Thursday, December 7, 2023

Aquatic plant offers protein

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The thin, green layer seen on most duckponds might not seem the most attractive culinary option but researchers and food experts believe it does hold the promise of being a powerful new source of protein and B12 with some strong provenance value. Amos Palfreyman of FoodHQ spoke to Richard Rennie about duckweed’s potential as a food crop.
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In coming weeks researchers will be combing waterways and lakes around New Zealand hoping to collect an indigenous variety of innocuous duckweed, the thin green plant that floats on ponds and slow-moving waterways.

While prolific around the world, the chance to identify a variety native to New Zealand and reap the benefits of its dietary properties and local uniqueness has researchers and food companies excited.

Taranaki Maori corporate Parininihi Ki Waitotara, co-funded by Agmardt and supported by FoodHQ, is working to explore how the tiny aquatic plant could prove a valuable, fast-growing protein source.

“There is an understanding that if NZ is to go down the accepted plant protein route that requires cropping high-protein plants like peas we risk ending up in the same place we are already at with excess nutrients lost and large-scale water use,” Palfreyman said.

Waitotara’s interest in duckweed, also known as water lentils, came when chief executive Warwick Tauwhare-George and FoodHQ chief executive Abby Thompson came across it in a Dutch research centre last year.

“The Dutch are particularly good at intense cropping and have been experimenting with growing duckweed in stacked vertical farms indoors in a highly automated system. At this stage it’s not economic but the duckweed has some very strong attractions.”

Under the right conditions it can double in mass every 24-36 hours because of an exponential growth pattern. It is protein dense, comprising 40-60% of the plant’s drymatter, rich in amino acids and vitamin B12, is easily collected and much of the water used to grow it can be recycled. 

On a per-hectare basis the water lentils are six times more efficient at protein production than soybeans.

“Every 36 hours you can harvest a crop and the big technical challenge is how to extract a usable protein that is functional, can dissolve, has no smell or taste and can be mixed into other ingredients.”

The only water lentil food product available for consumption in NZ is imported from the United States and is a powder to add to smoothies and drinks, at a cost of about $4 a serve.

Southeast Asians eat a variety of duckweed as a vegetable dish known as khai-nam or eggs of the water and compare in taste and texture to combining kale, broccoli and spinach.

The iwi project has engaged with Manaaki Whenua’s plant taxonomist Peter Heenan and Maori development general manager Holden Hohaia to explore the possibility of a native NZ strain of the weed, Lemna disperma.

“Duckweed is not really a plant that gets a lot of attention from taxonomists, with research tending to be around rarer plants. But if we can identify a uniquely NZ variety there is potential here to licence it, not unlike what has been done with manuka honey.”

While it is a simple enough plant to harvest, dry and turn to powder the challenge is to remove remnant flavour and odour without damaging the high vitamin and protein content.

“This will be the biggest challenge and is very much a work in progress.”

Recent Dutch research found a high level of acceptability among consumers for using the plant protein in daily diets despite initial fears they might be put off by associations with pond water. 

The powder can be used in a range of applications as a plant-based protein source instead of peas, appealing to the growing vegan-flexitarian consumer market.

An application is due to be lodged to have the plant classed as a novel food suitable for human consumption and it already has approval in the US, Australia and NZ for human consumption.

Waitotara and FoodHQ are working with Massey University’s Professor Benoit Guieysse, founder of NZ’s only spirulina company NZ Algae Innovations, trading as Tahi Spirulina.

“Benoit brings the expertise on the production side of the project, including reviewing best practice for cultivation and setting up an initial pilot pond cultivation system.” 

While a bacteria, spirulina shares similarities with duckweed in terms of growing techniques.

With Waitotara being one of Fonterra’s largest milk suppliers with 20,000ha in Taranaki, the iwi group aims to establish a diverse portfolio of agri-food business interests underpinned by a strong sustainability ethos.

“It is still only early days but if we can identify a native version it could be possible for iwi to have their own protected product, sourced off their own land in what’s been an overlooked plant in the emerging plant-based food sector,” Palfreyman said.

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