Food

DNA tests for identifying beef: Should we shift our focus to meat safety instead?

Testing cooked meat may be challenging since heat degrades DNA

 
By Rohini Krishnamurthy
Published: Thursday 20 October 2022

DNA tests are gaining prominence in India since they are being used to identify beef samples in states with cow slaughter bans in place. Currently, Gujarat, Maharashtra and Delhi are some of the states that carry out forensic DNA tests to identify beef.

Such tests provide scientific aid in states where cow slaughter is banned

The process involves extracting DNA from raw or cooked meat. Polymerase chain reaction (PCR) technique is employed to rapidly replicate millions of copies of specific DNA.

Researchers use primers — short DNA segments that bind to certain locations — and synthesise new strands to create multiple copies. Primers target the mitochondrial DNA. And this DNA helps in identifying the species.

But in cases where an individual needs to be identified, nuclear DNA is used, said Ved Prakash, a wildlife forensics expert from Maaty-Biodiversity Conservation and Societal Research, a non-profit based in Uttarakhand. The latter can help settle disputes between people over ownership of cows.

Battery of tests

Species identification tests are not new. Serological tests have been widely used for the last 15 years, according to scientists.

But serological tests such as ELISA are falling out of favour. “The process is time-consuming and strenuous. And sensitivity is low,” said Sarita Kumari, assistant professor at Apollo Veterinary College and Hospital.

She highlighted that DNA tests have higher accuracy and sensitivity.

Since 2020, Gujarat’s Forensic Science Laboratory has been embracing a new DNA test to detect beef meat.

The new Loop-mediated isothermal amplification (LAMP) test generates results in under an hour. At the same time, conventional techniques like PCR can take a day or two.

LAMP was first defined in 2000 by researchers from Japan. The technique is performed at a constant temperature of 65 degrees Celsius, eliminating the need for expensive PCR machines. A water heater or other portable instruments can aid the test, Kumari explained. 

PCR is carried out with the help of a series of alternating temperature cycles. A PCR machine can cost around Rs 1-15 lakh. LAMP has also been used to diagnose infections such as COVID-19 and Tuberculosis.

“I wanted to test if it can be used forensically,” Nikunj Brahmbhatt, senior faculty at the National Forensic Sciences University, told Down To Earth.

Tests have showed that LAMP is 100 per cent accurate, Brahmbhatt claimed. He devised the technique during his PhD. The Gujarat Forensic lab is currently using it.

Testing cooked meat may be challenging since heat degrades DNA. “But if I recover DNA, LAMP can generate results,” he added. But Naresh Kumar, senior scientific officer at the Forensic Science Laboratory, Delhi, has some apprehensions.

“The technology is relatively new, so I cannot comment on its accuracy. If the test gives false results, it may create problems because this is a legal issue,” he said.

We are confident about the accuracy of PCR-based DNA tests, he added.

Gujarat’s Forensic Science lab also performs serological tests. 

“Scientists apply the LAMP test in cases where they think that serological methods are not providing conclusive results,” Brahmbhatt noted. Delhi’s forensic science laboratory uses PCR-based kits to detect cow and buffalo meat, Kumar said.

The lab provides services to the police department. They receive two-three samples per month. Most samples tested in the lab turn out to be cow meat, Kumar said.

But a 2019 Times of India, a daily, report found that only seven per cent of the 122 seized meat samples sent to the National Research Centre on Meat (NRCM) between 2014 and 2017 belonged to cows.

India reported 123 mob attacks between 2010 and 2018 on suspicion of possessing or transporting cow meat, according to the data journalism portal India Spend.

DNA tests for species identification are expensive. A single test on a suspected beef sample at NRCM can cost up to Rs 10,000. Delhi’s Forensic Science Laboratory spends roughly 2 lakh rupees on a kit that can test 100 samples, Kumar said.

The lab supports the Delhi police in collecting biological samples.

“Our control room works 24x7. Our lab has deployed scientific staff or mobile crime scene teams for instant collection of biological samples,” said Sanjeev Kumar Gupta, assistant director of Forensic Science Laboratory, Delhi.

More applications

India should routinely focus on using these tests to check meat adulteration, said experts.

Adulteration involves replacing the meat of an animal with cheaper or inferior meat. This could threaten the health of consumers, according to a 2021 paper published in the Indian Journal of Animal Research.

“There is more focus on testing beef meat in states that have banned cow slaughter and not so much on adulteration,” Prakash said.

Governments should use DNA tests in malls, shops and airports to check adulteration, he added.

Some researchers tested 106 meat products sampled from the Ernakulum district in Kerala. Some 52.3 per cent of them was mutton, 55.5 per cent was buffalo meat. Around 27.2 per cent of beef products were mislabelled.

“Such adulteration may lead to health hazards associated with exposure to drug residues such as phenyl butazone in horse meat and allergens, bacteria and parasites in porcine meat,” the study read.

Such tests can be used to solve wildlife crimes and conserve endangered species. 

It has helped forensic scientists monitor the illegal trade of ivory and detect the source population of whale meat confiscated from Japanese markets, according to a book titled Forensic Analysis - Scientific and Medical Techniques and Evidence under the Microscope.

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