Starter culture design for the development of a novel lupin-based quark with in situ vitamin B12 fortification

Due to its high fibre and protein content and suitability for sustainable production, lupin beans ( Lupinus albus ) are an excellent plant-based ingredient to produce fermented dairy alternatives such as quark. We designed two types of starter cultures containing lactic acid bacteria (LAB) and/or propionic acid bacteria to ferment lupin paste into a novel plant-based quark with tailored functionalities such as (i) quark-like characteristics and (ii) presence of vitamin B 12 . Optimal quark-like characteristics were achieved with mixed-cultures of Lactiplantibacillus plantarum with Lactococcus lactis or Lactococcus cremoris. Compared to single strain cultures, the mixed-cultures resulted in faster acidification, higher bacterial counts, and more organic acids. Furthermore, the mixed-cultures produced a higher concentration of the buttery aroma compound acetoin, reduced the beany off-flavour volatile hexanal, and increased the umami-tasting glutamate and aspartate levels. A second starter culture, consisting of LAB and the vitamin B 12 -producing species Propionibacterium freudenreichii , resulted in elevated levels of vitamin B 12 of 2.0 μg/100 g fresh lupin quark, independent of LAB species while retaining similar quark-like attributes. These findings highlight the potential of these starter cultures to use for lupin-based quark alternatives. • Novel fermentation processes were designed to develop a lupin-based quark • Lupin paste was fermented with Lactococcus spp. and Lactiplantibacillus plantarum • Mixed-cultures resulted in better quark-like attributes than single strain cultures • In-situ vitamin B 12 fortification was realized with Propionibacterium freudenreichii