3B Biologically Aged Wines 83
with wine alcohol to an ethanol content of 15.0–15.5 vol.%; this operation is known
asencabezado. In Montilla-Moriles, however, the favourable climatic conditions
and the characteristics of Pedro Xim ́enez grapes, which constitute the dominant
variety in the region, allow musts with alcohol contents in excess of 15 vol.% to be
obtained in a natural manner, so no fortification is required.
The wine is stored prior to incorporation into the biological aging system. During
the intervening time, it undergoes malolactic fermentation and spontaneously devel-
ops a yeast film, thereby incipiently acquiring the typical features of biologically
aged wine. Wine stored in this way is referred to assobretablaswine.
Subsequently, the wine is aged in American oak casks of variable capacity
depending on their position in the aging system. The casks are filled to four-fifths
in order to allow a biofilm of flor yeasts to develop on the wine surface. Biologi-
cal aging proper is accomplished by using thecriaderas and solerasystem, which
involves stacking the casks in rows calledcriaderas(scales) in such a way that
all casks in a row contain wine of the same type and aged for an identical length
of time.
The row standing on the floor, which is called thesolera, contains the oldest
wine in the system. It is from this row that the commercial wine is withdrawn for
bottling, extraction never exceeding 40% of the cask contents per year, and this
process is carried out three or four times each year. The amount of wine extracted
from thesolerais replenished with an identical volume of wine from the upper
row, which is called thefirst criadera. Likewise, the amount extracted from thefirst
criaderais replenished with wine from the next row (thesecond criadera) and so on.
Finally, the topmostcriadera, which contains the youngest wine, is replenished with
sobretablaswine. The number of scales typically ranges from four to six; usually,
the greater the number, the higher the quality of the final wine.
The transfer of wine from one scale to the next is calledroc ́ıoand is preceded
by a series of operations intended to homogenize the wine in each scale and hence
its degree of biological aging (Berlanga et al. 2004a). The wine extracted from the
casks in a scale is homogenized in a tank and then transferred to the casks in the
next (older) row. This operation must be performed with care in order not to disrupt
the “flor” film present on the wine surface.
This dynamic process results in thesoleracasks containing a complex mixture of
wine in terms of age. However, is very homogeneous, which allows wine of similar
sensory features to be obtained year after yearirrespective of the particular vintage.
Also, theroc ́ıooperation brings older wine into contact with younger wine, the
latter supplying the nutrients required for the yeast film to form and remain. Also,
it provides aeration, which is highly beneficial for wine and flor yeasts (Berlanga
et al. 2001, 2004a).
In other world regions, the biological aging process is static; such is the case with
the production of “jaune” (yellow) wines in Jura (France). In other countries, USA
(California) or South Africa, winemakers use a shorter dynamic process in order
to cut costs. “Jaune” wines are obtained from Savagnin grapes (Traminer type) and
possess an alcohol content of ca. 12 vol.%. Following malolactic fermentation, they
are held in used casks of 228 L which are filled to 5–6 L less and tightly closed for