Search

Aims: The aim of the study was to apply Fourier Transform Infrared spectroscopy (FTIR) as a rapid screening method for moulds in a specific food production environment (cured meat) and to evaluate whether the method was sufficiently accurate to distinguish Penicillium species that constitute a hazard for the food quality and safety (Penicillium solitum and Penicillium nordicum) from closely related species., Methods and Results: FTIR was applied to classify the indigenous mycobiota of two production sites for dried and cured meat products in Norway. Results showed that FTIR was suitable to analyse large amounts of data. While correct classification rates varied depending on the species, overall results indicated that FTIR was able to distinguish the undesired mould species P. solitum and P. nordicum from other species and may hence present an option for rapid screening of large numbers of samples to identify changes in mould composition on site., Conclusions: FTIR presents a potential method for detecting changes in levels of undesired fungi in meat-processing environments., Significance and Impact of the Study: This is the first study that applies FTIR to a specific food production environment and it increases the knowledge on both possibilities and limitations of the method in classification of fungi., (© 2021 The Authors. Journal of Applied Microbiology published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.)

Amplified fragment length polymorphism (AFLP) analysis was performed on isolates of Penicillium commune and Penicillium palitans originating from cheese and indoor environment in four cheese factories. The AFLP method was found to be a useful tool for identification of P. commune and P. palitans on, as well as below, species level. However, AFLP in combination with M13 fingerprinting described in a previous paper provided better resolution at the intraspecific level than either of the methods alone. Specific P. commune and P. palitans strains were found in the same factories over a period of more than a year and showed that the cheese factories have contaminating strains that are well established. The majority of the P. commune and P. palitans strains were found only within a single factory, but several were found in different cheese factories. The combined fingerprinting data could relate strains isolated from cheese to specific points in the production plants. Several of cheese-contaminating Penicillium strains could be related to air in the wrapping room, which must be considered to be a critical point for contamination of cheese.

Visible mould from 225 blocks of the Norwegian semi-hard cheeses Jarlsberg and Norvegia from four factories were subcultured and identified. Altogether 23 different fungal species were detected. The two most important contaminating species were Penicillium commune and P. palitans, constituting 21.4% and 17.9% of the total isolates, respectively. The other dominating contaminants were P. roqueforit spp. roqueforti, Geotrichum candidum, P. solitum and P. crustosum. These species, together with P. commune and P. palitans, represented 80.9% of the total isolates. P. commune, P. palitans, P. roqueforti spp. roqueforti and P. solitum were most common contaminants on cheese produced in all four factories, while G. candidum was found to be important on Jarlsberg cheese from only one factory. P. crustosum was one of the dominating species on Norvegia cheese.

Visible moulds were isolated and identified from 102 samples of each of the Norwegian types of semi-hard cheeses called Norvegia and Jarlsberg. Penicillium species made up 98.1 and 89.2% of the isolates from the Jarlsberg and Norvegia cheeses, respectively. The most frequently occurring species on both was P. roqueforti subspecies roqueforti. The four species Penicillium roqueforti subspecies roqueforti, P. commune, P. palitans and P. solitum made up 69.8% of the total number of isolates from the Norvegia cheese and 81.0% of the total number of isolates from the Jarlsberg cheese.

Penicillium commune and Penicillium palitans isolates previously isolated from cheese samples and the indoor environment in four cheese factories were investigated using Polymerase Chain Reaction (PCR) fingerprinting with the core sequence of the phage M13 as primer. In total, 55 isolates of P. commune and 49 isolates of P. palitans were investigated. Four and seven different M13 fingerprinting profiles were found among the P. commune andP. palitans isolates, respectively. Three fingerprinting profiles dominated for each species, comprising 98% and 86% of the P. commune and P. palitans isolates, respectively. Each of the dominating profiles was found in at least three factories and was thus not factory-specific. For each species, one of the fingerprinting profiles was found only once. In addition, one profile of P. palitans was found twice and in one factory only. The M13 fingerprinting grouped theP. commune and P. palitans isolates and gave useful information with respect to identifying whether isolates of the same species could originate from the same contaminating strain. [Copyright &y& Elsevier]