The American start-up Perfect Day uses fermentation to make proteins that are genetically identical to milk proteins. The company developed genetically modified yeast bacteria to produce whey and casein. The resulting milk products are lactose-free, vegan and more organic than cow milk. In combination with plant-based fats and sugar, the first ice cream product has now been made, which is indistinguishable in taste and make-up from dairy ice cream. In future, Perfect Day plans to deliver its goods to large food companies.