White Wine Harvest

White wine grapes are harvested at cool ambient temperatures when the sugar, acid and flavour levels are determined to be suitable for the wine style being produced.

Harvested grapes are transported to the winery for processing.

White Wine Crushing

Grapes can be chilled upon arrival at the winery, especially in warmer regions with Mediterranean climates. Grapes are destemmed and crushed to produce the must (juice and grape solids) prior to pressing. With whole bunch pressing this step is not required.

White Wine Pressing

The must is pressed to obtain the juice for fermentation. This produces free run juice (no pressure is applied) and pressings, which are usually fermented separately but can be blended back in some proportion later in the process.

Adjustments of tartaric acid or sugar concentration can be performed at this stage, depending on local regulations, and sulfur dioxide may be added prior to pressing.

White Wine Fermentation

After pressing, white juice is typically cold-settled and decanted to another vessel to provide clarification of the juice prior to inoculation with yeast. The juice is inoculated with the selected yeast (many available) that is usually pre-cultured by the winery or added as active dry yeast.

Fermentation occurs in stainless steel tanks, or oak barrels in some instances, depending on the style the winemaker aims to produce.

Yeast nutrients may be added if the grapes are deficient, and a steady fermentation rate is preferred; this can be maintained by manipulating the temperature of the ferment if necessary (around or below 20 °C).

Aeration during the first few days of fermentation can ensure a healthy yeast population (efficient conversion of sugar and non-stressed yeast).

White Wine Clarification

Once a ferment has reached the desired residual sugar (< 2 gm/L for a dry wine), the wine is cooled and allowed to settle, then racked off gross lees under an atmosphere of inert gas to prevent oxygen from spoiling the wine.

Sulfur dioxide is added prior to racking.

White Wine Storage

The exact operation at this point depends upon the type of wine being produced.

The wine may be matured in oak barrels or undergo lees ageing for several months, with some form of occasional agitation of the lees; this can be used to enhance the flavour and mouthfeel properties of the wine.

Malolactic fermentation (MLF) can also occur, to deacidify the wine by metabolising malic acid into lactic acid, and contribute aroma characteristics.

White Wine Preparation

Wine is blended and undergoes fining, where phenolic compounds or other components are moderated to give the desired sensory profile.

Wine is then stabilised against precipitation of natural grape proteins and tartrates.

Wine is analysed, adjusted, clarified and carefully stored in readiness for sterile filtration prior to bottling.

White Wine Bottling

Bottling may be done in house or through a contractor and any equipment that will make contact with the wine is sanitised prior to use. Wine is filtered through a membrane filter for bottling under sterile conditions to remove microorganisms which may lead to spoilage.

White Wine Bottle maturation

Additional changes can occur over a period of time which improve wine after it is bottled. There is further moderation of sensory characters and development of complexity.

Red Wine Crushing

Grapes are destemmed and crushed to produce the must (juice and grape solids) required for fermentation.

Red Wine Mixing

Tartaric acid, oenological tannins and sulfur dioxide can be added at this stage, depending on local regulations. The must is pumped to the fermentation vessel in readiness for fermentation.

Red Wine Fermentation

The next part of the process largely relates to extracting colour from the grapes and different techniques can be employed to achieve this.

Additions, such as yeast, tartaric acid, sugar, tannin, enzymes, and nutrients are undertaken.

Some juice may be run off prior to inoculation to increase the ratio of skins to juice in the remaining must. Pre-fermentative cold-soaking or must heating can be used to facilitate extraction of phenolic compounds, and anthocyanins in particular.

In the days after fermentation begins, the skins rise to the top of the fermenter and form a thick “cap”. The conventional practices aimed at extracting the phenolics and other matter from the cap can involve periodic operations such as pushing down the floating skins, pumping the fermenting juice over the cap, or decanting and returning the fermenting juice over the cap. Heading-down boards can be used instead to keep the cap submerged under the surface of the fermenting juice, or specifically designed fermentation vessels can be employed.

The choice of yeast strain is another factor that affects red wine colour (and flavour).

Red Wine Pressing

The ferment is drained and pressed from the grape solids when the winemaker is satisfied with the alcohol content, residual sugar, colour, flavour and mouthfeel profiles of the wine.

There may be a period of post-fermentation extended maceration on the grape solids for several days or weeks to further extract phenolics. Free run (no pressure applied) and pressed wine fractions are fermented to dryness, usually in separate tanks to enable blends to be made later.

Red Wine Storage

Red wines undergo an important part of the ageing process in tanks or oak barrels after fermentation. This maturation allows the wine to stabilise and clarify, imparts beneficial oak components when barrels are used, and leads to reactions which impact wine colour and mouthfeel; that is, reactions which occur to make the colour long-lived and the mouthfeel less harsh.

Additions of sulfur dioxide and tartaric acid can occur at this time, along with fining to moderate the phenolic profile, mostly related to astringency; there is also periodic decanting of the wine from any sediment, then returning it to the vessel.

Red Wine Clarification

Wine is then decanted from the settled solids and further clarified if necessary (e.g. by centrifugation) and inoculated for malolactic fermentation (MLF) to deacidify and improve sensory characters. MLF can also occur spontaneously and concurrently with alcoholic fermentation.

Red Wine Preparation

After a period of maturation in tank or barrel, the wine is decanted and blended to produce the final wine, further stabilised if necessary, clarified, analysed and adjusted, and carefully stored in readiness for bottling.

Red Wine Bottling

Bottling may be done in house or through a contractor, and any equipment that will make contact with the wine is sanitised prior to use.

Wine is often filtered through a membrane filter for bottling under sterile conditions to remove microorganisms. Winemakers may decide to bottle with minimal or no filtration, to avoid stripping of components (primarily colour-related).

Red Wine Bottle maturation

Additional changes can occur over an extended period of time which improve wine after it is bottled. There is further moderation of sensory characters and development of complexity.