Colour is an essential feature of food and beverages. Food colour affects consumer perception of flavour, freshness and product quality. Natural and synthetic food dyes are therefore frequently added to processed foods to enhance or correct food colour to meet consumer expectations. Concerns raised by consumers and food authorities alike about synthetic food additives have increased the demand for natural food colourants. The global market for natural food colours was estimated at US$1.5–1.75 billion in 2022 and is expected to grow. Most natural food colors are currently produced by extraction from plant sources, but the process is notoriously inefficient and resource-intensive, given the pigments' low natural concentration, impurities that get co-extracted, and the seasonality of plant harvesting.
A biotechnological process where colors can be produced by fermentation, similar to how enzymes and bioethanol are made, presents an attractive alternative. Natural colors can be made cheaper, with less environmental impact, and on demand.
In this project, we tackled the challenge of producing betalain-type natural food colours. Betalains are radiant water-soluble colours in the yellow-to-red spectrum. They have strong antioxidant properties and are health-beneficial. While over 75 different betalains have been found in nature, only one betalain pigment is extracted commercially - betanin from red beet, marketed in the EU as the food additive ‘beetroot red’ (E162). Beetroot contains only 0.2% of betanin on wet weight basis, hence, the production generates a lot of beetroot pulp as a side product. We have engineered oleaginous yeast Yarrowia lipolytica to produce several betalain-type pigments at high titers from glucose or glycerol as the sole carbon sources. Engineered Y. lipolytica strains are being used in industry for the production of omega-3-fatty acids (DuPont), stevia glucosides and carotenoids (DSM), lipids (Novogy), Lepidoptera pheromones (BioPhero), and other products. It is a yeast species that commonly occurs in food such as cheese or sausages. Our technology can deliver a pallet of betalain colours to the food industry and consumers, with variations of hue and stability properties, at lower cost and with less environmental footprint.
