Protocol for isolation of vanillin from ice cream and yoghurt to confirm the vanilla beans origin by C-EA-IRMS

An analytical method for the stable isotope ratio analysis of vanillin in ice cream and yoghurt is described. The milk proteins were removed by precipitation and vanillin was extracted by liquid–liquid extraction. Several solvents were tested to achieve maximum recovery for vanillin. Separation from accompanying components was performed by semipreparative HPLC. After chromatography several sample preparation techniques for the off-line transfer of the vanillin fractions were tested and optimised to minimise losses of vanillin. The ¹³C/¹²C ratio of the fractions was determined by ¹³C-EA-IRMS. The method was applied to samples obtained from local food stores. The majority of the samples contained authentic vanillin.