Effect of thermal treatment and ethanol on Salmonella spp. and postharvest quality of 'Tommy Atkins' mango fruits

Studies have shown that mango (Mangifera indica L.) fruits imported from South America were contaminated by the water used in the hydrothermal treatment (phytosanitary barrier). This study evaluated the effects of ethanol in the hydrothermal treatment for Salmonella spp. control in mangoes and its influence on fruit quality during storage. In vitro microbiological tests were carried out using ethanol (up to 5% v/v, at 55, 60, and 65°C) and a pool of Salmonella. 'Tommy Atkins' mango fruits at maturation stage 2 were used in in vivo tests, when the same pool of Salmonella was inoculated on the mango fruit surface; then the fruits were immersed in the water/ethanol bath in the foregoing conditions. Microbiological counts were done by serial dilution on plates and results expressed as CFU mL^-1. For the quality control tests 140 mango fruits were immersed in water (55°C for 1 min) at 0, 3 and 5% v/v ethanol, cooled down (21.1°C) and stored at 25°C and 75% RH (Relative Humidity) for 7 days and at 10°C and 75% RH for 14 days, then transferred to 25°C and 75% RH for 6 days. The physical-chemical determinations carried out were soluble solids content, pH, titratable acidity, skin and pulp color, and appearance tests. Statistical analysis demonstrated ethanol effectiveness in reducing Salmonella, but the fruits treated with ethanol and stored at 10°C showed worse appearance than the control ones. We found that immersion in 3 and 5% ethanol at 55°C for 1 min may be a viable alternative to control Salmonella in mango fruits at 25°C.