We recently launched a new product around 6 months ago. This product is a raw granola mix - rolled oats, flax seeds, pumpkin seeds, sunflower seeds, and quinoa puffs.
Since its first month of production, our metal detector has detected metal in this product on multiple occasions. Of course, I isolated the metal fragment from the product and disposed of the product thereafter. The metal fragments that were typically found were metal rocks or thin metal wires. We presume the contamination is from one of our suppliers, since none of our gluten-free flours have this issue - thereby ruling out equipment failure.
To determine the root cause, we have tried to determine which ingredient was responsible for the source of contamination, but is difficult to do so. We tried to metal detect the 50lb bag of ingredient through the metal detector, but the apateur of the metal detector is too narrow and would always kick off the metal detector. I found no metal contamination when I broke down the 50lb bag into smaller portions, however it was very time consuming and this would increase the risk of handling contamination. Additionally, the chance of finding a metal fragment may occur 1kg product out of 2000kg batch.
We continuously have this problem, and are unsure what to do at this point.
Should I just let it go, and just keep a trend record for when our product has been contaminated by metal?