Firstly we need to determine the extent of the contamination. We do this by: Examining any existing microbiological results. Physically examine the foods Have they blown Is the product off Showing any signs of spoilage Test additional samples from the same batch to determine extent of problem. Is the contamination sporadic or has it affected the entire batch? Testing batches immediately before and after the affected batch. These would tell us if there is a trend that has developed or a ‘once off’ concern.