Instruction Manual Mi453 REDUCING SUGARS Photometer for wine analysis
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GENERAL DESCRIPTION
Thank you for choosing Milwaukee. This instruction manual will provide you the necessary
information for correct use of the meter.
Mi453
is an auto-diagnostic portable microprocessor meter. It has an advanced optical
system based on a special tungsten lamp and a narrow band interference filter that allows
most accurate and repeatable readings. All instruments are factory calibrated.
The auto-diagnostic feature of this meter ensures always optimal measurement conditions
to perform most precise readings. The light level is automatically adjusted each time a
zero-measurement is made, and the temperature of the lamp is controlled to avoid
overheating.
SIGNIFICANCE OF USE
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 to 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 making 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
colorimetricly. 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 decolorized prior
to analysis. Wine also contains non-fermentable reducing sugars like pentose which will
also be analysed by this method.
