health & science

The smart knife revealing steak secrets

Fumes from cutting meat with a special, ‘smart’ scalpel can reveal what the animal ate, where it lived, its flavour profile and even clues about the farm's environmental practices. The same technology could be used on milk and wine, raising intriguing prospects for marketing Kiwi exports.

Imagine cutting into a lamb shank with a clever knife that tells you where the animal lived, its diet, and whether you're likely to enjoy the taste.

AgResearch scientists have found a way to do it, although it won't be available at the dinner table anytime soon.

Say you want to be sure of your steak’s country of origin, or to verify that the farmer really used a climate-friendlier animal feed, as promised on the meat's label. Researchers at AgResearch can do it by testing molecules in meat vapour.

Vapour, you say?

Meaty fumes are produced by slicing into a beef steak or lamb chop with a heated electric scalpel, originally designed for human surgery. The cutting and searing releases fat molecules, which are sucked from around the incision and into a tube to be analysed by a machine called a rapid evaporative ionisation mass spectrometer (REIMS); an ultra-fast, ultra-sensitive set of scales that precisely measures the mass of the meat’s fat molecules.

Like people, sheep and cows are - literally - what they eat, since their diets supply the building blocks for their fat molecules. Since there are thousands of different kinds of fat, or lipids, an animal’s genes and lifestyle (including its diet) combine to produce a distinctive fatty signature, says AgResearch senior scientist Alastair Ross.

The composition of a beast's lipids holds clues to the animal’s diet, breed, provenance and flavour because its lifestyle leads to tiny differences in the molecular mass of its fat, which the REIMS machine detects.

The test is so sensitive it can show whether a sheep ate clover, plantain or ryegrass during its life, or a mixture of two of those pasture species. It could also, potentially, show whether the flavour is more likely to appeal to the tastes of diners living in China, versus European shoppers, or people in other export markets.

There’s no immediate prospect of getting a smart knife for your own home, since each REIMS is high-spec, sensitive, and costly. However scientists demonstrated the process to farmers at Fieldays. Right now, the only REIMS machine in Australasia is one AgResearch purchased late last year from the United Kingdom, which is used for running experiments at the crown-owned research institute's Lincoln campus. Ross say his team is looking for ways to get similar results, cheaper, and is talking to the manufacturer about future uses in the agricultural sector - for example making a version for use in abattoirs. 

While Ross and his team haven't yet tried using the machine to identify whether an animal ate grain or grass, or had its feed supplemented with palm kernel, the fact that it can tell apart animals fed different pasture species means it is very likely to be able to do both of those things, says Ross. “We don't have that many grain-fed animals here so we haven't tried it, but I'd be very surprised if it doesn’t work," he says.

Similar tests could supply consumers with proof that farmers were using crops that had been proven to be gentler on the climate or waterways. Plantain, for example, has shown promise at reducing both nitrogen run-off to water and emissions of the greenhouse gas nitrous oxide from animal urine.

Ross says two animals bred with the same genes, but raised differently, can contain very different fats. The researchers have shown they can tell New Zealand lamb from Welsh lamb, for example, though they haven’t yet analysed exactly why the countries produce distinct types of meat. “The difference between Wales and New Zealand will be things like different seasons, as well as what they are eating, all that gets jumbled up, so we’re seeing the interaction between environment and genetics,” says Ross.

Promisingly, the scientists have found there are certain molecules associated with tastiness, he says.

“We have analysed lambs from 10 different kinds of pasture, and got 160 consumers to eat them and rank them by taste, so we could pick out molecules that relate to the liking of lamb,” says Ross. “There’s a lot of potential to see if making changes to our pasture will impact people’s liking of the product.”

Made for surgery

The REIMS technology wasn’t invented just to parse the fat make-up of lamb shanks. The initial plan was to improve outcomes for people undergoing cancer surgery.

The original idea behind the machines was to detect which tissue is cancerous and reveal, in real time, to surgeons where a tumour starts and ends, so they don’t remove more tissue than is needed – and can also make sure they get out all of the cancer.

Trials in hospitals in the United Kingdom are seeking to prove that the smart scalpel could save lives, by preserving healthy organ tissue and avoiding the need for a second surgery to remove cancer that was missed.

AgResearch, however, spotted the possible applications for Kiwi exports, and bought a machine to see what it could do.

“We’ve been testing it on different samples since last year, and we’ve been very impressed," says Ross.

"We can measure the molecules that come from when you cook, so we’ve been able able to collect the vapour from cooking and see differences between cooking beef and cooking lamb."

The basic technology behind the machine has existed for many years, says Ross, but previously, AgResearch scientists would have had to freeze-dry the meat, grind it up into a fine powder, weigh it, add solvent, shake it and extract the solvent before putting it in a mass spectrometer to analyse it, he says. “Now we just get the package out of the fridge and cut it. For the test of where the lamb comes from, we did the analysis in just over an hour - we went through 60 samples and measured each sample three times. That would have taken us a couple of weeks otherwise. It’s a beautiful thing.”

As well as learning about meat, the machine could be used to glean information about wine and milk (a video shows a researcher putting milk in a cup and "cutting" through it). Anything that can create a vapour can be tested. 

Ross hopes similar tests will one day be used to pick out products that will sell better in certain countries, or at different ends of the market, to help exporters get the most money for their products. It could help spot dud food, too. 

Say Ross: “If we can pick out a signature for fantastic lamb we can sell it to top-of-the-line restaurants, and if we pick out something awful we can make sure it ends up in dog tucker.”

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