Winemaking
Fermentation and maturation vessels
Steel, barrel, foudre, concrete, amphora, qvevri — what each actually does about oxygen, temperature and extraction.
The short answer
A vessel is chosen for three properties: how much oxygen it admits, how it behaves thermally, and whether it contributes anything to the wine. Almost every claim made for a vessel reduces to one of those three, and the ones that do not usually reduce to marketing.
Overview
Vessel choice has become unusually fashionable, and the material is now sometimes printed on labels. Much of the accompanying claim is difficult to support.
The useful framework is to ask what a vessel does about oxygen and temperature before asking what it does about flavour, because the first two are where the real differences lie.
Step by step
1 Stainless steel
Airtight, inert, and easy to temperature-control with a jacket. Contributes nothing and admits nothing. The default where fresh primary fruit is the objective, and the technology that made modern white winemaking in warm regions possible.
2 Oak barrel (225–500 L)
Admits oxygen slowly through staves and bung. High wood contact per litre. Contributes flavour when new and diminishing amounts thereafter. Also the most labour-intensive vessel to keep clean.
3 Large oak (foudre, botte, 2,000 L+)
Much lower surface area per litre, so oxygen ingress and flavour contribution are both far smaller. Traditional for Barolo, Rioja and Chianti, and the standard answer where oxygen is wanted and oak flavour is not.
4 Concrete tank
Effectively airtight when epoxy-lined, slightly permeable when bare. High thermal mass, so temperature changes slowly — a real advantage in a hot cellar. Contributes no flavour.
5 Concrete egg
The shape is claimed to promote convection currents that keep lees in suspension. The claim is widely repeated and not well demonstrated. What is uncontroversial is that it is bare concrete with no corners, which does keep lees moving and does simplify cleaning.
6 Amphora and terracotta
Porous unless lined, so oxygen ingress can be substantial and is harder to control than in a barrel. Contributes no oak flavour. Used for skin-contact whites and for producers wanting oxidative development without wood.
7 Qvevri
The Georgian tradition: large earthenware vessels lined with beeswax and buried to the neck, which gives near-constant cool temperature. In continuous use for millennia and UNESCO-listed.
8 Glass-lined and epoxy-lined tanks
Inert and airtight like steel, and historically important as the first way to get an inert surface at scale before stainless steel was affordable.
What people get wrong
1 widely repeated claim this page corrects.
Several vessel claims — particularly around concrete egg shape and amphora "energy" — circulate widely without supporting evidence. WineHQ describes the properties that can be stated and declines to repeat the rest.
Vessel marketing is unusually assertive. The oxygen and thermal behaviours here are well established; claims about shape-driven convection and about vessels imparting character beyond those mechanisms are not, and are labelled accordingly.
Sources
Sources consulted
- WSET educational materials and the Systematic Approach to Tasting — Wine & Spirit Education Trust
- The Australian Wine Research Institute — AWRI
- Ancient Georgian traditional Qvevri wine-making method — UNESCO Representative List of the Intangible Cultural Heritage of Humanity — UNESCO
- The Oxford Companion to Wine — Oxford University Press
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Fermenting grape juice in contact with the skins, which is where colour and tannin come from.
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Pressing the juice off the skins before fermentation, then fermenting the clear juice.