Transparency

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.

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.

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.

Transglutaminase

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.