Sunday, December 27, 2009


Happy holidays!

When I hear the word transparency, I think of the thin sheet that is placed on a projector and written on. This pastry technique is similar, but edible.

Using pectin (a gelling agent used when making jams or jellies) and a low temperature oven, one can make flavored "glass" sheets.

Example: At the restaurant Alinea, chef Grant Achatz makes a raspberry transparency dusted with yogurt powder.

Raspberry juice is cooked with water and pectin (1 gram of pectin to 70 grams raspberry juice). The mixture is poured onto an acetate sheet. An acetate sheet is just an extremely thin plastic sheet, commonly used for chocolate work. The sheet is then placed in a 105 F oven for 8 hours, until the raspberry sheet has a glass like consistency.

Saturday, December 19, 2009

Sous Vide

Sous vide is French for "under vacuum". It is a method of cooking in which a food is sealed in a plastic bag and cooked for a long period of time at a low temperature. This process prevents the evaporative loss of flavor volatiles (the chemicals in food that give it taste) and moisture.

Chicken, vacuum sealed, flavored with orange.

The sealed bag of food is placed into a water bath--usually temperature controlled by an electric heating element--and left to cook. By cooking in a liquid that is of uniform temperature, the bags contents are raised to the temperature of the water. Over cooking, in the traditional sense, is impossible.
**Foods can become mushy if left in the water bath for too long.

The most commonly used example is that of a steak. When cooking a steak (aiming for medium-rare), you use an extremely hot (usually around 600 degrees fahrenheit) surface to create a caramelized crust and bring the center of the steak of 120 degrees fahrenheit. However, this technique invariably leads to a steak that is well done around the edges, medium, and finally medium rare at the center. By using the sous vide method, the steak is placed into a 120 degree F water bath and cooked until the entire steak is 120 F, from edge to center.

Below are three images. The first is a steak vacuum sealed. The second is a steak cooked sous vide. The third, for comparison, is a steak cooked to medium rare using a traditional grill and broiler (as you can see, it is not uniformly cooked).

In restaurants, sous vide is done using an immersion circulator, shown below.

This technique is usually used on meats (steak, chicken), fish and fruits (poached pear).

Example: For a sweet example, custard base can be vacuum sealed into a cylindrical mold and cooked sous vide. Here, Meyer lemon custard (the yellow disks) is paired with a tarragon liquid gel (the green sauce), yuzu caramel (yellow sauce), and black pepper blood orange sorbet.

Friday, December 11, 2009

Agar Agar

Agar Agar is a gelling agent very similar to gelatin. Unlike gelatin, which is derived from animal products, agar agar is obtained from seaweed. It is stronger than gelatin, and mixtures will set to a solid state at room temperature. It can be purchased as a powder, flakes, or sheets.

Traditionally used for desserts, agar agar can also be used to make savory "jello".

For most applications, agar agar can be used at a ratio of .5% to the total mass of the liquid. For example, if you were to make a watermelon gel, you would use 500 ml (equivalent to grams) watermelon juice and 2.5 grams agar agar.

To use, combine agar agar and liquid and boil to dissolve. Pour into container and allow to set.

Agar agar is extremely stable, and will retain its gelled state up to 85 degrees Celsius.

Example (Sweet): Grapefruit and yuzu gels with orange segments

Example (Savory): Short rib covered in a sheet flavored with Campari and beet. Here, the agar agar is used to make a thin sheet that acts as a "sauce" for the meat below.

Saturday, December 5, 2009


More commonly known as "meat glue".

This stuff has been around since the sixties, used by chains like McDonalds to hold their chicken nuggets together. It is also used to turn finely pulverized surimi into sticks of Krab.

It is a white powder that works by creating a covalent bond between the glutamine and lysine ends of a protein. Or, put simply, it holds meats together.

The most basic application of this chemical would be to take two proteins and bind them together. Shown below are alternating pieces of tuna and scallop.

This is done by rubbing one side of a protein with the powder, firmly pressing the two sections together, and refrigerating overnight.

Example: At WD-50, chef Wylie Dufresne uses transglutaminase to create "shrimp noodles". Shrimps are pureed and mixed with a small amount of meat glue (usually at a ratio of about 10 grams transglutaminase to 1 pound protein). The mixture is extruded through a fine tube into 165 F water (the temperature at which shrimp cooks). Upon hitting the water, the noodles cook, and the result is a pasta made entirely of shrimp.

Sunday, November 29, 2009

Liquid Nitrogen

Liquid nitrogen (LN2) is really, really cold. Water boils at 212 F, LN2 boils at -320 F.

Its ability to instantly freeze liquids is ideal for ice cream making. Traditional ice cream is made in a batch freezer. Ice cream base (dairy, flavorings, stabilizers) is placed into a cylindrical freezer whose edges are cooled to 22 F. Water in the base freezes and the ice crystals are scraped from the walls by metal blades. When the base becomes the consistency of soft-serve, it is removed and placed in a colder freezer to harden.

Smooth ice cream is achieved by forming the smallest ice crystals possible in the shortest amount of time. LN2 does this by freezing the water molecules on contact. There is also no overrun (air) added to the base, so the resulting ice cream is extremely dense.

To make ice cream this way, simply prepare an ice cream base of any flavor (without mix-ins, they would become rock hard) and place in a large metal bowl. While stirring with a wooden spoon, slowly add liquid nitrogen. Keep adding until desired consistency is reached--it will usually take between three and five liters.

Example: At the Fat Duck, chef Heston Blumenthal serves Bacon and Egg Ice Cream (made using liquid nitrogen) atop caramelized french toast.

**Always be extremely careful while handling liquid nitrogen. However, for a neat party trick, dip your fingers in a bowl of liquid nitrogen for a second or two. The temperature of a human hand is so much higher than that of the LN2, that your fingers will create a pocket of steam in the LN2, and you will not be harmed. This only works for a couple of seconds, so don't get carried away.

Sunday, November 22, 2009

Xanthan Gum

Xanthan gum is a polysaccharide, meaning it is composed of several sugars linked together. Its structure makes it ideal for thickening, stabilizing, and emulsifying.

When a very small amount is added to a mixture (on the order of 1% by weight), the mixture gains pseudoplasticity--it becomes very viscous, and retains that viscosity when shaken, stirred, heated/cooled. Pseudoplasticity is what gives a bottle of Heinz ketchup its impossible-to-pour quality; without xanthan gum, we would either buy ketchup as thin as water, or as thick as peanut butter.

In the kitchen, xanthan gum can be used to stabilize a foam. By pureeing any fruit or vegetable and blending the liquid you can aerate it enough to create a foam, but without a stabilizer the air bubbles will rapidly deflate.

The appeal of a foam is flavor. Any foam can be added to a dish, imparting its flavor but not physically affecting the dish in any way. Once eaten, the foam "disappears", imparting only its flavor.

To make a foam, combine any amount of fruit juice, vegetable puree, or any other liquid, with .5% by mass xanthan gum. Whip with hand mixer or in blender until desired consistency is achieved.

Example: At WD~50, chef Alex Stupak tops a dessert of braised pineapple and mustard ice cream with a coconut foam.

Saturday, November 14, 2009

Rotary Evaporation

Necessary? No. Awesome? Yes.

Rotary evaporators are used to distill solvents. Distillation is the process of separating a mixture into its components based on their volatilities (how easily they vaporize). This is done by evaporating and condensing the solvent.

A solvent is placed into the evaporation flask. The vacuum is used to greatly reduce the boiling point of the solvent. This allows the solvent to vaporize just above room temperature--higher temperatures would destroy the flavor and aroma compounds. As the solvent evaporates it travels into the condenser where it re-condenses (big shock) and drips into the receiving flask.

So now you're probably thinking, how the hell would this process apply to a restaurant kitchen?

Say you were making a dessert and wanted a sauce made from blood oranges.

By running freshly squeezed blood orange juice through a rotary evaporator, you could remove the water from the juice. Left in the evaporation flask would be a thin syrup, the "essence" of the blood orange juice. Using this syrup to make your sauce would result in a product that was more "orange-y" than anything you could achieve by reducing blood orange juice on a stovetop.

Example: At the French Culinary Institute, Dave Arnold uses rotary evaporation to make the "perfect" gin and tonic. He uses the evaporator to make concentrated lime juice and distill his own gin (flavored with any aromatic conceivable). Arnold even does away with the Schweppes and injects CO2 straight into the drink.

Tuesday, November 10, 2009

Tapioca Maltodextrin

Tapioca maltodextrin is a modified starch that thickens and stabilizes fatty compounds. It is produced from tapioca starch and comes in the form of a white powder. Maltodextrin has been used for some time as a fat-substitute in commercial products because it is easily digestible (similar to glucose) and retains its properties when frozen/thawed.

In the kitchen, tapioca maltodextrin can be used to bind fat and turn any high-fat ingredient into a powder. Upon consumption, the powder immediately reconstitutes in the mouth. This technique is usually applied to desserts (peanut butter, nutella, marshmallow fluff). However, it can have savory uses (bacon fat, foie gras).

When using tapioca maltodextrin, fats should be liquified, chilled, and combined in a starting ratio of 60% fat to 40% maltodextrin. The mixture should be blended and passed through a tamis (or sieve).

Example: At Grant Achatz's restaurant Alinea, caramel powder is made by combining crushed caramel and tapioca maltodextrin. The powder is served in a shot glass, garnished with salt.