Yoghurt is a popular fermented milk product produced by lactic acid bacteria. Plant-based milk alternatives can also be processed into yoghurt alternatives using similar fermentation approaches. Fermentation affects both the texture as well as the flavor of the final product. Vegetable proteins, especially those from peas, are often associated with an unpleasant grassy off-flavors, mainly due to aldehydes such as hexanal. These can be degraded during fermentation, while desirable, aroma-active compounds are formed simultaneously. Diacetyl, which has a characteristic buttery aroma and is formed via the citrate metabolism, plays a central role here. This study aimed to enhance the flavor of a pea-based yoghurt alternative by influencing citrate metabolism.

A substrate based on pea protein was fermented with a starter culture comprising Streptococcus thermophilus and Lactobacillus rhamnosus, and citrate--metal complexes were added. The impact on the formation of aroma-active volatile organic compounds was analyzed using headspace gas chromatography--mass spectrometry.

However, no significant increase in the concentration of diacetyl could be achieved, so far. Further experiments are therefore necessary to investigate additional influencing factors that could affect the aroma profile.