When it comes to making hard cider, adding yeast is not always necessary. This is because there is natural yeast present in the juice itself, which will ferment the sugar into alcohol. This natural yeast is often referred to as “wild yeast” or “ambient yeast.” It can be found on the skin of the apples or in the surrounding environment.
In fact, many traditional cider makers rely solely on the natural yeast present in the juice to initiate fermentation. This can result in a unique and complex flavor profile, as the specific strains of wild yeast present can vary depending on the region and the apples used.
However, it's important to note that relying solely on wild yeast can be unpredictable. The fermentation process may take longer and the end result may not be consistent from batch to batch. This is because wild yeast strains can vary in their efficiency and ability to convert sugar into alcohol.
For those who want more control over the fermentation process and a more consistent end result, adding commercial yeast is a common practice. Wine yeast strains, specifically selected for their ability to ferment fruit juices, are often used in cider making. These strains can ensure a more efficient fermentation and produce a cider with desired characteristics.
Some fermentation processes call for killing all the yeast in the pure cider with sulfur dioxide, waiting 24 hours, and then adding wine yeast. This method is sometimes used to eliminate any unwanted or potentially harmful microorganisms that may be present. However, for the average home cider maker, this step is not necessary and can be skipped.
Personally, I have made cider using both wild yeast and commercial yeast. When using wild yeast, I found that the fermentation process took longer and the resulting cider had a more rustic and funky flavor. On the other hand, when using commercial yeast, the fermentation was quicker and the cider had a more clean and predictable taste.
To summarize, adding yeast is not required to make hard cider as there is natural yeast present in the juice. However, adding commercial yeast can provide more control over the fermentation process and result in a more consistent and desired flavor profile. Ultimately, the choice of whether to add yeast or rely on wild yeast is a personal preference and can result in different outcomes.