With brewers looking to lower alcohol beers to embrace consumer attitudes towards healthier lifestyles, yeast is being looked at in an entirely different way. Brews News caught up with Technical Manager Brewer at Fermentis, Philippe Janssens, who developed SafBrew™ LA-01.
While alcohol can be removed from traditionally fermented beer, the equipment required is well out of the reach of smaller brewers. However, yeast selected for specific characteristics, such as Saccharomyces cerevisiae var. chevalieri, are a popular alternative.
The chevalieri strain, known commercially as SafBrew™ LA-01, was identified and developed by Fermentis’ Philippe Janssens.
Janssens works for Fermentis as its resident Technical Manager, Brewer after a career that has included patent engineer for AB InBev and as a business development manager in the hop industry, within Yakima Chief-Hopunion.
He says that the identification of SA-01 came about as he was mining the Saf yeast collection for yeasts with characteristics that could be used to create low-alcohol beer while retaining the best characters of beer.
“Rather than look elsewhere I started looking at what we already had,” he said.
“I compared a number of microorganisms that had potential and are maltose negative or perceived as maltose negative,” he said.
“Chevalieri was part of the Saf collection, and as I saw what it could do I was excited.
“We performed trials and we discovered that while some yeasts partially assimilated maltose, or assimilated it very slowly, they were different to Chevalieri which is absolutely maltose negative.
Janssens said that with maltose representing half of the sugars in the average wort, being maltose negative is an important attribute.
“The typical wort is made of up a blend of sugars, including sucrose at 10-15 per cent, maltose will represent 50-60 per cent of weight, the maltotriose between 10 and 20 per cent and the rest will be the dextrins,” he explained.
“If we have a microorganism that assimilates maltose, we would never reach 0.5 ABV with something that is well balanced.”
Janssens said that he trialled what is now SA-01 along with a range of other strains using a standardised wort made of 100 per cent pilsner malt, mashing at 65°C for 50 minutes with a rest of 10 minutes at 73°C. Fermentation was at 22°C.
Chevalieri was chosen as the team found that it only assimilates the simple sugars, glucose and fructose, and then it stops.
“After the assimilation of the simple sugars it completely stops the fermentation and there is no risk, with a normal fermentation, of the production of a higher level of alcohol and over-carbonation,” Philippe said.
“The desired level of alcohol is reached after 60 hours, according to our trials, at 22 degrees.”
Janssens stresses that after the main fermentation and the alcohol level is reached, it is important to pasteurise the product.
“The media still contains a lot of sugar so it’s important to stop the fermentation and pasteurise the product, otherwise over-fermentation can occur from exogenous microorganisms,” he explained.
As part of their trials Janssen’s team took the finished beer, and then cross-contaminated it with another yeast and pasteurised samples at 63°C for long enough to attain 25, 50, 75 and 100 pasteurising units (PU).
“After that we plated in a media to allow everything to grow, the yeast and other microorganisms,” he said.
“What we detected is that after 50 PU we didn’t have any microorganisms that are contaminating the SafBrew LA-01, which means the introduced organisms were completely destroyed.
He said that at 25 PU there was a balance between both microorganisms living so that was not sufficient.
“With this beer that is still rich in sugar, 50 PU is what we consider the minimum. Our recommendation is between 50 and 100 is the pasteurising conditions,” Janssens said.
“It’s not easy for all brewers to pasteurise, but it is critical that brewers even use something like a bath to immerse the packaged product in and have the equivalent of 50 PU as the target.”
Asked whether sterile filtration was sufficient, Janssens said pasteurising is recommended.
“Sterile filtration will help, but will never remove 100 per cent of all the yeast, so there is still a risk that it contains some microorganisms, maybe small amounts but they will survive in this matrix that is rich in the residue sugars,” he said.
“Having said that, it may be that if filtration is used, 50 PU may not be necessary. But I prefer we maintain the 50 PU.”
Janssens said a POF positive yeast aids brewers to balance flavour in lower alcohol beers.
“Being POF positive if has the capacity to use the ferulic acid contained in the malt and transform it into the precursor for phenolic compounds and so produce phenols such as 4-vinyl guaiacol,” he explained.
“It’s produced in small amounts that contribute significantly to the flavour and aromatic profile of the beer.
“As you’d imagine, as we ferment less of the sugars, we also have less of the aroma compounds compared to a traditional beer. These phenolic compounds contribute to the balance to get some flavour in the beer. So it’s a positive.”
He said that brewers that wanted to enhance the phenolic profile can look to their mash.
“The ferulic acid is contained in the malts but f you wanted to increase the level of ferulic acid it’s possible to add a 50-55 degree rest at the beginning of the mash to dissolve more ferulic acid.”
“It will increase the 4VG or phenolic production.
“Brewers should not get other off-flavours. There is no diacetyl production or other off flavours and if we pasteurise the product correctly, we will have a very safe beer.”
Janssens to ensure beer quality and stability, he recommends a warmer ferment.
“It’s a fast fermenting yeast that finishes after 60 hours and the ideal temperature would be between 15 and 25 degrees.
“In those parameters we can anticipate an apparent degree of fermentation of 50 per cent and a 0.5 ABV or an OG of between 5 and 8 Plato.”
Janssens stresses that brewers should not re-use yeast.
“There should be no repitching and it is a first utilisation only,” he said.
“If you reuse, you may multiply exogenous microorganisms that may impact negatively the quality of beer and certainly the alcohol.”
The world of fermentation is now a click away! The Fermentis application is available on both Apple Store and Android Store.
As a brewer, you will be interested in exploring new sensory pathways, fine-tuning the originality of your aromas, or perhaps exploit fermentation potential of your wort at its best. That’s why we are proud to introduce you to the Fermentis app…
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