FORAGING FRIDAY: FRUIT CAVIAR

Foraging Friday documents Kitchen Toro's exploration of New York's diverse restaurants, neighborhoods, stores and their ingredients and flavors (from left to right: Agar Agar, Sodium Alginate, Calcium Chloride, again, Agar Agar, and Calcium Lactate).

Warning: this post includes a lot of behind-the-scenes-web-research for future reference purposes and food chemistry.

A few months ago I read an article in The Times' Dining Section titled, "Fruit Gets Dressed Up As Caviar," about a process "pioneered by Ferran Adrià of El Bulli near Barcelona," that enabled Will Goldfarb, the chef and owner of Room 4 Dessert, a dessert bar, to create something called fruit caviar-- fruit juice on the inside of small globules. It piqued my interest as did the restaurant. The technique seemed like something to play with once I'd had a little more experience in the kitchen.

When we moved into Level Three and the pastry kitchen I noticed one of the Level Four students, Nelson, playing with the technique. I remembered the article and suddenly, watching him do it, it didn't seem as complicated anymore. My most recent foraging goals were to find both the materials that enabled the process and instructions to follow in order to duplicate the results.

Sodium Alginate and Calcium Lactate are the materials that enable the process. According to Wikipedia, "the chemical compound, Sodium Alginate is the sodium salt of alginic acid. It is an extract of seaweed and is used as a thickener in the food industry and as a gelling agent and emulsifier. It is also used in indigestion tablet. The major use of Sodim Alginate is in textile industry where it is being used for Reactive Dye Printing. Its empirical chemical formula is NaC₆H₇O₆."

Again, according to Wikipedia, Calcium Lactate is "a white crystalline salt made by the action of lactic acid on calcium carbonate; used in foods (as a baking powder) and given medicinally. Calcium lactate is often found in aged cheeses. Small crystals of it precipitate out when lactic acid is converted into a less soluble form by the bacteria active during the ripening process. In medicine, calcium lactate is most commonly used as an antacid and also to treat calcium deficiencies. Calcium lactate can be absorbed at various pHs and does not need to be taken with food for absorption for these reasons."

I've found some indication online at Chowhound.com that Chef Goldfarb is actually selling mini-kits of Sodium Alginate but I hadn't been able to buy them online and I still haven't made it down to the restaurant so I ended up purchasing the Sodium Alginate from L'Epicerie which I stumbled across on Google (I'd actually never heard of it before). It's an interesting site and they also have the Boiron Fruit Purees we use at school which I'd been looking for unsuccessfully at my local grocers' and Whole Foods. I also bought xxx and xxx mistakenly buying the xxx in stead of the Calcium Lactate.

The materials recently arrived (left) and suddenly stuff was being offered to me at school! Nelson was kind enough to bring in some extra Calcium Lactate for me to use (image at top, film cannister on right) and a student from Level Two offered to bring some in as well (image at top, left in silver packet) but it turned out to be Agar Agar. The next foraging installment in this project is to find some instructions. I'd love to have information from Chef Adria himself and he does have a cookbook, "El Bulli, 2003–2004 by Ferran Adrià."

WD-50's pastry chef, Sam Mason, was quoted in Food and Wine magazine as saying, "I should take Spanish classes so I can read it," adding, "but the pictures are ridiculously great. Worth the $210."

Well, Amazon's selling it for $129.50 but for only being in Spanish it's too rich for my blood. I'm going to have to figure out the instructions some other way. On a website called Starchefs.com there's a segment down on the lower right side that looks like this with an accompanying video demonstration:

Talks on This Year’s Important Contributions
Ferràn Adria, El Bulli
Modifying processes and products in textures created on the basis of liquids and purées.

Furthermore, on the site, Texturaselbulli, there are pages describing sphere preparation, and something titled "Sferificacion. Recipes," which gives indredients and processes for melon cantaloupe caviar, spherical mango ravioli and spherical tea ravioli. Further digging reveals that the Texturas site also sells a kit which supposedly includes all necessary ingredients and directions as well as xantham gum, a thickener which I saw WD-50's Wylie Dufresne using on Iron Chef America the other night in a battle against Mario Batali, but one project at a time.

EGullet has a thread about where to get the ingredients and points the way to some instructions at a site called Hungry In Hog Town. It was here that everything seemed to come together, he details the process of making pea spheres, notes that the technique can be reversed so that the balls don't continue to turn into solid gel. The EGullet forum also directs readers to Will Goldfarb's site which actually sells the powder, willpowder.net.

On willpowder, the ingredients and processes are fairly simply described:

For a calcium chloride bath mix: 6.5G Calcium Chloride & 1L Water.

For caviar mango in the style of El Bulli mix:

• 250G Mango Puree
• 250ML Mango Water
• 1.8G Sodium Alginate
• 1.3G Sodium Citrate
  

The directions say to bring the water to a boil to dissolve the sodium alginate. Allow to cool, mix well with mango puree and sodium citrate. Drop into calcium solution, allow to set, strain, rinse and reserve cold.

There are a couple of other neat tricks that are noted on willpowder as well like the "Key Lime Cloud," and something called "Tea Air," as well as a Meyer Lemon Fluid Gel. Have I said cooking is fun yet? I mean, sure, it's a lot of work that goes into producing these spherical color globules, this "Music of the Spheres," which wouldn't otherwise be seen but if you ever were a kid that wanted to do magic this is pretty close.

Meyer Lemon Fluid Gel

• 300ML Meyer Lemon Juice
• 300ML Water
• 300G Sugar
• 9G Agar Agar
  

Bring water and sugar to a boil to dissolve agar. Allow to cool before mixing with lemon juice. Allow to set until cold. Process in vitamix until creamy, strain, reserve at ambient temperature.

Another thread on EGullet notes:

"We were doing the Alginate thing for awhile in Miami. We were making the solution as follows."

• 1 liter water
• 20G Alginate, Iimmersion blend/no lumps/rest overnight
• 100G Alginate solution to 150G flavour/may have to adjust for acid, etc.
• Calcium Cholride solution was 20G to 1L water.
  

"What we did was, because of the volume we needed, was copy the set up that they use(d?) at El Bulli. If you go to imagegullet, or better yet, do a seach in the Spain forum, you'll find a thread by a stagier from El Bulli, and he has pics of the set up.

"Those plastic dropper type syringes you can get at any pharmacy, as mentioned." Lastly he adds, "regarding heating the Alginate: We never found it necessary."

Now to actually try to make the stuff!