"The purpose of this guideline is to provide industry with reference material on best practices for responding to customer complaints of adulterated and misbranded meat and poultry products. FSIS developed this document in response to an increase in the number of recalls of meat and poultry products adulterated with foreign materials. In many cases, the recalling establishments had received multiple customer complaints prior to these recalls."
By regulation, firms are to notify USDA FSIS if the firm finds the product is adulterated. So technically, if complaints are received that there is a foreign material, the product is adulterated. This is to be done within 24hrs.
What are the notification requirements under 9 CFR 418.2? §418.2 Notification.Highlights from the document - https://www.fsis.usda.gov/wps/wcm/connect/8d0a0e73-1e6f-424f-a41f-ea942247a5ff/Guideline-for-Industry-Response-Customer-Complaint.pdf?MOD=AJPERES
Each official establishment must promptly notify the local FSIS District Office within 24 hours of learning or determining that an adulterated or misbranded meat, meat food, poultry, or poultry product received by or originating from the official establishment has entered commerce, if the official establishment believes or has reason to believe that this has happened. The official establishment must inform the District Office of the type, amount, origin, and destination of the adulterated or misbranded product.