In sparkling wine production, what is added to the base wine to start the second fermentation?

The addition of yeast and sugar to the base wine initiates the second fermentation, a crucial stage in sparkling wine production. This process is known as méthode champenoise or traditional method. During the second fermentation, the yeast consumes the sugar, producing both alcohol and carbon dioxide. The carbon dioxide is trapped in the sealed wine bottle, creating the characteristic bubbles of sparkling wine.

The inclusion of sugar is essential because it provides the yeast with the necessary fermentable material. The yeast’s activity during this fermentation contributes to the development of flavors and aromas in the wine, making this step vital for the overall quality and complexity of the final product.

When considering the other options, water and sugar would dilute the wine rather than enhance its characteristics, while yeast and carbon dioxide do not provide for fermentation initiation, as carbon dioxide does not act as a fermentable sugar source. Lastly, yeast and fruit extracts would not yield the fermentation needed for sparkling wine but rather introduce different flavors without the proper fermentation process. Thus, yeast and sugar is the correct choice to start the second fermentation in sparkling wine production.