The present invention relates to a method for the preparation of a water-soluble extract based on a vegetable biomass of the Melissa officinalis family, which extract is used as a sulphite substitute in the aforesaid winemaking process, which method comprises one or more of the following steps: a) harvesting the herb, b) drying the herb obtained in step a), c) extracting the dried herb obtained in step b), wherein the aforesaid extraction step c) comprises at least two sub steps, a first sub step comprising a first extraction step with water, wherein the aqueous phase thus obtained functions as the starting material for the second sub step comprising an extraction step with an organic solvent, wherein the aqueous phase is acidified before the second extraction step.