Gin fingerprint test could improve flavour and detect fakes

CHEMISTS at Heriot-Watt have trialled a new technique that takes a chemical fingerprint of gin in just seconds. 

Dr Ruaraidh McIntosh, Dr Dave Ellis and PhD student Kacper Krakowiak from Heriot-Watt worked with Professor Dušan Uhrín from the University of Edinburgh on the project. 

The team says their technique could help producers futureproof their gins and conduct quality control, while regulators could use it to detect fraudulent products. 

Dr Ruaraidh McIntosh said: “Gin production has exploded in Scotland and the UK over the past 20 years, but compared to Scotch whisky it’s very loosely defined and regulated, and not well-researched. 

“Producers need to know more so that they can ensure they have years of sustainable, flavoursome gin ahead of them. 

“And consumers and importers need to know that gin is genuine and the quality they’re expecting.”

Alcohol, water, botanicals 

Gin is quite loosely defined, but the EU states that it must contain a minimum of 37% alcohol and the spirit is traditionally associated with flavourings provided by juniper berries.

Dr Dave Ellis said: “We know from whisky research that chemical compounds have a huge impact on the flavour and sensory properties of a dram, even though they are in very low concentrations. 

“Understanding which compounds are in a gin, and have an impact on flavour and mouth feel, could help distillers improve their gin, or guarantee uniformity of flavour.” 

The Heriot-Watt researchers used nuclear magnetic resonance (NMR) spectroscopy to examine the gin. It’s a technique more commonly used in the structural determination of molecules. 

Ellis said: “At the moment, most gin analysis is carried out using mass spectrometry. It’s effective and highly sensitive but does not provide a complete picture of the composition in a single experiment in the way that NMR can.  

“NMR basically fingerprints the gin’s chemical compounds. It does this by detecting the signals given by the hydrogen atoms in each compound. These act as markers and enable identification.”

“In under five minutes, we end up with an overlay of all these fingerprints, providing a snapshot of the compounds present. .” 

Molecules affect gin’s flavour and scent 

The team put 16 different gins to the test, some they bought from the supermarket and some samples were provided by colleagues at Heriot-Watt’s International Centre for Brewing and Distilling (ICBD). 

Dr Dave Ellis said: “We determined which compounds were present in each gin, and in which quantities. 

“NMR can distinguish between different structural forms of individual molecules, and there are many of these cases in gin. 

“For example, the flavour compounds pinene and limonene have the same atomic makeup but have different structures and, critically, flavours. 

“We tested some fruit gins and gin liqueurs. The NMR identified the different varieties of sugar present in the gin, which are introduced through flavour additives, and their quantity. This is important information for consumers. 

“UK distillers rely on imported juniper berries for their gin, and climate change could affecttheir quality and availability. If their traditional supply dries up, will sourcing juniper berries from elsewhere change the flavour? That’s what we could determine with this technique.

“NMR has huge potential for the gin industry.” 

“It’s like the wild west” 

Dr Ellis points out the contrast between gin and whisky. 

“The whisky market is very well-regulated, but there’s no equivalent for gin. The EU imposes some requirements, but essentially, you can make anything, call it a gin and nobody will give you any trouble. It’s a bit like the wild west. 

“Colleagues at the Heriot-Watt International Centre for Brewing and Distilling have created a database of botanicals and this could be used as a basis of standardisation in the future, but we shouldn’t discourage innovation in gin production. 

“We just need to try and find a way of reassuring consumers that the ‘gin’ that they are drinking really is gin.”

The researchers are expanding their studies to embrace many more types of so-called gin and other alcoholic beverages. 

The findings are reported in the Journal of Brewing and Distilling

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