Mild heat and freezing to lessen bacterial numbers on chicken liver

Authors: Berrang, Mark; Cox Jr, Nelson; Meinersmann, Richard - Rick; Bowker, Brian; Zhuang, Hong; HUFF, HANNAH - University Of Georgia

Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2019
Publication Date: 12/25/2019
Citation: Berrang, M.E., Cox Jr, N.A., Meinersmann, R.J., Bowker, B.C., Zhuang, H., Huff, H. 2020. Mild heat and freezing to lessen bacterial numbers on chicken liver. Journal of Applied Poultry Research 29(1):251-257. https://doi.org/10.1016/j.japr.2019.10.012.
DOI: https://doi.org/10.1016/j.japr.2019.10.012

Interpretive Summary: Foodborne outbreaks of campylobacteriosis traced to pate or mousse prepared from undercooked chicken liver have become more prevalent in the last several years. This has lead the USDA-Food Safety Inspection Service to list Campylobacter contamination of chicken liver as a critical research need. In earlier work, we found that Campylobacter can be readily detected on fresh raw chicken livers in the processing plant and at retail. In the current work, we tested a mild heat and/or freeze treatment as means to lessen Campylobacter contamination of fresh chicken livers. One and five minute heat at 60oC and 24 and 48 h of freezing at -25oC were tested. We found that a five minute immersion in 60oC water was effective to significantly lower Campylobacter numbers on chicken liver. Forty-eight hours at -25oC in a household freezer was moderately effective. When heat and freezing were combined in series, we found a nearly 99% decrease in the number of naturally occurring Campylobacter both on the surface and within inner tissue of chicken liver. A mild heat process followed by freezing livers for presentation at retail may be useful to lessen consumer exposure to Campylobacter.

Technical Abstract: Foodborne campylobacteriosis has been traced to undercooked chicken liver. We have detected Campylobacter in raw chicken livers from retail and processing plant samples. In the current study, we tested a 1 or 5 min 60oC heat treatment, a 48 h -25oC freeze treatment and a combination of both as a means to pasteurize raw chicken liver lobes. We cultured treated and untreated liver lobes to determine numbers of Campylobacter and total aerobic bacteria. Overall, the 1 min heat treatment was ineffective. The 5 min heat treatment significantly lowered Campylobacter numbers. Freezing was also moderately effective. The combination of both heating and freezing resulted in nearly 99% decrease in Campylobacter numbers but was accompanied by significant lightening of the liver tissue. A mild heat treatment with or without subsequent freezing will not assure elimination of Campylobacter but may lessen consumer risk due to exposure in kitchen and during meal preparation.