Page 82 - Terčelj, Dušan. 2015. The Culture of Wine in Slovenia. Edited by Aleš Gačnik. University of Primorska Press, Koper.
P. 82
he Culture of Wine in Slovenia
each other or with tannins into larger, more stable forms. New compounds change hue
from pronouncedly ruby or violet-red to the colour of brick or brownish red. In research
into phenolic substances, in particular antocyanins, I ascertained27 that, in comparison
to other varieties of grapes, the Refošk variety in Kraški Teran has a high anthocyan
delphinine content.
Tannins
have a similar composition to antocyanins, i.e. three phenolic rings, but have different
chemical properties. They give wine tartness and fullness. They appear in grape skins
and in pips. They can appear freely or bound to each other and with antocyanins. Chemi-
cally, they are divided into a number of groups; the most noticeable among flavans is
catechin with its isomers. Catechin forms two sub-groups: procyanidols, which release
anthocian cyanin, and prodelphinidins, i.e. gallocatechins.
There are other groups of tannins which we shall not list here. We need only to be aware
that, during the processing of grapes and the maceration of crushed grapes, numer-
ous tannin substances are transferred from the skin and pips into the juice. Tannins
give red wine its character and have a bitter taste. They are alcohol soluble and leach
faster when alcohol appears during fermentation. Tannins may oxidise with the aid of
oxidising enzymes, but they themselves have a reducing effect. When oxidised, they
turn the juice dark brown and spoil the appearance of must and wine. When tannins
in wine bind to each other into ten or more molecules, they lose their unpleasant bit-
ternes. Thus they affect changes in flavour during the maturing of wine. Tannins bound
to polysaccharides give wine its body. Of particular importance are tannins coming
from pips, as they have a different composition from those in the skin. Wine can be
enriched in tannin substances, in particular in proanthocyanidols, by adding a greater
quantity of pips during the maceration of crushed grapes. Wine enriched in this way
is beneficial for heart disease. Wines of this kind can be recognised by a special name,
such as Paradoks from Vipava.
Tannins have an antioxidising effect. They bind harmful free radicals that accelerate
atherosclerosis. Tannins also have a slightly septic effect on yeast and bacteria. They
bind to proteins, causing them to sink, thus having a stabilising effect.
Tannins in oak wood are of a different composition: these are ellagitannins, but they
behave similarly to tannins in grapes. They bind to each other into larger molecules.
They, too, give a bitter and astringent taste. Due to the varied bitterness they bring to
wine, tannins and colours are very important for red wines. The composition of phenolic
substances changes during the maturing of grapes. Noble tannins which give wine a
pleasant sweet and tart flavour can be found only in well-ripened grapes.
Pectins
are large molecules, consisting of galacturonic acids, bound in long chains. There are
a number of different pectins. Chemically they are colloids. They are very soluble, but
change into an insoluble state, making wine cloudy and creating sediment. Pectins give
27 T erčelj, Dušan: Vpliv vinifikacije in običajnih tretmanov na gibanje barvnih snovi in organoleptičnih
lastnosti Kraškega terana. Disertacija. Fakultet poljoprivrednih znanosti sveučilišta u Zagrebu 1983.
78
each other or with tannins into larger, more stable forms. New compounds change hue
from pronouncedly ruby or violet-red to the colour of brick or brownish red. In research
into phenolic substances, in particular antocyanins, I ascertained27 that, in comparison
to other varieties of grapes, the Refošk variety in Kraški Teran has a high anthocyan
delphinine content.
Tannins
have a similar composition to antocyanins, i.e. three phenolic rings, but have different
chemical properties. They give wine tartness and fullness. They appear in grape skins
and in pips. They can appear freely or bound to each other and with antocyanins. Chemi-
cally, they are divided into a number of groups; the most noticeable among flavans is
catechin with its isomers. Catechin forms two sub-groups: procyanidols, which release
anthocian cyanin, and prodelphinidins, i.e. gallocatechins.
There are other groups of tannins which we shall not list here. We need only to be aware
that, during the processing of grapes and the maceration of crushed grapes, numer-
ous tannin substances are transferred from the skin and pips into the juice. Tannins
give red wine its character and have a bitter taste. They are alcohol soluble and leach
faster when alcohol appears during fermentation. Tannins may oxidise with the aid of
oxidising enzymes, but they themselves have a reducing effect. When oxidised, they
turn the juice dark brown and spoil the appearance of must and wine. When tannins
in wine bind to each other into ten or more molecules, they lose their unpleasant bit-
ternes. Thus they affect changes in flavour during the maturing of wine. Tannins bound
to polysaccharides give wine its body. Of particular importance are tannins coming
from pips, as they have a different composition from those in the skin. Wine can be
enriched in tannin substances, in particular in proanthocyanidols, by adding a greater
quantity of pips during the maceration of crushed grapes. Wine enriched in this way
is beneficial for heart disease. Wines of this kind can be recognised by a special name,
such as Paradoks from Vipava.
Tannins have an antioxidising effect. They bind harmful free radicals that accelerate
atherosclerosis. Tannins also have a slightly septic effect on yeast and bacteria. They
bind to proteins, causing them to sink, thus having a stabilising effect.
Tannins in oak wood are of a different composition: these are ellagitannins, but they
behave similarly to tannins in grapes. They bind to each other into larger molecules.
They, too, give a bitter and astringent taste. Due to the varied bitterness they bring to
wine, tannins and colours are very important for red wines. The composition of phenolic
substances changes during the maturing of grapes. Noble tannins which give wine a
pleasant sweet and tart flavour can be found only in well-ripened grapes.
Pectins
are large molecules, consisting of galacturonic acids, bound in long chains. There are
a number of different pectins. Chemically they are colloids. They are very soluble, but
change into an insoluble state, making wine cloudy and creating sediment. Pectins give
27 T erčelj, Dušan: Vpliv vinifikacije in običajnih tretmanov na gibanje barvnih snovi in organoleptičnih
lastnosti Kraškega terana. Disertacija. Fakultet poljoprivrednih znanosti sveučilišta u Zagrebu 1983.
78
