Aroma maple syrup

The a-keto adds and their metabolic byproducts are excreted in urine, and these compounds cause the characteristic sweet, "maple syrup"aroma. 

The most elementary, nontechnical method of identifying a polysaccharide is to burn it, observe the yellow-to-brown color, and sniff the perfumelike aroma that should be reminiscent of the aroma of maple syrup, if the test is positive. If the caramelized residue is shaken with egg white and a visible reaction produces an insoluble, pigmented deposit (melanoidin), it is empirical proof that the sample was a polysaccharide. 

C-11) (1-9) Maple Syrup Urine Disease. There is a block in the degradation of the branched chain amino acids. Leucine, isoleucine, valine, and their ketoic acids are elevated in the blood and urine. Assays for these chemicals can be done in the laboratory. The urine acquires a maple syrup aroma. Infants with the condition have a variety of neurologic problems, including mental retardation. The condition is treated by dietary restriction of the affected amino acids. 

QHjOj, Mr 112.13 cryst. with a spicy, caramel-like odor resembling that of liquorice, mp. (monohydrate) 106 °C soluble in alcohol (25%), water (2.5%), but hardly soluble in petroleum ether it is formed from glucose by the Maillard reaction and is present in the flavor of thermally prepared foods such as maple syrup, bread, coffee, roasted nuts, and roast pork. It is mainly obtained from beech wood tar and used as a flavor compound, e. g., for the above-mentioned aromas. 

Cyclotene (2-hydroxy-3-methylcyclopent-2-en-l-one) is a secondary transformation product of sugars (see Figure 4.62) the odour of which resembles caramel. It is a characteristic aroma component of maple syrup obtained from the sugar maple tree Acer saccharum, Aceraceae). 

Certain 2-hydroxy substituted y-lactones (3-hydroxy furan-2-ones) derived from ycrotonolactone, however, have a specific odour. Typically 3-hydroxy-4,5-dimethyl-5//-furan-2-one (sotolon) has an aroma resembling fenugreek or curry at higher concentrations, and caramel, maple syrup or burnt sugar at lower concentrations. Sotolon occurs as a mixture of -)- R)-and (-F)-(S)-enantiomers (8-111). The perception threshold of (S)-sotolon (0.8 (xg/1) in a model wine solution was 100 times lower than that of the (l )-enantiomer (89 p-g/l), indicating that mainly (S)-sotolon contributes to the characteristic aroma of wines. The key component of acid protein hydrolysates is the higher... 

---