The Big Picture - The Red Raw Ingredient
The key difference between white and red winemaking is that red wine is made by fermenting the juice, skins and seeds together and then pressing the wine. Depending on the style of wine being made and the condition and ripeness of the stalks, whole bunches of grapes are sometimes fermented along with de-stemmed and/or crushed berries. Again, depending on the grape variety, the style of the desired wine and the condition of the fruit, the winemaker chooses whether or not to crush the berries and to what degree.
Crushing and Destemming
Fermentation, Extraction and Maceration
Red wines are fermented at higher temperatures than whites, typically in the range of 28 to 30 degrees Celsius, and the total period of maceration varies tremendously, from as little as two to three days to one month or more, depending on the desired wine style.
Prior to the commencement of fermentation, the temperature of the must can be adjusted to allow a period of cold maceration. This allows the gentle extraction of compounds from the skins without the presence of alcohol (a powerful solvent) and is particularly important in preserving the delicate character of lighter red wine styles.
Because the extraction of compounds from the red grape skins is the key to red winemaking, the correct ratio of juice to solids (skin, pips and sometimes stalks) during fermentation is crucial. To regulate this, juice can be run off prior to fermentation and vinified separately as rosé.
There are various styles and sizes of fermentation vessels available, ranging from rotary fermenters (rotating stainless steel barrels) to large static vessels. Most high quality red wines are fermented in open, static fermentation vessels to allow greater control of the extraction process. Once yeast cells are active and fermentation is underway, the solids (skins and pips) are pushed upwards by carbon dioxide gas, forming a solid layer known as the cap. Winemakers then carefully manage the extraction of compounds from the skins and pips, particularly tannins, anthocyanin pigments (that give red wine its colour) and compounds that form flavours and aromas.
Red Wine Making Process
Full-bodied red wines warrant deeper extraction of these compounds and lighter reds suit a gentle, softer touch. For extremely delicate extraction, the cap is plunged down into the fermenting juice using a plate on the end of a pole, known as hand-plunging or pigeage. This process is now mechanised in some wineries.
Alternatively, juice can be drained from the bottom of the fermentation vessel and pumped over the top of the cap by hose, known as rack and return or it can be continuously pumped over. Another method uses wooden boards to hold the cap submerged beneath the juice. Each of these techniques, used in isolation or combination, will have a strong influence on the structure of the finished wine (ie how rich in colour, tannin and ultimately flavour the wine will be).
Maturation
As the alcoholic fermentation finishes, the wine is racked and the skins are pressed. Some winemakers will separate and mature the wine extracted in the latter stage of pressing as it may contain more aggressive tannins and bitter flavours. This can be blended back at a later stage if desired.
Most red wine is then aged in oak barrels and the choice of oak type, oak age and size of barrel has a strong impact on red wine style. Regardless of the time and type of maturation, all red wines undergo a secondary malo-lactic fermentation in which malic acid is converted by bacterial activity into softer lactic acid, giving the finished wine a smoother, rounder edge.
The total period of maturation varies depending on grape variety and desired wine style and may vary from a few weeks to several years. During maturation the characteristics of the wine change due to slow contact with oxygen, contact with oak and polymerisation of tannins, producing a highly complex set of aroma and flavour compounds. Finally the wine is racked (moved post-fermentation from tank to barrel or another tank), stabilised and in some instances fined and filtered in preparation for bottling.
A Case In Point - Chris Ringland, Winemaker – Ringland Vintners, Barossa Valley, South Australia
“Red winemaking is unique because you have to think about creating a wine that’s delicious and has ageing potential. You need to think about how you extract the flavour and structure from the grapes and have an understanding of balance and harmony, negotiating between immediacy and longevity. You need a clear understanding of the harmony between palate structure, astringency, acidity and primary flavour components.
The critical period is that time when you are managing the extraction of components from skins. You draw on experience and instinct because often the wine doesn’t come into focus until many weeks after fermentation has finished.
Winemakers are a bit like chefs in that a combination of experience and an innate talent for understanding flavours and aromas can make the difference. It’s not just a rational process and I find the more vintages I do the more I operate on instinct, a bit like a golfer that hits the best balls sub-consciously.”