did you do a step control?
What is the micro count before heating (normal range or higher than usual)?
Is the fruit puree free of micros after heating?
Did you check conditions of thee packaging?
There are also a lot of possibilities to have trouble with equipment
- wrong / miscalibrated thermocouple
- leaking heat exchanger, contaminating product within the heat process
- leaking valves on bypass of heat exchanger (giving possibility to pump unsterilized product into the "sterile" section after heat exchanger
- having junctions with dead ends in the piping. So unsterile product may be "stored" in dead ends, resulting in contamination afterwards during production
- any change in equipment? new sanitizer...? new pipes...?
- broken stirrer, so heat distribution is not equal within the system
- blocked tubes in bundle heat exchanger, so time of sterilisation is much shorter
- plates heat exchangers plates or sealing may be installed in wrong order
Perhaps there are some comments, which may help in solving the problem.