Winemaking Evolution

Musings from Wirra Wirra CEO, Matthew Deller MW. 

This two-part exploration examines how winemaking practice has evolved across McLaren Vale and the Adelaide Hills, viewed through the working realities of Wirra Wirra, Ashton Hills and Hahndorf Hill. The relevance of this evolution is practical rather than stylistic. It reflects how increasing climatic variability, greater understanding of phenolic behaviour and more precise vineyard inputs now shape structural outcomes in the glass well before wines enter barrel. What follows is not a catalogue of techniques, but an examination of how intent has shifted and how that intent now governs decision making from the first pick onward.

Part 1: In the Vineyard

Part 1 focuses on the front end of the winemaking process, specifically harvest and crush, where freshness, site expression and extraction potential are now largely determined. Part 2 continues the sequence through fermentation, extraction management, pressing and maturation, and considers how élevage has become a confirming stage rather than a corrective one.

Over the past two decades, winemaking practice in McLaren Vale and the Adelaide Hills has changed materially. These changes are best understood through the chronological sequence of decisions made from harvest through fermentation, pressing and maturation. Across Wirra Wirra in McLaren Vale and Ashton Hills and Hahndorf Hill in the Adelaide Hills, the direction of change reflects a shift from corrective cellar intervention toward predictive management of phenolic outcomes, with greater emphasis on freshness, site expression and structural clarity.

Harvest

Winemaking evolution in both regions begins at harvest, where intent has shifted materially over time. Earlier practice in McLaren Vale frequently prioritised sugar accumulation and flavour development compatible with higher alcohol levels and new oak integration, that resulted in phenolic maturity as a default of later picking times. In the Adelaide Hills, earlier practice was more often concerned with achieving flavour ripeness while avoiding green phenolics and structural dilution, particularly in cooler or compressed seasons. In both regions, these approaches constrained subsequent cellar decisions.

A major factor that has allowed us to change our picking criteria is the work done in the vineyard. We now have a much better understanding of how to grow Cabernet for optimum quality and keep Shiraz vines functioning while ripening. These defining practices, along with viticulture and winemaking working together to achieve combined goals, means picking decisions are now more reliable to achieve desired style outcomes.

Current practice places primary emphasis on freshness and site expression, with phenolic maturity assessed in parallel rather than subordinated to flavour ripeness alone. Freshness is defined operationally through the alignment of titratable acidity, pH, flavour definition and phenolic readiness, rather than as an abstract stylistic goal. Harvest timing is increasingly determined by this alignment, with an explicit objective of retaining acid structure and appropriate pH that support tannin perception, microbial stability and sulphur dioxide effectiveness downstream.

This shift has been accelerated by increased climatic variability. Heat spikes, compressed ripening windows and greater vintage volatility have altered harvest risk frameworks. Picking decisions now account for fruit condition, forecast risk and canopy function, favouring earlier intervention where freshness and structural balance are threatened by rapid sugar accumulation or declining photosynthetic capacity.

Site expression is operationalised through increased parcelity at harvest. Multiple picks within a single block, segmentation by aspect, soil depth, vine age and row position associated with exposure or vigour gradients, and selective exclusion of overexposed fruit are now common. This allows structural and flavour differences within sites to be preserved rather than averaged, increasing precision in subsequent fermentation and maturation decisions.

Harvest intent is variety specific. In McLaren Vale Cabernet Sauvignon, the objective is line, length and tannin definition without extending ripeness to the point of non-varietal vinous dark fruit characters In Shiraz, harvest timing seeks to retain energy and red fruits while avoiding berry shrivel / desiccated fruit. Grenache is harvested to preserve perfume and brightness alongside tannin finesse, rather than maximal sweetness or weight. In the Adelaide Hills, Pinot Noir is picked for flavour definition and acid balance while monitoring stem maturity and avoiding generic red berry fruit characters or overt tannin potential. Chardonnay and aromatic whites, including Grüner Veltliner and Riesling, are harvested to balance flavour potential with acid tension to enhance site derived character.

This change in harvest intent, combined with more selective extraction and fraction management, has materially reduced reliance on oak derived structure and flavour contribution. It has expanded the range of viable crush, fermentation and maturation strategies, allowing cellar decisions to respond more directly to vineyard character rather than compensate for excess ripeness or structural imbalance established at harvest.

Crush

Crush decisions now exert greater influence over wine structure than in earlier practice. Destemming protocols have shifted toward maximising whole berry retention. Earlier approaches favoured aggressive destemming and crushing to ensure rapid juice release and fermentation initiation. Current practice seeks to preserve berry integrity to delay seed tannin extraction and allow limited intracellular fermentation in intact berries.

Whole bunch inclusion is determined at crush and applied selectively. Historically excluded due to the risk of herbaceous bitterness, stems are now incorporated only where lignification and flavour development justify their inclusion. At Wirra Wirra, whole bunch inclusion is used occasionally in Shiraz and Grenache to extend tannin architecture, give aromatic lift and moderate mid palate concentration. When the practice is employed in Shiraz, existing phenolic density and stem tannin interaction can reduce the structural benefit and increase the risk of pH distortion. Cabernet Sauvignon remains a higher risk variety for stem inclusion due to the risk of herbaceous character and green aromatic expression and is therefore used selectively rather than routinely.

At Ashton Hills, whole bunch inclusion in Pinot Noir is contingent on seasonal stem maturity and vineyard condition. Where lignification is adequate, limited inclusion contributes structural extension and aromatic complexity. Where conditions are unsuitable, the technique is omitted. Across all varieties, stem inclusion is treated as a structural decision made at crush rather than an extraction technique applied during fermentation.

These crush stage decisions establish the extraction trajectory of the ferment and constrain subsequent cap management, maceration length and pressing options.

Part 2: In the Winery

This second part examines how winemaking practice has evolved across McLaren Vale and the Adelaide Hills through the working experience of Wirra Wirra, Ashton Hills and Hahndorf Hill, focusing on what happens from fermentation through to maturation. The emphasis is on how fermentation behaviour, extraction management, pressing and élevage now translate vineyard intent into tannin shape, texture and structural coherence in the finished wine.

Fermentation

Harvest and crush decisions have transitioned from prioritising operational efficiency and rapid extraction kinetics to maximising the potential of each unique parcel of fruit using smaller fermenter sizes and nuanced extraction techniques.

At Wirra Wirra, the adoption of 2 tonne open fermenters enabled more bespoke fermentations for colour, flavour and tannin extraction in Shiraz and Cabernet Sauvignon.

Cap management techniques can be adjusted in response to tannin development and stylistic preference rather than fermentation stage alone, often leading to greater time on skins at lower sugar levels.

Yeast selection is determined prior to fermentation and reflects improved predictability of fruit condition. At Ashton Hills, indigenous yeast fermentation is viable due to moderate sugar levels, relatively low disease pressure and acid profiles that support microbial stability. While fermentation variability persists, outcomes remain predictable within defined parameters. In McLaren Vale, cultured yeast remains central to Wirra Wirra red winemaking, to ensure ferment completion and maintain tannin control, particularly at higher sugar levels. Incomplete or stressed fermentations increase the risk of harsh tannin extraction and reduced aromatic clarity.

At Hahndorf Hill, parallel fermentation pathways are employed. Grüner Veltliner is fermented under contrasting conditions, including cool stainless-steel fermentation, indigenous fermentation on full solids in old oak and warmer ferments designed to increase phenolic and textural contribution. Structural assembly occurs post fermentation through blending rather than reliance on a single fermentation outcome.

Extraction

With a shift in stylistic preference, fruit sourcing, and a winemaking desire to use a broader range of winemaking techniques, extraction management has become more tailored and less prescriptive.

Pump-over or plunging regimes, as assessed by a daily ferment tasting, have transitioned from using temperature and time on skins as key decision-making factors, to focusing how fruit potential can be optimised. 

Early extraction is used to establish colour and aromatic lift while alcohol remains low. As alcohol becomes more available, intervention is reduced. This sequencing has reduced the need for corrective measures later in the winemaking process.

Maceration length is determined by tactile assessment rather than fixed protocols. At Wirra Wirra, pressing decisions are made on evaluation of tannin integration rather than fermentation completion. In some cases, extended post fermentation maceration is employed to promote early tannin integration and polymerisation under controlled reductive conditions. This reflects improved phenolic maturity at harvest and increased confidence in oxidation management. 

Pressing

Pressing represents a critical structural selection point. Earlier reliance on higher pressure pressing systems prioritised volume recovery and frequently introduced coarse phenolics into the wine.

Current practice favours basket pressing, allowing greater discrimination between press fractions. Free run and early pressings are frequently retained for their contribution to mid palate continuity and structural completeness. Later pressings are excluded at the onset of phenolic hardness. Volume recovery is deprioritised in favour of tannin coherence.

Maturation

Maturation strategy responds to structure established earlier in the process. Earlier approaches frequently relied on higher proportions of new oak based on consumer preferences and allowed winemakers to compensate for uneven tannin development or impose structure post fermentation. In McLaren Vale, this often resulted in oak derived tannins masking varietal expression. In the Adelaide Hills, it occasionally overwhelmed wines with limited phenolic mass.

As vineyard derived tannin maturity and extraction predictability have improved, the functional role of oak has narrowed. At Wirra Wirra, new oak selection and usage is determined in conjunction with both our style and the wines’ phenolic density rather than brand hierarchy. Oak ages, types and sizes are carefully aligned to variety and maturation length for each parcel of wine. Wines with greater tannin mass or fruit power are allocated higher proportions of new oak, as they are better able to integrate oak derived flavours, tannins and oxygen ingress during extended élevage. Parcels with finer tannin profiles are matured predominantly in older oak to avoid disproportionate structural impact. These days, wines are rarely matured in new oak percentages over 30% and there is a preference for larger format oak.

In the Adelaide Hills, maturation strategies reflect lower phenolic load and higher acid retention. At Ashton Hills, Pinot Noir maturation favours a high proportion of seasoned French oak, with limited new oak introduced only where tannin development during fermentation indicates sufficient buffering capacity. Maturation is used to stabilise tannin continuity rather than increase structural mass.

Malolactic fermentation is commonly conducted in barrel for red wines across all 3 wineries. Completion in barrel promotes earlier integration of oak influence and encourages a more uniform tannin profile. Carbon dioxide generated during malolactic fermentation facilitates gentle lees movement, reducing the need for mechanical stirring and contributing to a more texturally interesting palate. 

Lees management has evolved accordingly. Earlier reliance on frequent racking to clarify wines and limit reductive character has been replaced by selective intervention. Extended lees contact is employed where fermentation derived tannins indicate benefit from additional colloidal support. Racking decisions are made in response to reductive risk or textural imbalance rather than as routine practice.

Sulphur dioxide management reflects this shift. Earlier strategies favoured early and higher additions to secure microbial stability. Current practice delays sulphur dioxide addition until completion of malolactic fermentation and relies on lower total additions where phenolic maturity and pH permit. This supports ongoing tannin integration during élevage while maintaining wine stability.

Winemaking evolution in McLaren Vale and the Adelaide Hills is expressed through changes in harvest intent, crush stage decisions, fermentation kinetics, extraction sequencing, pressing and maturation strategy. These changes reflect increased emphasis on freshness and site expression, alongside greater confidence in vineyard derived phenolic maturity and reduced reliance on corrective cellar practices. Across Wirra Wirra, Ashton Hills and Hahndorf Hill, structural outcomes are now largely determined before maturation begins, with élevage functioning to confirm rather than reshape decisions made earlier in the winemaking process.