Agriculture Reference
In-Depth Information
population of lactic acid bacteria by 3 log CFU/g after 8 days storage at 10 ° C. Ukuku
and others (2004b) reported that treating whole cantaloupes for 1 min with hot water
(70 or 97 ° C) caused 2.0 or 3.4 log CFU/cm
2
reductions of
Salmonella,
respectively,
on whole cantaloupe surfaces, and treatment with 5% H
2
O
2
(70 ° C, 1 min) led to a
3.8 log CFU/cm
2
reduction of
Salmonella
.
Vacuum Steam Vacuum (VSV), developed by USDA scientists, employs a short
exposure of food to vacuum to remove insulating fl uids on the surface, followed by
a quick burst of steam that rapidly transfers energy to the food (Morgan 1994; Morgan
and others 1996). Then a second exposure to vacuum cools the product surface to
prevent thermal damage. The process time is on the order of 1 to 2 s. Ukuku and others
(2004a) treated whole cantaloupes with a VSV processor, and fresh-cut pieces were
prepared from the treated samples. The VSV treatment resulted in about 1.0-log reduc-
tion of aerobic mesophilic bacteria, 2.0-log reductions of yeasts and molds, and 1.5-log
reductions of
Pseudomonas
spp. on cantaloupe surfaces. VSV treatment signifi cantly
reduced the transfer of yeasts and molds and
Pseudomonas
spp. from whole canta-
loupe surfaces to fresh-cut pieces during preparation (P
0.05). The texture and color
of fresh-cut pieces prepared from VSV-treated whole melons were similar to those of
nontreated controls. The results indicated that using VSV process to reduce the surface
populations of yeasts and molds and
Pseudomonas
spp. on whole cantaloupes will
reduce subsequent transfer of these microbes to fresh-cut pieces and enhance the
microbial quality of the fresh-cut product.
Sapers and Sites (2003) reported that treating cantaloupes with 1% H
2
O
2
at 40 ° C
was ineffective against
E. coli
NRRL B-766, a surrogate for
S
. Poona. Ukuku (2006)
sanitized whole cantaloupes with 200 ppm chlorine, 2.5% H
2
O
2
solution, or hot water
(96 ° C) for 2 min, and then stored the fruit at 5 ° C for 24 h. The hot - water treatment
reduced the microbial populations on the cantaloupe surface by approximately 4.9 log;
only 2.6-log reductions were observed in the cantaloupes treated with H
2
O
2
or chlorine
solutions. Cantaloupes were reinoculated with
Salmonella spp.
following sanitation
or hot-water treatments and were stored for up to 7 days at 5 °C. Higher counts of
Salmonella
were recovered from hot-water-treated cantaloupes than those from can-
taloupes treated with chlorine or hydrogen peroxide. The results showed that hot-
water-treated cantaloupes are susceptible to recontamination during subsequent
handling (Ukuku 2006 ).
Solomon and others (2006) found that treatment with water at 85 °C for 60 and
90 s resulted in reductions of up to 4.7 log CFU/cm
2
of
Salmonella
Poona on the
surface of cantaloupes. However, melons treated at 85 °C for 90 s were noticeably
softer than those treated for 60 s. Thermal penetration profi les were measured, and
computer simulations were conducted to verify the effect of hot-water treatment condi-
tions on the internal temperatures of cantaloupe melons. Experimental and simulation
data indicated that the internal temperature of melons treated with hot water did not
increase as rapidly as the surface temperature (Figs. 13.3, 13.4). Regardless of the
process temperature used or the temperature of the edible fl esh, 10 mm from the can-
taloupe surface remained at least 40 °C cooler than the surface temperature of the
melon
Annous and others (2004) developed a pilot-scale surface pasteurization process
for treatment of whole cantaloupes. Using this process, they reported that surface
<
