Irradiation to kill Escherichia coli O157:H7 and Salmonella on ready-to-eat radish and mung bean sprouts

Food Hygiene Laboratory, National Food Research Institute, Kannondai 2-1-12, Tsukuba 305-8642 Japan.
Journal of food protection (Impact Factor: 1.85). 11/2004; 67(10):2263-8.
Source: PubMed


A study was carried out to evaluate the effectiveness of ionizing radiation in eliminating Escherichia coli O157:H7 and Salmonella on commercial ready-to-eat radish and mung bean sprouts and to assess the chemical and physical quality of these sprouts. The use of ionizing radiation was investigated as a means of reducing or totally inactivating these pathogens, if present, on the sprouts. Treatment of mung bean and radish sprouts with a dose of 1.5 and 2.0 kGy, respectively, significantly reduced E. coli O157:H7 and Salmonella to nondetectable limits. The total vitamin C content was gradually reduced with the increase in irradiation dose (P < 0.0001). However, the effect of storage interval on the loss of vitamin C was nonsignificant for radish sprouts and significant for mung bean sprouts (P < 0.04). The color, firmness, and overall visual quality of the tested sprouts were acceptable when effective doses were applied to both radish and mung bean sprouts. Therefore, ionizing radiation could be useful in reducing the population of pathogens on sprouts and yet retain acceptable quality parameters.

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    • "It was recommended by Food and Drug Administration that seeds be decontaminated before germination (Caetano- Anolles et al., 1990; NACMCF, 1999), as total microbial count and amounts of organic materials from which microbes benefit are lower in seeds than in sprouts (Hara-Kudo et al., 1997; NACMCF, 1999). For the decontamination of seeds before germination, numerous studies have been performed to investigate the effectiveness of a wide range of methods, such as treatment with chemicals or organic compounds (Piernas and Guiraud, 1997; Lang et al., 2000; Singh et al., 2003; Jin and Lee, 2007; Luksiene et al., 2007), irradiation (Rajkowski and Thayer, 2000; Bari et al., 2004; Waje and Kwon, 2007; Waje et al., 2009), heat treatment ( Jaquette et al., 1996; Piernas and Guiraud, 1997; Weiss and Hammes, 2005), high pressure (Penas et al., 2008, 2010), and=or their combinations. "
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    ABSTRACT: In this study, total aerobic mesophilic bacteria (TAMB), total coliform (TC), yeasts and moulds (YM), and Escherichia coli, Salmonella, and Staphylococcus aureus counts of wheat seeds and sprouts germinated for 9 days under different relative humidity (RH) (90% and 95%) and temperatures (18 °C, 20 °C, and 22 °C) were determined. The disinfection capabilities of sodium hypochlorite (NaOCl) (100, 200, and 400 ppm) and hydrogen peroxide (H(2)O(2)) (3% and 6%) on wheat seeds/sprouts were also investigated. It has been found that native TAMB, TC, YM, and E. coli population significantly increased (p<0.05) with the germination; however, no Salmonella and S. aureus were detected on the seeds and/or sprouts. Again, increasing the temperature and RH resulted in a rapid proliferation of microorganisms. On the other hand, E. coli population could be completely eliminated by the treatment of different concentrations of NaOCl or H(2)O(2) before the germination of wheat seeds. Again, increasing the NaOCl and H(2)O(2) concentrations resulted in additional reductions of TAMB, TC, and YM population; and the highest reductions in sprouts were observed when the seed was soaked in 400 ppm NaOCl for 30 minutes followed by tap water wash and germination for 9 days. Population reduction of 1.46 log colony-forming unit (cfu)/g of TAMB, 1.97 log cfu/g of YM, and 0.84 log cfu/g of TC in sprouts was achieved when compared with the control. The chemical sanitization did not negatively affect the germination capability of the seeds. Therefore, soaking the seeds in 400 ppm of NaOCl for 30 minutes followed by a germination environment of 18 °C and 90% RH was found to be the most appropriate germination condition for wheat sprouts with reduced microbial population.
    Full-text · Article · Dec 2010 · Foodborne Pathogens and Disease
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    • "The use of RF is technologically complex and rapidly raises the internal temperature of produce to be disinfected. Ionizing radiation has been shown to greatly reduce potential microbiological risk without damaging the texture/colour of the produce and does not lead to nutrient losses or have an adverse effect on the nutritional status (Niemira et al., 2003; Bari et al., 2004; Dhokane et al., 2006; Mintier and Folley, 2006). However, the long-term consumption of irradiated produce remains a cause of concern to the general public. "
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    ABSTRACT: It is well known that fresh-cut processors usually rely on wash water sanitizers to reduce microbial counts in order to maintain quality and extend shelf-life of the end product. Water is a useful tool for reducing potential contamination but it can also transfer pathogenic microorganisms. Washing with sanitizers is important in fresh-cut produce hygiene, particularly removing soil and debris, but especially in water disinfection to avoid cross-contamination between clean and contaminated product. Most of the sanitizing solutions induce higher microbial reduction after washing when compared to water washing, but after storage, epiphytic microorganisms grow rapidly, reaching similar levels. In fact, despite the general idea that sanitizers are used to reduce the microbial population on the produce, their main effect is maintaining the microbial quality of the water. The use of potable water instead of water containing chemical disinfection agents for washing fresh-cut vegetables is being advocated in some European countries. However, the problems of using an inadequate sanitizer or even none are considered in this manuscript. The need for a standardized approach to evaluate and compare the efficiency of sanitizing agents is also presented. Most new alternative techniques accentuate the problems with chlorine suggesting that the industry should move away from this traditional disinfection agent. However, the use of chlorine based sanitizers are presented as belonging to the most effective and efficient sanitizers when adequate doses are used. In this review improvements in water disinfection and sanitation strategies, including a shower pre-washing step and a final rinse of the produce, are suggested.
    Full-text · Article · Jun 2009 · International journal of food microbiology
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    • "Thus, radiation dose of 1 and 2 kGy did not affect the overall acceptability of the irradiated sprouts. Bari et al. (2004) have reported similar observations in which they have shown that gamma irradiation up to 1.5 kGy did not affect the visual quality of mung bean sprouts up to 3 days. "
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    ABSTRACT: In the present study, radiation processing of minimally processed green gram and garden pea sprouts was carried out at doses 1 and 2 kGy. The effect of this treatment on different quality parameters like vitamin C content, total carotenoids content, sensory quality, texture, and color was determined over a storage period of 12 days at two different temperatures, a 4 and 8 °C. It was observed that treatment of irradiation (1 and 2 kGy) and storage period did not have any significant effect on vitamin C content of control as well as irradiated sprout samples stored at 4 and 8 °C. Total carotenoids content of sprouts stored at 4, as well as at 8 °C, for 12 days remained almost unchanged after irradiation as well as during storage. Sensory evaluation studies showed that irradiation had no significant effect (p>0.05) on the ratings of any of the sensory attributes in green gram as well as garden pea sprouts and, thus, did not alter the overall acceptability of the irradiated sprouts. Textural studies revealed that there was no significant change (p>0.05) in the firmness of irradiated sprouts (1 and 2 kGy) as compared to control samples at both the temperatures. Storage period of 12 days also did not affect the firmness of sprouts significantly. Color measurement results indicated no drastic change in the color coordinates of the green gram samples except greenness of controls stored at both the temperatures, which showed insignificant decrease in the a* values. Thus, the nutritional as well as sensory quality of minimally processed green gram and garden pea sprouts did not alter significantly after gamma irradiation with a dose of 1 and 2 kGy.
    Full-text · Article · Oct 2007 · Radiation Physics and Chemistry
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