SCU researchers discuss the progress of Australia’s involvement in the WCR varietal trial

International Multilocation Variety Trail

Coffee has been grown in Australia since the 1800s. The variety that has shown the most promise for Australia’s long ripening season in subtropical climates was the Kenyan varietal K7, which produces high quality beans, is high yielding and rust resistant, and was deemed suitable for machine harvesting.

With nearly all of the approximately 40 coffee farms in Australia using machine harvesting and relying heavily on K7 and Catuai as their varietals of choice, the Australian coffee production industry has established itself as a commercial entity, delivering high quality product to the domestic, tourist, and specialty export markets.

However, according to Professor Tobias Kretzschmar of Southern Cross University in Northern New South Wales, the vigour of K7 on the red soils of northeast New South Wales and southeast Queensland has proven to be a problem. Over time, this excess vigour has resulted in coffee trees that are too large for machines to harvest them effectively. The best way to control the size of these trees is cutting them back. While pruning is a successful management practice with other coffee varieties in different coffee growing environments, it has proven unsatisfactory with Australian subtropical grown K7. For example, little benefit arises if the plants are pruned high, while cutting the plants low results in multiple stems that are unsuitable for machine harvesting.

“Trying to prune the trees correctly becomes a frustrating art. At best, one year of production from mature plants is lost after pruning, followed by two years of production, with pruning again required in the fourth year. This is too much maintenance for most Australian coffee farmers, who are looking to harvest coffee, not run a landscaping business,” says Tobias.

When Tobias became aware of the World Coffee Research (WCR) International Multilocation Variety Trial (IMLVT), it struck him as a perfect answer to Australia’s challenge. The IMLVT gathered 31 top performing coffee varieties from 11 suppliers around the world and distributed them to coffee growing countries for long term evaluation on research plots.

“IMLVT participation allows us to assess a range of international coffee cultivars which are likely to be high quality and high yielding, and some of them rust resistant,” he says.

“Since our trial site is established right in the centre of the subtropical coffee growing regions, it will allow us to evaluate which of these varieties further display a growth habit and architecture that is suitable for machine harvesting.”

A unique element of Australia is that the country is relatively free of coffee specific diseases and pests that plague other growing areas.

“This makes Australia a safe haven for coffee germplasm management and conservation. By assessing performance of an international diverse set of coffee such as the IMLVT varieties, we can get a better idea if and how Australia can contribute to global coffee conservation efforts, with the potential to serve as a regional coffee genetic resource centre,” Tobias says.

After spending over half a year under quarantine at Southern Cross University, as part of Australia’s strict biosecurity measures, the IMLVT trees were planted in the summer of 2019. Tobias says that public interest in the trial and the industry engagement in helping establish this trial has been exceptional.

“We had our first proper harvest last year and assessed production parameters, such as cherry and green bean weight, and took the beans all the way through into cupping,” Tobias says.

In March 2023, coffee researchers from Southern Cross University held cupping panels in Melbourne, Sydney, and Brisbane to assess 16 of the 31 varietals.

“Professional tasters and roasters were welcomed to evaluate existing local varieties with the newer varieties that we have selected, so we have industry approval of which cultivars are the most favourable,” Tobias says.

“They all performed really well and were graded about 83 and above. This is a great result, but I think we can improve on it. Our cuppers noticed that the green bean moisture content percentage was too high, so we need to try and reduce moisture in this year’s harvest and improve our processing methods. I’m confident we can get those cupping grades even higher.”

While Tobias can’t disclose just yet which cultivars are frontrunners, he says several varietals look very promising.

“I can’t say exactly which varietals are performing well. I can say that some of them are coming from Brazil. And we’ve found that some of the varieties that perform well here in Australia are performing well all over the globe, indicating that they are adaptable to changing climates,” says Tobias.

“This could be because Brazil is one of the few coffee growing countries that does have occasional cold weather spells, especially in southern Brazil, similar to Australia. Both countries have a need for cold tolerance and have similar subtropical lowland climates.”

Running of the IMLVT over its five year duration is supported by AgriFutures Australia as part of its Emerging Industries Program, which closely aligns with the Australian Subtropical Coffee Association’s (ASTCA) efforts to increase the footprint of Australian grown coffee.

In a subdivision of the project, Dr Ben Liu of Southern Cross University is working to define the terroir of Australian coffee alongside colleague Dr Simon Williams.

“The aim is to identify and describe the unique sensory attributes of Australian coffee, particularly in relation to terroir, and how these findings relate to the palates of coffee consumers,” says Simon.

Simon and his colleagues from Southern Cross University’s Faculty of Science and Engineering developed a colourful sensory character wheel derived from academic and industry sources with some surprising mouthfeel and acidity descriptors for coffee like gritty, silky, winey, and vinegary.

Using data from coffee tasting panels, Ben’s team can match the chemical markers identified in the lab to a vocabulary of descriptors, a roadmap for coffee growers to reproduce a flavour profile more accurately.

“We want to develop a system that allows the impartial prediction of sensory characteristics without having to rely on cupping panels, as they can be quite time consuming and often result in diverse opinions,” Simon says.

Tobias says the next stage for WCR will be to use the varietals that are performing well in a breeding program.

“Once we go through these next couple of years of tastings, we can determine exactly which beans are suitable for the Australian climate,” he says.

Simon is confident that once both projects are completed, the Australian coffee industry will be one step closer to finding high quality, high yielding, and disease resistant home grown varietals.

“In an ideal world, Australian coffee growers have a horde of information that allows them to make informed decisions about which varietals they have access to, how well they grow, and what their cupping scores might be. I believe these trials will get us there,” he says.

This article appears in the MICE Showguide 2023. View the Showguide HERE.

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