Manseng Noir: an alternative red grape variety for low-alcohol wines with a robust structure and soft tannins

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The search for red grape varieties capable of delivering full phenolic maturity at lower sugar accumulation is one of the most pressing challenges in modern viticulture. Prof. Francisco Carrau (University of Montevideo, Uruguay) presents the research path that led his team from sandy-soil experiments with Tannat to the rediscovery of Manseng Noir — the only known sister variety of Tannat, nearly extinct in France by 2013. Through genomic sequencing, metabolite analysis and four commercial vintages in Uruguay, the research investigates why Manseng Noir consistently reaches optimal tannin polymerisation and colour stability at 11–12% alcohol, opening a concrete and scientifically documented perspective for producing structured red wines with significantly reduced alcohol content.

Manseng Noir: an alternative red grape variety for low-alcohol wines with a robust structure and soft tannins

Balancing phenolic maturity with moderate alcohol content remains one of the central challenges of contemporary viticulture. In high-structure red varieties, tannin polymerisation and colour stability typically require a level of berry ripeness that translates into elevated sugar concentrations — and consequently into wines above 14% alcohol. Prof. Francisco Carrau of the University of Montevideo, Uruguay, presents a research programme that addresses this challenge through a multidisciplinary approach: varietal screening, genomic sequencing, metabolite profiling and sensory analysis, applied to Manseng Noir, a nearly forgotten grape from the French Pyrenees.

The starting point: Tannat and the search for moderation

Uruguay’s flagship variety, Tannat, is renowned for its deep colour, rich tannin content and typically high alcohol — between 14 and 15% in most vintages. Carrau’s team explored several strategies to reduce alcohol without compromising structural complexity:

• Sandy soils: early tannin maturation allowed a reduction of up to 2% alcohol while maintaining colour intensity and aromatic quality
• Alternative yeast strains: reductions remained modest, generally below 1%
• Clonal selection: no significant differences were identified within the existing Tannat clonal pool

The breakthrough came from an INRA Montpellier microsatellite screening of 2,500 varieties, which identified Manseng Noir as the only known sibling variety of Tannat — a grape that had effectively disappeared from French vineyards by 2013, with fewer than two hectares remaining.

From extinction to commercial production

The recovery and introduction of Manseng Noir into Uruguay involved a structured research timeline:

• 2013–2014: identification of Manseng Noir through genomic parentage analysis; genome sequencing of both Tannat and Manseng Noir in collaboration with the University of Verona
• 2019: plantation of nursery material imported from France
• 2022: first experimental vintage
• 2022–2025: four consecutive vintages at pilot and commercial scale, consistently producing wines between 11 and 12% alcohol

The genomic work — which included the first published Vitis vinifera commercial variety sequence, Tannat, in 2013 — provided the molecular foundation to understand why the two sister varieties express such different maturation dynamics.

The science behind the difference: anthocyanins, tannins and polymerisation

Comparative metabolite analysis between Tannat and Manseng Noir revealed several key differences:

• Colour: comparable intensity to Tannat at 11% alcohol, with higher concentrations of acylated and methylated anthocyanins — responsible for greater long-term colour stability
• Tannin structure: Manseng Noir accumulates significantly lower levels of gallated procyanidins (the primary source of harsh astringency in Tannat) and undergoes faster tannin polymerisation in the grape, resulting in softer, more approachable tannins even in young wines
• Flavour profile: no significant differences were detected in flavour compound composition compared to Tannat

These characteristics — underpinned by differences in methyltransferase gene copy numbers — mean that Manseng Noir achieves phenolic and chromatic maturity at a point where sugar accumulation is still moderate, without the need for barrel ageing.

Practical implications for the wine industry

Sensory evaluation confirmed that Manseng Noir wines at 11–12% alcohol are perceived as structurally comparable to Tannat, with a noticeably softer palate in young vintages. The variety is now in commercial production in Uruguay and is attracting renewed interest in France, where cooperative plantings have expanded from two to over 35 hectares in recent years. For winemakers working on alcohol reduction without sacrificing red wine structure, Manseng Noir represents a well-documented and replicable solution.

The lecture reproduced in this video was presented at the 25th edition of Enoforum (Verona, 21–23 May 2025)