Yes, traditionally, some forms of Guinness, specifically cask beers like Guinness, have used a product derived from fish during their production process.
The Role of Isinglass in Guinness
According to information regarding traditional brewing practices, a substance called isinglass is used. This isinglass is a gelatine-like substance.
- Source: Isinglass is made from the air-bladders (or sounds) of fish, such as the sturgeon.
- Purpose in Brewing: It is added to cask beers like Guinness to assist in clarification. The reference states that isinglass helps any remaining yeast and solid particles settle out of the final product. This process, known as "fining," results in a clearer beer.
Therefore, while you won't find chunks of fish in your pint, the use of isinglass derived from fish has been a historical method in the production of certain Guinness products to achieve clarity. It's worth noting that practices can evolve, and formulations may differ depending on the specific product type (e.g., canned, bottled vs. cask) and region. However, based on traditional methods applied to cask versions, fish-derived isinglass has been part of the process.
