In 2022, Preserve Botanica secured US$100 000 (almost R1,9 million) in funding from Anheuser-Busch InBev SA/NV’s (AB InBev) 100+ Accelerator 100+ Programme for research into the valorisation of waste generated during the harvesting of hops.

Wanda du Plessis, CEO of Preserve Botanica, says hops have numerous applications beyond brewing: “Hops aren’t just for beer; they can be used as a medicinal herb, in skincare products, as a flavouring agent in foods, and even as insect repellent and animal feed. Our research aims to unlock these opportunities and reduce waste in the beermaking process.”

But what drove Du Plessis to explore this opportunity with the world’s largest brewer?
She explains that she and her husband, Jaco de la Rouviere, started Preserve Botanica in 2016.

“I had seen 8 700 clients as a physical therapist up until then and was looking for a new challenge. Combining my passion for people, healing and nature, I turned to the production of medicinal plants.”

She evaluated various medicinal plants and initially thought of focusing her attention on honeybush, because it is a unique South African product.

However, the realisation that most honeybush is harvested in the wild, and the variation this would cause in the distilled product, changed her mind about the plant. Hops proved an ideal fit, as production is highly standardised and concentrated around George in the Western Cape, where she lives.

Along with this, she found that the industry produced a lot of waste, which could potentially be used for producing herbal medicines.

“We started looking at possible yields, equipment parameters, scalability and cost through garage trials in 2021, and used this information to pitch for funding in 2022,” she explains.

Insights gained

With the funding, Preserve Botanica was given an opportunity to design and build a 1 050ℓ steam distillation unit to extract essential oils from hops waste and scale the pilot programme in the African region with AB InBev.

The waste is collected and distilled on farms during the six week-long harvest season from mid-February to end-March.

Du Plessis explains that during processing, steam is used to condensate water into a hydrosol, which basically is water with soluble aroma fractions that can be used for applications in teas, flavoured waters and kombucha. The essential oils produced during the process are insoluble so they float on top of the hydrosol.

“The essential oils have colours ranging from yellow to amber, are very potent and contain the plants’ typical flavour profile,” says Du Plessis.

During the harvesting of hops, only the cones are picked for beermaking, while the rest of the material is wasted. So far, the team’s research revealed that for every unit of cones processed, the brewing industry generates 1,5 times that amount as waste.

Of this, two-thirds, consisting of leaves and unprocessed hop cones, are suited for processing through distillation, whereas the stems are too hard.

To put this in perspective, Du Plessis notes that a typical farm that harvests 400t of hops will produce 1 200t of waste, of which 800t would be suited for distillation.

During the first year, Preserve Botanica managed to distil 0,04g of oil for every 100g of waste processed, which was upped through improved efficiencies to 0,8g in 2024.

“This type of research is crucial to calculate the volume of waste available for processing and volumes available for product development,” says Du Plessis.

Applications

Hops are primarily used to give flavour and aroma to beer. In the whole of Africa, they are only produced in a small area, about 400ha, around George in the Western Cape, and conditions even there are not ideal.

Du Plessis explains that this is because hops require long summer days and freezing winter temperatures.

This region of the Cape has three hours of sunlight less than the ideal as well as mild
winters, which means that specific varieties of hops – Southern Star, Southern Promise, Southern Passion and Southern Dawn – had to be developed for production there.

International production is under threat because of climate-related risks and extreme weather. According to Hopsteiner’s 2023 Guidelines for Hop Buying, dry periods and high temperatures resulted in the European hops crop falling by 27% year-on-year to 48 811t in 2022, on nearly the same area of production of 32 247ha.

In the Czech Republic the crop fell by 50% to 4 452t, and the US’s 46 087t crop was also below average due to challenging growing conditions. Worldwide the crop of 106 599t was 24 000t less than in 2021.

While the European crop of 57 580t was less than in recent years in 2023, the total world crop increased by nearly 10% on 2022 to 117 000t.

Du Plessis’ research has revealed that the hydrosol and essential oils produced from distilling hops are suited for use as flavourants in beer, so the brewing industry could use these to derisk production, augment local supplies and unlock additional income for farmers.

“We found that volatile fractions [the components of a substance that can easily vaporise, such as essential oils] are abundantly available in Preserve Botanica hop oils, about 3 000 times more so than in hop pellets. In our brewing trials we saw that only 0,1g to 0,3g of oil was needed in a hectolitre of beer to get the same result as using 40g of dried product for every 100ℓ of beer,” she explains.

She adds that it might also help to develop an export market for the industry, as some of the South African varieties are in good demand especially among home brewers in the US.

Further value

Du Plessis is also researching the antimicrobial and medicinal properties of hops essential oils.

“Interestingly, hops were first used for sleeping and mood disorders before they were used to flavour beer. They also have the potential to improve gut health and serve as an appetite suppressant,” she explains.

However, exploring these applications will require much more funding, research and product. Thus, for the time being, Du Plessis is focusing on the brewing applications.

Nevertheless, she points out that preliminary trials and data suggest that hops extracts might help to treat resistant tuberculosis.

Preserve Botanica has launched five varieties of hop oils in different sizes, which can be used in small and large applications; a collection of five 1g oils; and various hydrosols, all available on their website. The oils are ISO/IEC 17025-certified as being undiluted and without impurities.

“Our goal for now is to develop products that we want to sell in bulk to companies who want to add value to this,” says Du Plessis.

Email Wanda du Plessis at [email protected]. Visit preservebotanica.co.za.