Dairy Establishment Inspection Manual – Chapter 14 - Aseptic Processing and Packaging Systems
1.14.14 Cooling Section

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This section of the sterilizer uses chilled water and /or glycol to cool the hot product down to packaging and filling temperature. Since the FDD is located downstream from this section, the cooling section may become contaminated with potentially unsterile product during divert, and must be re-sterilized as part of the thermal limit controller sequence logic after a divert event.

Flash coolers are sometimes installed on the divert line to prevent injury to by-standers if a divert event occurs during the re-sterilizing of the holding tube and cooling section, when there is no cooling turned on.

1.14.14.01 General Conditions

The cooling sections must be clean and in good condition. They must be constructed of stainless steel or other corrosion resistant and easily cleanable material. The design should allow easy cleaning, and should not entrap product in crevices, joints, seams or openings. During operation, there should not be any leaks at gaskets, seals, or connections.

A routine program to monitor the condition of plates and tubes (pin holes in plates, gasket condition, cracks, tube clamps, etc.) must be established by plants. The integrity of all food contact heat exchange surfaces must be checked at least once per year by an acceptable method (e.g. dye penetration, permanganate recirculation, pressure retention, Helium testing, etc.). However, if the plant has experienced problems with heat exchanger integrity, a more frequent inspection program must be implemented to verify that the problem has been remedied. Appropriate records must be kept to show proper testing has occurred. These records should also document the age of all the plates and which ones are replaced, the cause of the holes (e.g. age, compression, metal fatigue, etc.). If pin holes are found in any plate then all plates of the same age should be checked.

1.14.14.02 Pressure Differentials

This task will only assess the actual differential of pressure. The equipment used to monitor (gauges) will be assessed under Pressure Differential Controllers.

In the cooling section, the system must be designed to maintain pressure on the sterilized product side of the plates at least 14 kPa (2 psi) higher than on the cooling medium side of the plates during forward flow. During diverted flow conditions, higher pressure must be maintained on the sterilized product side of the plates than on the medium side of the plates. This reduces the possibility of chemical contamination in the event a pinhole leak develops in the plates.

An automated mechanism is the only way to achieve the correct pressure relationship in the cooling section during forward flow, divert and shutdown conditions so that the pressure on the sterilized product side is greater than the cooling media side.

Pressure gauges, if used, must be checked for accuracy upon installation and at least once per year. Gauges shall be clean and in good condition. Pressure differential controller sensors, and pressure gauges, shall be located at the cooling media inlet and at the sterilized product outlet.

1.14.14.03 Cooling Medium

Cooling medium (usually sweet water or water-glycol mixture) must be checked at least monthly for microorganisms (e.g., coliforms, psychrotrophs).

Records shall document the safety of any cooling water additives and cooling media products used, as well the microbial testing results.

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