Port anD the Douro 127ideal as the grapes at the bottom of the dorna are frequently crushed under their own
weight. If weather conditions are warm or there is a delay, fermentation will already have
commenced before the grapes reach the winery. Conversely, if heavy rain falls during the
vintage and the dornas are not covered with plastic sheeting, the juice will be diluted. But
worse than these are the plastic bags into which some small growers compress their grapes
and leave them out on the roadsides awaiting collection. Most quality-conscious growers
and shippers now use small, stackable plastic crates with holes in the sides to allow water
(or juice) to drain away. With a capacity of no more than about 25 kilos each, the grapes
tend to arrive at the adega intact and undamaged.
Mechanical harvesting is only possible in some of the larger, flatter vineyards of the
Douro Superior. Apart from the considerable potential saving in labour costs, the chief
advantage of mechanical harvesting is speed. It would also be possible to harvest in the cool
of the night, thereby reducing the refrigeration required when the grapes reach the winery.
Footwork
Peel the skin from most red grapes and you will find that the pulp or flesh is grey-green in
colour. With the notable exception of red-fleshed teinturier varieties, all the pigmentation
and most of the flavour compounds are to be found in the skins and adjacent cell structure.
Producers of ‘light’ or unfortified red wine have the luxury of a relatively long period of
fermentation and maceration to extract the necessary colour, tannin and flavour from the
grapes. In the case of a fine red, like a classed-growth Bordeaux, extraction may take place
over a period of two weeks and may be followed by a period of post-fermentation maceration
or cuvaison. Port producers have no such time on their hands. The deep crimson–black hue,
firm tannin structure and ripe flavours that characterise a young, premium quality Port have
to be extracted before the fermentation is prematurely arrested by the addition of colourless
grape spirit. Depending on the rate of fermentation, the grape juice or must may be in
contact with the skins for forty-eight hours or less. The key to the production of a quality
red Port is, therefore, found in the vigorous extraction of colour and flavour compounds
from the grape skins.
The crucible for this extraction process is the lagar, a square stone tank made from
granite (or occasionally epoxy-coated cement), usually 80cm to 1 metre in depth with
a capacity varying between 15 and 25 pipes (8,000–14,000 litres). The lagar is filled to
within about 15 to 20cm of the brim – the width of an outstretched hand is the crude
measurement. Before the advent of electricity, baskets of grapes arriving from the vineyard
were emptied directly into the lagar or into a hand-turned roller-crusher. Foot crushing
whole bunches is not only hard work but the stalks, if green and unripe, can introduce
a herbaceous character into the wine. Nowadays, electric roller-crushers, de-stalkers and
pumps are used and the stalks are removed. Some may be added back to the lagar at a later
stage. It is generally believed that the tannins from the stalks contribute to the structure of
the wine, though this depends on the overall ripeness of the crop. But stalks do help when
it comes to pressing the solids once the must has been run off and fortified.