Optimisation of preservatives for dealcoholised red wine using a survival model for spoilage yeasts

To optimise the application of preservatives in a new commercial dealcoholised red wine (DRW), a survival model of Rhodotorula mucilaginosa and Saccharomyces cerevisiae was developed. A factorial design included three variables, each at three levels: potassium sorbate, sodium metabisulphite and dimethyl dicarbonate (0, 100 and 200 mg L^?1). DRW samples were inoculated with a cocktail of yeasts and counts were performed after 1, 2, 3, 4, 6 and 8 weeks of incubation. Logistic regression analysis was used to create survival models. Potassium sorbate and sodium metabisulphite did not show any fungicide effect alone, while the model predicts that dimethyl dicarbonate at 185 mg L^?1 has fungicide activity. The interaction of potassium sorbate and dimethyl dicarbonate was statistically significant, so both could act as synergic preservatives. The logistic model obtained was validated with a 100% of accuracy for the conditions tested. Combining use of the studied preservatives reduced the individual dose for preservation of DRW.