We make a wide range of preserves, chutneys and acidified sauces from more than 200 different ingredients, all of which have their suppliers specifications, most of which provide a statement of microbial activity on delivery.
Virtually all our products are heat processed (cooked) and most are hot filled and have pH<3.5. Some have 3.5<pH<4.1 and undergo an additional 6-log pasteurisation process (Tref=93.3C, z=8.3C) after hot filling and sealing to do even more lethal damage.
How do we set pragmatic 'site standards' for ingredient microbial contamination levels for our ingredients without setting them 'per ingredient'?
We understand the link between initial microbial loads and delivered lethality in our thermal processes - but want to avoid the complications of D values in different pH regimes. Life is already complicated enough with so many ingredients!
Currently we classify our ingredients (raw fruit, spices, pre-processed (canned, sugar etc) etc) but we risk rejecting some so we can maintain a relatively low microbial threshold. For instance we want to use mushrooms in a sauce and their supplier even appears to tolerate the presence of E.coli, Salmonella and Listeria monocytogenese!
If we 'lift' the reject level to avoid rejects - why have a reject level?
Routine micro includes finished products and ingredient samples (as well as end-of-life products, equipment swabs, air plates, water samples, hand swabs, drain swabs etc), almost the only 'micro positives' relate to raw ingredients (OK - we get occasional issues with drains and machine surfaces - but they reflect cleaning efficacy more than cross contamination from ingredients).
Our finished product microbiology conforms with the IFST guidelines - we cook 'very well' and (shhhh .. they are listening - so don'tread this bit out loud!!) we haven't had a finished product micro positive for more than 2 years - so should we be too concerned about incoming ingredient microbiology?
We've searched the literature and sought advice from real microbiologists but we have so far failed to identify a simple pragmatic approach that we would feel confident of defending in front of our next BRC auditor.
I'm hoping there are a few practical 'foodies' out therethat will be prepared to share their experiences - please
Thanks in advance
Graham