Chill or Thrill? The Effect of Storage Temperature Regime on Listeria Growth in Fresh-Cut Fruit Cocktails

Fresh-cut fruit salads (fruit cocktails) are marketed as a convenient food item with a limited shelf-life (4 days at 4 °C). Given rising electricity prices, increased cooling temperature during production, transport, and retail from 4 °C to 8 °C and extended shelf-life from four to eight days without compromising food safety are discussed. This study investigates the proliferation of <i>Listeria monocytogenes</i> in ready-to-eat (RTE) fresh-cut fruit cocktails at three temperature regimes. The fruit cocktail, consisting of pineapple, red apples, cantaloupe, and red grapes, was inoculated with a clinical strain of <i>L. monocytogenes</i> (SLV 444; CCUG 69007) and stored at 4 °C, 8 °C, or a dynamic temperature regime (4 °C for one day, 8 °C for seven days). After four-day storage at 4 °C, growth of <i>L. monocytogenes</i> was not supported. Despite the fruit cocktail's pH below the minimum requirements of the target organism, all other treatments supported growth of <i>L. monocytogenes</i>, but below the legal limit of 2 log CFU + 1 g^-1 per fruit cocktail. There is an increased risk of exceeding the microbiological safety end product criteria, especially at 8 °C or dynamic storage temperatures, if seemingly insignificant <i>Listeria</i> contamination is present in or on fruit cocktail ingredients.