Survival of Salmonella in Spices and Growth in Cooked Food

Transcription

1 70 Vol. 49, No , Survival of Salmonella in Spices and Growth in Cooked Food Yurie UG67: 1,Yuji M>C6> 1,Minoru H6<6 1, Yoshiko SJ<>I6-KDC>H=> 2,Atsushi IH=><JGD 3 and Yukiko H6G6-KJ9D 2, 1 Tamagawa University, Tamagawa-gakuen, Machida, Tokyo , Japan; 2 National Institute of Health Sciences, Division of Microbiology: Kamiyoga, Setagaya-ku, Tokyo Japan; 3 Donq, Tanakamachi, Higashinada-ku, Kobe-shi, Hyogo , Japan; Corresponding author Contamination of spices with pathogens has been reported worldwide, and Salmonella might result in foodborne infections, In this study, we investigated the survival of Salmonella in black pepper and red pepper, and the growth of the surviving Salmonella in cooked food. Salmonella Enteritidis, Salmonella Weltevreden and Salmonella Senftenberg were inoculated into spices, and their survival during storage was examined. In black pepper, S. Enteritidis was no longer viable after storage for 28 days, but S. Weltevreden and S. Senftenberg remained viable. In red pepper, S. Weltevreden and S. Senftenberg survived for 28 days although S. Enteritidis was not viable after 7 days. Salmonella Weltevreden and Salmonella Senftenberg were inoculated into cooked food, and their survival during storage was determined. In potato salad, egg salad, namul and kimchi as cooked foods, both pathogens grew at 30, butnot at 10. Our results indicate that cooked food should be stored at low temperature after addition of spices, such as black pepper and red pepper, following the cooking. (Received October 23, 2007) Key words: food spice; Salmonella; survival; growth; cooked 1 1), 2) 3) 5) 1g ) 7) 9) 1g 1, g )

2 April Salmonella Enteritidis SE315 Salmonella Weltevreden SEC 442 Salmonella Senftenberg SEC (1,050 g) 10 (140 g) (105 g) (700 g) (105 g) (1,360 g) 20 1,140 g (220 g) (1,390 g) 10 (1,146 g) (72 g) (72 g) (1,238 g) 10 (1,180 g) (50 g) (8 g) 25 g 0.1 g 0.25 g 1g 3. (A w ) ph A w ph AW GSI ph IQ240 TOHO 4. 1 Trypticase soy broth (TSB, Oxoid, UK) 10 ml , PBS 10 ml PBS 10 ml PBS ml Trypticase soy agar (TSA, Oxoid) 37, S. Enteritidis, S. Weltevreden S. Senftenberg 10 g S. Enteritidis, S. Weltevreden S. Senftenberg 10 6 CFU/g 90 ml PBS GSI 15 PBS 10 5 CFU/g 10 Xylose Lysine Desoxycholate agar (XLD, Oxoid) 0.1 ml XLD 2 Bu#ered Peptone Water (BPW, Oxoid) 100 ml 37, 18 XLD XLD Oxoid 25 g 8 6. S. Weltevreden 0.1 g S. Weltevreden 10 3 CFU/0.1 g g 10CFU 25 g PBS 225 ml 1 PBS 10 XLD 0.1 ml BPW 250 ml XLD XLD Oxoid 25 g

3 72 7. S. Senftenberg 0.25 g 1g S. Senftenberg CFU/0.25 g 10 3 CFU/g g 1g 10CFU 0.25 g 1g 25 g g 8 Table 1. Properties of food samples Potato salad Egg salad Namul Kimchi A w ph Energy (kj/100 g) 569 1, Protein (g/100 g) Lipid (g/100 g) Carbohydrates (g/100 g) Sodium (mg/100 g) Calculated from the values in ref. 15 Vol. 49, No Polymerase chain reaction (PCR) 5, 6 7 inva PCR 0.1 ml 4 10 (10,000 ) 50 mm NaOH 0.1 ml MTris HCl (ph7.0) 16 ml 4 10 (10,000 ) Template DNA inva inva 139 inva ) 1 PCR 10 PCR bu#er 5 ml, dntp mixture 4 ml, Primer inva 139 (40 pmol/ml) 0.5 ml, Primer inva 141 (40 pmol / ml) 0.5 ml Ex Taq polymerase (5 U/mL) 0.25 ml ml Template DNA 5 ml 50 ml (DNA Engine PTC-200, MJ Research, USA) PCR PCR inva (284 bp) 1. A w ph A w (0.930) (0.962) 0.98 (Table 1) ph Fig. 1. Survival of Salmonella Enteritidis, Salmonella Weltebreden and Salmonella Senftenberg inoculated onto the surface of black pepper. IL: inoculation level, ND: not detected by plating, but detected in enrichment culture, NDE: not detected in enrichment culture S. Enteritidis, S. Weltevreden S. Senftenberg CFU/g S. Enteritidis CFU/g 1 10 CFU/g 28 (Fig. 1) S. Weltevreden CFU/g S. Senftenberg CFU/g 7 S. Enteritidis CFU/g 7 (Fig. 2) S. Weltevreden S. Senftenberg CFU/g 7 10 CFU/g 28

4 April Fig. 2. Survival of Salmonella Enteritidis, Salmonella Weltevreden and Salmonella Senftenberg inoculated onto the surface of red pepper. IL: inoculation level, ND: not detected by plating, but detected in enrichment culture, NDE: not detected in enrichment culture. Fig. 4. Growth of Salmonella Senftenberg in namul and kimchi stored at 10 and 30 IL: inoculation level, ND: not detected by plating, but detected in enrichment culture, NDE: notdetected in enrichment culture, : Significant di#erence from data at 0 h (Student s t-test: p 0.005) Fig. 3. Growth of Salmonella Weltevreden in potato salad and egg salad stored at 10 and 30 IL: inoculation level, ND: not detected by plating, but detected in enrichment culture, NDE: not detected in enrichment culture, : Significant di#erence from data at 0 h (Student s t-test: p 0.005). 3. S. Weltevreden S. Weltevreden CFU/0.1 g CFU/0.1 g CFU/g, CFU/g (Fig. 3a) CFU/g (Fig. 3b) 4. S. Senftenberg S. Senftenberg CFU/0.25 g CFU/g 7 10 CFU/0.25 g 1 g CFU/g (Fig. 4a) (Fig. 4b) 0 10 CFU/g 12) 14)

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