encapsulate whatever it is you’re working with. In these two dishes, one is made by pureeing and then straining olives to give a concentrated olive juice – it’s slightly thickend with some xanthan gum just so that it doesn’t spread out too quickly in the water bath before the capsule forms, and then the finished “olives” are put in some olive oil that’s been infused with herbs and spices, or a cocktail, or… who knows? The other dish is simply yogurt that was piped into the alginate bath in little knots, a capsule forms around it (hard to see because of the color), and then it’s served, more likely as a garnish than as here, in a simple caper vinaigrette. What makes them kind of cool is that when you break, or bite into, the thin gelled shell, you get a burst of whatever the liquid is inside.

Encapsulated olivesCloseup of encapsulated olive juice
Yogurt knots Closeup of yogurt knot

Up next week, I believe, from what one of the instructors said, we’ll be looking at one main ingredient, prepared in multiple different ways using these various techniques that have come up over the first three classes.


{ 3 comments… read them below or add one }

julietagb May 26, 2007 at 14:44

I want to know everything about these classes: who, where, how much, etc
I´m really interested in working with such gels.

dan May 26, 2007 at 15:50

It’s an introductory class – demos only, we don’t get to participate. Conducted in Spanish at the Instituto Argentino de Gastronomía, at their continuing education building at Montevideo 968. It’s an eight session class, once a week for three hours, cost is a little steep, especially for a demo class, but they have the advantage of being, apparently, the only cooking school around, possibly in South America, that’s offering this program – it runs 640 pesos for the eight sessions.

Tom April 20, 2010 at 01:46

This is a very interesting class that I would love to attend, being a cook and having an interest in science, things like hydrocolloids and carrageenans can really improve a food if done properly.

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