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United States Department of Agriculture

Agricultural Research Service

Research Project: PATHOGEN REDUCTION AND OPTIMIZATION OF WATER USAGE IN POULTRY PROCESSING OPERATIONS

Location: Poultry Processing and Swine Physiology Research

Title: Cooling of Poultry Using Immersion or air chilling

Author
item Northcutt, Julie

Submitted to: Poultry Waste Management Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 20, 2006
Publication Date: September 25, 2006
Citation: Northcutt, J.K. 2006. Cooling of Poultry Using Immersion or air chilling. Poultry Waste Management Symposium Proceedings. p. 102-108.

Interpretive Summary: During processing, poultry carcasses must be cooled to 40 F or below within 4 to 8 hours after slaughter to retard growth of pathogenic and spoilage microorganisms. There are three methods that are typically used to cool poultry: 1) immersion chilling by submersion in cold water or an ice-water mix; 2) dry air chilling using cold-air blast; or 3) evaporative air chilling using cold-air blast and water mist. In the U.S., poultry has traditionally been cooled using immersion chilling, but changes in USDA regulations regarding moisture retention, environmental concerns (water availability, water quality and discharge restrictions), and European Union trade restrictions on immersion chilled poultry have caused processors to consider air chilling as a viable option. Preliminary research on dry air chilling and immersion chilling of poultry has demonstrated that both methods reduce carcass bacteria counts by about 1 log. Dry air chilling provided no microbiological advantage over immersion chilling. Immersion chilled carcasses gained about 9% moisture based on pre-chill weight while dry air chilled carcass lost about 2.5% of their pre-chill carcass weight. Additional research is needed to examine cross contamination during immersion and air chilling and to evaluate the effects of various antimicrobial treatments during chilling.

Technical Abstract: During processing, poultry carcasses must be cooled to 40 F or below within 4 to 8 hours after slaughter to retard growth of pathogenic and spoilage microorganisms. In the U.S., poultry has traditionally been cooled using immersion chilling because this method is both economical and efficient; however, recent changes in USDA regulations regarding moisture retention, environmental concerns (water availability, water quality and discharge restrictions), and European Union trade restrictions on immersion chilled poultry have caused processors to consider air chilling as a viable option. Most of the research on air chilling of poultry has been conducted in Europe and their slaughter operations vary from those used in the U.S. (high current stunning, longer bleed times, lower scald temperatures, etc.). For this reason, a series of projects were conducted to evaluate the microbiological and quality implications of poultry processed using conditions commonly employed in the U.S. Broiler carcasses were chilled by immersion in a non-chlorinated ice-water mix for 50 min or dry air chilled in a 32 C cold room for 150 min. Time to reach a deep breast muscle temperature of 40 F was 35 or 90 min for immersion and air chilling, respectively. Counts of bacteria (coliforms, Escherichia coli, Salmonella and Campylobacter) recovered from carcasses that were immersion chilled were not significantly different from the counts of bacteria recovered from air chilled carcasses (P > 0.05). When recovery of bacteria from pre and post-chill carcasses were compared, both chilling methods resulted in significantly reduction bacteria counts (0.6 to 1.4 log10 cfu/mL). Immersion chilling resulted in a 9% moisture retention based on pre-chill carcass weight while dry air chilled carcasses lost about 2.5% of their pre-chill carcass weight. Additional research is needed to examine cross contamination during immersion and air chilling and to evaluate the effects of various antimicrobial treatments during chilling.

Last Modified: 4/20/2014
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