Sour beer with a flavour of fruit from Telemark

Rows of plum, apple and cherry trees are growing outside the walls of the brewery, and it is the fruit from these trees that will give the beer its distinctive taste.

A beer for discerning palates

“It is our aim to develop an exclusive sour been which absorbs the unique properties of the soil, air, fruit, climate and environment here in Gvarv,” says brewer Eivin Eilertsen.

The farm and brewery are run jointly by Eivin and his wife Ingeborg Lindheim, who is the fourth-generation heir and fruit farmer on the farm. They both work at Lindheim and also have two employees. Eivin says that beer production has resulted in a few changes in their farming operations.  They have planted new varieties of apple and cherry trees which are eminently suitable for beer and cider production. Their aim is to brew the best beer, not to be the largest producer, and to develop several different varieties and flavours, based on the local conditions and fruit. This type of beer requires long-term storage and consequently plenty of space.

Precision is essential

Brewing spontaneously fermented sour beer is a completely different process to that used for brewing ordinary beer, although the process is more or less the same up until the wort (which is water mixed with malt) boils. The wort is then cooled overnight in an open-top flat vessel, called a coolship, and after the temperature reaches 40°C it potentially absorbs microorganisms from the air in the brewery. When the temperature reaches 30°C the apples from the farm are added. A few hours after the apples have been added the wort is transferred to oak barrels and stored for a long time at approx. 13^oC. That is when the microorganisms start to become active and the wort ferments and turns into beer.

The questions that Eivin is keen to find answers to are: how do microorganisms from the environment on the farm and the apples affect the wort, and what significance does this have for the end product? He is hoping that the scientists will be able to help him with this. They are taking samples and undertaking measurements and analyses both before and after the apples are placed in the wort and from the beer in the barrels. Sampling is initially being conducted on a regular basis, but as times passes fewer samples will be taken.

During the first three weeks while the beer was being brewed, Eivin and Ingeborg had a doctoral student from the University of Brussels living on their farm. She took frequent samples at precise intervals. These samples were initially processed at the University of South-Eastern Norway, and were then subsequently divided and stored prior to being transported to both Norfina and Brussels for further thorough, more detailed analysis.

However, they have not yet completed sampling. This will continue throughout the maturation period and samples have also been taken from other batches of sour beer. This is necessary in order to understand what happens to the beer as it matures.

Brewing knowledge

This is not the first time that wort, beer and the indoor and outdoor environment at the brewery have been monitored and analysed. Nofima’s researcher has previously carried out preliminary investigations of the microorganisms during a trial project. He has taken samples from the air, fruit and beer and examined the types of yeast and bacteria that these contain.

“We have also carried out a number of analyses on the chemistry and the microbial community in these new samples. So far we can probably say that the process is similar to the findings in similar studies in Belgium, but we do not have all the details,” says Lars Axelsson.

The researchers have also isolated some yeast strains. However, they still have a fair amount of work to do because the most effective way of doing this is to collect and analyse the samples together. Consequently the researchers cannot reach any definitive conclusions yet.

Lars Axelsson adds: “This is quite a test of patience for Eivin and Ingeborg, who are curious about how things are going and how they can use the results.”

“During the preliminary project we found some special types of yeast, but we do not have any answers about their effects or where they come from. We are hoping to learn more about this now that we have taken many samples and will be conducting even more detailed analyses”, says Eivin.

Lindheim is aiming to obtain more knowledge which can in turn help to improve management and stability.

“We envisage that the knowledge we obtain about the yeast and bacteria strains that we have here at the farm and in the brewery will enable us to develop new distinctive types of beer, as well as create new business opportunities,” Eivin concludes.

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