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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Poultry Microbiological Safety and Processing Research Unit » Research » Publications at this Location » Publication #303403
Title: A buffering system to reduce pH drop during pre-enrichment of broiler feeds and feed ingredients

Author
item Cox Jr, Nelson
item Cosby, Douglas
item RICHARDSON, K - Anitox Corp
item CASON, J - Retired ARS Employee
item Berrang, Mark
item Rigsby, Luanne
item HOLCOMB, N - Anitox Corp
item DEROME, L - Anitox Corp

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/2014
Publication Date: 7/14/2014
Citation: Cox Jr, N.A., Cosby, D.E., Richardson, K.E., Cason, J.A., Berrang, M.E., Rigsby, L.L., Holcomb, N., Derome, L. 2014. A buffering system to reduce pH drop during pre-enrichment of broiler feeds and feed ingredients [abstract]. Meeting Abstract. Annnual Meeting of Poultry Science Association, July 14-17, 2014.

Interpretive Summary:

Technical Abstract: Previous research has demonstrated that during preenrichment for the detection of Salmonella in feed and feed ingredients the pH decreased from 6.8-7.0 to 3.9-5.6 after 24 hr incubation. These acidic conditions can kill and injure salmonellae which might result in contaminated feed going undetected. The objective of this study was to develop a preenrichment medium which would prevent or minimize a pH drop. Several experiments were conducted. The first experiment used the current preenrichment broths: buffered peptone water (BPW) and lactose broth (LB), as a starting point with the addition of phosphate equivalent to double (2X), triple (3X) and quadruple (4X) standard phosphate buffer. The second experiment incorporated the following buffering systems: carbonate; phosphate and tricine which have a range of pKa values between 6.35 and 8.06 at 25oC. In the first experiment, at 18 hrs, 4XBPW and 4XLB maintained an average pH of 5.7; at 24 hrs both broths maintained an average pH of 5.3 compared to BPW and LB values of pH 5.0 and 4.7 at 18 hrs and a pH value of 4.7 and 4.4 respectively at 24 hrs. In the second experiment, a tricine-carbonate-phosphate (TCP) buffer showed an average decrease in pH of 1.45, while there was an average decrease in pH of 1.09 for the carbonate-phosphate (CP) buffer at 18 hrs. At 24 hours, the average pH decrease was 1.34 for the TCP buffer and 1.12 for the CP buffer. Controlling for the drop in pH of the preenrichment of feed and feed ingredients is possible using the enrichment buffers described above instead of BPW or LB. Maintaining a consistent pH in the enrichment is a starting point for the recovery of salmonellae which do not survive our methods for culturing feed and feed ingredients. An effective preenrichment method will provide valuable information regarding feed as a possible source of contamination in poultry and poultry products which may not be possible with currently methods. Key Words: Salmonella; pH; feed; methods; and preenrichment