You might not think it, but the gin and tonic you have on a Friday night has a significant and damaging environmental footprint. The process of its production – including the cultivation of wheat, production of enzymes, heat, electricity, packaging materials and transport – results in CO2 emissions.

It is estimated that 2.3kg of CO2 equivalent is pumped into the atmosphere for each 70cl bottle of gin, or the equivalent of 160g CO2 equivalent for a large 50ml measure. However, researchers have found a way to produce gin in a much more environmentally friendly way with a surprising ingredient: peas.

In a paper published to Environmental International, a team including Trinity College Dublin botanist Prof Mike Williams and NUI Galway’s Dr David Styles ran a series of trials at Arbikie Distillery in Scotland. In this trial, kernels of dried, de-hulled peas were milled and fermented in place of mashed wheat grain.

The study was part of the pan-European project, ‘Transition paths to sustainable legume-based systems in Europe’, led by Dr Pietro Iannetta, who is a molecular ecologist at the James Hutton Institute in Scotland.

The results showed that the environmental footprint of pea gin was significantly lower than for wheat gin across 12 of 14 environmental impacts evaluated. This included how it impacted water, air pollution and fossil fuel consumption.

Or just don’t drink gin

Speaking of how this works, Williams said: “Peas – working with specialised bacteria in their roots – are able to convert nitrogen from the atmosphere into biological fertiliser.

“As a result, they don’t require applications of polluting synthetic nitrogen fertilisers, which are widely and heavily used in industrial agriculture.”

He added that pea hulls and distillery co-products provide protein-rich animal feeds that can replace soybean imported from Latin America, where cultivation is driving deforestation.

The co-products from one litre of pea gin substitute up to more than half a kilogram of soybean animal feed, or twice as much gained from the production of wheat gin. By taking into account other processes involved in gin’s production, from deforestation to transport, it can even be considered carbon-neutral.

However, for Styles, a simpler way to dramatically shrink our environmental footprint would be to just eat the peas “instead of drinking gin and eating beef fed on these co-products”.

Colm Gorey

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