Port anD the Douro 131in short supply in the 1960s. Most outlying quintas were without electricity altogether and
the power supply in other parts of the Douro was at best unreliable and often insufficient
to feed the battery of pumps and appliances that are now commonplace in a well-equipped
modern winery. The solution was autovinification. Adapted from an Algerian design known
as the Ducellier System, autovinification provides for a vigorous and thorough extraction
and has the singular advantage that the process is self-sustaining, being powered by the
build-up of carbon dioxide – the natural by-product of fermentation.
The mechanics of the autovinification system are as follows. The vat (illustrated in
figure 2) is filled to within a metre or so of full capacity. The autovinifier is then closed
by lowering the central unit (A) into place. As the fermentation begins, carbon dioxide
is given off and the pressure builds up inside the tank. This forces the fermenting must
up an escape valve (B), which spills out into an open holding tank on top of the vat.
Once a certain pressure has built up inside the autovinifier, the carbon dioxide escapes
through a calibrated hydraulic valve (C). No longer supported by the pressure inside the
vat, the fermenting must falls back down the central autovinification unit by force of
gravity, spraying the floating cap or manta below. At the same time the hydraulic valve
resets itself, ready for the pressure to build up and the autovinification cycle to begin
again. At the start of fermentation, this cycle is relatively slow but after a few hours,
when sufficient carbon dioxide is being given off, the build-up of pressure inside the vat
Figure 2. Autovinification