Manufacturing process: Endogenous vs. exogenous
Perlwein can be produced in two fundamentally different ways, which differ in the origin of the carbon dioxide: endogenous and exogenous.
Endogenous method
In the endogenous method, the carbon dioxide comes directly from the winemaking process. Here we distinguish between two main variants:
Second fermentation in a pressure tank: the base wine undergoes a second fermentation in a pressure tank, also known as steel tank fermentation. During this process, the yeast converts the added sugar into alcohol and carbon dioxide. As the gas cannot escape, it dissolves in the wine and produces the characteristic bubbles.
Méthode ancestrale: Here, secondary fermentation takes place inside the bottle. This can occur naturally, i.e. without the addition of yeast. However, it can also be forced by adding yeast to a wine with a certain amount of residual sugar and then sealing the bottle with a crown cork. This gives winemakers the choice of removing the dead yeast cells before sale or leaving them in the bottle.
Endogenous Perlwein: prominent examples
The endogenous process results in a particularly fine and long-lasting perlage, which is highly appreciated by wine lovers. The best-known endogenous Perlwein are, for example, Prosecco Frizzante from Italy or the Portuguese Vinho Verde.
While Prosecco Frizzante is produced using a pressure tank process, the fine sparkle of Vinho Verde comes from natural secondary fermentation in the bottle. The méthode ancestrale comes into play here - the most original form of sparkling wine production, which we also know from a Pétillant Naturel. These are also the most prominent example of endogenous sparkling wines outside of the pressure tank process.
Exogenous process
In contrast to endogenous production is the exogenous or impregnation process. In this process, technically produced carbon dioxide is added to the finished still wine under pressure and at a low temperature. This process, also known as carbonation, is cheaper and faster than the endogenous method.
The exogenously added carbon dioxide tends to evaporate more quickly and often produces larger, less fine bubbles. In Germany, this method requires the label to explicitly state “Perlwein with added carbon dioxide”.
However, there are other ways to add carbon dioxide to a Perlwein. Namely by reusing the fermentation carbon dioxide. In this process, the carbon dioxide produced during the primary winemaking process is captured and later added back to the finished still wine.
Exogenous Perlwein: prominent examples
In many modern versions of Lambrusco, producers add carbon dioxide to create the typical light sparkle. German Secco is also usually produced in this way. However, more and more winegrowers are switching to the endogenous method.
Large wine houses often use the impregnation process for their mass productions in order to guarantee consistent quality at lower costs. These international branded sparkling wines then usually have a good margin up their sleeve for the specialist wine trade.