California beer scientists say they've made a hoppy tasting brew that's 100 per cent hops-free.

According to a UC Berkely paper published in the journal Nature Communications, researchers used DNA-editing software to splice genes from mint and basil plants into brewer's yeast.

That gave the brew a fruity and zesty flavour without having to use hops, a plant that requires a lot of water and energy to cultivate, said co-author Charles Denby.

One pint of craft beer can require 50 pints of water merely to grow the hops, according to UC Berkeley.

"And then transporting them and refrigerating them before you make beer with them — all of those things require a lot of natural resources," Denby, a molecular biologist, told As It Happens host Carol Off.

"So we saw this as a great opportunity to make the brewing process more sustainable," Denby said.

Hops gives beer its unique flavour, but it takes a lot of water and energy to cultivate. (Carl Court/Getty Images)

But how does it taste?

Denby said they teamed up with the Lagunitas Brewing Company to do some quality control, and a panel of beer tasters reported the hops-free brew actually tasted hoppier than most beers.

"That was very exciting," Denby said.

Bryan Donaldson, innovations manager at Lagunitas, also sampled the product and reported notes of "Fruit Loops" and "orange blossom" — which, Denby said, is a good thing.

Denby said different types of flavours could be incorporated into the yeast to create other unique flavours of beer.

"What these experiments show is there is a tremendous amount of potential that we have for making new brewing yeast strains to generate new flavours that are potentially even more desirably than what conventional hops is capable of," he said.

Charles Denby and Rachel Li have launched a startup called Berkeley Brewing Science to create sustainable gene-edited beers. (University of California Berkeley )

Denby and co-author Rachel Li have launched a startup called Berkeley Brewing Science and they hope to market their DNA-spliced yeasts to the beer industry.

They are using CRISPR-Cas9, a gene-editing tool.

It could be a tough sell to convince beer-lovers to buy a brew that's lacking such an essential ingredient, Denby said, but he's optimistic.

"Once people find out that their beer is being made in a much more sustainable way, I think people will be really excited and I think people will get behind that," he said.

"I'm banking on it."

Written by Sheena Goodyear. Interview produced by Mary Newman.