Instruction Manual Mi451 COPPER 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.
Mi451
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
Grapes accumulate normally only a small amount of copper by natural translocation from
roots. Unless exposed to significant airborne pollution or vineyard sprays, increased
concentrations in wine result from contamination during post-fermentation processing,
like contact with non stainless steel equipment and as impurities in fining agents and filter
media.
The copper concentration in wine is normally low, less than 0.10 to 0.30 mg/L, because
excess copper is precipitated during fermentation due to adsorption onto the yeast cells.
This adsorption and precipitation can reduce the initial copper concentration with 40 to
89%. At higher concentration copper plays an important role in catalysing oxidation reac-
tions of wine phenols.
It is important to check the copper content both in must and in wine, because at levels
above 9 mg/L copper becomes a metabolic toxin that inhibits or delays alcoholic
fermentation, and concentrations exceeding 1 mg/L may be sensorial detected and should
be avoided.
Other copper related problems can be manifested as formation of white haze (in white
wines) and later as a reddish-brown amorphous precipitate. This precipitated ‘casse’
develops only under the strongly reducing conditions found in bottled wines. It has been
found that this
casse is a mixture of copper compounds and proteins.
