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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: Scalding: Effects of Additives on Carcass Microbiology and Wastewater Discharge

Author
item Cason Jr, John

Submitted to: Poultry Waste Management Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 23, 2006
Publication Date: October 23, 2006
Citation: Cason Jr, J.A. 2006. Scalding: Effects of Additives on Carcass Microbiology and Wastewater Discharge. Poultry Waste Management Symposium Proceedings. p. 172-175.

Interpretive Summary: Dipping poultry in hot water before removing feathers has been done for thousands of years, but bacteria were discovered relatively recently by comparison. The health consequences of foodborne bacteria were unknown until relatively recently. Scalding in hot water is effective and cheap, so other methods of heating the feather follicles have not replaced traditional scalding. Multiple-tank scalding is widely used by the poultry industry because there are fewer bacteria in the last tank that carcasses pass through compared to older scalder designs. Transfer of bacteria between carcasses should be reduced in cleaner water. Acidic and basic treatments of scald water have reduced survival of bacteria in scald water, but reductions in numbers of bacteria on fully processed carcasses are not always found.

Technical Abstract: Scalding poultry before removing feathers has been practiced for thousands of years, but spoilage and pathogenic bacteria were discovered relatively recently by comparison. The microbiological consequences of scalding and other practices used in converting live birds to food was unknown, although it had been noticed that scalded carcasses spoil faster than dry-picked carcasses. Scalding in hot water is effective and cheap, so alternative methods of transferring heat to the feather follicles have not had much success at replacing immersion scalding. Multiple-tank or counterflow scalding is one innovation that has been widely implemented by the poultry industry as a way to reduce opportunities for cross-contamination of bacteria between carcasses via the water. Numbers of bacteria in the first tank of a multiple-tank scalder are about one thousand times higher than in the third tank, so carcasses in such systems pass through relatively clean water just before being defeathered, compared to older designs. Adjustments of water pH have been tried to further reduce the numbers of bacteria in scald water. Both acidic and basic treatments have been shown to reduce survival of bacteria in scald water, but improvements in the microbiology of fully processed carcasses are more difficult to demonstrate.

Last Modified: 7/28/2014
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