Currently, only a very small amount of fallen leaves are used. Most often, they are left on the ground, composted or burnt.

Autumn leaves contain orange and yellow carotenoids and red anthocyanins. In addition to pigments, autumn leaves contain many beneficial compounds, such as phenols, lignin, carbohydrates and proteins. There is a growing need for natural pigments in various industries around the world. For example, these natural pigments can even have health-promoting effects and be used in nutraceuticals.

In a process developed by VTT, compounds are extracted from leaves collected from gardens and parks are dried and ground. The treatment processes were developed in VTT's R&D laboratory in the pilot phase.

Pigments for cosmetics and textiles

Pigments from leaves can be used to colour cosmetics and textiles, as the chemical composition of leaves varies widely from one species to another. Added value can be obtained by treating only the autumn leaves of certain types of trees, thus producing well-defined compounds suitable for new products.

Future prospects: bioactive compounds and nutritional supplements

Other applications could be developed for this raw material. The compounds obtained from the leaves can be used as food colouring and preservatives, or as nutritional supplements. In addition, these dyes could be used to improve the nutritional properties of the edible plant cells being developed at VTT. New bioactive compounds could also be obtained for the cosmetics and pharmaceutical industries, using biotechnological methods to modify pigments.

The carbohydrates extracted from the residues could be used to produce protein-rich feed for livestock and protein supplements for human consumption. This nutrient-rich residual biomass can also have domestic applications, for example in the cultivation of mushrooms.

Source : Pigments naturels et matières premières à partir de feuilles automnales, IAR Tremplin, 01.11.2016