Biomedical Engineering Reference
In-Depth Information
et al.
1997
). Also, lactic acid at 2 % for 15 s was used to reduce
Aeromonas caviae
on minimally processed carrot by 2.54 log CFU/mL (Uyttendaele et al.
2004
).
Moreover, the application of mixture of organic acids (malic, lactic and citric) at
2 % in combination with ultrasound for 5 min showed a reduction of
E. coli
O157:H7,
S
. Typhimurium, and
L. monocytogenes
by 2.75, 3.18, and 2.87 log
CFU/g, respectively, in fresh lettuce leaves. In addition, color and texture parame-
ters did not affect (Sagong et al.
2011
). These studies demonstrated the capability of
organic acids to reduce and inhibit pathogenic bacteria in fresh-cut fruits and
vegetables.
4.2.5
Ozone
Ozone as an aqueous disinfectant was declared to be generally recognized as safe
(GRAS) (Guzel-Seydim et al.
2004
). Ozone has been more effective to inhibit bac-
teria, viruses, and fungal spores than hypochlorite (Khadre et al.
2001
). The lethal
effect of ozone is a consequence of its strong oxidizing power (Seymour
2003
).
Microbial studies in laboratory testing typically show a 2 log reduction in total
microbial counts and signifi cant reduction of spoiling microorganisms commonly
found in fruits and vegetables (Khadre et al.
2001
). Ozone has been found to be
effective against
S
. Typhimurium,
Y. enterocolitica
,
S. aureus
, and
L. monocyto-
genes
at 20 ppm (Xu and Wu
2014
). Kim et al. (
1999
) reported a 2 log CFU/g reduc-
tion in total counts for shredded lettuce suspended in water ozonized with 1.3 mM
ozone as compared to water washing (0.74-1.0 log cfu/g reduction). In addition,
ozone at 5 ppm were able to inactivate
E. coli
with a 2.2 log reduction in tomato
after 15 min of exposure (Bermúdez-Aguirre and Barbosa-Cánovas
2013
).
It has been reported that effi cacy of ozone treatments can be improved by extend-
ing the exposure time. Xu and Wu (
2014
) evaluated the effi cacy of ozonized water
(6.25 ppm) at 3 levels of exposure times (1, 5 or 10 min) in green onions inoculated
with S
almonella
spp. Their results showed that reduction of
Salmonella
spp.
increased from 1.90 to 3.10 log with the increasing time from 1 to 10 min. Ozone
treatment in combination with UV-C illumination (UV) reduced microbial fl ora of
fresh-cut onion, escarole, carrot, and spinach wash waters by 6.6 (O
3
-UV), 4.0 (UV)
and 5.9 log CFU/ml (O
3
), respectively (Selma et al.
2008a
,
b
).
4.2.6
Hydrogen Peroxide
Hydrogen peroxide (H
2
O
2
) is a compound Generally Recognized as Safe (GRAS)
and possesses bactericidal and inhibitory activity due to its oxidative properties and
their capacity to generate other cytotoxic oxidizing species such as hydroxyl radi-
cals (Ayala-Zavala and Gonzalez-Aguilar
2011
). The use of H
2
O
2
has been reported
