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Analytical technology From May 2018 newsletter

Analysis in food safety - research

A new member funded project looking at the next generation techniques for microbiological and chemical food safety has started. The new project builds on a previous one that assessed the use of next generation analytical techniques to provide more rapid results, greater sensitivity and the ability to detect emerging food safety hazards. Some of the outcomes from the project that ran from 2015-2017 follow.


Chemistry


Chlorate and perchlorate


EFSA is investigating this issue so that a risk assessment of food on sale to consumers can be undertaken. In response to this we sought to develop a rapid and sensitive analytical method based on LC/MS/MS.


We have developed an efficient, simple and rapid procedure using Ultra High-Pressure Liquid Chromatography and Mass Spectrometry (UHPLCMS/MS) and multiple reaction monitoring (MRM) for the detection of chlorate and perchlorate. This method shows exceptional specificity and sensitivity, coupled with simple sample preparation, and can achieve microgram level sensitivity. This makes this method ideal for determining residues in a wide range of foods and beverages. The current limit of detection for this method is set at 0.5μg/kg.


Food authenticity - rapid testing by REIMS


Industry requires fast and sensitive methods for quality assurance purposes. Methods that detect and confirm the identity of a raw material or ingredient enable food operators to monitor their supply chain for inadvertent cross-contamination and prevent.


We assessed the feasibility of REIMS (rapid evaporative ionisation mass spectrometry technology) in food testing and showed that the technique provides an instant response for various identifications. This method could be the fastest technique in a range of food testing applications including food fraud.


Herb authenticity


Contamination and adulteration of herbs and spices with other plant materials have led to the need for improved methods of detection. There is a need for alternative non-targeted DNA approaches that can be used to screen for unknown plant material. We investigated non-targeted DNA screening by PCR-RFLP profiling and Next Generation DNA Sequencing (NGS).


Our results showed that PCR-RFLP offers the potential to screen for plants species present, but further work is needed to ensure that PCR primers are capable of amplifying from all species. NGS offers the possibility of sensitive detection of adulterant plants species, but it may also detect species present at low levels due to adventitious contamination.


Microbiology


In parallel the project also considered microbial food methods. Two of the key outcomes were: receiving UKAS accreditation for virus testing; extending our metagenomic expertise and client services.


Advanced microbial profiling


Metagenomics is a technique that allows huge numbers of different individual DNA sequences to be read at any one time. We analysed DNA profiles generated from spoiled poultry samples to show the benefits of using a metagenomic approach over a culture based analysis. Media culture based analysis uses microbiological media which selects for groups of organisms able to grow under set incubation conditions. Our results showed the influences these choices of culture media can have on the understanding of the microflora. The highest proportion of reads was assigned to Photobacterium profundum, an organism currently associated with fish, contradicting the accepted wisdom that Pseudomonas spp. would comprise the dominant microflora.


The ability to identify all major groups of organisms in a sample using culture-independent means will give much greater understanding of the true nature of microbial populations in food over time. It remains to be determined if this can be related to culture-based enumeration.



UKAS virus accreditation


There has been a global movement directed towards better understanding and development of food borne virus detection methods in recent years.


Our detection method, based on the current ISO Standard ISO15216-2013 part 2, has been verified for the detection of norovirus genogroups I and II (Nov) and Hepatitis A (HAV) in a variety of fresh and frozen fruits and produce. This involved an internal evaluation of samples spiked with different levels of the target virus. We are also participating in external proficiency schemes to demonstrate competency.


The method is intended for use as a qualitative determination of the presence or absence of Norovirus GI and/or GII and/or HAV in fresh produce samples. Campden BRI is the only UK laboratory to offer a UKAS accredited detection service for Norovirus and Hepatitis A.



Contact: Suzanne Jordan
+44(0)1386 842013
suzanne.jordan@campdenbri.co.uk



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