When properly designed, a microbiological risk assessment (MRA) is an objective and systematic evaluation of existing scientific knowledge to help risk managers making an informed decision about how to handle food safety issues. Together with epidemiological based information and economic analysis it can provide the best information for control measures. One of these control measures concerns setting food safety criteria. In this document some historical backgrounds are presented how food safety management has been evaluated in course of time from mythology, via prohibition and precautionary principles to a science based approach. MRA-tools are described and examples of risk assessment approaches are presented as a basis for setting microbiological criteria.
A total of 52 Penner O group Campylobacter jejuni strains isolated from humans and chickens were found to represent 15 different types by PFGE (pulsed-field gel electrophoresis) according to an investigation conducted by three institutes in Akita, Saitama and Shizuoka prefectures. Our study indicates that the discrimination ability of C. jejuni by PFGE is different among serotypes. C. jejuni strains of the Penner O group showed higher clonarity than those of Penner B, D groups on the basis of the physiological tree constructed by UPGMA (unweighted pair group method with arithmetic mean). As two PFGE types were identical to human isolates, chicken is thought to be one of the causative foods for Penner O group C. jejuni infections.
Some Alicyclobacillus species cause the spoilage of acidic beverages resulting in an odor of phenolic compounds such as guaiacol. We have already developed a discrimination method based on the gyrB sequence for A. acidoterrestris, which is the most frequently isolated species from spoiled products. Furthermore, in order to discriminate the other Alicyclobacillus species, we determined gyrB sequences of additional Alicyclobacillus species and comparative analysis of gyrB sequences was performed among all Alicyclobacillus species. The results showed species-specific regions in each Alicyclobacillus species. Using these regions as primers, each Alicyclobacillus species could be clearly detected with the PCR technique. Moreover these primer sequences could be applied to the LAMP method, and each Alicyclobacillus species could be rapidly and easily detected without amplification of non-target species. It is suggested that these species-specific regions are useful for discrimination of Alicyclobacillus at species level in quality control laboratories.
The swelling phenomenon of packages containing Mamakari fish treated with vinegar seasoning was observed. Analysis of the swollen sample revealed lactic acid bacteria but not in a normal sample, and the isolate was identified as Lactobacillus brevis. The process of carbon dioxide gas production was supposed by heterofermentation and glutamate decarboxylation. Growth of the isolate was inhibited additively in a mixed solution containing acetic acid, lactic acid and NaCl. Accordingly, it is shown that growth of the isolate causing swelling of the package was inhibited by vinegar seasoning containing appropriate organic acid contents.