Robust, automated quantitation of proline in wine

Proline is an abundant wine metabolite shown to impart sweetness, viscosity, and increase flavour intensity. While several techniques are available to quantitate proline in wine, they are either costly, laborious, or prone to severe interferences. Proton nuclear magnetic resonance (¹H NMR) analysis of wine has provided a method for rapidly measuring several important wine metabolites, including proline. In this paper, we present a method for the automated quantitative measurement of proline by ¹H NMR. In the thousand wine samples analysed, the majority (84.9%) were processed automatically, with the remainder requiring visual assessment by the analyst using a parallel workflow. Repeatability of the NMR method was shown to be excellent in achieving intraday and interday coefficients of variation of less than 1.2%. Additionally, the approach significantly reduced analyst time requirements and increased reliability and repeatability across a wide range of concentrations and wine styles. The workflow is freely available at https://github.com/AWRIMetabolomics/nmr-pro-quant.