Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/10/2007
Publication Date: 10/8/2007
Citation: Northcutt, J.K. 2007. Post-harvest Microbiological Intervention Strategies: Effects of Poultry Chilling. Meeting Proceedings. p. 82-87. Interpretive Summary: Research was conducted to examine the microbiological and quality implications associated with immersion and air chilling of poultry carcasses. During the first experiment, poultry carcass microbiology was compared after immersion or dry air chilling and results showed that there was no difference in populations of bacteria. Carcass yield was significantly higher (9.3% versus -2.5%) for immersion versus dry air chilled poultry. Subsequent breast fillets also differed in cook yield with those originating from air chilled carcasses with 2% higher yield. A greater percentage of the air chilled fillets were categorized as “tender” after cooking compared to immersion chilled fillets. Subsequent studies focused on poultry carcass contamination before and after immersion chilling. During commercial processing using a 3 tank immersion chilling system, bacteria were found in chiller water collected from tank 1, but not in water collected from tanks 2 or 3. This did not change when chiller water was filtered and recycled in tanks 2 and 3. Carcass bacteria were reduced during immersion chilling by 1.5 to 2 logs. Bacterial counts were also compared after immersion chilling with chlorine or chlorine dioxide. Carcass counts were the same after immersion chilling, but more bacteria were found in the chiller water collected from the chlorine dioxide tank as compared to chlorine tank. These results demonstrate that air and immersion chilled carcasses, without any chemical intervention, are microbiologically comparable. Commercial chiller water may be recycled without compromising carcass microbiology provided it meets established guidelines.
Technical Abstract: The USDA-Food Safety and Inspection Service requires commercial processing plants to chill poultry to an internal temperature of 40°F or less immediately after slaughter and evisceration or they must freeze or cook the product (USDA, 2006). Chilling is required primarily because it prevents growth of pathogenic bacteria (food poisoning) and other microorganisms that can reduce the quality and shelf-life (yeast, molds, and Psychotropic bacteria) of poultry and poultry products. Commercial poultry may be chilled by one of three methods: 1) traditional immersion chilling in cold water or an ice-water mix; 2) dry air chilling by cold-air blast; or 3) evaporative air chilling by cold-air blast while misting carcasses with cold water. In the U.S., a majority of the processing plants cool poultry using immersion chilling because it is the most economical and efficient method of the three. However, air chilled poultry is gaining in popularity because products bring a premium price and because immersion chilling is still associated with issues such as cross-contamination, carcass moisture retention and water-related environmental concerns. Although air chilling may seem like a viable alternative to immersion chilling, there are several factors to consider before a commercial operation makes the switch.