Researchers at Germany’s Fraunhofer Institute for Molecular Biology and Applied Ecology IME have developed a protein-based sweetener claimed to be around 10,000 times sweeter than sugar.

In the joint research project, titled NovelSweets, the researchers have teamed up with partners to use biotechnology methods to produce innovative, protein-based sweeteners that could replace sugar and existing artificial alternatives.

Researchers are working with industry partners MetaX Institut für Diätetik and Candidum, to support the German Federal Ministry of Food and Agriculture in its efforts to reduce the sugar content of ready-made products and beverages in response to the rise of health issues caused by poor nutrition.

The World Health Organization recommends a maximum daily intake of 25g of table sugar per person, equivalent to about five to ten teaspoons. Many processed foods such as convenience foods, sauces, fruit juices, breakfast cereals, fruit-flavoured yogurts and soft drinks are high in sugar – a 250ml glass of cola contains 27 grams, more than the recommended daily amount.

Sweet-tasting proteins (SPs) are molecules that occur naturally in some plats and fruits. Due to their structure, they bond very readily – like sugar – to human taste receptors on the tongue.

One of the most well-known SPs is brazzein, a protein found in the African plant Pentadiplandra brazzeana. Several start-ups in the food-tech space are working with brazzein to develop new sweetener ingredients, such as Oobli and Ginkgo Bioworks.

As extracting the protein from the plant is a ‘lengthy and laborious’ process, the NovelSweets team partners are developing protein varieties based on the protein sequence of brazzein, optimising them with an eye to pH and temperature stability, then using biotechnology tools to produce them.

Additionally, they are improving the new varieties in terms of sweetness and flavour – Stefan Rasche, a researcher at  Fraunhofer IME, explained that brazzein naturally feels ‘scratchy’ in the throat.

“We’re changing the protein sequence to prevent this kind of undesirable effect. The goal is a better sensory experience, without any unpleasant flavour or aftertaste,” he said.

Microbial fermentation is used to produce the improved candidates. The gene that encodes the SP, containing a description of the protein’s amino acid sequence, is implanted into yeast cells, which multiply inside a bioreactor under controlled conditions to produce as much of the SP as possible.

Following purification and drying, the protein-based sweetener is ready. The researchers have named the sugar substitute ‘X3’. According to the team, X3 tastes ‘a little like honey,’ making it an ideal sweetener ingredient.

“A single gram of the substitute is as sweet as about 10kg of sugar,” said Rasche. “This means that by working with our partners, we have managed to develop an SP that is about 10,000 times sweeter than table sugar.”

“A typical cola contains about 106g of sugar per litre. That’s equivalent to 1,800 kilojoules (kJ). Just a few milligrams of our SP is enough to achieve the same level of sweetness, so the calorie content can be significantly reduced.”

Rasche added that since it is entirely sugar-free and has “practically no calories,” it does not raise blood sugar levels or cause dental cavities.

The team’s first plan is to add the substitute to beverages. Project partner MetaX is currently testing and developing the first range of products containing X3, such as a low-protein beverage powder made with cocoa.

Before the approval process can start, the manufacturing process must be optimised along with further product validation measures, so the full potential of the X3 protein version can be unlocked.

Top image: © Fraunhofer IME

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