Dairy Establishment Inspection Manual – Chapter 17 - Higher Heat Shorter Time (H.H.S.T.) Processing and Extended Shelf-Life (ESL) Dairy Products
1.17.08 Holding

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This is the part of the H.H.S.T. processing system 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 H.H.S.T. processing system, and may include the sensing chamber at the end. The sensing chamber is that portion which houses both the official indicating thermometer and the S.T.L.R. hot milk temperature sensors.

1.17.08.01 General Conditions

The holding tube and all connections shall be of sanitary design and construction, and shall be clean and in good mechanical condition.

The holding section shall be located after the F.C.D. with no intervening flow promoters, and after the final heating section, but before the FDD or any cooling section.

No device shall be permitted for short circuiting a portion of the tube or for the removal of a section of the tube such that the holding time is reduced below that specified by the scheduled process. No portion of the holding section between the inlet and the sensing chamber shall be heated.

1.17.08.02 Slope and Support

When the holding section is comprised of a holding tube, it is required to have a continuous upward slope (including elbows) of at least 2% (2 cm per 100 cm). The slope is required to eliminate any air entrapment in the holding tube, which would displace product and reduce the holding time. To prevent variance in the slope, the holding tube shall be permanently fixed by mechanical supports.

1.17.08.03 Holding Verification and Records

The holding time is determined by calculation, and is specified in the scheduled process. The calculations must include the extra condensate volume from steam added, if direct heating from steam is used. Results determined will dictate the length of the holding tube needed to provide the proper holding time, based on the flow rate used.

The actual length of the holding tube installed may be compared to the measurement determined by calculation in the scheduled process. Records shall indicate the measured flow rate of the system under the conditions outlined in Task 1.17.06.02 Set and Sealed. This measured value must be the same or lower than the value used in the calculation for the scheduled process.

Re-calculation of the holding tube length may be necessary if changes are made to the system that could alter the flow rate, or if the process itself is changed in any manner.

Verification of proper holding tube length and flow rate shall be done upon installation, annually, or whenever the seal on the F.C.D. is broken, and after any change is made to the system that could affect the holding time. The appropriate records shall be kept on the plant's file, including all supporting calculations.

Product pressures in the holding tube shall be monitored as per task 1.17.07.03 - Pressure Limit Recorder Controllers.

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