Graham’s winery at Quinta dos Malvedos combines the best of traditional and ground-breaking modern methods for making its premium ports. There is but one single-minded objective here – to produce the very finest port possible.
During the harvest, all our grapes are picked by hand and transported to the winery in small crates that hold no more than 20 to 22 kg of fruit. In the heat of the Douro, if the grapes were to be crushed during the picking and transport, fermentation would begin before they ever reached the lagares, and we would have to throw them away, lest they spoil the rest of the batch.
Every bunch of grapes is carefully examined and unripe or damaged fruit discarded; this is done by the harvest team as they work in the vinyard, and again at the winery by our winemakers. Only then are the grapes transported into the lagares – the large shallow tanks where the grapes are treaded.
So far, so traditional. Historically, the grapes for port have always been treaded by foot, and there have been very sound reasons for this method to have continued in the Douro long after winemakers elsewhere in the world converted to mechanical crushing of the grapes.
To better understand those reasons, first a little digresssion: In cooler regions making dry red wines, the crushed grapes and juice can rest in tanks and macerate typically for a period of 6 to 12 days before and during fermentation, so that colour and flavour compounds can be extracted from the skins of the grapes. Fermentation – the process by which yeasts consume sugars and produce alcohol – cannot occur if the temperature of the must is below 20° C and will shut down if the temperature rises over 35° C. For a dry wine, fermentation is allowed to run to its natural conclusion, when either the yeasts have consumed all the available sugars, or the alcohol level has reached about 15%, which level will kill off any remaining yeast. The process of fermentation throws off carbon dioxide and heats up the must, and the solids – skins, pips, stalks – will rise to the top of the vat whilst the liquid settles to the bottom. Re-combining the cap with the liquid periodically helps extract more flavour, colour and tannins.
Now back to Port and the Douro: we have a few challenges in our winemaking compared to the temperate climate maker of a dry red wine. First is our climate – temperatures are generally at least in the mid 20’s and often into the mid 30’s during harvest. Second, we are making a sweet wine – so we want to monitor the fermentation very closely and arrest it when the sugar levels meet our requirements. When the wine is ready to be fortified, it is run off the solids, lest the high alcohol levels leech bitter tannins from the cap. Between the warm climate and the desire to preserve a high level of natural sugars, our fermentation period generally only runs about 2 days. That means we have 48 hours in which to extract the maximum of colour and flavour from our grapes, not a week or two.
Hence foot treading – it really is the optimum way to break up the grapes and knead the skins a bit to extract all the colour and flavour possible in the short time available. At the same time, it is important not to crush or crack the pips of the grapes, as they can release potentially bitter flavours into the must. The human foot is ideally suited to crush the grape without crushing the pips (you could prove this to yourself by dropping a bunch of grapes on the kitchen floor and trying this at home!).
But there is one more challenge – manpower. Graham’s has been exceptionally fortunate to have strong relationships with many local families in the region, who have been working our harvests for years, sometimes for generations. But as in so many rural areas, manpower can be scarce at the best of times, and it is hard to ask someone who has been picking grapes all day to stick around to tread them for four hours at night.
In the late 20th century most port makers experimented with various mechanical methods of crushing the grapes and then re-combining the cap and must during fermentation, most of which were derivative from the kinds of systems used for making dry wines.
The Symington family pursued a different concept, and invented the robotic lagar – a machine that actually treads the grapes exactly the same way a team of men would. The first lagares were trialled in 1998, and since 2000 we have had three robotic lagares in use at the Malvedos winery.
Like a traditional lagar, the robotic lagar is a low square tank, but stainless steel rather than granite, and fitted with a line of mechanical pistons which exactly mimic the rythmic goose-step like treading of a human treading team as they move slowly from one end of the lagar to the other. The pistons have special silicon pads which are of a density and texture very like a bare foot – if you visit the Graham’s lodge in Gaia you can see and handle a spare treading pad to see and feel what we mean. Finally, the pistons are calibrated to tread the grapes against the floor of the tank at the same pressure as a 70 kg man. All our wines are treaded in the lagares, and they can be treaded robotically at any hour of day or night, as required by the winemakers.
Another advantage of the stainless steel robotic lagar is a system of panels in the pistons and three sides of the lagar which are filled with water. This water can be cooled or heated to manage the temperature of the must in the lagar during treading and fermentation.
After treading, we monitor the fermentation closely and when we are ready to fortify, the robotic lagar again proves its worth. Pneumatic lifts simply tip up the lagar from one side and the wine runs out, to be captured in a tank in the lower levels of the winery. Next, the remaining solids are tipped out of the lagar, and by means of an archimedes screw shifted into a press. Our winemaking team deeply appreciate being spared the job of pitchforking tons (literally) of spent grape solids out of a stone lagar at odd hours of the night.
When the alcohol and sugar are at the desired levels, the fermentation is arrested by the addition of aguardente – a pure grape spirit of 77% alcohol. This is colourless and has neither aroma nor flavour – if you were to sample it, you would find it looks like water and goes down like liquid fire, but makes no taste impression at all.
The wines will be kept in storage in the Douro over the winter, and in the spring will be transported to our lodge in Vila Nova de Gaia, where they will age, and eventually be blended and bottled to create one of our outstanding range of premium ports.