Duckweed could be Europe’s next food trend

The Western diet is under pressure, particularly where meat is concerned. Cattle farming is bad for the environment and heavy consumption of animal products is linked to all kinds of diseases. The movement for plant-based diets is growing in popularity.

In the US, the number of people identifying as vegans has increased hugely in the last few years. This has likely been helped by the number of celebrities, such as Beyonce and Jay-Z, talking publicly about their vegan diets.

Meanwhile, the rising global population will require us to produce more food. The UN Food and Agriculture Organisation estimates that the world's farmers will need to produce 70 per cent more food by 2050 to feed an expected population of nine billion. With most farmland already in use, the answer will be denser production, without increased environmental harm.

Duckweed, or Lemnoideae, is a sub-family of flowering aquatic plants that float on or near the surface of still and slow-moving bodies of fresh water. It grows very quickly, in almost any climate, and does not require precious arable land. While it has typically been seen as a nuisance in the West, it's eaten in soups and curries in South East Asia, particularly Myanmar, Laos and Thailand.

The plant has a nutty taste, similar to spinach, and researchers have found that Western consumers are willing to try it in recipes that already contain vegetables, particularly salads or as a garnish in sandwiches. For some consumers, though, the association with ponds was off-putting and they considered duckweed to be "dirty".

LemnaPro, started by two ETH Zurich Pioneer Fellows, aims to change the attitude to the type of duckweed known as wolffia. Melanie Binggeli, who has a MSc in Agricultural Sciences from ETH Zurich, and Cyrill Hess, who has an MSc in Environmental Sciences, also from ETH Zurich, began their one-year fellowship in September 2019 and will spend the year developing their idea with funding from the ETH Foundation.

Ms Binggeli says: "Industry has recognised the relevance of this field: there’s been a huge amount of interest in our research."

A significant attraction of wolffia is that it contains a similar amount of protein in its dry weight as soybeans, which are typically viewed as the ideal protein source. However, LemnaPro's tailored hydroponic production system allows wolffia to be farmed in such density that it can yield up to 20-times more protein per area than soy.

"Wolffia grows very quickly. Under optimal conditions, it can double in mass in a day," says Mr Hess. "It can also be grown in stacked layers – a practice known as 'vertical farming' – and you can eat the entire plant. All of this makes it uniquely resource-​efficient."

LemnaPro is establishing Zurich as a duckweed "competence centre", bringing together researchers from ETH Zurich and the Zurich University of Applied Sciences (ZHAW) to help build on the plant's potential.

The task will not be an easy one. The pair found in their research that attempts were made to introduce wolffia to Europe decades ago, but they failed because of plant diseases that can spread easily in large production facilities. Mr Hess says, "Progress in the world of agritech means that we are in a better position than our predecessors."

Translating that into a commercially successful food that takes its place in Western diets is a challenge and it's one with a lot at stake. The environment, public health and food sustainability all depend on the solution.