Friday 19 November 2021

Lallemand Verdant IPA - Yeast Overview

 

Lallemand Verdant IPA Yeast package (11g)


LalBrew® Verdant IPA was specially selected in collaboration with Verdant Brewing Co. (UK) for its ability to produce a variety of hop-forward and malty beers. Prominent notes of apricot and undertones of tropical fruit and citrus merge seamlessly with hop aromas. With medium-high attenuation, LalBrew® Verdant IPA leaves a soft and balanced malt profile with slightly more body than a typical American IPA yeast strain. This highly versatile strain is well suited for a variety of beer styles including NEIPA, English IPA, American Pale, English Bitter, Sweet Stout and Sours.

We've used this yeast recently for the first time so wanted to compile details on some of it's unique and interesting aspects. It's a new yeast variety, released in 2020 so it's good to get some more information about this 'new kid on the block' to help those who already are, or may be looking at using this particular yeast variety in their next brew.

As outlined in the blurb above (taken directly from Lallemand's website), Verdant IPA is a specialty ale yeast, made in collaboration between Verdant Brewing Co in the UK and Lallemand.  "Collaboration" is an interesting term - the story appears to have started with Lallemand approaching Verdant Brewing Co (along with other breweries) to trial a new strain of NEIPA yeast back in 2017. The results of this trial aren't exactly known (but it was potentially what is now the Lallemand American East Coast ale yeast). Presumably not entirely happy with the yeast provided by Lallemand, Verdant went back to them suggesting they instead look at their house strain of yeast - which had recently been 'banked' in a laboratory.

Verdant had been using this particular house yeast strain for years - originally derived from the English ale strain -  London Ale III, it had been harvested and re-pitched several times which caused changes/mutation of the yeast to occur. This mutated version was comprised of three (3) separate yeast strains, and the specific yeast strain used to make Verdant IPA was captured and isolated from this original culture. The specific strain was chosen as it was the domainant strain in the culture, but also because of it's unique properties - throwing notes of apricot and creamy vanilla. You would suspect this particular strain to be somewhat similar to London Ale III, and it probably is, but Lallemand insist it is "genetically different".

Although the name Verdant IPA indicates it's a dedicated IPA yeast - it can certainly be used in other styles of beer - from English Ales all the way to Stouts, Porters and even Sours. Verdant Brewing Co themselves tend to focus on hop forward styles like IPA's so it's no surprise that these are the sorts of beer styles this yeast is suited to. 

We do feel though that having "IPA" in the name was perhaps misleading, since it's definitely suitable for other styles and may lead people to negate it as an option if they're looking at yeasts to use for non-IPA beers - like those previously listed.

The flavour profile is described as clean with slight fruity esters. Common flavour descriptors are most notably apricot, slight peach undertones and some sweeter notes such as creamy vanilla. 

Some of the general properties of the Verdant IPA yeast is that it's a top cropping yeast which generally creates a large, fluffy krausen. Fermentations tend to start quite fast after pitching yeast, with minimal lag times and usually signs of fermentation being underway within 24 hours. Fermentation generally completes quickly, sometimes in as little as five (5) days. This of course varies depending on a number of factors such as fermentation temperature, pitching rates, wort gravity/fermentability etc.

Pale Ale with Verdant IPA yeast fermenting - note the fluffy white krausen

Verdant IPA yeast differentiates itself from existing Lallemand yeast strains because of it's attentuation rate. Whereas other Lallemand yeasts such as their New England American East Coast, BRY-97 American West Coast or Nottingham have attentuation rates over 81%, Verdant IPA only has an (average) attentuation rate of 78%. Although this is only a few percent points of difference, it does lead to a noticeable difference in the finished beer. It also has notably different biotransformation properties when compared to other ale yeasts in the Lallemand range.

Fermentation Schedule 

James Heffron from Verdant Brewing Co outlines the fermentation schedule they use for this yeast, which is to pitch at 18c, hold the fermentation at 19c, then when there's about 10 gravity points left let the temperature "free rise" up for a diacetyl rest - usually to somewhere around 22-23c. It is known for producting diacetyl but does a good job of cleaning it up at the end of fermentation. He also mentions that for low gravity beers they pitch at 19c, then let the temperature from fermentation ramp up to 22c where it is capped and controlled/maintained.

They then typically perform a soft crash, which involves dropping the temperature of the fermenter down to 15c to help the yeast drop out of suspension, and then dry hop at this temperature. This is to help avoid hop creep and the over attenuation associated with it. The dry hops are added at 15c, and this temperature is maintained for about 24 hours after which point the hops are roused (presumably with CO2) and the cold crash is started. The total contact time for dry hops is quite low, at around 72 hours total time before being transferred to the bright tank.

Dry hopping during active fermentation to achieve biotransformation is of course possible but not something James recommends and is not something they do at Verdant Brewing Co. James argues that you inevitably lose some of the hop flavours and aromas when dry hopping during fermentation due to the CO2 being created and expelled from the fermenter that can carry the desirable aromas from the dry hops out of the fermenter and beer.

In relation to yeast pitching, James suggests pitching the yeast directly into your wort and that prior rehydration is not necessary - even for higher gravity beers. Lallemand do recommend though that you consider yeast stress levels when making higher gravity beers by adjusting pitching rates and ensuring sufficient nutrients and oxygen levels are present in the wort to ensure a healthy fermentation.

With regards to pressure fermentation, Verdant don't ferment their beers under pressure, however Lallemand advised that a number of tests performed by other breweries were done under pressure so it is definitely possible to do with this yeast. It is well known though that pressure fermentations tends to suppress ester formations which may not be desirable with this particular yeast. James does note that they "cap" or seal their fermenters right at the tail end of fermentations to build some positive CO2 pressure in the headspace (and beer) to help prevent oxidation from occurring during the dry hopping phase.

Key Stats/Information

Beer Styles

New England IPA (NEIPA), English IPA, American Pale, English Bitters, Sweet Souts, Sours

Attenuation

Medium to high (~78%)

Pitching Rate

0.5-1g/L of wort to achieve a minimum of 2.5 - 5 million cells/mL
Verdant Brewing Co pitch at 0.75g/L for all their beers according to James Heffron

Floculation

Moderate

Recommended Fermentation Temperature

18-23c (64-73F)

Alcohol Tolerance

10% ABV

Source: Youtube video - https://www.youtube.com/watch?v=QNVWwSjIOEY


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