Effect of Storage Temperature on the Microbial Composition of Ready-to-Use Vegetables

Four different salad preparations were investigated from microbiological point of view: two were packaged in air and two under Modified Atmosphere. The samples were stored at 4°C and 10°C and analyzed at established times. Total Bacterial Count (TBC) was taken as the most relevant index to define their hygiene and quality at both temperatures. Lactic Acid Bacteria, yeasts and moulds were found only occasionally. In general the most important factor was the packaging technique: TBC was lower when the product is packed under modified conditions. The packaging technique also influences the microbial population: Gram negative aerobic rods are dominant in air-packaged products, while the presence of Enterobacteriaceae becomes important in salads packaged under modified atmosphere. Pseudomonas fluorescens, with all its biovars, was the most frequently found species among the aerobic isolates, while for the Enterobacteriaceae strains there was no dominant species.