Suitability of FTIR to distinguish pure cultures of problematic mould species from closely related species in the meat industry.

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.

Designing a risk-based surveillance program for Mycobacterium avium ssp. paratuberculosis in Norwegian dairy herds using multivariate statistical process control analysis.

Surveillance programs for animal diseases are critical to early disease detection and risk estimation and to documenting a population's disease status at a given time. The aim of this study was to describe a risk-based surveillance program for detecting Mycobacterium avium ssp. paratuberculosis (MAP) infection in Norwegian dairy cattle. The included risk factors for detecting MAP were purchase of cattle, combined cattle and goat farming, and location of the cattle farm in counties containing goats with MAP. The risk indicators included production data [culling of animals >3 yr of age, carcass conformation of animals >3 yr of age, milk production decrease in older lactating cows (lactations 3, 4, and 5)], and clinical data (diarrhea, enteritis, or both, in animals >3 yr of age). Except for combined cattle and goat farming and cattle farm location, all data were collected at the cow level and summarized at the herd level. Predefined risk factors and risk indicators were extracted from different national databases and combined in a multivariate statistical process control to obtain a risk assessment for each herd. The ordinary Hotelling's T(2) statistic was applied as a multivariate, standardized measure of difference between the current observed state and the average state of the risk factors for a given herd. To make the analysis more robust and adapt it to the slowly developing nature of MAP, monthly risk calculations were based on data accumulated during a 24-mo period. Monitoring of these variables was performed to identify outliers that may indicate deviance in one or more of the underlying processes. The highest-ranked herds were scattered all over Norway and clustered in high-density dairy cattle farm areas. The resulting rankings of herds are being used in the national surveillance program for MAP in 2014 to increase the sensitivity of the ongoing surveillance program in which 5 fecal samples for bacteriological examination are collected from 25 dairy herds. The use of multivariate statistical process control for selection of herds will be beneficial when a diagnostic test suitable for mass screening is available and validated on the Norwegian cattle population, thus making it possible to increase the number of sampled herds.

Feasibility of NIR interactance hyperspectral imaging for on-line measurement of crude composition in vacuum packed dry-cured ham slices.

There is a growing market for packaged slices of dry-cured ham. The heterogeneity of the composition of slices between packages is an important drawback when aiming to offer consumers a product with a known and constant composition which fits individual consumer expectations. The aim of this work was to test the feasibility of NIR interactance imaging for on-line analysis of water, fat and salt and their spatial distribution in dry-cured ham slices. PLSR models for predicting water, fat and salt contents with NIR spectra were developed with a calibration set of samples (n=82). The models were validated with an external validation set (n=42). The predictive models were accurate enough for screening purposes. The errors of prediction were 1.34%, 1.36% and 0.71% for water, fat and salt, respectively. The spatial distribution of these components within the slice was also obtained.

Mitochondrial oxygen consumption in permeabilized fibers and its link to colour changes in bovine M. semimembranosus muscle.

Animal and muscle characteristics were recorded for 41 cattle. The oxygen consumption rate (OCR) of M. semimembranosus was measured between 3.0-6.4h post mortem (PM3-6) and after 3 weeks in a vacuum pack at 4°C. Colour change measurements were performed following the 3 weeks using reflectance spectra (400-1,100 nm) and the colour coordinates L, a and b, with the samples being packaged in oxygen permeable film and stored at 4°C for 167 h. Significant individual animal differences in OCR at PM3-6 were found for mitochondrial complexes I and II. OCR of complex I declined with increased temperature and time PM, while residual oxygen-consuming side-reactions (ROX) did not. OCR of stored muscles was dominated by complex II respiration. A three-way regression between samples, colour variables collected upon air exposure and OCR of 3 weeks old fibres revealed a positive relationship between OCR and complex II activity and also between OCR and OCR(ROX). The presence of complex I and ß-oxidation activities increased metmyoglobin formation.

Strain-level characterization of nonstarter lactic acid bacteria in Norvegia cheese by high-resolution melt analysis.

The nonstarter lactic acid bacteria (NSLAB) constitute an important microbial group found during cheese ripening and they are thought to be fundamental to the quality of cheese. Rapid and accurate diagnostic tests for NSLAB are important for cheese quality control and in understanding the cheese ripening process. Here, we present a novel rapid approach for strain-level characterization through combined 16S rRNA gene and repetitive sequence-based high-resolution melt analysis (HRM). The approach was demonstrated through the characterization of 94 isolates from Norvegia, a Gouda-type cheese. The HRM profiles of the V1 and V3 variable regions of the 16S rRNA gene of the isolates were compared with the HRM profiles of 13 reference strains. The HRM profile comparison of the V1 and V3 regions of the 16S rRNA gene allowed discrimination of isolates and reference strains. Among the cheese isolates, Lactobacillus casei/paracasei (62 isolates) and Lactobacillus plantarum/Lactobacillus pentosus (27 isolates) were the dominant species, whereas Lactobacillus curvatus/Lactobacillus sakei were found occasionally (5 isolates). The HRM profiling of repetitive sequence-based PCR using the (GTG)(5) primer was developed for strain-level characterization. The clustering analysis of the HRM profiles showed high discriminatory power, similar to that of cluster analysis based on the gel method. In conclusion, the HRM approach in this study may be applied as a fast, accurate, and reproducible method for characterization of the NSLAB microflora in cheese and may be applicable to other microbial environments following selective plate culturing.