Method of producing a composite fermented beverage using genetically modified yeast strains

Method of preparing a composite yeast fermented beverage such as beer including lager, with predetermined content of flavour compounds, comprising combining separate batches of beverage, of which at least one is a base beverage produced with a yeast strain having reduced or lacking production of one or more flavour compounds or flavour stabilizing compounds. In the method are used yeast strains including S. cerevisiae and S. carlsbergensis which have reduced or lacking production of sulphite, dimethylsulphide, thiols, thioesters, hydrogen sulphide, higher alcohols including isoamyl alcohol and/or alcohol esters.