When John went to Roseworthy Ag College to study oenology in the early eighties the very learned professor had students draw flow diagrams in blue and red ink for white and red grapes. The grapes flowed from the crusher to the press then fermenter and so on. This gave our callow youth an understanding of the machines involved, but didn’t explain how is wine made? Reading textbooks on wine should be enlightening. Unfortunately they too fail to deliver. They are good at explaining the various chemicals that make up wine and how they react. But how is wine made?

Jack Mann – the most famous Western Australian winemaker by far – said “Winemaking is entirely a natural process. And no person has the right to assume the title winemaker. Nature is the winemaker and man, if he is skilled, gives nature the opportunity to perform to best advantage. That is the art of winemaking.”

So if the scientists can’t tell you and the winemakers won’t, how do you find out how to make wine? Well of course one has to drill down into what they both have to say and find the answer somewhere in between.

What Jack Mann was alluding to was that winemaking was a natural process that the winemaker merely guided. What the scientists know is that there are a series of interrelated and complex chemical and biological reactions each of which plays a role in the final outcome of the winemaking process.

We know that man has made wine for over 5000 years – well before he had any scientific understanding of the process. If grapes are mashed up and the juice drawn off it will ‘boil’ and the taste will have changed to that of wine. (And drinking this is as popular today as it was then.) The role of microorganisms in the conversion of sugar to alcohol was only discovered by Louis Pasteur in the mid nineteenth century. Today even fairly fundamental knowledge such as why wine tastes the way it does is still not fully understood. However we also know that since we have begun to understand the science we have been more able to manipulate and manage the winemaking outcome. Whilst rustic wine can still be made in a bucket with no scientific knowledge, it is essential for modern commercial winemaking.

So winemaking exists somewhere between elevating winemaking to an art form and the study of the science of wine – oenology. Because we don’t know all of the science behind winemaking, winemakers must rely in part on experience and judgment to achieve their desired outcome. Modern winemaking involves managing a series of physical processes and naturally occurring reactions. Winemakers select the most appropriate processes to achieve their preferred reactions and resultant taste.

The processes involved in winemaking – crushing grapes, pressing the skins, pumping over the fermentation, fining and filtering, and so on are fairly mechanical, and hence easily described and understood. What is difficulty is selecting when and how to apply these processes to any given batch of fruit. We believe doing this successfully is the craft of winemaking.

To understand this craft one must consider what is the winemaker’s goal, and what can he manipulate to achieve this.

Winemakers think of wine in terms of types – red/white, sweet/dry, still/sparkling, natural alcohol/ added alcohol; and styles – simply fruity or complex in flavour, crisp or soft, light bodied or full.

For example at Faber, John would categorise the wines as follows

Wine Type Style
Blanc de Blanc Dry white sparkling Complex, crisp, light bodied
Swan Verdelho Dry white table wine Fruity, crisp, full bodied
El Sol Semillon Sweet white table wine Fruity, soft, light bodied
Chardonnay Dry white table wine Complex, soft, full bodied
Petit Verdot Dry red table wine Fruity, soft, medium bodied
Reserve Shiraz Dry red table wine Complex, soft, full bodied
Liqueur Muscat Sweet red fortified wine Complex, soft, full bodied

Once the appropriate fruit is selected the winemaker can manipulate three things – flavour, the acid-sugar balance, and the tannins. Put simplistically, flavour manipulation determines whether the wine is fruity or complex, acid-sugar balance determines whether the wine is soft or crisp, and tannins determine the degree of body of the wine.

The winemaker has lots of flavour options. The main sources of flavour are the grapes, fermentation (alcoholic and malolactic), contact with yeast lees, oak, fortification with alcohol, tirage (the second alcohol fermentation used in sparkling winemaking), and bottle age. Where the grape flavour is the predominant flavour the wine is fruity or simple in style. The winemaker can select more or less ripe fruit, fruit affected by Botrytis (noble rot) or free of disease, fruit from different climates, and so on. Where secondary flavours are dominant the wine is considered complex. Often the fermentation is manipulated to influence flavour – such as the selection of yeast that synthesis more aromatic byproducts, or by changing the temperature of fermentation. Oak is commonly used to flavour the wine to achieve a more complex result.

The sugar-acid balance is manipulated by selecting more or less ripe fruit, adding acid or grape juice (adding sugar is illegal in Australia), or by halting the fermentation before all the sugar is converted to alcohol. This allows the winemaker to make wines across the spectrum from steely to luscious.

Winemakers have an almost infinite ability to manipulate tannin levels. They do this by selecting more or less tannic varieties, riper or less ripe grapes, the degree of contact between and force exerted on the juice and skins, the use of oak, addition of tannin extract, or removal of tannins from the wine by ‘fining’ with compounds such as eggs white, fish protein, gelatin, or skim milk.

So if our winemaker has a sound background of oenology, can source suitable grapes, puts the right options together, and selects the most appropriate processing technology, the wine should come out tasting as planned. Easy!

So that is how wine is made!