Ethanol sugar fermentation, detection

Experiments with glyceraldehyde and dihydroxyacetone showed them to be fermentable, but results with methyl glyoxal were conflicting. With Lebedev juice no lactic acid was formed, but with top yeast Neuberg reported that lactic acid was detectable. In 1913 he and Kerb therefore proposed sugar was converted to methyl glyoxal from which pyruvic acid and ethanol were derived ... 

Hydrolysates D contained 32 g/L of glucose, 18.11 g/L of xylose, 6.5 g/L of arabinose, and 1.5 g/L of acetic acid. Glucose was readily fermented in addition, 69.4% of the xylose was fermented in 48 h. The ethanol was produced from fermentation of this hydrolysate was 22 g/L (Fig. 5). The yield of ethanol from consumed sugars reached 96.7% of the theoretical yield. Xylitol production was not detected in this fermentation. 

Due to the inability to reliably detect beet sugar additions, the site-specific natural isotope fractionation nuclear magnetic resonance (SNIF-NMR) method used widely in the wine industry was adapted for the maple industry (Martin et al., 1996). This method determines the site specific isotope concentrations of organic compounds by nuclear magnetic resonance of ethanol fermented from the suspect sample. 

The extent to which ethanol is derived from added sugar in fermentation can be determined by the NMR spectroscopic measurement of the ratio of the hydrogen isotopes H to H. The method is based on the fact that the plant-specific H/ H ratio (R value, cf. 18.4.3) of the sugar also appears in ethanol about 2.24 (com sugar), about 2.70 (beet sugar), about 2.45 (wine). The detection... 

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