The yeasts that live inside a grape during fermentation play a significant role in determining the flavors of the finished wine. Some winemakers rely solely on wild yeast that is present in the vineyard to start and finish fermentation, while others rely on cultured yeasts specifically designed for the task at hand. Look into the Best info about Method of Sustainable Farming.
Yeasts are a diverse group of microorganisms that metabolize sugar to create alcohol. Some have specific abilities to ferment more sugar than other yeast strains. In addition, factors such as nutrient availability, temperature, rehydration, and redox potential (the ratio of oxidized to neutral compounds in a sample) can influence the yeast’s tolerance to alcohol production.
There are thousands of species of yeast that have been bred for specific tasks. Yeasts have been bred to rise bread, make wine, produce bio-degradable oils and more.
Flavor, the impression a food or beverage makes on us, is made by combining data from our three chemical senses: smell, taste and mouthfeel. This data is influenced by other inputs such as visual impressions, age, sex and cultural influences.
In the context of winemaking, the most common yeast is Saccharomyces cerevisiae – a type of fungus that can handle different temperatures, tolerate high levels of alcohol and sulfur dioxide as well as survive acidic conditions. It also has a high tolerance to heat stress, which is often important in the production of white wines and fortified wines.
Other yeasts can also affect flavor, such as the film yeast Candida and Pichia that can cover the surface of a wine with a sticky film. While this film can protect the wine from airborne bacteria that cause spoilage, it can also produce high amounts of acetic acid, which contributes to volatile acids in a finished wine.
Some yeasts may produce acetaldehyde, a compound that has been commonly associated with spoilage but can be desirable in some cases. It’s a natural by-product of yeast metabolizing sugar and is used to add complexity to the wine.
Many of the most famous and popular winemakers use a variety of specialized yeast strains developed for the specific needs of their wines. For instance, some yeasts can help maintain a certain “house style” at a winery while others are designed to finish the fermentation of a particular wine after it has reached its desired dryness level.
These specialised yeasts can be bought from companies like Lallemand in Canada or Chr. Hansen in Denmark, and they are available to be infused into a bottle of wine or added as a starter culture.
There are many reasons to choose a specialized yeast, including if you have poor grapes in your vineyard, want to make a particular style of wine, or have a hole in your finished product that requires filling.
For example, some yeasts have been bred to produce more carbonation in a wine, while others can improve color. These specialized yeasts can be incorporated into the fermentation of white and red wines alike.