Agriculture Reference
In-Depth Information
It is typically not necessary to adjust the pH of the source water to maintain the
effectiveness of POAA; however, it works best below a pH of 8 (Block 1991). POAA
is completely soluble in water and does not have the potential to off-gas like chlorine
at pH below 5, or like chlorine dioxide and ozone with increasing water temperatures
or agitation. Additionally, POAA does not react with organic matter to form toxic
residues, and the breakdown components (hydrogen peroxide, oxygen, acetic acid)
are innocuous (Fraser 1987).
On apple surfaces inoculated with
E. coli
O157:H7, 80 ppm of POAA reduced
the population by 2.6 logs with a 2-min exposure (Wright and others 2000), which
were consistent with the fi ndings of Park and Beuchat (1999) when they reviewed
reductions on cantaloupes and honeydew melons. Rodgers and others (2004) achieved
much higher reductions against
L. monocytogenes
and
E. coli
O157:H7 (4.3
and 4.5 log, respectively) using 80 ppm peracetic acid for 5 min on various commodi-
ties. With increased concentrations and exposure times (
160 ppm for 15 min),
Wisniewsky and others (2000) achieved a 5-log reduction against
E. coli
O157:H7
inoculated on whole apples using POAA. When treating fresh-cut apples with
80 ppm POAA,
E. coli
O157:H7 populations were reduced by 2.7 log with a 5-min
treatment and POAA was more effective than chlorine at 80 ppm and AEW at 70 ppm;
however, it caused more quality degradation than the other treatments. POAA can
also be used to control postharvest fruit decay (Mari and others 1999; Brown and
Schubert 1987 ).
The use of POAA on leafy vegetables and carrots has also been reviewed. When
initial contamination levels were
<
100 CFU/g, reductions obtained with a 60 ppm
POAA solution (1.8 log CFU/g) were signifi cantly larger than those obtained with
water (0.8 log CFU/g) on lettuce when used by food-service employees (Smith and
others 2003). Hellström and others (2006) found that a 500 ppm POAA solution
reduced the number of
L. monocytogenes
signifi cantly more than a 2500 ppm citric
acid-based produce wash or a 100 ppm chlorine solution at 1.7, 1.0, and 0.7 log CFU/g,
respectively, on shredded lettuce. However, at lower concentrations Beuchat and
others (2004a) found lettuce treated with 80 ppm POAA or 100 ppm chlorine was not
signifi cantly different. On shredded carrots POAA reduced levels of
Salmonella
,
E.
coli
O157:H7, and
L. monocytogenes
by 2.1, 1.24, and 0.83 log CFU/g, respectively,
(Ruiz-Cruz and others 2007); however, these results were not as good as ASC, which
reduced populations to undetectable levels. Gonzalez and others (2004) found that
when treating shredded carrots in process water, the effectiveness of POAA and ASC
were not affected by the high organic content.
The effi cacy of a peroxyacetic/octanoic acid mixture was compared to peracetic
acid alone for use in fruit and vegetable process water (Hilgren and Salverda 2000).
Results suggest that the combination of peroxyacetic acid and peroxyoctanoic acid
are more effective against yeast and mold population over peracetic acid alone when
used in a commercial vegetable processing facility in celery, cabbage, and potato
process water.
Peracetic acid has also been reviewed against viruses. Lukasik and others (2003)
found 100 ppm POAA to be as effective as 200 ppm ASC against bacteria and viruses
on fresh strawberries, and both chemicals were better than stabilized chlorine dioxide
(100, 200 ppm). Allwood and others (2004) concluded that 200 ppm sodium hypochlo-
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