Effects of Low‐dose Gamma Irradiation on the Shelf Life and Quality Characteristics of Cut Romaine Lettuce Packaged under Modified Atmosphere

Abstract

Cut romaine lettuce, packaged under modified atmosphere, was subjected to 0.15 and 0.35 kGy gamma irradiation. Irradiation at 0.35 kGy decreased aerobic plate counts by 1.5 logs and yeast and mold counts by 1 log; these differences were maintained through the 22-d storage. Irradiation at 0.15 kGy caused smaller reductions in microbial counts. A decrease in headspace CO 2 was observed in the 0.35-kGy-treated lettuce, although CO 2 concentrations increased in all samples with storage. O 2 concentration was not affected by irradiation. Ten percent loss in firmness was observed at 0.35 kGy, while other sensory attributes such as color, generation of off-flavor, and appearance of visual defects were not affected.

Effect of γ irradiation on quality-maintaining of fresh-cut lettuce

“…The result indicates that 1.0 kGy or 1.5 kGy irradiation effectively reduced the spoilage from microorganisms and the shelf life of fresh-cut lettuce irradiated with 1.0 kGy was at least for 9 days from the view of microbiological safety. Prakash, Guner, Caporaso, and Foley (2000) found that a dose of 0.35 kGy of gamma irradiation decreased aerobic counts by 1.5 logs on cut romaine lettuce. Prakash, Inthajak, Huibregtse, Caporaso, and Foley (2000) also found that 1.0 kGy of irradiation eliminated Listeria monocytogenes and Escherichia coli inoculated on diced celery while extending shelf life by 1 wk.…”

Influence of oxygen and long term storage on the profile of volatile compounds released from polymeric multilayer food contact materials sterilized by gamma irradiation

“…The use of modified atmospheres is a common practice to extend the shelf life of foods. Nevertheless, most of the published studies [22][23][24] are not focused on the packaging itself, but on packaged foodstuffs such as lettuce or mushrooms at low gamma doses, such as 4 kGy. In our case, nitrogen has been used as representative of an inert atmosphere.…”

Gamma Irradiation for Fresh Produce

“…It has been reported that irradiation does not increase the temperature significantly and therefore, there is retention of color, flavor and textural properties (Willis, 1982). In a previous study, celery irradiated at 1kGy, was suggested to be better-quality in sensory qualities as compared to celery subjected to blanching, chlorination, and acidification (Prakash, 2000). Follet and Sanxter (2002) found that Chompoo and Biew Kiew fruit to be more satisfactory when treated with 0.40 kGy than with the currently used hot-water immersion.…”

“…According to Chervin andBoisseau, 1994 andBuchanan et al, 1998, ionizing irradiation is a fitting method to control the microorganisms on fruits, fresh fruit juices, fresh-cut vegetables, salads, sprouts, seeds and other, minimally processed foods. The efficacy of irradiation is not only limited to the surface, but it can penetrate the product and eliminate microorganisms that are present in crevices and creases of vegetables such lettuce (Prakash et al, 2000). According to Takeuchi and Frank 2000, Solomon et al 2002, bacteria gets inside tissues of leafy vegetables through natural openings or through breakage caused by insect and mechanical in harvesting.…”