Optimization, validation, and measurement uncertainty of HPLC-UVD method for quantification of thaumatin in food

Thaumatin is a low-calorie protein sweetener extracted from Thaumatococcus daniellii Benth. Its ADI (Acceptable Daily Intake) was concluded as “not specified” by the EFSA (European Food Safety Authority). This study was conducted to select a sample preparation method and validate the proposed method by applying a matrix-matched calibration curve using HPLC-UVD. In the results, the calibration curve (5–200 mg/L) represented good linearity (r² ≥ 0.9995). LOD and LOQ ranged from 1.28 to 2.00 mg/L and from 3.89 to 6.07 mg/L, respectively. The intra- and inter-day accuracies and precisions ranged from 91.5 to 103.0%RSD and from 0.50 to 3.42%RSD, respectively. Furthermore, the relative expanded uncertainty was evaluated and the result satisfied the CODEX guideline (≤ 16%). Additionally, the application of the validated method was confirmed by using thaumatin-containing foods distributed in Korea. Thaumatin intake and exposure assessments for consumers can be conducted based on this study.