Vinification is the process that transforms the grapes into wine. The process of vinification differ from region to region, financial state of the winery and the grape types. The harvesting time and the type of oak used for aging are based on the region in which the wine grapes are grown.

Wine making process involves the following stages:

  • The first step in wine making process is Harvesting or Picking. Grapes should be harvested at the right time in order to make good wine. Harvesting can be done either mechanically or by hand.
  • The process of separating the grapes from the stems and cluster parts is called Destemming. Some of the wine makers keep some fragments of the stem to increase the wine tannin.
  • After destemming the grapes are crushed to extract the juice from the skin. This is done before the fermentation process begins. In the olden days bare feet is used to extract the grape juice, now a day machines like crushers are used.
  • Separation of grape juice and the skin is named as pressing. After crushing the grape juice will flow freely, selected wineries use pressers to make sure maximum juice is released.
  • Once the grapes are pressed they are introduced into the process of fermentation. During this process the grape juice are converted into alcoholic beverage. The yeast interacts with the sugar in the grape juice and converts them into ethanol and carbon dioxide.
  • Once the wine is purified and refined, they are preserved with sulfur dioxide or potassium sorbate. During the natural process of fermentation a minimum amount of sulfites are produced, but more is added for the use of commercial preservation.
  • Wines are aged for a particular amount of time to get more welcoming wine. Once after purification, the wines are moved to wooden barrels for aging. Metal vats, concrete vats and glass carboys are also used in some cases to increase the flavor.
  • After aging, the wines are bottled. During the process of bottling a final dose of sulfite is added to the wine to prevent it from uninvited fermentation in the bottle. The bottles are then sealed with cork and screw caps.
Wine yeast
In the world of wine, the use of yeast is commonly associated with the species of saccharomyces (‘sugar fungus’) cerevisiae, also known as brewer’s yeast

Living substance responsible for the production of the enzymes that permit fermentation, the conversion of sugar into alcohol, with heat and carbon dioxide as by products.

The post Wine yeasts: How do they impact wine flavour? - Ask Decanter appeared first on Decanter.


Wine yeast
In the world of wine, the use of yeast is commonly associated with the species of saccharomyces (‘sugar fungus’) cerevisiae, also known as brewer’s yeast

Living substance responsible for the production of the enzymes that permit fermentation, the conversion of sugar into alcohol, with heat and carbon dioxide as by products.

The post Wine yeasts: How do they impact wine flavour? - Ask Decanter appeared first on Decanter.

Wine yeast
In the world of wine, the use of yeast is commonly associated with the species of saccharomyces (‘sugar fungus’) cerevisiae, also known as brewer’s yeast

What are yeasts

Yeasts are single-cell microorganisms that are responsible for the production of the enzymes that permit fermentation; the conversion of six-carbon sugar molecules into ethyl alcohol and carbon dioxide while releasing heat.

During fermentation, yeasts also produce small amounts of volatile compounds, such as esters, aldehydes and sulphur, which can contribute to the varied aroma and flavour profiles of the finished wine.

In the world of wine, the use of yeast is commonly associated with the species of saccharomyces (‘sugar fungus’) cerevisiae, also known as brewer’s yeast because it is used to make beer and leavening bread.

Cultured vs indigenous yeasts

One of the most controversial subjects in the winemaking realm is whether to use yeasts naturally present in vineyards and wineries (ambient or ‘wild’ yeasts) or those that have been manually cultivated to serve certain winemaking needs.

Traditionally, spontaneous fermentation is a combined effect of a mixture of naturally existing yeasts.

While the indigenous Saccharomyces species is usually found on the surface of grape berries, there are also other (non-Saccharomyces) wild yeasts that are present in the environment.

Although they can also impact on the flavour and quality of the wine, they tend to give way to the brewer’s yeast when the alcohol strength in the must goes significantly higher than 5% abv, or there is sufficient level of sulphur dioxide to restrict their activities.

While there is still debate about the issue, indigenous yeasts are considered by some winemakers as part of the local terroir. They are believed by some to give a more balanced and complex flavour profile to a wine.

Decanter columnist Andrew Jefford previously cited research that found indigenous yeast can not only ‘maximise personality differences, but take each wine to a different resting point in terms of sugar conversion’.

Also read: Yeast – Call Me Dad

However, using naturally existing yeasts always presents the risk of unwanted strains – such as Brettanomyces – causing aromas and flavours that are considered undesirable by some. Equally, wild Saccharomyces yeasts can also be ineffective and unpredictable.

In order to eliminate such risks and ensure a smoother, more controlled fermentation, many modern winemaking operations choose to use one or more pre-selected yeast strains.

In an earlier Decanter article, Benjamin Lewin MW estimated that use of so-called cultured yeast in winemaking ‘ranges from 70%-90%’ worldwide.

These cultivated strains, which were originally isolated from ambient yeasts, can vary widely in their characteristics, including the aromas and flavours they promote (see below), their tolerance to the environment (e.g. sulphur dioxide levels, heat and alcohol levels) and their efficiency in converting sugar to alcohol.

Producers can thus pick-and-choose the most ideal characteristics to make their wines.

Defenders of wild fermentation argue that the use of a single, cultured yeast strain leads to somewhat artificial flavours or a lack of diversity between wines,

However, some winemakers are experimenting with blends of cultured yeasts from the more than 200 strains available in the market.

Yeasts and flavours

Yeasts ‘can colour, shape and mould the entire sensual presence of the wine’, as Jefford puts it.

‘The gooseberry aromas of Sauvignon Blanc, the lychee of Gewürztraminer, the strawberry notes of Pinot Noir – none of these are found in the grapes, but they are released or created by yeast during fermentation,’ according to Benjamin Lewin MW.

Read the full feature: Yeasts – do you know what’s flavouring your wine?

Lewin pointed out that the influence of yeasts is most evident in aromatic wines, because ‘small changes in the concentrations of key components can greatly affect varietal character’.

The banana notes of Beaujolais Nouveau, for instance, are believed to come from the increased formation of isoamyl acetate due to yeast strain 71B. The CY3079 yeast can increase the hazelnut and brioche notes of Chardonnay.

The amount of monoterpenes released by yeasts is also understood to significantly alter the expression of aromatic varieties such as Gewürztraminer and Muscat.

The gooseberry and passion fruit aromas of Sauvignon Blanc can be traced back to elements in the grapes, which are converted into sulphur-containing compounds during fermentation.

Yeasts can continue to contribute to wine flavours even after they are dead.

When left in the wine after fermentation, the dead yeast cells, or lees, start to dissolve due to the enzymes in a process called autolysis.

Also read: What are lees in wine? – Ask Decanter

This process can provide a rounder mouthfeel and richer textures to a linear base wine, while adding brioche and biscuit-like flavours.

Lees aging is widely used in producing some white wines, such as in parts of Burgundy and Muscadet. It is also crucial in making Champagne, as well as ‘traditional method’ sparkling wines more generally.

Reference: The Oxford Companion of Wine

The post Wine yeasts: How do they impact wine flavour? - Ask Decanter appeared first on Decanter.


Read full article on decanter.com


Each wine is unique. Soil, weather, geology, varietals, and the style of wine making, are all decisive yet variable factors that give each wine a unique character.
Each wine is unique. Soil, weather, geology, varietals, and the style of wine making, are all decisive yet variable factors that give each wine a unique character.
Winemakers all over the world are combining wine making traditions of millennia with innovative approaches and ideas, to address consumer demand for high quality products and a sustainable and healthy lifestyle.
Winemakers all over the world are combining wine making traditions of millennia with innovative approaches and ideas, to address consumer demand for high quality products and a sustainable and healthy lifestyle.

Laurel Gray Vineyards

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