My fiance and I will be getting married this October at the German Society of Pennsylvania in Philadelphia. I will be brewing all the beer for our wedding, so needless to some of my brewing this year is going to focus on fine tuning the beers for our big day. The plan is to brew four 10 gallon batches of moderate alcohol beers and serve a 2.5 gal keg of either the Cognac or Bourbon Lets Grow Old Together Ale, depending on which tastes better, throughout the evening. While neither my fiance nor I are particularly German, we have fully embraced the venue and are planning an Oktoberfest themed wedding with Brats, Spatzel, and of course a good ol’ German style Hefeweizen.
The recipe is fairly straight forward for a German Hefeweizen with a 3:2 wheat to barley grist ratio. I added a small amount of Vienna Malt for color and some added complexity to the overall mouthfeel. I selected traditional German hops in Hallertauer Mittelfrueh for its mild bitterness and herbal flavor contributions. A great Hefeweizen is made by the yeast and the mash schedule as they contribute to the production of the classic banana and clove flavors. I wound up using WLP351 Bavarian Weizen described as imparting “moderately high, spicy, phenolic overtones reminiscent of cloves.” and a traditional Hefeweizen step mash schedule of 111, 126, 151, and 168 degrees.
My original thought was to experiment with several different Hefe yeast strains, however I had to change my plans when a trip to my LHBS turned up only one Hefe strain. After a bit of research I discovered that the yeast pitch rate can directly influence ester production that gives the classic clove/banana flavors of a hefeweizen. Although this is somewhat of a contested thought (many people believe the risks of under-pitching outweigh any potential rewards) I decided to give it a try. Generally speaking there are three ways to create a more banana flavored hefeweizen. The first is yeast strain selection, the second is temperature, and the third is pitch rates. The hotter a hefeweizen ferments (66-68 Deg plus) the more banana flavors will be produced, similarly if the yeast is under-pitched and thus stressed during the ramp up phase of fermentation it will also produce these flavors.
Since I ferment my beers in a fairly stable cool basement (ambient temperature 62 Deg.) and WLP351 is described as producing clove forward hefeweizens one would assume with a proper pitch of yeast I would finish with a clove forward hefeweizen with little to no banana flavors. Since I wanted to brew two unique beers from one batch I decided to pitch one carboy with the proper yeast rates and the second with 40% less yeast in an effort to create a more banana forward less clove flavored beer. However, like many things in life, the best laid plans often go awry. After spending a week diligently growing the proper amount of yeast required for my experiment I wound up with a much more efficient mash than usual (79% vs the usual 72%) and in turn a much stronger OG than I had planed for. After some debate I decided to add sanitized water to my final volume so that I would still be at my planned OG of 1.048, albeit with 12 gallons instead of 11.
While usually I would be thrilled with a more efficient brew-day, my carefully planned yeast pitch experiment went by the wayside. Since I didn’t have time to grow additional yeast I wound up under-pitching both 6 gallon batches. The first carboy was under-pitched by 25% and the second carboy was under-pitched by 55%. While the increased efficiency caused my experiment to lose its control I’m still looking forward to the results. By some accounts under-pitching 25% will have little to no overall impact on the final flavor profile of the beer so I am still hopeful I will finish with two distinct hefeweizens, one clove forward and one banana forward. Check back for the results in a few weeks.
Batch Size: 12 Gallons
Original Gravity: 1.048
Est. Final Gravity: 1.010
Color: 4.7 SRM
Boil Time: 60 Min
66.7% Wheat Malt
27.3% Belgian Pilsner
6.1% Vienna Malt
1 lb Rice Hulls
1 Oz Hallertaur Mittelfrueh (4% AA) at 45 min
1 Tbsp Irish Moss at 15 min
1.25 Oz Hallertaur Mittelfrueh (4% AA) at 20 min
4.11 L Starter of White Labs 351 Bavarian Weizen Yeast
15 minutes at 111.2 F (Feurilic Acid Rest)
10 minutes at 126 F (Protein Rest)
45 minutes at 150.8 F (Saccharification Rest)
10 minutes at 168 F (Mash Out)
Carboy #1 25% Under Pitch: 2.75 L
Carboy #2 55% Under Pitch: 1.135 L
Ferment at ambient air temperature of 62 F
Update: So after sampling both batches I could not tell a significant difference between the two different pitched batches. With that being said I did feel that the underpitched batch tasted a bit thinner and had some extremely slight off flavors (potentially from extreme yeast stress, but i’m not sure), there is also a chance this is just my mind trying to rationalize that they should taste different.
I have come to conclude that while underpitching hefeweizen yeast maybe able to directly effect the clove/banana ratio in the final beer there is a temperature or temperature range that if fermented below, no matter what amount of yeast pitched will directly limit the banana flavor profile of a hefeweizen. I’m assuming that the ambient air in my basement (65 deg) must be below this threshold as I was unable to successfully alter the two beer flavor profiles in a significant way. In the end the risks outweigh the reward in my opinion, and the best bet would be to pitch the proper amount of yeast and work on altering the fermentation temperatures to achieve the desired banana/clove ratios.