Liquid Nitrogen: Part 3
In Liquid Nitrogen: Part 1, Liquid Nitrogen (LN2) was described as the liquid form of Nitrogen which while normally a gas, in its liquid state is extremely cold, −195.79°C. This property allows for some very interesting uses in modernist cuisine including Cryofrying, a technique used to great effect by Nathan Myhrvold and his team at Modernist Cuisine to create Cryoburgers and Cryo-grinding described by the team at ChefSteps and in Liquid Nitrogen: Part 2. In this installment I describe Cryo-shattering.
You may recall from Part 2 the video clip of a flower being shattered after dipping in LN2. This is an example of Cryo-shattering and can be used to advantage in the modernist kitchen. It is most commonly used to “shatter” raspberries and blackberries into its individual drupelets. Let me explain.
A drupe is a botanical term defined as a type of fruit in which an outer fleshy part surrounds a shell or pit which contains a seed. (Entymology: diminutive of “Drupe” Mid 18th century from Latin drupa ‘overripe olive’, from Greek druppa ‘olive’). Drupes include peaches, plums, and cherries. Some fruits are composed of multiple small individual drupes called drupelets. Examples of these aggregated fruits include raspberries and blackberries. (Although commonly considered “berries”, strictly speaking they are not a true berry which is defined as a fleshy fruit without a stone or pit.) If you freeze raspberries and blackberries, they can be “shattered” into their individual drupelets.
The video below filmed in super slow-motion beautifully illustrates cryo-shattering.
Super slow-motion video produced by the team at ChefSteps beautifully illustrates cryo-shattering.
The technique requires the “berries” to be frozen solid so the fruit is sufficiently brittle to break it up into its individual drupelets. It is very important to freeze the fruit as quickly as possible or you risk damaging the fruit. Water makes up more than 90% of most fruits and vegetables. This water is contained within the walls of the cells that make up the fruit. When water freezes, it forms crystals which because water expands when it freezes, punctures the cell membrane disrupting the structure and texture of the fruit. Further, when the fruit thaws, the melting water leaks out the damaged cell wall. The end result is a mushy and watery fruit or vegetable. This can be minimized by rapid freezing, as the faster water freezes, the smaller the crystals that form and the less the cell wall is disrupted. At −195.79°C, LN2 can rapidly freeze berries with minimal damage. At least until you smash them into their individual drupelets!
These individual drupelets make a nice garnish or accent to a dish. Also, with blackberries, it allows one to separate the white core (known as the “receptacle”) which makes for a more pleasant eating experience.
Freezing raspberries and blackberries in LN2
After only a few seconds, the berries are frozen rock solid!
After freezing, all one has to do is lightly tap the frozen berry to “cryo-shatter” them into their individual drupelets.
The berries broken into their individual drupelets. Note the blackberry drupelets have separated from the whitish core.
The final plating served with a delicious chocolate zucchini muffin for breakfast!
Stay tuned, there is more LN2 fun to come in future posts!