Sodium Alginate Decreases the Concentration of Calcium in Wines, Possibly Lowering the Risk of Calcium Tartrate Instability

Calcium tartrate (CaT) instability in bottled wines has become a recurrent issue. Conventional stabilization strategies, such as cold stabilization or the use of protective colloids, can be ineffective or yield inconsistent results. Cation-exchange resins and electrodialysis can reduce the risk of CaT precipitation, but their use is limited by cost and availability. Therefore, the aim of this study was to assess sodium alginate, a natural divalent metal chelator, as a processing aid to remove calcium and improve CaT stability. The study began with the characterization of the alginate composites formed in wines, followed by an evaluation of different doses and contact times. Subsequently, a series of conventional and dealcoholized wines was evaluated, showing significant reductions in calcium concentration (i.e., 27–32% in conventional wines and 10–21% in dealcoholized or reduced-alcohol wines) and improved CaT stability. Besides a significant increase in sodium content, conductivity, and turbidity (p < 0.05), most other compositional parameters remained stable, with variations observed only in some wines for certain parameters (e.g., CIELab parameters). These findings demonstrate the potential of sodium alginate as a practical calcium-binding agent and suggest the need for further studies to continue evaluating its applicability in winemaking.