Using SIFT-MS for detection of beer spoilage bacteria and compounds causing off-flavour in beer

Selected ion flow tube mass spectrometry (SIFT-MS) was used for detection of spoilage bacteria in wort and beer. Samples were analysed in triplicate using SIFT-MS Full Scan mode to identify volatile compounds in the headspace of the samples. Volatile compounds in wort headspace included acetaldehyde, propanol, 2-methylpropanal, hexanal, methanethiol, 2-methylbutanal. Volatile compounds in the headspace of the wort inoculated with Lactobacillus brevis included ethanol, acetic acid and propanol. The following compounds were identified in the headspace of the sample of degassed beer: ethanol, propanol, 2-methyl-1-propanol, acetaldehydes, and ethyl formate. The detected volatile compounds coming from the headspace of wort inoculated with Lactobacillus brevis revealed changes in the compounds due to unwanted bacterial fermentation. In addition, an unidentified product ion having m/z 39 was detected. Calculations of relative abundance for this product ion and further investigations demonstrated that it can be considered as a result of compounds formed due to contamination with L. brevis. These data suggest that SIFT-MS has great potential for detection of volatile compounds coming from beer spoilage bacteria

Integration of new biological and physical retrospective dosimetry methods into EU emergency response plans : joint RENEB and EURADOS inter-laboratory comparisons

Purpose: RENEB, 'Realising the European Network of Biodosimetry and Physical Retrospective Dosimetry,' is a network for research and emergency response mutual assistance in biodosimetry within the EU. Within this extremely active network, a number of new dosimetry methods have recently been proposed or developed. There is a requirement to test and/or validate these candidate techniques and inter-comparison exercises are a well-established method for such validation. Materials and methods: The authors present details of inter-comparisons of four such new methods: dicentric chromosome analysis including telomere and centromere staining; the gene expression assay carried out in whole blood; Raman spectroscopy on blood lymphocytes, and detection of radiation induced thermoluminescent signals in glass screens taken from mobile phones. Results: In general the results show good agreement between the laboratories and methods within the expected levels of uncertainty, and thus demonstrate that there is a lot of potential for each of the candidate techniques. Conclusions: Further work is required before the new methods can be included within the suite of reliable dosimetry methods for use by RENEB partners and others in routine and emergency response scenarios