Biosynthesized pigments from fungi could be used as a reliable source of natural colorants, according to a new review.
Researchers from Denmark have stated that industrial interest in fungi as sources of natural colorants has been “revived” after DSM gained EU approval for fungal synthesis of beta-carotene.
The review, published in Trends in Biotechnology, outlines the key issues and trends in the production of food grade natural colorants from fungal sources, claiming biosynthesis of pigments from fungus remained a relatively unexplored resource.
“The ability of the polyketide class of natural pigments from ascomycetous fungi to serve as sustainable natural food colorants has largely escaped the attention of food scientists, both in academia and in industry, despite the tremendous economic and marketing potential,” wrote the researchers, led by Professor Anne Meyer from the Technical University of Denmark.
Currently most EU authorised natural food colorants are extracted from raw materials from insects and flowering plants.
As such, production of current natural colours can vary from batch to batch, depending on the supply of external materials and seasonal factors, state the researchers.
However, many fungi and lichens are known to naturally produce and secrete a wide range of pigments, with a considerable range of colours.
Fungal pigments are generally biosynthesized as secondary products during metabolism - such secondary metabolites are known as polyketides. The authors noted that this method of production could minimise batch-to-batch variations.
They stated that fungal synthesis of natural colorants “has the main advantage of making the manufacturer independent of the seasonal supply of raw materials.”
“The potential for exploring the vast fungal biodiversity for novel and safe pigment producers… remains untapped,” they added.
The aim of the new study was to review the potential of producing polyketide pigments from fungal strains in an industrial setting.
The authors report “tremendous potential for the development of robust fungal production systems for polyketide pigments.”
According to the researchers, the biosynthesis of natural colorants from fungi could ensure “colorant production is accomplished under controlled conditions in bioreactors that offer the colorant manufacturer independence from the external, seasonal supply of raw materials, and potentially minimize batch-to-batch variations.”
The recent approval by the European Union for the use of fungal carotenoids as food colorants has strengthened the prospects for fungal synthesis of polyketide pigments, note the authors.
In addition, new legislation adopted by European Parliament, states foods containing synthetic colorants - like tartrazine, quinoline yellow, and sunset yellow carmoisine - require a label stating the product ‘may have an adverse effect on activity and attention in children’.
The authors note that if taken together with the permission of the fungal carotenoids obtained by DSM, the EU legislation “could be viewed as a gradual change in the outlook …for the novel sources of existing natural pigments, most likely in response to the rising demand for safe and healthy alternatives to synthetic colorants.”
“It should be possible to secure efficient and controlled production of polyketide pigments in chemotaxonomically selected, potentially safe Penicillium strains using current knowledge, without genetic manipulation,” stated the authors.
“We believe that the time is ripe to capitalize on fungal sources of natural food colorants because filamentous fungi hold enormous potential as alternative or additional readily available sources for pigment production,” they added.
Natural colours – which lost their appeal when synthetic colours arrived on the scene, promising higher consistency, heat stability, colour range and cost – are coming back into fashion as consumer awareness increases over the link between diet and health.
The value of the international colourings market was estimated at around $1.15bn in 2007 (€731m), up 2.5 per cent from $1.07bn (680m) in 2004, according to Leatherhead Food International (LFI).
Natural colours now make up 31 per cent of the colourings market, compared with 40 per cent for synthetics, according to LFI.
Source: Trends in Biotechnology
Volume 28, Issue 6, pages 300-307, doi: 10.1016/j.tibtech.2010.03.004
“Fungal polyketide azaphilone pigments as future natural food colorants?”
Authors: S.A.S. Mapari, U. Thrane, A.S. Meyer