Variations in wine

Commercially-available types of oak

We have studied the behaviour of the same wine in oak casks from different commercial origins, all of which are of sawn oak with staves of 28-30 mm.

In a wine cellar in Haro, the wine was put in to cask in July 1976 and taken out in January 1978, undergoing two rackings. The wine in question was red of 15°. The results after drawing off from these new casks were as follows:

Cask	Lustre	Potassium mg/l.	pH	Tartaric g/l.	Malic g/l.
A	+++	1.008	3,35	3,6	0
B	++++	760	3,25	4,1	0
C	+++	820	3,25	4,0	0
D	++++	630	3,25	4,2	0,2

Cask	Oak aroma	Oak taste	Colour of the wine
A	++++	++++	Low and of old appearance
B	+++	++	Normal, old appearance
C	+	+	Low and young
D	+	-	Normal and old appearance

We can see that the influence on the composition of wine is important, but by tasting more than by analysis: Aroma,Taste and Colour.

The effect is such, that a young wine in different types of oaks, when drawn off, gives the sensation of being of different ages. Another study was undertaken to compare the behaviour of a wine in wood from the same origin, already exposed to wine, but with staves of 20 and 28 mm.

After eight months, including one racking, the results were as follows:

	Control	28 mm.	20 mm.
Alcohol	12,6º	12,54º	12,50º
Volatile acidity	0,38	0,47	0,66
Colour(1)	2,1	1,9	2,2
Loss/decanting	--	0,7%	1,9%

Oak and steel

Anthocyanins are the red colour of purple grapes.

Using standard research techniques for the decrease of anthocyanins in red wine in different vats/casks we have tried to determine their behaviour in young red Tempranillo wine from the Rioja with a pH of 3.55, alcohol content of 12.7· and 488 mg/l of anthocyanins.

Wine is preserved in a new sawn cask with 28-mm staves, whilst another portion of the same wine is preserved in stainless steel for one year. In the second year the same operation is carried out with the used cask from the previous wine. The wine is drawn off from the casks every six months.

Wine	Initial anthocyanins	After a year in steel	After a year in oak
1980	488	378 (-22%)	462 (-5%)
1981	612	483 (-21%)	556 (-9%)

Practically the same criteria are met here as by other authors. New oak defends against the drop in anthocyanins in Tempranillo red wine. Stainless steel facilitates the loss of part of the grape colour in red wine. Oak, particularly when new, helps it resist the loss for a longer period.

Content of total tannins

In sawn oak casks with 28-mm staves a study was carried out on the total tannin enrichment of white wine in a new cask. Also, in another five year old cask manufactured by the same cooper.

Initial tannins	Final tannins	Tannins After one year
	New cask	5-year-old cask
1,32 grs./l.	1,97 grs./l.	1,58 grs./l.

Logically, the young oak increases the tannin in the wine.