Retort Control in the Food Industry using the C1960
AG/RCP–006_2
4
The Retorting
Process –
Steam Cooking
The cooking sequence is similar in both vertical and horizontal retorts:
•
Load retort with canned product
•
Lock cover or door
•
Vent the retort
•
Raise to cooking temperature
•
Cook product for a predetermined period of time
•
Either cool with water under pressure. (normally used for large cans)
or pressure relieve (Normally used for small cans)
•
Water cool at atmospheric pressure
•
Unload retort
Loading, locking the cover or door and unloading are strictly manual functions.
▲
Venting Period
Venting the retort is the first step in the cooking cycle and takes place after the door,
or cover, is screwed down tightly on the loaded retort. Its purpose is to eliminate the
air in the retort. Steam is used to purge the air from the retort in order to obtain a
steam-only atmosphere. It is important to get the air out of the retort before the
cooking period starts because air, due to poor heat conductivity, acts as an insulator
preventing the canned product from being adequately cooked.
Proper venting is
achieved by purging for a preset time period and to a desired temperature - there
are no shortcuts.
▲
Raise-to-Cook Temperature Period
This period occurs after the completed vent period and is the interim period from
the vent temperature to cook temperature.
C100
Pressure Controller
Steam
C1960
Multi-Recipe
Profile Controller
Current to
Pressure
Converter
Steam
Control
Valve
Current to
Pressure
Converter
Pressure
Control
Valve
Gauge
Pressure
Transmitter
Fig. 3 Loading a Horizontal Retort