Hi Lean z,
Getting coliforms in your final cheese product is a very serious problem. There are two possiblities, one is improper pasteurization and second post processing contamination.
To determine the source of contamination, you will need to do a line study. You should be sampling the product/intermediate product at each and every step. For e.g. raw milk (raw cream, skim milk, skim milk powder etc.), after pasteurization, before adding culture and enzyme, after culture and enzyme, before cutting, after cutting, Whey draining step, at salting stage, milling stage, pressing stage, etc. and conduct micro analysis, specifically coliform detection. Please do all these test for same batch/lot no. An enumeration of SPC and coliforms will also help to determine if the counts are increasing or decreasing at subsequent stage.
I would also suggest you to do surface swabs of all the equipments being used for cheese manufacturing. i.e. all the equipments coming in direct contact with product just before using them for production.
It would also be benificial to conduct micro analysis for ingredients like Calcium Chloride, salt, enzyme, starter culture, colour (if being used), packaging material etc.
All these steps would give you a broader picture of your processing steps in context to contamination of your product and a detailed analysis of test results will help you to implement control measures to prevent contamination.
Coliform in final cheese product will give you bad quality of cheese and will hit hard on the profit of your company.
Hope you are able find and fix the problem as soon as possible.
I recently joined a cheese manufacturing, making fetta cheese, most of the rejects here are due to coliform. Fetta cheese have been brined for min 7 days, but after packing, sometimes the result for coliform are more than 1100 cfu/g. The swobs shows me minimum counts but finish products are disaster. Help!!