The completed study provided information on the ability of foamed pig carcasses to be rendered. We obtained three foams, Foams A, B, and C, used for the humane killing of groups of animals in emergencies, i.e., foams used for depopulation activities. We evaluated the foams for components that could be potential residues in rendered products using mass spectrophotometry and light chromatography (MS/LC) since MS/LC is an accepted method used in food production/food safety laboratories to detect and characterize contaminants and residues, such as antibiotics and chemical growth-promoting agents. After optimizing the LC/MS method for the foam components, we humanely killed three groups of pigs with nitrogen-gas-filled foam, one group for each Foam A, B, and C, n=3 pigs per group. An additional pig (n=1) was humanely killed by captive bolt and served as a negative (no foam, i.e., no residues) control. After confirmed death and transportation to the rendering laboratory, we collected, measured, and weighed sections of skin, snouts, ears, and legs (external tissues/areas of the pig carcass in contact with the foam) from all carcasses. We determined if cooking at temperatures, times, and conditions that mirror the rendering process eliminated the residues from the collected tissues in contact with the foam. There were no detectable foam residues after rendering tissues from carcasses exposed to two of the foams (Foam A, plant-based; Foam C, Green-certified, Class A/B firefighting foam) and only minimal levels detectable for Foam C (a class A firefighting foam). Having rendering as a disposal option will not only help in the adoption of using foam-based humane killing and depopulation methods in the U.S. but also provide a cost-recovery option for producers that have depopulated pigs via foam methods by allowing the carcasses to be rendered rather than composted.
