Cold Brew Filter Packs – Micro Testing Recommendations?

Good morning, super smart food safety team!

I find a lot on the forum about cold brew coffee that is pre-made (canned), but we are trying to do something different. We have customers interested in doing their own cold brewing from filter packs. These could be used for personal, restaurant, c-store situations.

Green coffee is obviously roasted, and this is a kill step. We do random testing and have never had a micro issue. But brewing for coffee is to follow. This will no longer be the case with cold brew. 

Does anyone have recommendations for me for testing? We've done some "shelf life" testing...post brew coffee is best within the first 2 days. 

Thanks for input!

We have a new cold brew item hitting the market - the only thing we need to run tests on are the filters to ensure no chemicals, no bleaching, no coatings etc. We use a local harvester and bulk roaster that completes the standard tests on coffee.