HANNA HI 83746-01

The determination of concentration of reducing sugars ( RS) is one of the most important parameters that need to be measured during the wine making process. Following the increase of RS during maturation of grapes can help decide when to start harvest. Having the highest possible sugar content is important because this is the main parameter that defines the commercial value of grapes. During the alcoholic fermentation instead, the decrease of sugars can be followed to decide when fermentation is completed, or allows the taking of corrective actions if the content of RS is too low to obtain the desired alcohol degree or sweetness.

The predominant RS in grape products are glucose and fructose ( hexoses) . After reaction with excess alkaline cupric tartrate ( Fehling reagents) , the RS content can be determined colorimetrically. The Fehling method is not an exact determination but an index of the reducing sugar concentration, because the reaction depends upon the amount and kind of RS present. When the reducing sugar content is known at the beginning of fermentation, the potential alcohol degree can be estimated multiplying the sugar concentration ( in g/ L) by 0.06. Phenols interfere in the Fehling reaction and therefore red wine must be colorized prior to analysis. Wine also contains non-fermentable reducing sugars like pentose which will also be ­ ­ analyzed by this method.

Order Information:
HI 83746-01 ( 115V) and HI 83746-02 ( 230V) is supplied with glass cuvettes and caps ( 4) , reagents for about 20 tests ( HI 83746A-0 and HI 83746B-0) , HI 93703-59 Charcoal, 200 µ L automatic Pipette with two plastic tips, 1000 µ L automatic pipette with plastic tips ( 2) , instruction sheet for automatic pipette, spoon, funnel, filter paper ( 25) , cuvette cleaning cloth, 1