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

Abstract

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 B₁₂. 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 B₁₂-producing species Propionibacterium freudenreichii, resulted in elevated levels of vitamin B₁₂ 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.