• Cut apples (reserve one for garnish) and toss with ascorbic acid (vitamin C).

• Juice the sliced apples and strain the juice.

• In small pot combine the the apple juice, gelatin, sugar, and glucose syrup. Warm while whisking until everything has fully dissolved.

• Blend the apple juice, egg white, and malic acid.

• While blending, add the apple juice and gelatin mixture from step 2. Continue to blend on high for another minute.

• Place the mixture from step 3 into a whipping siphon and charge with three gas charges.

• Chill the siphon until very cold.

• After siphon is very cold, check consistency of the foam. It should hold a stiff peak for at least a minute.

• If base discharges and is light and fizzing, may need an additional charge of gas or further chilling.

• Chill four wide mouth canning jars (pint size) in freezer.

• Fill jars half way with the green apple foam. Working quickly, place a lid and ring band on to the jar.

• Place the jars into vacuum chamber and pull a vacuum until the foam just bumps the lid. Then stop the vacuum cycle. The lid should seal the jars when the pressure is restored to the chamber, preventing the expanded apple foam from collapsing.

• Place the jars into the freezer.

Tip: it's important to use jars that don't taper at the neck, this will make it much easier to remove the frozen foam later.

• Prepare small bath of liquid nitrogen.

• Peel and cut the one reserved green apple into thin slices and freeze these in the liquid nitrogen.

• Once frozen, place the frozen slices in a spice grinder and cryo-mill into a powder.

• In small bowl, add the apple power, malic acid, and sugar.

• See here to purchase malic acid.

• This mixture can be stored frozen until needed.

• With a bath of liquid nitrogen prepared, remove one frozen jar of apple foam from the freezer. Twist of lid and pry open lid.

• Run a long knife along the sides of the jar to remove the frozen apple foam from the jar.

• Quickly cut this cylinder of frozen green apple foam into portions and drop them into the liquid nitrogen to harden them again.

• Place the portions of aerated green apple sorbet into pre-chilled serving vessels.

• Using a cold spoon, dust the aerated sorbet with apple powder.

• Allow a minute or so for any remaining pools of liquid nitrogen to evaporated from the pockets of the foam, and then serve promptly. Or reserve in a freezer until needed.

NOTES

WHEN SERVING: Take care to not serve directly from the liquid nitrogen. The porous sorbet can harbor pools of liquid nitrogen that can burn your mouth.

FREEZING: Liquid nitrogen is not strictly necessary to prepare this recipe. It can be done with a very cold domestic freezer if you reduce the sugar by about 20% so that the sorbet freezes solid at a warmer temperature (sugar depresses the freezing point of the sorbet).

Another alternative is to create ad hoc ultra-cold freezer by filling a cooler filled with some dry ice. Pack the jars in pellets of dry ice to freeze solid. And after you slice the sorbet, return the portions to this bed of dry ice to harden them before serving.

COLLAPSE: If the aerated foam appears to collapse, do not serve it. Without proper aeration, the combination of a dense chunk of sorbet and it's extremely low temperature will burn the tongue.