Agriculture Reference
In-Depth Information
can be used for the marketing of whole fruit due to potential thermal damage to the
rind. Venkitanarayanan and others (2002) applied a process to treat orange fruit with
1.5% lactic acid plus 1.5% hydrogen peroxide solutions for 15 min at 40 °C and found
that more than 5 log of reduction per fruit in the population of surface-inoculated
E. coli
O157 : H7,
S.
Enteritidis, and
L. monocytogenes
was achieved by such
treatment.
Grapes
Mlikota Gabler and others (2005) found that treating grapes with water at 50 °C for
1 min signifi cantly reduced grey mold incidence, and treatment with 35% (v/v) ethanol
at 25 °C was better in reducing mold incidence than the hot-water treatment (50 °C,
1 min). Treatment with 35% ethanol at 50 °C was more effective in reducing the mold
incidence than the other two treatments. It is unclear how effective these treatments
would be in reducing populations of foodborne pathogens. Kou and others (2007)
found that a signifi cantly lower decay rate was observed in samples treated with hot
water (45 °C, 8 min) than that in the control or in the samples treated with hot air
(55 °C, 5 min) throughout the entire 14 days of storage. Color and texture were not
signifi cantly (P
0.05) affected by either heat treatment or stem removal. However,
the mild heat treatment could not be used to enhance microbial safety of grapes
because of the inadequacy of the lower temperature (45 °C) in inactivating foodborne
pathogens.
>
Tomatoes
A hot-water-brushing system has been developed and commercialized for treatment of
tomatoes and other commodities to reduce decay and chilling injury (Fallik and others
2002). Fresh tomatoes have been frequently associated with major outbreaks of salmo-
nellosis. Sapers and Jones (2006) dipped
Salmonella
- inoculated tomatoes into 200 ppm
chlorine at 20 ° C for 3 min, water at 20 ° C for 3 min or at 60 ° C for 2 min, 1% H
2
O
2
at
20 ° C for 15 min or at 60 ° C for 2 min, and 5% H
2
O
2
at 60 °C for 2, 3, or 5 min. No
greater than 1.3 log in the bacterial counts were observed with the chlorine, hot-water,
and 1% H
2
O
2
treatments. Slightly higher reductions (
2 log CFU/g) in bacterial counts
were observed with the application of 5% H
2
O
2
at 60 °C. However, no additional reduc-
tion was observed by increasing the treatment time or adding surfactants. The treatment
also caused damage (skin darkening) to the fruit. Venkitanarayanan and others (2002)
spot - inoculated
S.
enteritidis
, E. coli
O157 : H7, and
L. monocytogenes
onto the smooth
surface of tomato fruit and then immersed the inoculated fruit in 1.5% H
2
O
2
plus 1.5%
lactic acid at 40 °C for 15 min. More than a 5-log (CFU/fruit) reduction in the popula-
tion of all three pathogens was achieved without damage to fruit. Spraying tomatoes,
inoculated with
S.
typhimurium and
E. coli
O157 : H7 on the surface and in the stem
scar area, with 2% lactic acid at 55 °C resulted in
∼
2.9 log CFU/g reductions in the
bacterial counts (Ibarra-Sánchez and others 2004). In the study conducted by Sapers
and Jones (2006) the interval between tomato contamination and sanitizing was 24 h or
longer; a much shorter interval between inoculation and treatment was used in the
studies conducted by Venkitanarayanan and others (2002) (1 h) and Ibarra - S á nchez and
others (2004) (40 min). Sapers and Jones (2006) argued that the short time used in the
studies conducted by Venkitanarayanan and others (2002) and Ibarra - S á nchez and
>
