Real-time monitoring of fermentation processes in wine production with benchtop H NMR spectroscopy.

The flexibility, affordability and ease of use of benchtop H NMR spectroscopy makes it potentially very interesting for assessing the quality of wine types and monitoring the fermentation process. However, the low spectral resolution of benchtop H NMR spectroscopy and the complexity of the mixtures hinder the direct quantification of important wine parameters and, thus, prevent its widespread use as an analytical tool in wineries. We show here that these problems can be solved using model-based data processing. In a first step, the accuracy of the new approach was evaluated by analyzing gravimetrically prepared test mixtures representing different fermentation stages. Good agreement was found, demonstrating the reliability of the new method. In a second step, benchtop H NMR spectroscopy combined with model-based data processing was used for the real-time monitoring of real fermentation media. Wine fermentation processes with different feed strategies (batch and fed-batch) were investigated and compared and the evolution of important wine constituents as well as effects caused by the different feeding strategies were monitored, demonstrating the applicability of the new approach also in demanding applications. This opens the way to using benchtop NMR spectroscopy for optimization and decision making in wine production.