BSG-derived protein isolate as a base for fermented protein beverages – modulation of techno-functional and sensory characteristics using different lactic acid bacteria strains

Brewers’ spent grain protein, EverPro™ Light fraction (ELF), is suitable for beverage applications due to its high solubility. However, challenges include poor techno-functional properties, and unfavourable sensory profile often causing astringency and off flavours. This study investigated the potential of lactic acid bacteria (LAB) fermentation to improve the techno-functional and sensory properties of ELF, in a simple beverage system. Beverages containing 10 % (w/v) ELF and 5 % (w/v) sucrose were fermented using three single LAB strains using Lactiplantibacillus plantarum FST 1.7, Leuconostoc citreum TR116, and Lactobacillus amylovorus FST 2.11. Fermentation performance was assessed including pH, total titratable acidity (TTA), viable cell counts, sugar and acid profiles. TR116 showed the fastest growth, while FST 1.7 and FST 2.11 produced the highest acidification. Techno-functional changes were strain dependent and included a darker colour, increased viscosity, turbidity, and separation rate compared to the non-fermented control. Tribological measurements showed increased friction for FST 2.11, while FST 1.7 and TR116 improved lubrication. Sensory analysis revealed fruity notes in FST 1.7, dairy-like flavours in FST 2.11, and reduced malty/cereal flavour in TR116. Overall, LAB fermentation enhanced flavour profiles and mouthfeel characteristics of ELF based beverages, highlighting its potential for high protein fermented plant based soft drinks.