Enzymatic method for glucose and fructose measurement
D-Glucose and D-Fructose are the main reducing sugars present in grapes and other fruits. Its determination in the grape allows to verify their state of maturity to establish the optimum moment of harvest. In the must, allows to estimate the amount of alcohol that will be produced during the fermentation. Finally, at the end of the fermentation, to assess the remaining sugar that could produce an undesired fermentation.
D-Glucose and D-Fructose are the main reducing sugars (fermentable) present in grapes and other fruits. The content of D-glucose and D-fructose in grapes is similar (in a ratio between 0.74 and 1.12), with small variations depending on the ripeness of the grape and its variety. Since D-glucose is fermented more rapidly by yeasts, monitoring the relationship between D-glucose and D-fructose, in addition to its total sum, provides information on both the fermentation process and the final degree of expected sweetness. Fructose levels are calculated from the total glucose and fructose content (code SY2404) by directly subtracting the glucose content.
Enzymatic method for sucrose, glucose and fructose measurement
In addition to monomeric hexoses (glucose and fructose), the must contains small amounts of sucrose disaccharide, which is hydrolyzed into fructose and glucose by the enzyme β-fructosidase (β-F). The natural sucrose content in the must is relatively low (and zero in the finished wine), and its addition is specifically prohibited in some countries. However, the addition of sucrose is a specific practice of the process of the production of sparkling wines (second fermentation) and in the captalization (to increase the alcoholic strength artificially, in specifically authorized areas). The determination of the total sugar content, including the one derived from the hydrolysis of sucrose, improves the control of the fermentation process both at its beginning and at the end (residual sugars), improving its general control.