Development of a method for water determination in lactose

► Water content of lactose cannot be determined by usual oven drying at about 102 °C. ► The water of crystallisation is only partly detected using this technique. ► The total water content of lactose can be analysed by Karl Fischer titration. ► A suitable Karl Fischer method was developed and proposed as international standard. ► It was accepted by the International Dairy Federation (IDF) and by ISO.