Microbiological stability and diversity in raw pre-peeled potatoes packed in different atmospheres

Microbial growth on raw pre-peeled potatoes was analysed in relation to different process and storage parameters. Raw peeled potatoes with or without tumbling were packed in vacuum or modified atmosphere (MA) and stored at 4 °C and 15 °C for 7 and 5 days, respectively. Microbial growth was analysed throughout the storage period and growth was observed for mesophilic and psychrotrophic bacteria, lactic acid bacteria, Pseudomonas spp., and coliform bacteria. Growth at 4 °C was significantly lower compared to 15 °C. The number of bacteria was after seven days significantly higher on tumbled potatoes stored at 4 °C than on the untumbled potatoes. The bacterial counts generally exceeded 10⁶ CFU/g on tumbled potatoes after 7 days at 4 °C and 5 days at 15 °C, respectively. The CO₂ content increased during the storage period. A total of 243 isolates were grouped according to ITS-PCR profiles. Of these 47% had similar band profiles and thereby constituted the dominating flora at the end of shelf life. The dominating flora, identified on the basis of sequencing and microbial analysis of a subset of isolates, belonged to Enterobacteriaceae and consisted mainly of Enterobacter spp. and Kluyvera spp.