Infiltration and survival of Salmonella spp. on tomato surfaces labeled using a low-energy carbon dioxide laser device

Abstract

Infiltration and survival of a rifampicin-resistant five-serovar Salmonella cocktail was investigated in laser-etched tomatoes (Lycopersicum esculentum) and smooth (untreated) and punctured (dye solution only) tomato surfaces in storage for 14 days at 25 °C/60% relative humidity. Surviving Salmonella, populations were enumerated on tryptic soy agar supplemented with the antibiotic rifampicin. In the first survival study (laboratory-etched tomatoes), the population of Salmonella spp. in wounds increased to 6.8 log cfu/fruit, whereas cells on smooth surfaces decreased to undetectable levels during 14 days of storage. For etched tomatoes, the storage reduced 2.7 log cfu/fruit after the first 3 days; however, an increase was observed at 7 days, followed by a population decreased to 2.9 log cfu/fruit at 14 days. In the second survival study (pilot plant-etched tomatoes), the populations decreased a total of 3.5 log cfu/fruit and 2.5 log cfu/fruit comparing 1 day with 14 days for smooth and etched surfaces respectively. Infiltration of the dye solution or Salmonella beyond the area of immediate tissue damage was not observed on any tomato surface tested.