Impact of fermentation conditions and dextran structure on the rheological and textural properties of a novel high-protein, high-fiber and low-fat plant-based cheese

Fermentation by exopolysaccharide-producing lactic acid bacteria offers a clean-label approach to enhancing plant-based cheese texture. This study developed a high-protein, high-fiber, low-fat plant-based cheese using in situ dextran production by Weissella confusa VIII40. The cheese, made with wholegrain oat flour, oat bran concentrate, and soy protein isolate, was evaluated for the effects of fermentation conditions on acidification, dextran production, and textural and rheological properties. Response surface models successfully predicted optimal fermentation conditions to maximize gel firmness and viscoelasticity. Dextran was isolated and characterized for structure and molecular weight, and its functionality was compared across three types of dextrans with varying branching and molecular weights in cheese-like matrices. The fermented cheese exhibited semisolid, elastic properties influenced by fermentation time, temperature, and inoculum concentration. High inoculum concentrations reduced dextran production, likely due to acidification's inhibitory effect on dextransucrase activity. Incorporating high molecular weight dextran at moderate concentrations enhanced molecular interactions, including hydrogen bonding, as well as protein structural modifications, supporting a stable, elastic texture. Notably, in situ-produced dextran outperformed externally added dextran in improving texture and mitigating acidification's negative impact on viscoelasticity.