Smell and taste are an essential part of people’s lives. However, industrial production of flavours and fragrances harms the environment. Now researchers have succeeded in getting yeast to produce them, which will reduce the use of chemicals and energy. Beer flavour produced by yeast is already on its way to the market, and new studies show that yeast can also produce the fragrances used in cosmetics and cleaning products.
Most beer lovers know the bittersweet taste of hops. Unfortunately, aroma hops, the kind of hops that are used in the more flavourful types of beer, are grown almost exclusively in the United States, with thousands of litres of water needed to grow a single kilogram. Researchers have created small specialised factories in yeast for producing flavours that hop farmers currently use considerable resources, water and energy to produce. However, according to the researchers, this breakthrough is only the first of many.
“The challenge of getting yeast to help us produce these fragrances and flavours has been to separate the production from the yeast’s normal processes. The new production is placed in separate compartments of the yeast cells, so that the processes that make yeast cells grow do not compete with the processes that make the valuable products. This has enabled us to get yeast to produce both beer flavour and now also fragrances that can be used in perfumes and cleaning products,” explains an author behind the research, Sotirios Kampranis, Professor of Biochemical Engineering at the Department of Plant and Environmental Sciences, University of Copenhagen.
An idea for non-alcoholic beer
The scientific basis for the new sustainable method for producing fragrances and flavours was created years ago. However, using cell factories to produce fragrances and flavours belonging to the monoterpenoid family had been extremely challenging since many of the biochemical steps leading to the formation of these compounds were very inefficient in yeast.
“Researchers transferred genes that encode the enzymes that could enable yeast to perform the processes, but this triggered competition with existing processes in the yeast since these took place in the same parts of the yeast cell. We decided instead to try to locate them in separate organelles called yeast peroxisomes, which usually oxidise fatty acids,” says Sotirios Kampranis.
The researchers knew that the yeast did not need peroxisomes when cultured on sugar-based media, and as long as sugar is present, the yeast peroxisomes can be manipulated without adversely affecting yeast growth. The researchers then established production of a key compound – geranyl diphosphate, a universal building block that is a precursor to many monoterpenoid fragrances and flavours used in the food and cosmetics industries.
“We hijacked the yeast to help us to produce valuable substances while it just continued its normal activities. We asked ourselves: which compounds should we first start producing to address sustainability concerns and also benefit society? So, we came up with the idea of improving non-alcoholic beer, partly because hops farming is water-draining while their transport is energy-intensive, and partly because the poor taste frequently associated with non-alcoholic beers makes it harder for customers to select it as an option. The main challenge in making non-alcoholic beer taste like the real thing is that the processes used to reduce the alcohol also reduce the hoppy flavour, so the beer tastes flat and watery,” explains Sotirios Kampranis.
Creating similar factories is relatively easy
The researchers have gotten yeast to produce the flavours that can be added to the non-alcoholic beer. However, Sotirios Kampranis thinks that the relevance of the flavour of aroma hops applies to more than brewing non-alcoholic beer. In general, traditional brewing relies on flavours from hops, which are intensively farmed, consume substantial amounts of water and cause considerable emissions of carbon dioxide.
“Compared with using hops, the new technology can reduce water consumption by a factor of 10,000 and carbon dioxide emissions by a factor of 100, for making the same amount of beer. The improvement in the taste of several non-alcoholic beers tested was so great that we have created a company, EvodiaBio, focusing on getting the first hops extract product ready for breweries in autumn 2022 as a prototype and by spring 2023 as a final product,” says Sotirios Kampranis.
With support from the BioInnovation Institute, EvodiaBio is now well on its way to being able to market its flavours, and several breweries have already shown interest.
“But we are already discovering new applications for this technology. The next step will be to produce fragrances based on the same process for cosmetic products, hand soap and detergents. So, we can relatively easily create similar factories in yeast to make the necessary fragrances for cosmetics and household products,” explains Sotirios Kampranis.
In addition to the environmental benefits, the researchers have found another reason to use yeast. The demand for natural fragrances for cosmetics is so great that more than half are produced synthetically. The fragrances of roses, lemons and pine needles are usually produced through energy-intensive, industrial chemical processes that use petrochemicals as starting materials and toxic catalysts and solvents in the process.
“Even though the yeast is genetically modified, the products are not and are completely identical to natural flavours and fragrances. The big difference is that we do not have to irrigate plants, transport anything over long distances or use lots of chemicals and energy. So, if we want to make our lives more sustainable and fight climate change, this is a much more sustainable way to produce these flavours and fragrances,” concludes Sotirios Kampranis.
