1. Pre-freezing of the sample is most important. The sample should be thoroughly frozen preferably as a thin layer in a suitable container

2. Check that the condensate has been drained from the freeze drier and close the top

3. Switch on at the mains. Place Perspex cover over the chamber. Press 'Refrigerate' and allow to cool until the condenser temperature reaches 40ºC (several hours). Closing the main lid of the unit will assist cooling

4. Transfer the sample from the deep freeze to the specimen trays in the chamber. Connect all the heating leads between the trays and insert the thermocouple into the sample

5. Replace the Perspex cover over the chamber. Close the 'air to chamber' and 'air to pump' valves. Open the 'isolate chamber' valve

6. Press 'pump' and hold Perspex cover in place until it has sealed

7. As the chamber evacuates gently tap the Pirani 10 dial to measure the chamber pressure
(At the start of the drying operation the temperature of the frozen product is somewhere below - 30ºC at the centre and surface. As sublimation commences latent heat from within the sample will be extracted and thus reduce the sample temperature even further. To avoid a state of equilibrium and also decrease the drying cycle, the temperature can be regulated to establish a delicate balance)

8. Adjust the Sunvic dial carefully such that the temperature of the sample is -5ºC

9. The process is completed when the sample remains at a constant weight. The time required will vary according to the type of food and sample size. Leafy products will dry faster than dense products (E.g. diced potato)

10. When the sample has dried, switch off the refrigeration. Close the 'isolate chamber' valve. Turn off the sunvic dial

11. Open 'air to chamber' valve slowly to equalise the pressure. Switch off the pump and admit 'air to pump'

12. Remove samples

13. Allow the chamber to defrost for a few hours then drain the condensate from the coil

13. Switch off at the mains