After fermentation, a period of maturation is required to soften tannins. The choice of the maturation vessel and the maturation period depend on the style of wine to be produced including quality and cost factor. Less maturation time, less cost.
Barrel, stainless steel or amphora?
The transformation from simple grape juice to the complexity of wine represents the aim of modern winemaking technology. To control the entire process, many options are available depending on factors including grape variety, tradition, wine style and cost.
Most maturation vessel include wooden barrels or stainless-steel tanks. Stainless steel is an ideal storage material because of its properties being impermeable to gases such as oxygen and easy to control temperature. The wine can be stored until bottling. To save expenses and get a quick return of the cost, some wineries will bottle their wine shortly after fermentation. Sometimes deacidify the wine and leave residual sugar to make it more drink ready.
However, most high-quality wines are matured in barrels and given time to develop, from a few months to a few years. During, this period the wine will undergo a controlled oxygenation process and absorb some oak products like oak tannin and vanillin. Absorption is highest in a new barrel and much less in used barrels. Many of the famous Bordeaux, Burgundy or Napa Valley wines are matured in new barrels, a costly expenditure that also demands for the bottled wines to be settled for a longer time in the bottle, at the consumers cost as they release their wine ‘en primeur’. Sometimes these wines can be over-oaked. For our wines I prefer to work with a mix of new and older barrels with the new barrels only used for wines that will not be released before a few years barrel and bottle maturation. This happens in our winery at our own cost for our customers to savour when they are sufficiently matured.
Barrel size affects maturation as well, as smaller the size as quicker the maturation. In the last few years, I invested in 500 litre puncheons for slower maturation and less wood contact, especially for the whites. All our barrel fermented, and barrel matured whites are kept in puncheons e.g. Chardonnay, Viognier, Mistral, Sauvignon Blanc, Gruner Veltliner and Riesling.
Temperature also plays an important part, the lower the temperature the slower the maturation. It is important to exclude oxygen during this phase, maintaining the barrel to be always full. This means any evaporation must be refilled with the same wine, making long term barrel ageing extremely expensive (especially for our Montepulciano, Spirit of Marlborough and Nebbiolo which can be up to 36-month in barrel).
Fermenting and storing wine in stainless steel allows us to retain the crispness and purity of fruit. While oak is porous, stainless prevents oxidation without imparting any flavours. What comes in, come out. That is why I mostly use stainless maturation for aromatic wines like our Gewürztraminer or subtle flavoured wines like Arneis, Verdelho and Pinot Gris or sometimes a part of our Sauvignon blanc. However, the wines are given plenty of time to mature and kept natural without additions or alterations.
Stainless steel is hygienic and easy to clean with steam or water blaster with high pressure. It can be cooled down with cooling systems, area movable and can be custom made to any size. Ideally for some of my small experimental parcels.
Clay and Terracotta Amphoras
For thousands of years, terracotta containers called Amphora or Qvevri were the only option available to transform grape juice into wine. Georgia, the cradle of wine, claims to use them since 8,000 years. It’s a new trend, especially with the natural wine movement, often claiming that these vessels are more expressing of wine and terroir.
Due to the porous material of the clay, a gentle microoxygenation can occur without the oak flavour of a barrel. Microoxidation means exposing the wine to microscopic amount of oxygen, too low to cause actual oxidation but able to positively fix colour and soften aggressive tannins.
Amphoras are still made completely by hand following the rules of an ancient technique called “Based Work”: the Amphora stands still while the artisan goes round and round attaching new clay. The whole process takes three months including a long drying and a slow firing.
With the success of our Georgian grape variety Saperavi I wanted to experiment and see the difference between the wine out of an amphora or the traditional barrel we use for this powerhouse of a wine. Despite a wonderful week in Georgia visiting qvrevi makers and wine producers of qveri wine, I hesitated to buy one. Their clay is quite porous, and the biggest problem is hygiene, keeping the qvevri and the wine clean. Bacteria control is an issue. The wines were sometimes too oxidized losing the typicity of the grape variety and every so often smelled of the bee wax coating.
We have decided to use an Amphora from Italian wine producer Fontodi. Known not only for its quality wines but the winery’s owner long experience in the production of terracotta tiles. Their clay is less porous; the abundant presence of Galestro in the terroir of Chianti Classico, gives special features to the Amphoras. Among the natural components of which Terracotta is made, the salts and the calcium carbonates confer the right microporosity, enabling the wine to breathe correctly. These features, combined with the antioxidant and antibacterial action and the high thermal insulation capacity seem to make this terracotta an ideal tool for the production of a great natural Saperavi!
We will keep you posted about our experience…