Research round-up: FTIR as fraud tool, dipstick detection and waterborne outbreaks
Firstly, Fourier transformed-infrared (FTIR) spectroscopy and chemometric models for classification and quantification have been used to identify animal products in ground beef by researchers at the University of British Columbia.
The technique was able to determine with 99% accuracy whether ground beef samples included other animal parts and with 80% accuracy which animal parts were used and in what concentration.
DNA testing can identify foreign species in meat products but cannot identify offal - hearts, livers, kidneys and stomachs - mixed in with meat of the same species.
UBC researchers aimed a spectrometer at meat samples they had prepared by grinding together beef and offal from supermarkets at various concentrations.
Because animal products have different chemical compositions, their molecules absorb and scatter energy from the spectrometer’s laser in different ways.
The spectrometer captures these signals - or spectra - to produce an ‘image’ of each substance. These images can serve as a library for comparison with other samples.
Nucleic acid extraction dipstick methodology
Dipstick technology for pathogen detection has been developed by University of Queensland scientists.
Untreated cellulose-based paper can capture nucleic acids and retain them during a single washing step while contaminants in complex biological samples are removed.
Professor Jimmy Botella, school of agriculture and food sciences researcher, said the nucleic acid extraction dipstick methodology can obtain amplification-ready DNA and RNA from living organisms in 30 seconds without specialised equipment or personnel.
“We have successfully used the dipsticks in remote plantations in Papua New Guinea to diagnose sick trees, and have applied it to livestock, human samples, pathogens in food, and in detecting environmental risks such as E. coli-contaminated water.
“Our technology eliminates the need for a specialised laboratory for sample preparation, and is a lot simpler, faster and cheaper than anything else available, making diagnostics accessible to everyone.”
Current commercial kits isolate DNA and RNA through a long and cumbersome process requiring specialised laboratory equipment.
UQ's commercialisation company, UniQuest, has filed a patent application on the dipstick technology and is seeking commercial partners.
Campylobacter and norovirus
Kingston University researchers have shown Campylobacter uses another organism's cells as a Trojan horse.
They found the bacteria can infiltrate microorganisms called amoebae, multiplying within their cells while protected inside its host from harsh environmental conditions.
The Kingston University team used a modification of a process that assesses the bacteria's ability to invade cells – called the gentamycin protection assay.
Ana Vieira, lead author, said the research could help efforts to prevent the spread of infection.
“Establishing that Campylobacter can multiply inside its amoebic hosts is important, as they often exist in the same environments – such as in drinking water for chickens on poultry farms – which could increase the risk of infection."
Researchers showed how a system used by the bacteria to expel toxins – known as a multidrug efflux pump – plays a role in its ability to thrive within the amoebae.
Denmark, France, Italy, the Netherlands and Norway contributed the majority of norovirus alerts as notifying countries, according to a RASFF analysis covering all alert and border rejection notifications until the end of August this year.
France and Serbia were cited more often in alert notifications as countries of origin and Italy and Spain submitted the majority of border rejection notifications.
Third Countries implicated frequently in border rejection notifications for norovirus in bivalve molluscs were Vietnam and Tunisia and China and Serbia for fruits and vegetables.
A project led by Dr Meijun Zhu, an associate professor in the School of Food Science at Washington State University, Pullman, will provide industry with data to optimize spray-wash process control and practices during apple packing.
Pacific Coast apple packers apply antimicrobial sprays to fruit on the packing line but there is limited scientifically determined data to optimize process parameters to reduce the risk of Listeria monocytogenes cross-contamination and persistence potential.
Zhu has conducted lab tests with about a half dozen antimicrobial products either registered for use on food or close to being registered.
They are looking to see if Enterococcus faecium NRRL B-2354, a non-pathogenic microorganism would be a viable surrogate for L. monocytogenes in non-thermal inactivation applications.
Co-investigator of the two year project is Dr Trevor Suslow, a University of California, Davis, extension research specialist in postharvest quality and food safety.
Suslow will lead trials using a pilot-scale packing line running Granny Smith and Fuji apples.
Manal Mohammed looked at high-throughput CRISPR typing compared to conventional phage typing in epidemiological surveillance and outbreak investigation of Salmonella Typhimurium.
High throughput clustered regular interspaced short palindromic repeats (CRISPR) typing could replace phage typing.
Phage typing has been used for subtyping S. Typhimurium to determine the epidemiological relation among isolates.
Mohammed found different phage types of S. Typhimurium share identical CRISPR type.
Phage typing is still the gold standard method for epidemiological surveillance of the pathogen until it is replaced by Whole Genome Sequencing.
Allergen research
Children at one year old who have eczema or atopic dermatitis (AD) and are sensitized to an allergen are significantly more likely to have a food allergy by age three.
Using data from more than 2,300 children in Canada in the CHILD Study, researchers evaluated the presence of AD and allergic sensitization at age one.
When the children were three, researchers did a clinical assessment to determine the presence of asthma, allergic rhinitis, food allergy and AD.
Combined effect of AD and allergic sensitization was found to be greater than the sum of their individual effects, both on the risk of asthma and on reported food allergy.
Findings build on another CHILD study finding, which showed that children who avoid cow’s milk products, egg, and peanut during their first year are at increased risk of allergic sensitization to these foods later on.
Meanwhile, researchers have found that a protein serves as a ‘food allergy amplifier’.
A novel biochemical mechanism governing histamine-releasing factor (HRF) activity, paves the way for blood tests to predict which patients will respond to allergy therapy and supports the idea that drugs designed to block HRF could prevent food allergy attacks.
The ‘prevailing view’ of the allergy cascade is: 1) allergens ramp up levels of antibodies called immunoglobulin E (or IgE), which then 2) bind to mast cells, and 3) when allergen touches IgE, mast cells release histamine.
Toshiaki Kawakami, La Jolla Institute researcher, said: “But when we began these studies, we suspected that allergens are often present at very low levels, possibly too low to activate mast cells by this pathway.
“Our new paper confirms that once triggered by allergens, HRF proteins bind to IgE and then both synergistically activate mast cells and enhance inflammation."
Kawakami's group engineered mice to become allergic (‘sensitized’) to egg protein and treated them with an oral HRF inhibitor the lab had developed for use in asthma-related experiments.
Untreated mice developed diarrhea and signs of gut inflammation. However, symptoms were delayed or less severe in inhibitor-treated mice and the inhibitor reduced allergen reactivity of mast cells isolated from the gut of allergic mice.
"The fact that orally-administered HRF inhibitors can prevent development of food allergy in a mouse strongly hints that we could create similar medicine to treat humans with food allergy," said Tomoaki Ando, an assistant professor at Juntendo University in Tokyo.
During 2013-14, 42 drinking water–associated outbreaks accounted for at least 1,006 cases of illness, 124 hospitalizations and 13 deaths.
Legionella was associated with 57% of the outbreaks and all deaths.
A total of 69% of reported illnesses occurred in four outbreaks in which the etiology was determined to be either a chemical or toxin or the parasite Cryptosporidium.
Finally, Cawthorn has received International Accreditation New Zealand (IANZ) accreditation for a PCR (polymerase chain reaction) test to detect Listeria in food and environmental swabs.
It will cut sample processing time from two days to one meaning producers can clear product faster and potentially ship exports earlier.
Mark Englefield, Cawthron microbiology section head, said it was important to ‘test the test’ thoroughly before bringing it to market.
“As new technology comes to the fore, so do opportunities for us to improve our services. PCR technology has traditionally been used for research purposes, but we recognise the opportunity to apply it to food safety testing.”
