Investigation of different pre-concentration methods for NMR analyses of Brazilian white wine

This work describes the investigation of different preparation methods of wine samples such as direct analysis, freeze-drying and nitrogen-flow concentration in the characterization of Brazilian Chardonnay wine composition by means of (HNMR)-H-1 spectroscopy. The direct analyses of the wine presented some limitations for the detection of "minor" compounds and substances whose signals were expected in the region from 3.6 to 4.0 and 0.8 to 1.3 ppm. The freeze-dried sample showed that a low quantity of ethanol remained in the lyophilisate. The freeze-dried process also revealed restrictions concerning long-time consumption and reproductibility. Diminution of the ethanol signal was observed in the H-1 NMR spectrum of wine samples which were concentrated under nitrogen-flow to allow the determination of compounds such as butylenglycol and alanine. The nitrogen-flow shows advantages in the identification of compounds present as minor compounds with less time consumption. (c) 2004 Elsevier Ltd. All rights reserved.