Morton Coutts — Continuous Fermentation System

DB Breweries logoMorton Coutts revolutionised the ancient art of brewing beer by developing what is known as continuous fermentation.

New Zealander Morton Coutts was only 15-years-old when he first took over the family brewing business after the First World War and by the 1960s had revolutionised the ancient art of beer brewing.

Beer has been brewed for about 6000 years, since the time of the ancient Egyptians. The Egyptians in turn taught the Romans how to brew and the Romans taught the rest of Europe. Now beer is drunk all over the world. Yet it was a New Zealander working for Dominion Breweries in the 1950s who discovered a new way to brew which sped up the process by as much as 15 weeks to 18 hours.

Morton Coutts had brewing in his blood. His grandfather, Frederick Joseph Khutze, brewed beer for the goldminers in Otago last century before moving to Palmerston North to start his own brewery in 1900.

His son, William Joseph Khutze inherited the business and shifted it to Taihape to supply beer to the men working in timber milling and bush clearing in the area.

He changed the family name during World War One to the more English and less German sounding Coutts. William Coutts became sick and was permanently disabled during the worldwide flu epidemic in 1918 and so his son Morton, aged 15, took over the business.

Morton Coutts came up with what is now known as the continuous fermentation process for brewing beer. During the continuous brewing process raw materials are added to one end of the system and beer is continuously withdrawn from the other. The standard system for brewing beer has ingredients put in together and then after a period of time the brewed beer is removed and bottled altogether and at the same time.

To understand how the continuous fermentation system works it is first necessary to understand how beer is usually brewed. The brewing process begins with soaking barley in water, draining it and allowing it to sprout, or germinate. As soon as the first signs of roots appear the germination is stopped by heating.

These sprouted barley seeds are called the malt, which is then crushed without destroying the husks. It is mixed in hot water and allowed to settle.

The liquid, which now has the desired goodness from the malt, is separated from the ground mash. This liquid is called the 'wort' to which hops are added for flavour and then boiled.

It is next cooled and yeast is added which begins to grow and reproduce until there is five times as much yeast as was put in initially. The fermentation process, which produces the alcohol, then begins. This carries on for a number of days and then the beer is aged for between three weeks and three months before being bottled.

In the 1930s Mr Coutts began investigations into the nature of yeast which is the key ingredient in any brewing. Yeast is a mould found naturally on plants throughout the world. Mr Coutts had a realisation "that yeast could be properly controlled if you looked on it as a human being with a brain.

It has so many enzyme mechanisms to call upon to react to whatever is necessary for its survival. Instead of looking on the final product I always took notice of the yeast as an organism that produced whatever you ended up with."

In order to develop a continuous brewing process Mr Coutts first developed what he called the wort stabilisation process. After boiling the wort he cooled it to 0 oC for 48 hours which allowed more of the sediment to settle and leave a much clearer and more consistent wort. The next important step was to separate the fermentation stages. He had one stage where the yeast grew and another where the fermentation began. In each stage the yeast was encouraged to either grow or produce alcohol.

He believed this was what the yeast wanted to do. Continuous fermentation is the way yeast has always grown for millions of years. By splitting the fermentation into two stages Mr Coutts could create a continuous flow between them.

The wort was continually added to the yeast production stage, which in turn continually and steadily flowed into the alcohol production stage, which produced a steady flow of beer.

Control over the yeast was achieved by controlling the amount of oxygen the yeast cells were subjected to. The world's first exclusively continuous fermenting brewery began brewing at Palmerston North in 1957. There were of course those who doubted that continuous beer fermentation would produce good beer but these were largely silenced when a beer made with the process won the 1968 Commonwealth Beers Championship Cup.

There are a number of reasons why New Zealand was the first place to develop continuous brewing. At the same time as Morton Coutts came up with his continuous brewing process Dominion Breweries decided their breweries needed extensive rebuilding and so used the new process in their new and upgraded breweries.

New stainless steel brewing vessels allowed for greater cleanliness during the brewing process, which is vital for continuous brewing, and government excise laws on alcohol production were such that continuous brewing was liable for less taxation.

Morton Coutts' thoughtful and innovative approach to brewing gave New Zealand brewers an extra advantage and is perhaps one reason why we drink the fourth most amount of beer per head of population in the world.

Classroom activity - Yeast