De Bortoli Winemaking - From Grape to Bottle

Vintage

Fruit is harvested when the balance between fruit flavour, sugar and acidity is at optimum levels. Good quality fruit is essential to produce high quality wine.

The winemakers select premium parcels of fruit on based on a flavour profile. Flavour is important to the winemaker wanting to make a particular style of wine. This is relevant whether making wine in cool or warm climate regions.

Crushing

Once the fruit is picked and delivered to the winery it is then crushed into fermenters. During crushing the fruit is de-stemmed (the fruit is removed from the stem and any material other than grape is also removed). The fruit and juice crushed into the fermenters is from then on referred to as 'must'.

Traditional hand picking is still used for special parcels of fruit grown on old vines or for botrytis affected grapes but most fruit in Australia is now machine harvested. This reduces labour costs and allows the fruit to be harvested in the cool of the night.

Making White Wine

The must is drained and pressed then the two fractions of juice produced, 'free run' and 'pressings' are kept separate until post fermentation blending. 'Free run' is the juice that drains freely from the press, whereas the 'pressings' is the juice obtained by mechanically squeezing the must. Both fractions of juice are clarified and then yeast is added.

The temperature of the ferments is held between 13-17°C for 10-18days until the yeast has converted the sugar to alcohol.

Once fermentation is completed, the wine is racked (the clear portion on top is removed) and Bentonite is added for protein stabilisation.

Some white wines such as Chardonnay may be fermented and matured for a period in French or American Oak Barriques(small oak barrels). Most white wines though, for example unwooded styles such as Sauvignon Blanc and Riesling are stored in tank until they are ready for bottling. These styles are usually bottled soon after vintage, once fermentation, stabilisation, clarification and blending has occurred.

Making Red Wine

After crushing and de-stemming, yeast is added. To obtain colour and flavour,the juice from the must is taken from under the cap of the skins and used to irrigate the skins several times a day. The red must is fermented at temperatures between 22-30°C over a 5-7 day period.Premium parcels may be transferred into French or American oak barrels to complete fermentation. Once the sugar has converted to alcohol, and the colour and flavour have been extracted from the skins, the must is then pressed.

After pressing, the wine is clarified and inoculated with Leuconostoc oenos (malo-lactic bacteria) for secondary or malo-lactic fermentation. Malo-lactic fermentation is the conversion of malic acidinto lactic acid.

Once the malo-lactic fermentation is completed the wine is clarified and stabilised prior to blending. For premium parcels oak maturation in American or French oak barriques (225L) for a period of 9-12 months occurs.

Oak Maturation

Oak barrels are used for premium wine maturation. The type of oak used whether French, American or other depends on the winemaker's individual preference or the style of wine being made. Different levels of "toasting" are used in making a barrel, which imparts flavour from the oak into the wine. The barrels are filled and sealed with a silicon bung.

Some barrels are stored with the silicon bung upright and topped every 2-4 weeks. Some are rolled where the silicon bung is in the 2o'clock position. The barrels are stored where the temperature is constant. This keeps the wine in better condition and reduces the rate of expansion and contraction due to temperature fluctuations.

Clarification and Stabilisation

Wines are clarified to 'cellar bright' prior to bottling or long term storage. The means of clarification used in the winery are Centrifugation, Earth and Pad Filtration.

White wine is both protein and tartrate stabilised, red wine is just tartrate stabilised. Adding Bentonite to white wine ensures that the wine will not have an undesirable haze of deposit once bottled. The haze or deposit is associated with the de-naturisation of proteins,which occurs more rapidly at higher temperatures.

Tartrate stabilisation removes potassium bi-tartrate crystals from the wine, this is achieved by chilling the wine to below 0°C. Although not harmful, the presence of crystals in a white and red wine can be unacceptable to the consumer.

Blending

Each wine is blended according to the desired style and the label requirement of a particular blend. Blending occurs when all the wine has completed primary and secondary fermentation and has been protein and tartrate stabilised. Blending is regarded as the intricate part of winemaking. Commercial winemakers focus on maintaining the consistency of style from vintage to vintage.

Bottling

The wine is packaged after sterile filtration. Sulphur Dioxide is added and in some wines Ascorbic Acid is also added as a preservative. The food additive codes on the labels are Sulphur Dioxide (220) and Ascorbic Acid (300).