This study evaluated the potential use of an antimicrobial packaging system in
combination with electron beam irradiation to enhance quality of fresh produce.
Irradiated romaine lettuce up to 3.2 kGy showed negligible (p > 0.05) changes in color,
but texture and sensory attributes were less acceptable with increased dose.
We established the antimicrobial effectiveness of various active compounds
incorporated into the low-density polyethylene (LDPE)/polyamide films to increase
radiation sensitivity of surrogate bacteria (Listeria innocua and Escherichia coli). All
films showed inhibition zones in an agar diffusion test. In the liquid culture test, the
active compounds reduced the specific growth rate and decreased final cell concentration
of strains. Films incorporated with active compounds increased the radiation sensitivity
of the tested strains, demonstrating their potential to reduce the dose required to control
microbial contamination using electron beam technology. The active compounds
maintained their antimicrobial activity by exposure to ionizing radiation up to 3 kGy. Antimicrobial activity of LDPE/polyamide films incorporated with transcinnamaldehyde
was tested with fresh-cut romaine lettuce. Total aerobic plate counts
(APC) and yeast and mold counts (YMC) were determined as a function of dose (0, 0.5,
and 1.0 kGy) for 14 days of storage at 4ðC. Irradiation exposure significantly lowered
APCs of lettuce samples by 1-log CFU/g compared to the non-irradiated controls;
however, it only slightly reduced YMCs. The effectiveness of using irradiation with
antimicrobial films was enhanced with increased radiation dose and transcinnamaldehyde
concentration.
Electron beam irradiation up to 20 kGy did not affect the tensile strength and
toughness of the polymeric films. The filmâÂÂs flexibility and barrier properties were
significantly improved by exposure to 20 kGy. The addition of an active compound did
not affect the tensile strength and barrier properties of the films, but decreased the
percent elongation-at-break and toughness, making them slightly more brittle.
Ionizing radiation affected the release kinetics of the antimicrobial agent from the
packaging material into a model food system. Irradiated films exhibited slower release
rates than non-irradiated film by 69%. In addition, release rate was lower at 4úC by
62.6% than at 21-35úC. The pH of the simulant solution affected release rate with pH 4
yielding higher rates than pH 7 and 10.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4133 |
| Date | 30 October 2006 |
| Creators | Han, Jaejoon |
| Contributors | Castell-Perez, Elena |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 775643 bytes, electronic, application/pdf, born digital |
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