SURVIVAL OF Salmonella typhimurium ON 'CANTALOUPE' MELON DURING COLD STORAGE UNDER CONTROLLED ATMOSPHERES

Abstract

The survival of Salmonella typhimurium alone or associated with Rhizopus sp. was analyzed on 'Cantaloupe' melons (Cucumis melo L.) var. reticulatus during cold storage under controlled atmospheres (CA). Melons of uniform size were inoculated with 8.2 log10 CFU of a strain of S. typhimurium ATCC2356, kanamycin resistant (Km) and stored under the atmospheres: AC₁ at O₂ 3 %, CO₂ 12 % and N₂ 85 %; AC₂ at O₂ 5 %, CO₂ 15 % and N₂ 80 %; and air (O₂ 20.95 %, CO₂ 0.03 %, and N₂ 78.08 %) at 3.7 ºC and relative humidity (RH) of 93.6 ± 5.9 % by 192 h. Every 48 h inoculated tissue samples were taken from fruits for testing on enteric Hektoen agar with Km (50 μg mL^-1). Results showed that S. typhimurium can survive on the surface of the fruit in chilled atmospheres AC₁, AC₂ and air, although under these conditions the bacteria showed a decrease (P ≤ 0.05) in the population of 3.7, 4.3 and 4.7 log10 CFU per fruit, respectively. The presence of Rhizopus sp. did not affect the bacteria ability to survive or its population level at similar conditions of temperature and RH. Therefore, it is demonstrated the ability of S. typhimurium to survive in atmospheres with high CO₂ concentration and adverse temperature conditions, and the importance to prevent the contamination of 'Cantaloupe' melons during its production and marketing.