So how do we make our Chardonnay Blanc de Blanc?
Our inspiration for this wine comes from Swan Valley legend Dorham Mann. Dorham makes a bone dry sparkling white wine from Cabernet Sauvignon. The naturally low acidity of Swan Valley grapes allows us to make a wine from early picked grapes that don’t need sugar sweetness to balance what would be a very high acidity in a cooler region. Hence our lovely zippy, light fresh style.
We hand picked our fruit at about 12 0 Baume (Baume is a scale of density, which in juice is primarily a measure of sugar. 1 0 Be equates to roughly 1% alcohol in the finished wine.) The handpicked fruit is chilled overnight in the cold room and the following morning tipped straight into the press without crushing.
The aim of ‘whole bunch pressing’ is to avoid damaging the grape skins (apart from bursting them of course) so as to minimise extraction of phenolics compounds into the juice. We are seeking to make as fine and delicate a wine as possible and hence the less phenolics – which impart body, broadness and hardness – the better.
We only extract about 500 litres per tonne of grapes – well down on the 700 litres we would achieve if we crushed the fruit. However, the quality of the juice is outstanding. We do not add any sulphur dioxide as an antioxidant during pressing and the juice becomes quite brown. The phenolics compounds absorb oxygen and form larger, darker (brown) compounds. These precipitate during the subsequent fermentation further reducing the amount of phenolics in the wine.
Because the grapes have not been crushed the juice is relatively clear. We inoculate it with freeze dried yeast and commence the fermentation directly. Fermentation takes ten to twelve days. By opting for a moderately high temperature and rate of fermentation we seek to impart a strong yeasty character into the wine. This contributes to the overall aroma and flavour of the finished wine. We ferment until all the sugar is metabolised to alcohol by the yeast and we have a dry wine.
As soon as practicable we stabilise and filter the wine. Over three days we prepare another culture of yeast acclimatized to the conditions of the wine. It is much more difficult for yeast to grow in wine than juice. We add the sugar which will be converted to alcohol and carbon dioxide, add the yeast culture, and bottle the wine. The bottles are those in which the wine will be subsequently sold, but they are sealed with a crown seal.
The yeast grow and the second fermentation takes about eight weeks in the bottle. All of the added sugar is metabolised by the yeast, producing five times atmospheric pressure inside the bottle. Once the food source is exhausted the yeast die and form sediment in the bottle. The wine is left in storage in bottles for at least fifteen months. This period is called the ‘tirage’.
The wine continues to react with the compounds released from the yeast cells as they breakdown or ‘autolyse’. This contributes the typical nutty, yeasty, and even marmite-like aromas and flavours characteristic of bottle fermented sparkling wines. Once the wine is judged to be ready – with a balance between original fruit and wine flavours and yeasty matured flavours – the bottles are chilled and turned upside down and ‘riddled’ or shaken down. This takes a week, during which a compact sediment is formed on the underside of the crown seal.
The crown seal is flicked off and the wine ‘disgorged’ – the sediment is ejected and the bottle raised in a quick motion with little or no wine lost. The cold raises the solubility of the carbon dioxide so there is very little frothing. The bottle is topped up from another and the champagne cork, muselet and hood applied. The riddling disgorging is done by our friends at Myattsfield, who have the dexterity, the equipment, and the patience! We label and box the wine and it is ready to go.