Bacterial Biofilms Less Likely on Electropolished Steel

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					Bacterial Biofilms Less Likely on
Electropolished Steel

W            hen the news came out             Arnold’s findings are important.         “I think industry executives get
             that stainless steel can       One reason is that the federal HACCP     tired of people throwing chemicals at
             harbor bacterial biofilms,     (Hazard Analysis Critical Control        them as the only solution to Salmo-
a Dallas, Georgia, company decided          Points) inspection policy requires all   nella,” says Arnold. “What I have to
to test its metal against other materi-     meat producers to identify potential     offer will be an effective part of
als. The results were good news for         contamination areas and take preven-     contamination prevention—perhaps
anyone wanting to reduce bacterial          tive measures. The findings are          with reduced environmental impact.”
cross-contamination in poultry.             especially important to the poultry         Arnold says she now plans to
   Cross-contamination occurs as            industry because of the fast-paced       explore how and where various
poultry is processed and bacteria from      production.                              bacterial species develop biofilms in
carcasses attach to wet steel surfaces         “Some of our evisceration ma-         processing plants. She will also
on processing equipment. When the           chines can process 90 to 140 birds a     SANDRA SILVERS (K7970-4)

bacteria accumulate, they develop an        minute,” says Austin.
increasingly complex matrix by                 “If eletropolishing can prevent the
attaching to each other and forming a       cross-contamination of bacteria
bacterial film that stubbornly resists      between birds and the buildup of
normal washing.                             bacteria over time—that’s an impor-
   Wayne Austin is vice president of        tant quality control.”
Simmons Engineering Company. The               But it’s not just equipment manu-
firm specializes in poultry processing      facturers who worry about cross-
machines. Austin knew that ARS’             contamination. ARS sponsored a
Judy W. Arnold was testing various          special forum on poultry research at
kinds of steel for resistance to bacteri-   which Arnold presented findings that
al attachment. So he asked her to           caught the attention of Michael
include his company’s electropol-           Robach, vice president of food safety
ished steel as part of her research         at Continental Grain.
protocol.                                      Headquartered in Gainesville,
   Test results showed that the             Georgia, Continental Grain is the
process developed by Simmons to             sixth largest broiler producer in the
give their machine steel a shiny,           United States. The company distrib-
chromelike appearance also kept             utes 1.2 billion pounds of ready-to-
bacteria at bay.                            cook meat and 100 million pounds of
   Arnold, a microbiologist in the          ready-to-eat chicken each year.
ARS Poultry Processing and Meat                Robach says he plans to use           As bacteria accumulate on surfaces, they
                                                                                     exude a complex matrix of fibrils that
Quality Research Unit at Athens,            Arnold’s slides of bacterial biofilms    connect cells, and many bacteria align side
Georgia, found surface finishing            on steel to make a point when train-     to side. Magnified about 2,500x.
treatments such as polishing, sand-         ing plant managers on sanitation and
blasting, and grinding all reduced          safety.
buildup of bacterial biofilms. But             “We want to show them that just       explore new chemical pre-treatments
eletropolishing seemed to work the          because a steel surface looks clean      to prevent biofilms.—By Jill Lee,
best.                                       doesn’t mean it’s bacteria-free,” he     ARS.
   Electropolishing involves placing        says. “Our safety protocol includes         Judy W. Arnold is in the USDA-
steel in an acid bath, then running an      using chlorine dioxide to disinfect,     ARS, Poultry Processing and Meat
electric current through the solution.      and we replace our processing            Quality Research Unit, Russell
Arnold has a theory about why this          equipment regularly.”                    Agricultural Research Center, 950
prevents bacterial biofilms: The               Arnold says the surface treatments,   College Station Rd., Athens, GA
process may change the electrical           scouring and others, could be more       30604; phone (706) 546-3515, fax
charge on the metal. Bacteria are           effective than some cleansers and        (706) 546-3548, e-mail
negatively charged, and the charge on       may also reduce the amount of   x
a given surface can affect how well         chemicals required to keep plants
they attach to it.                          sanitary.

10                                                                                              Agricultural Research/February 1998   6

                                              Most of the surfaces in a               When bacteria attach to a
                                              food processing plant are               surface, they produce
                                              made of stainless steel that            extracellular polymers that
                                              is susceptible to bacterial             anchor the cells and provide a
                                              attachment, as seen here.               favorable site for attachment
                                              Magnified about 500x.                   and growth of more bacteria,
                                                                                      other microbes, and debris.
                                                                                      Magnified about 10,000x.

                                                                                                                       SANDRA SILVERS (K7970-3)

                           SANDRA SILVERS (K7970-2)


                                                                      Stainless steel that has been electropolished shows
                                                                      significantly fewer bacterial cells and beginning biofilm
                                                                      formations. Magnified about 700x.

The bacterial composite forms a biofilm
that is resistant to cleaners and sanitizers.
Magnified about 1,500x.

Agricultural Research/February 1998                                                                                                               11