Assessment of Microbiological Quality of Retail Fresh Sushi from Selected Sources in Norway

Abstract

Retail fresh sushi is gaining popularity in Europe. This study was conducted to investigate the microbiological quality of selected samples of fresh sushi with a shelf life of 2 to 3 days offered as complete meals in Norwegian supermarkets. Analysis of aerobic plate counts in 58 sushi samples from three producers revealed large variations in microbiological quality, and 48% of the analyzed sushi boxes were rated as unsatisfactory (> 6.0 log CFU/g). Mesophilic Aeromonas spp. was detected in 71% of the samples. In a follow-up study, we collected products and raw materials directly from the production facility of one producer and observed a significant decrease (P < 0.01) in aerobic plate counts compared with the initial sampling. The observed difference between products purchased in stores compared with those collected directly from the factory suggests that poor temperature control during distribution and display in stores leads to reduced microbiological quality. Microbiological analysis of the sushi ingredients revealed that potentially pathogenic bacteria such as mesophilic Aeromonas spp. or bacteria belonging to the Enterobacteriaceae can be introduced into sushi through both raw vegetables and fish. The results highlight the importance of high quality ingredients and proper temperature control to ensure stable quality and safety of these food products.