Creating enhanced food dyes by following a new beet: Study


Colour pigments used as natural colorants in the food industry may help boost crop disease resistance as researchers find a way to produce enhanced versions with a favourable ingredient profile.

The Israeli team detail a method used to produce betalain, normally found in fruit, in three major food crops: tomato, potato, and eggplant.

By producing betalain in this way, the team uncover a new direction that enables the biofortification of essential foods, as well as provide an innovative source for commercial betalain production.

"Some of these new pigments may potentially prove more stable than the naturally occurring betalains," said study author Guy Polturak, a postdoctoral student at the Weizmann Institute of Science in Israel.

"This can be of major significance in the food industry, which makes extensive use of betalains as natural food dyes, for example, strawberry yogurts."

Commercial betalain use

Current solutions for natural, yellow, water-soluble pigments for commercial use in the food industry are limited opening up an avenue of alternative sources for betalain production, and particularly betaxanthins.

Betalains are the pigments responsible for the deep red colour found in vegetables like beetroot and fruits such as red dragon fruit.

The two main betalain categories include the red/violet coloured betacyanins and betaxanthins, which appear yellow to orange.

Betalains hold much interest in the food industry as natural colorants but also antioxidants making them useful in dietary supplement use.

However, while numerous edible plant sources are a rich source of these pigments, red beetroot remains practically the only commercially used source for production of betacyanins as food colorants.

It is not without its drawbacks. As a source of food colorants, red beetroot mainly produces betanin and thus has limited colour variability.

In addition, it carries adverse earthy flavours as well as a risk of soil-borne microbes.

There are currently no natural sources in large-scale use for production of betaxanthins as food dyes.

Co-existing phenolics in yellow beet if unused can oxidize masking the yellow hue of betaxanthins.

Study details

Along with Polturak, Professor Asaph Aharoni of Weizmann's Plant and Environmental Sciences Department used two betalain-producing plants - red beetroot (Beta vulgaris) and four o'clock flowers (Mirabilis jalapa) in their experiments.

Using a combination of next-generation RNA sequencing and other techniques, the team isolated a gene involved in betalain production and identified a pathway plants use to convert the amino acid tyrosine into betalains.

Using genetically engineered yeast to produce the betalains, they were able to reproducing betalain in plants that do not normally create these pigments producing potatoes, tomatoes and eggplants with red-violet flesh and skin located in the fruit and leaving the leaves and stem untouched.

A boost in disease resistance was another welcome outcome as the team recorded 60% healthy antioxidant activity in betalain-producing tomatoes compared to its non-producing variety.

"Our findings may in the future be used to fortify a wide variety of crops with betalains in order to increase their nutritional value," commented Aharoni.

Further trials demonstrated a disease resistance in the tobacco plant as they found the pigment’s protective qualities applied to grey mould (Botrytis cinerea), a plant pathogen responsible for major crop losses.

The study showed that resistance to the mould rose by 90% in plants engineered to make betalains.

“Stable betacyanin and betaxanthin production without substrate feeding was also attained in tobacco (BY-2) cell-suspension culture,” the study commented.

Their stability and potential to upscale on a commercial production level bodes well for food makers.

Betalains is relatively stable over the broad pH range from three to seven which allows their application to low acidity foods that are characteristic of the dairy, confectionery, and meat sector.

Source: PNAS

Published online ahead of print: doi: 10.1073/pnas.1707176114

“Engineered gray mold resistance, antioxidant capacity, and pigmentation in betalain-producing crops and ornamentals.”

Authors: Asaph Aharoni et al.

Related News

Merck ties up Benelux colour distribution agreement with Azelis

Merck ties up Benelux colour distribution agreement with Azelis

Fungal sourced colours have big potential, say researchers

Fungal sourced colours have big potential, say researchers

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

Autumn trend? Leaf extracts used as food colourants and nutraceuticals

Merck's red food colour - a combination of silica and iron oxide - is a 'mineral-based and non-artificial dye alternative' to synthetic colours, it says. Photo: iStock

‘Non-synthetic’ food colours: Acceptable compromise or too far from nature?

Ohmic heating methods have the potential for use in the industrial production of natural colours.

‘Ohmic heating’ method backed for natural colour production

Back to the future? Are root crops gaining ground as new source of natural colours

Europe has the highest amount of innovation in the area of natural food colourings, the report claims

Demand for ‘natural’ drives Europe’s food colouring growth

Sensient launches yellow and orange colouring foods

Sensient launches yellow and orange colouring foods

Related Products

See more related products

Submit a comment

Your comment has been saved

Post a comment

Please note that any information that you supply is protected by our Privacy and Cookie Policy. Access to all documents and request for further information are available to all users at no costs, In order to provide you with this free service, William Reed Business Media SAS does share your information with companies that have content on this site. When you access a document or request further information from this site, your information maybe shared with the owners of that document or information.