In Situ Determination of Fructose Isomer Concentrations in Wine Using (13)C Quantitative Nuclear Magnetic Resonance Spectroscopy.
A practical method for simultaneously quantifying fructose and ethanol contents in wines using (13)C quantitative nuclear magnetic resonance (qNMR) spectroscopy is reported. Less than 0.6 mL of wine is needed, and the method leaves an unmodified sample available for subsequent testing or additional analyses. The relative ratios of the five known fructose isomers in ethanolic solutions at different pH and their variations with the temperature are also reported. The data are correlated with the sweetness of wines. The technique was applied to commercially available wines, and the results are compared to other methods. Sugar levels above 0.6 g/L can also be measured. A simple adaptation of the method permits measurement of different carbohydrates using integration of single peaks for each compound, in combination with an external reference (13)C qNMR spectrum of a sample with a known concentration. The method can be applied at all stages of wine production, including grape must, during fermentation, and before and after bottling.
Department of Chemistry, Simon Fraser University , 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
Cinzia
C
Colombo
Department of Chemistry, Simon Fraser University , 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
Clara
C
Aupic
Department of Chemistry, Simon Fraser University , 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
Andrew R
AR
Lewis
Department of Chemistry, Simon Fraser University , 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
B Mario
BM
Pinto
D005632:Fructose / Q000737:chemistry*; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D014920:Wine / Q000032:analysis*
D005632:Fructose
13C NMR spectroscopy; carbohydrate content; fructose isomers; qNMR; wine analysis