Plant-based bacteria used to make vegan yoghurt

Increasing global demand for plant-based alternatives to traditional milk products has led researchers at the Technical University of Denmark (DTU) to create a 100% vegan ‘yoghurt’ from lactic acid found in Danish plants. Traditional yoghurt is made with cow’s milk and a starter culture that consists of different lactic acid bacteria. At the appropriate temperature, the starter culture begins to break down the sugar in the milk, thereby fermenting the milk and turning it into yoghurt.

Commercially available plant-based ‘yoghurt’ products are made with existing starter cultures that were developed for use in milk-based products. Producers add sugar to enable the bacteria to grow enough to turn the plant-based products sour and lend a nice aroma. Alongside the added sugar, producers use other ingredients to give their products the desired consistency and taste, which results in a longer list of ingredients. Researchers at DTU have developed a plant-based yoghurt that can be made with three ingredients.

The vegan 'yogurt' is made with just three ingredients: soy beverage, spent grain and a plant-based starter culture. Image credit: DTU.

Researchers from the National Food Institute hypothesised that using bacteria from the plant kingdom would be most efficient when fermenting a vegetable product such as a soy beverage, given that these bacteria are optimised to break down sugar in plant material. Researchers collected samples of different plant materials from large parts of Denmark and examined the samples to see if they contained lactic acid bacteria with the properties that make it suitable as a starter culture in a plant-based yoghurt.

Through this, researchers have managed to isolate bacterial strains that can acidify a soy beverage and create a texture that is similar to traditional yoghurt. Researchers also incorporated spent grain — a side stream from the production of beer — in the production of the yoghurt. This third ingredient can make the yoghurt more sustainable and increase its fibre content. It can also give the final product an aroma, which can help conceal any unwanted flavours from the soy.

Researchers are continuing the work on optimising the consistency and taste of the product with the expectation that a commercial partner will be able to bring it to market. The work to develop the product has been carried out with a grant from the EU Innovation Fund Climate-KIC and in collaboration with Carlsberg, Naturli’ and Novozymes.