Dairy processing: Aseptic processing and packaging systems
Holding section
This is the part of the APPS in which heated product is held for the specified time required in the scheduled process. This section is located after the final heating section of the APPS, and may include the sensing chamber at the end. The sensing chamber is that portion which houses both the official indicating thermometer and the safety thermal limit recorder hot milk temperature sensors.
General conditions
Holding tube and all connections:
- have a sanitary design and construction
- are clean and in good mechanical condition
- the holding section is located:
- after the flow control device with no intervening flow promoters
- after the final heating section
- before the flow diversion device or any cooling section
- do not install any devices for short circuiting a portion of the tube or for removing a section of the tube
- such devices could reduce the holding time below that specified by the scheduled process
- do not heat any portion of the holding section between the inlet and the sensing chamber
Slope and support
A slope eliminates any air entrapment in the holding tube, which could displace product and reduce the holding time.
- Position the holding tube so that it has a continuous upward slope (including elbows) of at least 2% (2 cm per 100 cm)
- prevent variance in the slope by using mechanical supports to permanently fix the holding tube in place
Holding verification
The holding time is determined by calculation, and is specified in the scheduled process. If direct heating from steam is used, the extra condensate volume from the added steam is included in these calculations.
The calculated holding time is used to determine the minimum length of the holding tube needed to provide the proper holding time, based on the flow rate used.
- Calculate the proper holding tube length upon installation, and re-calculate it after any change is made to the system that could alter the flow rate and affect the holding time
- ensure the actual length of the holding tube is no less the calculated length
- Check the flow rate annually, whenever the seal is broken on the flow control device, and after any change is made to the system that could affect the holding time
- measure the flow rate of the system under the conditions outlined in the Set and sealed section
- verify that the measured flow rate is the same or lower than the value used in the calculation for the scheduled process
- Keep records of the above on file, including all supporting calculations
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