Rapid determination of alcoholic strength of egg liqueur using steam distillation and oscillation-type densimetry with peristaltic pumping Original Research Article

This paper introduces a new method of determining alcoholic strength in highly viscous samples like egg liqueurs. The method relies on fully automated steam distillation in combination with oscillation-type densimetry and peristaltic pumping. The procedure is much faster (taking less than 8 min per sample) and easier than the conventional reference method (distillation, pycnometry). This makes it possible to determine alcohol content efficiently and economically, both in official food control and in spirit production. In addition, the total dry extract of the liqueur can be indirectly calculated from the density of the sample and the density of the alcoholic distillate. The parameters for the automatic steam distillation were optimised for the analysis of egg liqueur samples (100% steam power, sample weight 25 g, 130 s distillation time, 50 ml receiver). Validation has proved the method robust and precise. The relative standard deviation was below 0.56% in all cases. By analysing spirit samples under routine conditions, a high correlation (R = 0.999) with the reference method was achieved.