Autumn trend? Leaf extracts used as food colourants and nutraceuticals

By David Burrows

- Last updated on GMT

Food colours, preservatives and nutritional ingredients. Finnish researchers have found plenty of value in fallen leaves. ©iStock/teksomolika
Food colours, preservatives and nutritional ingredients. Finnish researchers have found plenty of value in fallen leaves. ©iStock/teksomolika

Related tags: Nutrition

Researchers have developed a process allowing them to extract compounds from fallen leaves that could offer potential as natural colourants. 

The leaf-processing technology, developed at VTT Technical Research Centre in Finland, remains a closely guarded secret. 

However, pilots already underway to extract commercially useful compounds from leaves that otherwise would be composted, burned or landfilled. 

Autumn leaves contain a range of interesting substances, such as pigments, carbohydrates, proteins and even compounds that inhibit the growth of harmful bacteria.

Some of these can be extracted and, subject to the necessary approvals, could be suitable for use in foods, preservatives and nutritional supplements, the VTT team claimed.

Nature’s colour 

Autumn leaves derive their colour from orange and yellow carotenoids and red anthocyanins. These may not always be bright but they do look natural, VTT senior scientist Liisa Nohynek told FoodNavigator.

Given the trend towards more natural products, there’s definitely value in investigating further, she said. 

In addition to the pigments, they also found other beneficial compounds in the leaves they’ve swept up, including lutein, beta-carotene and anthocyanin.

There may therefore be other interesting applications. VTT is investigating compounds that could be used to improve the nutritional properties of the edible plant cells they are developing. 

The carbohydrates from the extraction residue could also be used to produce protein-rich feed for livestock and protein supplements for people. 

“In laboratory experiments we discovered several, promising alternative ways of utilising leaves,”​ Nohynek said.

“Piloting assays are under way, in which we are examining how our methods work in practice and what quantities of valuable compounds can be extracted from the leaves.” ​ 

The chemical composition of the leaves varies from one tree species to the next, which will allow the researchers to hone in on certain leaves and produce “well-defined compounds”​ suitable for new products. This could also make the technique more commercially viable. 

Given that leaves haven’t been used for food before, the leaf pigments would be considered a novel food.

This means they are likely to be subject to testing under the EU’s Novel Foods Regulation.

Nohynek conceded that it will be “some time”​ before the necessary tests are complete and the pigments are accepted for human consumption.

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