Dairy Establishment Inspection Manual – Chapter 17 - Higher Heat Shorter Time (H.H.S.T.) Processing and Extended Shelf-Life (ESL) Dairy Products
1.17.14 Cooling Section
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This section of the pasteurizer 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 unpasteurized product during divert, and must be re-pasteurized/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 bystanders if a divert event occurs during the pasteurizing of the holding tube and cooling section, when there is no cooling turned on.
1.17.14.01 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, etc.) must be established by plants, taking into consideration the design specifications, operating conditions and hours of operation, wear and the history of the plates and gaskets. The integrity of all food contact heat exchange surfaces must be checked at least once per year by an acceptable method (e.g. dye recirculation, dye check, pressure retention, Helium Testing etc). However, if the plant has experienced problems with heat exchanger integrity (plate or gasket issues), 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 cause of any failure (e.g. age, compression, metal fatigue, etc.). If pin holes are found in any plate in any section then all plates in the same section should be checked.
1.17.14.02 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/Gauges.
In the cooling section, the system must be designed to maintain pressure on the pasteurized 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 and shutdown conditions, higher pressure must be maintained on the pasteurized 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. Where an establishment does not have an automatic means to correct the pressure relationship as described above, the pressures must be monitored and recorded a minimum of twice daily.
An automated mechanism is the best way to achieve the correct pressure relationship in the cooling section during forward flow, divert and shutdown conditions so that the pressure on the pasteurized product side is greater than the cooling media side. In systems where there is not an automated mechanism the establishment must have a written program which includes the person responsible, what is to be done, how it is to be done, how often it is done (frequency), records to be kept and results of monitoring, verification procedures (both on-site and record review), and actions taken for deviant situations. The program must specify the parameters of acceptability/unacceptability and define the preventative measures taken to prevent the re-occurrence of deviations. The program must include at a minimum:
- records of the pressures recorded a minimum of twice a day during production, at beginning and end of run;
- microbiological cooling media checks (e.g., Coliforms, Psychrotrophs) at a frequency of at least once per week;
- pH testing of cooling media at a frequency of at least once per week;
- visual cooling media check at least once per week;
- pinhole testing and plate teardowns at a minimum of once every six months; and
- plate replacement program.
In the event that the written program does not adequately address the risks or there is failure to implement or follow the program then it will be mandatory for the plant to install an automated mechanism.
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, or pressure gauges, shall be located at the cooling media inlet and at the pasteurized product outlet.
1.17.14.03 Cooling Medium
Heating, pre-heating and chilled water media can be a potential source of contamination to the pasteurized product. Chilled water media must be checked at least monthly for microorganisms (e.g. psychrotrophs, coliforms).
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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