Tuesday, 21 July 2015

Sour Opprobrium - Tasting Notes

An ideal summer afternoon - Berliner Weisse, tunes and
a magazine on the backyard deck.
So the Berliner Weisse that was a topic of a rather extensive post two weeks ago is kegged and carbed, meaning its time for a tasting!

This beer was a rapid sour, produced by souring pre-hopped wort in the kettle using a mix of commercial Lactobacilli. After 3.5 days of souring a 35C the wort was briefly boiled, hopped with Hallertauer, and fermented with German ale yeast (Wyeast 1007). 8 days after mashing in the beer was fermented and in the keg...it carb'd up last week while I was away at the cottage and is now ready to drink.

Appearance: Its a Berliner - cloudy, pale yellow-white, soap-like head. In a bit of a surprise, the head lasts a while; a rarity in acidic beers.

Aroma: A mix of wheaty/bread and lactic acid dominate the aroma, some "yeast" aroma is in the background.

Flavour: Lactic acid is upfront, alongside a sweet malt character. The usual breadiness of a Berliner is present, but not as strong as I'd prefer. Yeast character is somewhat neutral. The degree of acidity is lower than I expected - perhaps due to the higher than expected malt sweetness altering the balance.

Mouthfeel: Dry, but not quite as crisp as I'd prefer. After taste is slightly sweet and sour.

Overall: Given  the acidity of the wort prior to pitching the yeast (3.4) I'm surprised this isn't more sour - the sourness is on-style, but is on the weaker end and edges towards insufficiently sour. I think this is a result of my overly high efficiency on this batch - I normally aim to use sucrose for 10-15% of the fermentables, which guarantees a crisp finish. In this batch my higher-than-expected efficiency meant I could not add any sugar without seriously exceeding the alcohol range I was looking for. In fact I had to dilute the wort an extra 10% just to get it where I wanted.

So its a good beer, but not the beer I was hoping for; in place of a sharply sour and crispy dry beer I instead have a softly sour, slightly sweet beer. Its still refreshing, and on-style, but its on the opposite side of the style guidelines from what I was looking for. The good news is that the residual sweetness should work well with the Brett added to the other half of the batch; over the next month or so it should consume those dextrans, leaving a much drier beer with a more pleasing sour character.

Wednesday, 8 July 2015

Choosing the Right Probiotics for Souring Beer

A more-and-more common practice for quick sour beers is to use probiotic pills as a source of lactobacilli for the souring process. Indeed, the Milk the Funk Wiki has a growing list of alternate sources for these bacteria, including many probiotic capsules. A question that seems to rise quite often on this topic is "can I use probiotic brand X for souring beer". So here is a quick guide on figuring out whether a probiotic will work for souring beer.

In general, probiotic organisms fall into four categories when considering using them for souring:
  1. Good choices
  2. Probably don't matter
  3. Avoid under some circumstances
  4. Avoid at all cost

Good Choices:

Bacteria that represent good choices are those which have the capacity to sour wort, and will do so with a minimal risk of off-flavours. These are solely species belonging to the Lactobacillus genus - i.e. Lactobacillus sp, where sp merely means "any species".  Lactobacillus plantarum and Lactobacillus rhamnosis are two of the more commonly seen probiotic strains, but any probiotic containing bacteria whose name starts with 'Lactobacillus' will work well.

Probably Don't Matter:

Species which "probably don't matter" are those which are unlikely to grow in wort; either because the homebrewer lacks the ability to lower the oxygen level in the wort to the point where these organisms grow, or because wort isn't nutritionally compatible with these species. The flip side is that if these organisms grow, they should do the same thing as Lactobacillus - i.e. sour the wort while producing minimal off-flavours. So that's why they probably don't matter - they're not likely to do anything, but if they do end up doing something, they will help your wort sour. Included among these are:
  1. Bifidobacteria sp. (again, sp means "any species")
  2. Streptococcus thermophilus
  3. Leuconostoc sp.

Avoid Under Some Circumstances:

Only one group of organisms fall into this grouping - the Saccharomyces, as in species of yeast from the same genus of yeast that brewing yeast come from. At the time of this post the only Saccharomyces commonly seen in probiotics is Saccharomyces boulardii. Saccharomyces sp. fall into the "avoid under some circumstances" category as they will ferment sugars to form alcohol. You probably should avoid these - they will compete with Lactobacillus for sugars, and thus limit acidification. In addition, if you are planning on heating the wort after souring (to either pasteurizing or boiling temperatures), you will boil off the resulting alcohol leading to a beer with very little sugar left for the subsequent fermentation.

So as a rule you will want to avoid these, although it may be an interesting experiment to see what kind of beer you get if you pitch a Saccharomyces boulardii-containing probiotic mix into your fermenter.

Avoid At All Cost:

The last group are those you want to keep as far away from your wort, beer and fermenter as possible. These are bacteria which can produce horrid off-flavours and ruin a beer. In this group there are currently three types used in probiotics, but this list may get longer in the future:
  1. Clostridium sp. These guys can make butyric acid, which smells and tastes of a mix of parmesan cheese and vomit.
  2. Enterococcus faecium. This bacteria can make bioactive amines, which some people are severely allergic to. Moreover, these amines are often quite unpleasant, and are what give shit and corpses (among other things) their unique odours.
  3. Bacillus sp. (most often Bacillus ereus, clausii, and pumilus) make diacetyl (butter) and may also make bioactive amines.
Clearly, we don't want t be dumping any of the above guys in our beer!

EDIT/UPDATE: Stefan Wiswedel has done some experiments looking at probiotics containing amylases (which break down starches/dextrans) and protinases (which degrade proteins) along side the usual probiotic bacteria. Turns out using these is a bad idea - it kills the body and flavour of the resulting beer. Stefan has posted additional details in the comment section, below.

A Simple Rule of Thumb

So that's a lot - but a good rule-of-thumb is to limit yourself to probiotics that contain only Lactobacillus species, which is easy to remember when you're at the store. 

But if your memory is better than mine, than any probiotic with Lactobacillus sp. plus any of Bifidobacteria sp.Streptococcus thermophilus or Leuconostoc sp. will be good as well.

And if the probiotic contains anything but the above 4 groups of organisms, I'd recommend you stay away.

Thursday, 2 July 2015

How I Sour Mash...& A Recipe!

Wort, souring in the garage
I get the occasional request to explain how I sour-mash/sour-wort. So you ask, so you shall (eventually) receive!

Along with a description of my method - which is not all that unusual compared to methods others have published - I'm going to add in a few microbiology insights, some information on determining when you want to stop the souring process, and some other random hints & tips.

If you missed it, I also put up a post a few weeks ago about preparing lacto starters - a key thing you will need to do for a good sour mash/wort. Around the same time, 5-blades brewing put out a good post on harvesting wild lacto safely - a method I've used myself. Eureka Brewing also put up a post on optimized "media" for lactobacillus culture. I haven't tried Sam's media recipe, but its sound from a microbiology point-of-view. For a complete picture of the sour-mash/worting method I'd recommend reading this post alongside these other posts.

I've prepared this post alongside a brew-day, so I've include my standard Berliner Weiss recipe at the end. I love this recipe - simple and straight-forward, is great straight-up, but also works as a perfect base for fruited (lemon & cherry are excellent), s (coriander & salt = pseudo-gose), or bretted for a funk & fruit finish.  I am doing a split batch this time around, to make the most of the recipe.

Details, as always, can be found below the fold.