Friday, December 28, 2012

Evaluating Yeast Character, part I

Unlike professional brewers who mostly rely on one or two yeasts to ferment all of their beers and are often unable to try new yeasts, homebrewers have no such restrictions. Rather, we are in the enviable position of having both a huge variety of yeast at our fingertips and the freedom to use them however we want. Yet, given the opportunity to try new ingredients, there are still many homebrewers who are completely content using the same yeast over and over again and won't even try anything else. While there is nothing wrong with using the same yeast exclusively - neutral yeasts do a great job at minimizing the risk of the yeast variable - I suspect part of the hesitation in trying something different comes from not knowing what these other yeasts taste like and how they might best be used. Therefore, to make choosing an English yeast a tad easier, I'm resurrecting my yeast spider-graphs.

After some consideration, I completely redid all of the yeast graphs. The problem I had with the old graphs, is that for them to be of any real use, the person using them must already have a frame of reference for whatever they are looking at. For instance, while a person with no previous knowledge of beer or yeast could easily compare two different graphs for attenuation or flocculation and still understand what the numbers mean, doing the same for yeast flavor and esters is less useful since the person would require some familiarity with the range of flavors that each of those numbers represent.

The biggest change I made to these 'new' yeast graphs was that I tried arrange the data points so it would be easier to compare yeasts based on the overall shape of their flavor profiles. For instance, the drier and less characterful yeasts would favor the top right side of the graph, while the estery and sweeter yeasts would fall on the left. Therefore, if you are familiar with one yeast, you can easily compare it to another. Moreover, in place of 'bottle stability,' at the top of each graph is 'yeast character' which is the overall amount of flavor each yeast imparts to a beer. I figured this would be more useful as not everyone bottle conditions and yeast stability is not always consistent. Lastly, most of the data points are self explanatory, although 'dry/mineral' refers not to attenuation, but rather if the yeast is prone to producing mineral flavors. 'Malt integrity' is not a degree of maltiness, but how the malt flavor (from the grain) stands up to the yeast character.

I should mention that all of the data I used in these graphs is from the manufactures data and my own experiences and brew logs...representing an 'average' of what can be expected. And whereas fermentation temperature, oxygenation, and pitch rate make it impossible to form a 'true' diagram of yeast character, I am presenting the data as if each yeast was fermented under ideal conditions and free from off flavors.

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With that said, the first set of yeast graphs represents some of the cleanest and most neutral tasting of English yeasts. These yeasts produce clean tasting beers with light, fruity esters and bready malt flavors with little to no diacetyl. Hop flavor and bitterness are not greatly affected and they typically attenuate and flocculate quite well. Some 'tartness' and off-flavors can be produced at higher temperatures. These yeasts are good for malty and hop forward beers or any style where you want a clean, neutral flavor profile and not much yeast character.




For the next graphs, I'll review three more yeasts that share similar characteristics and are more characterful tasting than these here. (There are a total of four groupings, with 14 yeasts represented altogether). I will also include more about the individual flavor profiles and some fermentation/style tips for each yeast.

First Rendition

8 comments:

  1. Your graphs are not to the same scale, makes comparing a bit less insightful.

    ingo.

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    1. Used the wrong ones. Fixed.

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    2. I'm still seeing a difference in order of the characteristics between the first rendition & the this post. i.e.

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  2. Excellent post again Will. I always look forward to your opinions on yeast as I'm still trying to sort out my English strains. Nottingham has been my strain of choice lately for clean fermentations, pale ales and IPAs. I haven't been too happy with the flocculation but that might not be the yeast's fault. What I haven't done is compared it to the other neutral, American strains but I'm not sure if that comparison is worth the effort.

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  3. You're way off on the WLP022 top crop rating, that stuff is an insane cropper. Hope you're off the mark on the character as well. I have a Best Bitter going with it now and a Brown porter finishing up in the secondary.

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    1. Hmm, what temp are you fermenting your beers at... bucket or carboy? In all the times I've used this yeast, I've not got much more than an inch or two of foam/krausen total, without much harvestable yeast once the first krausen and dirt has been removed. Although, I do ferment at cooler temps than what people associate with English yeasts. I'll have to try it out again.

      Flavor wise, its pretty clean, bready, malty, slighty tart, with some mineral. As always, individual results may vary.

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  4. Both the Brown Porter and the current Best Bitter were fermented in a 30L (6.5 imp gal) "ale pail". No air lock just a loose lid. Fermentation temps started at 62-64F and free rised to near 68F. For the best bitter, the top cropping yeast completely filled 8 Liters of the head space. I brew 10 gallon batches and was able to crop 300ml's of yeast.

    More info re my process: http://lowtechbrewer.blogspot.ca/2013/03/lowtech-best-bitter.html

    I am really hoping the breadiness comes through!

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    Replies
    1. Love the blog btw, really interesting stuff!

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