Continuous Fermentation

September 1, 2008 By Jay R. Brooks

One of New Zealand’s most interesting contributions to brewing sciences is the process known as continuous fermentation. This process was patented in 1953 by Morton Coutts, whose family had been involved in brewing since the 19th century. His father founded the Waitemata Brewery, which eventually become DB Breweries.

Essentially, Coutts created a “wort stabilization process” that made the wort more consistent and clear, and then separated the main functions of the yeast into two stages. In the first, yeast grew, and in the second, it fermented. By splitting these two functions, Coutts created a “continuous flow,” so brewers could continually add raw materials to the first stage, and draw off a steady supply of finished beer from the second thus allowing the brewery to run constantly.

It also shortened the brewing process by as much as several weeks. Recognizing the economic advantages to continuous fermentation, Lion and DB worked together jointly to develop a practical way to use the method in a commercial brewery, opening the world’s first continuous fermentation brewery in 1957 in Palmerston North, a town in the south central part of the North Island.

Continuous fermentation works best in a brewery making only one style of beer, because it’s difficult to stop the process and start up again with a new beer. As a result, Lion largely abandoned continuous fermentation in the 1980s in order to brew a wider variety of styles, while DB continues to use the method, as do several other large breweries around the world, such as Guinness.