WASHINGTON — Agricultural Research Service scientists in Athens, Ga., discovered that reducing water hardness may increase its ability to remove bacteria from broiler-chicken skin, writes Sharon Durham of A.R.S. — the principal intramural scientific research agency of the U.S. Department of Agriculture.

Water hardness differs in different geographical locations, but most water tested in the U.S. has some degree of hardness. "Hard" water has higher concentrations of dissolved minerals, such as calcium and magnesium. Water is softened by removing these minerals, either mechanically or chemically, according to Ms. Durham.

Studies comparing the ability of very hard, moderately hard, and "soft" water to rinse away bacteria like Campylobacter, Staphylococcus and Pseudomonas from the skin of broiler chicken carcasses were conducted by microbiologist Arthur Hinton, Jr., and chemist Ronald Holser of the A.R.S. Richard B. Russell Research Center in Athens.

Very hard water was prepared by dissolving calcium chloride and magnesium chloride in distilled water, and moderately hard water was prepared by diluting one part very hard water with one part soft water. Potassium citrate was used to reduce water hardness.

After five rinses in each water type, soft water removed up to 37% more bacteria from the chicken skin than did the other two water types.

Ms. Durham wrote that Campylobacter bacteria are found in the intestinal tract of birds and can contaminate the bird’s carcass during processing. Staphylococcus is normally found on the skin of the birds, and Pseudomonas is a type of spoilage bacteria that can be found in processing water.

Processing water used in commercial poultry processing facilities can play a major role in the quality of poultry meat produced at the facility. The pH, ammonia concentration, level of microbial contamination and hardness of water used in scald tanks, washers and chiller tanks are factors that may influence the ability of sanitizing procedures to remove microorganisms from carcasses during processing.

Water hardness may be one of the characteristics of processing water that should be monitored by poultry processors, Mr. Hinton’s and Mr. Holser’s studies indicate. By controlling water hardness, poultry processors may be able to improve the ability of processing water to remove bacteria from the skin of processed poultry.