Carrageenan as possible stabilizer of calcium tartrate in wine
Gabriele Fioschi, Ilaria Prezioso, Luigi Sanarica, Rosanna Pagano, Simona Bettini, Vito Michele Paradiso
Abstract
Calcium-induced instability has recently become a major issue in bottled wines, as an effect of compositional changes induced by global warming. Up to date, few tools are available for calcium stabilization purposes. The present research was aimed at evaluating the potential activity of carrageenans (mixture of ι- and κ-) as stabilizers of calcium tartrate (CaT) in white and rosé wines. Four white and two rosé wines, with differing CaT and potassium bitartrate (KHT) stability were characterized. The addition of carrageenans improved both CaT and KHT stability, determining a decrease of saturation temperatures of both CaT and KHT (T sat CaT and T sat KHT ). Sodium bentonite was used to evaluate possible synergic effect. The addition of carrageenans (0.75 g L −1 ) followed by sodium bentonite (0.5 g L −1 ) allowed to stabilize CaT in all wines, with a T sat Ca2+ mean value of 6.7 °C; all samples also reached protein stability, with the exception of one sample that slightly exceeded the conventional threshold of protein stability. As a plus, KHT stability was also improved. The mini-contact test with seeds of micronized CaT, DLS analysis and FTIR spectra confirmed that CaT stability was due to Ca 2+ ions colloidal stabilization rather than removal; that the mechanism of stabilization could include ternary complexes involving carrageenan, calcium ions and proteins; and that the synergic effect of bentonite could be attributed to competitive adsorption of proteins, with consequent adsorption of larger amounts of Ca 2+ ions by carrageenan. • Calcium tartrate precipitation is an emerging stability issue in bottled wines. • Carrageenan decreased the temperature of saturation of calcium tartrate in wines. • Carrageenan had a synergic effect with bentonite in stabilizing calcium tartrate. • Protein stability was reached and potassium bitartrate stability was improved. • DLS and FTIR analysis proved the interactions between carrageenan and calcium ions.