The hardware is slightly different as well: the glass section of the door of a washing machine is used as a vacuum chamber.
A vacuum chamber can be used to infuse a liquid into food. By creating the vacuum, the pore space of food that is occupied by air, gets saturated with the liquid.
This instructable is a variant on the set-up presented by Noahw. Please look here (https://www.instructables.com/id/Vacuum_Infused_Fruit_Cocktails) for some more information and an excellent video.
The main pupose however is different: infusing chunks of fruit with a water-sugar solution so they can be mixed in ice cream. The infused solution will partially act as a kind of anti-freeze resulting in fairly soft chunks of fresh fruit at low temperatures (freeze point depression, see also section 5 and 6).
It has taken a while, but here's my first recipe: Sugar infused Apple-Cinnamon icecream
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Step 1: What Do You Need?
1. The glass section of the door of a washing machine or any type strong glass (like Pyrex). Do not use any thin or poor quality glass as there is the risk of imploding the chamber!!!. Make sure it has a flat sealing face. Did I mention that following this instruction is at your own risk?
2. A wooden base plate (white MDF or any fairly solid type, 40x40x2 cm).
3. A gasket of the size of the glass bowl (green foil in the picture).
4. Two Aluminum pipes (length approximately 10 cm, outer diameter 1 cm)
5. Four pieces of wood for supporting the base plate.
6. Two hose clamps
7. Some hose
8. A Gauge
9. A vacuum pump (not shown)
Step 2: Prepare the Base Plate
Drill two holes in the base plate (diameter 1 cm). One is for the suction line, the other one is for the pressure gauge. If your pressure gauge is located on the vacuum pump, you will only need to drill 1 hole.
Glue the four supports to the wood. In the picture I have used 1 large en 2 short ones instead.
Step 3: Rig Up the Hoses
Fit the Aluminum pipes into the holes. If you need a small hammer to get them in, you’ll probably have an air-tight fit. If not, seal the edges with some glue. If your base plate is fairly thin, the pipes will probably not give a good air-tight fit.
Leave the pipes sticking out a bit, otherwise any liquid spoiled will be immediately sucked in by the pump.
Fit the hoses to the Aluminum pipes (one line to the pump, the other line to the pressure gauge unless your gauge is located on the vacuum pump). Use the hose clamps to rig-up the suction line and the gauge line.
Step 4: Finalise and Start-up
I have used a (perforated) rubber anti-slip foil as a gasket. It also prevents my food container from slipping. Other options are the inner tyre of a child’s bicycle or silicone rubber.
Place the glass chamber on the gasket and when you start the pump, you might need to push the glass chamber gently down until the gasket starts compressing.
Step 5: Discussion
Vacuum infusion relies on a combination of capillary pressure and osmotic pressure. It can be done with any liquid or type of food, but the following factors play an important role:
* The vacuum pressure.
* Porosity of the food
* The size of the blocks (small chunks will have a relative large surface).
* The composition of the liquid.
* Cell structure / texture of the food.
* The viscosity of the liquid. Hence the temperature is of influence as well.
* Surface tension.
This application is intended to infuse fruit with a water-sugar solution and to use it in ice cream. The infused solution will partially act as a kind of anti-freeze resulting in fairly soft chunks of fresh fruit at low temperatures (freeze point depression).
The remaininig solution, which contains some of the fruit flavors, can be re-used as sweetner in the ice cream mix provided the mix is corrected for this additional water (reduce the amount of milk and increase the amount of cream).
Step 6: Results
under construction (I'm currently working on some recipes. More to come soon).
Update 25th April 2010
Started with apple. Made batches and just froze them without making the ice cream (and tasted them once they were frozen).
I varied with: block size, sugar concentration, vacuum pressure, infusion time and infusion temperature.
Expect to post my first recipe this month...Sugar Infused Apple-Cinnamom Ice Cream.
Here it is: