Flavour by design: food-grade lactic acid bacteria improve the volatile aroma spectrum of oat milk, sunflower seed milk, pea milk, and faba milk towards improved flavour and sensory perception

Abstract

Background The global market of plant-based milk alternatives is continually growing. Flavour and taste have a key impact on consumers’ selection of plant-based beverages. Unfortunately, natural plant milks have only limited acceptance. Their typically bean-like and grassy notes are perceived as“of-favours” by consumers, while preferred fruity, buttery, and cheesy notes are missing. In this regard, fermentation of plant milk by lactic acid bacteria (LAB) appears to be an appealing option to improve aroma and taste. Results In this work, we systematically studied LAB fermentation of plant milk. For this purpose, we evaluated 15 food-approved LAB strains to ferment 4 diferent plant milks: oat milk (representing cereal-based milk), sunfower seed milk (representing seed-based milk), and pea and faba milk (representing legume-based milk). Using GC‒MS analysis, favour changes during anaerobic fermentations were studied in detail. These revealed species-related and plant milkrelated diferences and highlighted several well-performing strains delivered a range of benefcial favour changes. A developed data model estimated the impact of individual favour compounds using sensory scores and predicted the overall favour note of fermented and nonfermented samples. Selected sensory perception tests validated the model and allowed us to bridge compositional changes in the favour profle with consumer response. Conclusion Specifc strain-milk combinations provided quite diferent favour notes. This opens further developments towards plant-based products with improved favour, including cheesy and buttery notes, as well as other innovative products in the future. S. thermophilus emerged as a well-performing strain that delivered preferred buttery notes in all tested plant milks. The GC‒MS-based data model was found to be helpful in predicting sensory perception, and its further refnement and application promise enhanced potential to upgrade fermentation approaches to favour-by-design strategies.