Changes in the Microbial Quality of Nephrops norvegicus during Processing for Retail Packs

The microbial quality of whole tails of prawns, Nephrops norvegicus , caught in the Irish Sea, was determined after freezing. The effects of subsequent processing into frozen prawns and breaded and battered scampi, in retail packs, were then monitored. The mean TVC of the whole tails was 1.3 × 10⁶/g whilst that of the processed tails was 9.7 × 10⁵/g. Peeling and polyphosphate treatment caused a significant reduction in the total count of bacteria whilst gutting/sorting and reforming caused increases. Overall, processing caused an insignificant change in the TVC, when compared with the initial load. The ratio of coliforms: total count of bacteria increased steadily during processing and might serve as an indicator of the source of contamination with poor quality final product. Low-grade raw materials would have a low ratio and poor hygiene in processing but good quality raw materials would result in a high ratio. Both TVC and coliform counts are required to determine microbial quality.