Sugar in wines

In the case of the low abundance of some compounds, there are difficulties with signal overlap. To overcome these difficulties, there have been developments involving NMR hyphenation with techniques such as HPLC and mass spectrometry. In LC/NMR methods of analysis, NMR is used as the detector following LC separation and this technique is capable of detecting low concentrations in the nanogram range. This technique has been reported for the detection and identification of flavanoids in fruit juices and the characterization of sugars in wine [17]. 

The refractive index also varies with the amount of substance in a mixture. Most often, refractive index is used to assess the concentration of sugar in wine, soft drinks, cough medicines and other preparations having relatively high concentrations of sucrose. Refractive index is also used to determine the concentration of alcohol in fermented products. For sucrose solutions the refractive index varies from 1.3330 (pure water) to 1.5033 when the solution contains 85% sucrose. This is an increase of approximately 0.0002 in the refractive index for each 0.1%... 

The second half of the 1990s saw an increase in the use of dialysis (as a liquid-liquid extraction procedure). Its main advantage is the possibility of operating in an automatic mode by coupling a dialysis unit with an automatic injector, as demonstrated not only in HPLC analysis (17) but also in flow-injection determinations of reducing sugars in wines (18) and alcoholic fermentation broths (19). 

A method of this kind is used for the determination of sugars in wine (g.v.). 

Yeast. The desirable characteristics of yeast for secondary fermentation include the capability to ferment sugar in wines containing 11-14 percent ethanol and 150 mg/L or more S02 at low temperatures, 10°-15° C, without producing off flavors or odors and withstanding high pressure. For bottle-fermented sparkling wine, the yeast also should agglutinate well and... 

Traditional methods of analysis for determination of principal organic acids, glycerol and sugars in wine are based on enzymatic or colorimetric reactions ethanol is determined by distillation of wine and density measurement of the distillate. In Table 1.2, data of organic acids, glycerol, glucose, fructose and ethanol determined by HPFC are reported as a percentage of results obtained by the traditional methods. 

Compendium of international methods of wine and must analysis - OIV, Dosage of sugars in wine by HPLC (Resolution 23/2003), edition 2006, Vol. 1, MA-E-AS311-03-SUCRES, p. 14. 

A.F. Oliveira, O. Fatibello-Filho, J.A. Nobrega, Focused-microwave-assisted reaction in flow injection spectrophotometry a new liquid-vapour separation chamber for determination of reducing sugar in wine, Talanta 55 (2001) 677. 

Alcoholic fermentation is the basis for the brewing of beers and the fermentation of grape sugar in wine making. 

In routine use in more than 50 sites in Erance is the NIR measurement of alcohol and sugars in wine and distilled liquors [7]. The concentration of alcohol in wine was determined by Kaffka and Norris as early as 1976 [8]. The accuracy of their calibration is reported as better than 0.1% by volume at 11 to 17% alcohol using transmittance as the mode of detection. Sucrose in wine has also been investigated. An accuracy of 0.2% is achieved with a calibration for sucrose levels of 0.8 to 8.8%. 

Bisson L.F. (1991) Yeasts-metabolism of sugars. In Wine Microbiology and Biotechnology, pp. 55-75. Harwood Academic Publishers. 

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