Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2002
Publication Date: 5/14/2002
Citation: Murphy, R.Y., Berrang, M.E. 2002. Effect of steam and hot water post process pasteurization on microbial and physical property measures of fully cooked vacuum packaged chicken breast strips. Journal of Food Science. 67.Nr. 6, 2002-Journal of Food Science 2325.
Interpretive Summary: Listeria monocytogenes is a food borne pathogen that has caused disease due to it's presence in fully cooked poultry meat. It is possible for the commercially cooked product to become contaminated with Listeria after being cooked, before being packaged. In this study we looked at the results of applying a heat treatment to fully cooked poultry meat which had already been packaged. Hot water or steam at 88 C applied for 25 minutes led to a 99 to 99.9% decrease in Listeria numbers. A 35 minute heat treatment after packaging significantly reduced Listeria numbers. The post packaging heat treatment did not affect the tenderness of the meat. Likewise it did not affect moisture properties in the product. However, the treatment did lower the total moisture and expressible moisture of the meat. Losing moisture means a loss of yield for the processor and a possible negative affect on the sensory quality of the product. These results can be used by processors to help make decisions about the use of post process pasteurization to eliminate surface pathogens on poultry meat.
Technical Abstract: Fully cooked chicken breast strips were surfaced inoculated with Listeria innocua (107 cfu/g product), vacuum packaged, and treated via steam or hot water at 88 C for a time of 10 to 35 min. Parallel studies were also conducted using un-inoculated products to determine the heat treatments on water activity, expressible moisture, total moisture, and shear force. Both treatments lowered the numbers of L. innouca recovered from inoculated product. No significant difference was found on the survival rate of L. innouca between steam and hot water treatments. No significant difference was found on water activity and shear force among the treated and untreated products. However, significant difference was found on expressible and total moisture among treated and untreated products. When treated for 35 min in hot water, the expressible moisture was 30.4% lower than that of untreated products and 9.1% lower than steam treated. The total moisture of hot water treated product was 5.4% lower than untreated products and 3.7% lower that steam treated product. These data demonstrate that post process pasteurization with hot water or steam can lower microbial populations but also has an affect on the quality of chicken breast meat.