The mycobiota of the production environments of traditional Norwegian salted and dried mutton (pinnekjøtt)

In 2013, mould growth on Norwegian ready-to-sell pinnekjøtt (dried and cured lamb ribs) lead to the withdrawal of 200 tons of the product. The aim of this study was to identify the mycobiota at two Norwegian production sites and determine which species present the highest risk for reduced product quality and safety. A total of 485 samples from 2014, 2015 and 2016 were analysed for Penicillium and Aspergillus species. Both production sites showed a persistent mycobiota that remained stable over three seasons. Samples from site A were dominated by P. solitum while samples from site B were equally dominated by P. solitum, P. brevicompactum/bialowiezense and P. nordicum. The presence of P. nordicum was concentrated in one area of the production site where long-time stored hams were produced, but P. nordicum was also found sporadically in other parts of the site. Product samples taken from products with visible mould growth were at both sites dominated by P. solitum, highlighting its importance for product quality. P. nordicum was found frequently in the long-time stored hams, indicating a food safety risk of these products. However, P. nordicum was rarely isolated from pinnekjøtt. Aspergillus spp. were isolated from both sites at all samplings; however, there were no Aspergillus isolated from products, and no sites were repeatedly tested positive for identical species, indicating that Aspergillus is not a part of the persistent mycobiota, but enters the site sporadically. In conclusion, the study showed that a stable mycobiota consisting of few Penicillium species dominated the products and production environments of pinnekjøtt.