**[iTPA testing in experimentally inoculated food samples]**

Three kinds of foods were used for the study: peanut butters, egg yolk and chicken breasts. Food samples were processed as described in a previous study (Kim *et al*. 2007) with slight modifications. Briefly, A 500 ml Erlenmeyer flask (LB broth 225 ml) containing 25 g of chicken breast was incubated at 37°C overnight and then 9 ml of this solution was transferred into a 10 ml conical tube followed by adding 1 ml of inoculated buffered peptone water of *Salmonella* spp.(1.0 x 109 CFU / ml) to prepare a stock solution. Plastic food bags containing 25 g of chicken breast were inoculated with 1 ml of serial dilutions (1:10 to 1:108) of the stock solution and vigorously mixed using a homogenizer (Pro-media SH-001, ELMEX Ltd., Tokyo, Japan) for about 30 sec to distribute the bacteria followed by adding 225 ml of freshly made LB broth to prepare pre-enriched solutions. The sample preparations for peanut butters and other food samples were the same except that for peanut butters which required an additional washing with a washing solution (0.05% NaOH, 0.5% Tween 20 in PBS buffer solution) due to the high viscosity. 100 L of the preenriched solution was mixed with the washing solution and centrifuged at 10,770 x g for 5 min followed by discarding the supernatant. The pellet was washed with 100% ethanol and then with TE buffer solution twice. The washed pellet was suspended in 200 L of TE buffer solution and heated at 100°C for 10 min in a dry heating block. The crude cell lysate was centrifuged at 10,770 x g for 5 min and an aliquot (2 L) of the supernatant was used for the iTPA assay. For negative samples, the same amount of aliquot (2 L) of uninoculated food samples that had also undergone cultural pre-enrichment was used. The inoculated food sample tests were repeated 10 times and the lower limits of detection (CFU per assay) were reported.
