Method of ensuring constant product quality and safety when tailback conditions occur in pasteurizers

A method of ensuring constant product quality and safety when tailbacks occur in a pasteuriser, the pasteuriser being operated on a throughfeed basis in such a manner that the product passes from a pasteuriser inlet, through different temperature zones including a superheating zone and a pasteurising zone divided at least in part into controllable sub-zones, to a pasteuriser outlet, a keep-hot process being employed in the pasteurising zone to pasteurise the product, comprising:

• moving the product through said pasteuriser, from the pasteuriser inlet to the pasteuriser outlet, at a constant throughfeed speed at which, in the absence of tailbacks, the product is pasteurized,
• on the occurrence of a tailback, cooling a section of the pasteurising zone to a temperature which avoids an increase in the number of pasteurisation units applied in that section to the product up to that time to a level above a predetermined acceptable tolerance level, a pasteurising unit being defined as the pasteurising effect obtained by maintaining a product of 60.degree. C. for 1 minute,
• beginning the cooling at an exit end of the pasteurising zone and extending the cooling process towards an entry end of the pasteurising zone at a speed equal in magnitude to the throughfeed speed,
• as the cooling process progresses from the entry end of the pasteurising zone to the outlet end, switching off the keep-hot process,
• at the end of the tailback time t.sub.S, determining the time of duration t.sub.KD of the cooling process at whatever final position the cooling process has then reached by the difference between the pasteurising time t.sub.p and the tailback time t.sub.S, and
• subsequently switching on the keep-hot process again at the throughfeed speed in the section which has been cooled.