Table Saison - Open Fermentation vs. Closed

Introduction

Every beer nerd worth his or her brewing salts has probably had a beer that changed the game for them; a beer that opened their eyes to the possibilities of what could be called beer or just simply blew their hair back. For me this beer was Rocherfort 10. My intrigue with the beer fueled a thirst for knowledge about the beer style, the brewery, other Trappist Abbeys, and generally the country of Belgium. Stemming from this pursuit of good Belgian beer (in my experience there is very little bad Belgian beer), I began to learn more about saison and what a good saison was. After several years of really diving into the style I thought I had a pretty good grasp on what to expect in a good saison...
...and then I had a beer by The Commons called Urban Farmhouse.

Urban Farmhouse changed how I viewed saison and how I approached brewing saison. It was a beer that presented a simple complexity and finesse that I had not experienced previously. It didn't stomp on my tongue with overripe banana and pepper. It was highly intriguing and supremely drinkable. There are a number of incredible Belgian and French brewers who deserve extreme respect for the impeccable beers they produce, but I do have to say that American brewers are getting really good at brewing saison and other farmhouse ales. Saint Somewhere, Casey Brewing & Blending, Holy Mountain, Hill Farmstead, Jester King, Side Project, Blackberry Farm, Jolly Pumpkin, Logsdon Farmhouse Ales, Sante Adairius, etc. We are a blessed nation! Following my first taste of Urban Farmhouse, I posted on the Saison, Biere de Garde, & Farmhouse Ale Appreciation Society Facebook page looking for some recipe advice and was forwarded to Sean Burke of The Commons, the man responsible for brewing this magical beer that impressed me so much. I didn't straight up ask for the recipe for Urban Farmhouse, but with Sean's input and advice I developed my own recipe for a supremely drinkable table saison.

Approach

My first iteration of this beer utilized Imperial Yeast's Rustic strain. This strain was reported to be equivalent to Wyeast 3726, the yeast Sean said was used for Urban Farmhouse. Both of these strains are reported to originate from Brasserie de Blaugies, a brewery that produces another of my favorite saisons, Saison D'Epeautre. I kept the grain bill fairly simple, utilizing Belgian Pilsen malt for the majority of the grist while using starchy adjuncts such as wheat and oats (I am currently using raw triticale) to give some body to the low gravity beer that I intended to produce. I have re-brewed this beer multiple times now; mostly focussing on adjusting the hops, but decided to do a split batch of my latest version of the recipe that focussed on manipulating a fermentation variable. I had heard reports from a few professional brewers that open fermentation was beneficial in achieving quick and complete attenuation with saison strains that are prone to stalling like Wyeast 3724, Belgian Saison. Open fermentation is typically performed on the commercial scale in a shallow open top fermentor or a fermentor with a removable lid, such as a variable capacity wine tank. There is a very small amount of pressure that is applied to the fermenting beer when it is in a closed vessel with an airlock and it has been stated that this difference in pressure as well as the exposure to more oxygen is what causes the yeast to behave differently. Additionally, I have heard some brewers (both professional and home brewers) stating that they get more yeast character in open fermentation as the reduced pressure allows the yeast to express itself more. However, this seems contradictory to what is commonly stated about stress on yeast being the cause of increased fermentation character.

The Open Fermentor (back) and Closed Fermentor (front)
after being placed in the fermentation chamber

Following visits to multiple breweries that utilized open fermentation (Saint Somewhere Brewing Company in Tarpon Springs, FL and Heirloom Rustic Ales in Tulsa, OK), I was encouraged to attempt open fermentation in my own home brewery to see the difference for myself. The goal was to see what difference, if any, open fermentatin would have in my standard table saison recipe. I chose to ferment the 11-gallon split batch in identical PET carboys. One carboy had a standard 1-piece airlock installed and the other had a fine mesh bag placed over the opening of the carboy. Both carboys would be treated identically other than the variance in the airlock. Below is the recipe and notes for this beer with all values scaled down to 5.5 gallons (22L).

Recipe Specifications

Beer Name: Perfect Kingdom Batch 1

Brew Date: 12-1-2017

Batch Size: 5.5gal (22L)

Estimated OG: 1.045

Estimated: Color: 2.6 SRM

Estimated IBU: 29.1 IBUs

Brewhouse Efficiency: 75%

Boil Time: 90 minutes

Grain:

66.7% - 6.0lbs (2.72kg) - Chateau Belgian Pilsen 

33.3% - 3.0lbs (1.36kg) - Raw Triticale, locally grown

Hops:

Boil: 60 min - 0.3oz (8.5g) Sterling [10.5% AA] - 11.5 IBUs
Whirlpool: 30 min - 1.2oz (32.0g) Sterling [10.5% AA] - 17.6 IBUs
Dry Hop: 4 days - 0.83oz (23.5g) Sterling [10.5% AA] - 0.0 IBUs

Yeast:
Wyeast 3726 Farmhouse Ale

Mash:

Rest -  30min @ 148°F (64.4°C)
Rest -  30min @ 152°F (66.7°C)
Rest -  30min @ 156°F (68.9°C)
Mashout - 10min @ 172°F (77.7°C)

Sparge:
HLT maintained at 172°F (77.7°C) during sparge

Misc: 

Notes:
12-1-2017 A double batch of the above was brewed
 2.0lbs (0.9kg) - Rice Hulls added to mash
Heat sparge water to temperature in electric Hot Liqour Tank (HLT)
Transfer 6.125gal (23.18L) of heated water to empty Mash Tun (MT)
Add to mash water 10g Gypsum and 3.5tsp amylase enzyme
At beginning of 152°F rest step pH was 5.55 so 4mL Lactic Acid (88%) was added
At beginning of 156°F rest step pH was 5.37 so 4mL Lactic Acid (88%) was added
At beginning of Mashout pH was 5.32
Collected 14 gallons at 1.034
Boil for 30 minutes then add bittering hops
Add flavor/aroma hops at flameout and whirlpool for 30 minutes without chilling
Chill to 80°F (26.6°C)
Fill two 6 gallon PET carboys to 5.25gal (19.87L) mark.
No aeration or oxygenation
Put standard 1-piece airlock on one carboy (Closed Fermentation) and a fine mesh cloth over the other (Open Fermentation)
OG measured 1.045, actual target OG was 1.042.
Fermentation chamber set to 78°F (25.6°C)
12-2-2017 Fermentation chamber set to 85°F (29.4°C) after 24 hours at 78°F (25.6°C)
12-8-2017 Add 0.83oz (23.5g) Sterling [10.5% AA] to each carboy, no mesh bag
12-15-2017 bottle both carboys
Using a final gravity hydrometer measure FG
Closed Fermentation: 1.005
Open Fermentation: 1.0045
Bottle 5.125gal (19.4L) of each with 6.3oz (178.6g) beet sugar, targeting 3.0 volumes of CO2

Results

Side-by-side tasting of the Closed Fermenation (left)
and Open Fermentation (right) table saisons

Tasting Notes - Open Fermentation 

OG:1.045   FG:1.0045   ABV: 5.32%

Aroma: Low clean pilsen malt, Medium-Low bubblegum, Low banana, Medium-Low herbal/spicey hops

Appearance: Yellow with good clarity and a tall white head that persists well. Small particulate is seen floating in the glass

Flavor: Medium-Low, clean pilsen malt, Medium-Low herbal/spicey hops, Low pear, Low banana, Low phenolic spice. Medium-Low Bitterness

Mouthfeel: Medium-Light body with high carbonation. Effervescent. No alcohol warming or astringency.

Overall: This beer presented itself as being less yeast forward than the closed fermentation version. The yeast character was more delicate and bubblegum forward and as a result, the malt and hop character was more easily detectable.

Tasting Notes - Closed Fermentation

OG:1.045   FG:1.005   ABV: 5.25%

Aroma: Low clean pilsen malt, Low bubblegum, Medium-Low banana, Low spicey hops

Appearance: Yellow with slight haze and a tall white head that persists well. Small particulate is seen floating in the glass. I attributed the haze to this being bottle conditioned and pouring this beer too aggressively. I have poured many other bottles from this batch that were just as clear as the other half of the batch.

Flavor: Medium banana, Medium-Low pear, Medium phenolic spice, malt and hops are very low and pretty much hidden by the yeast character.

Mouthfeel: Medium-Light body with high carbonation. Effervescent. No alcohol warming or astringency.

Overall: This beer presented itself as being more yeast forward than the open fermentation version. The yeast character was more focused on the typical banana and spice and ultimately covered up a lot of the malt and hop character.

Conclusion

This batch has been in the bottle for almost five months now and over that time I have observed how each beer has changed. While the beers are notably different to my palate at 5 months old, I feel they were even more unique when younger. In this instance, the overall difference between the open fermentation and closed fermentation saisons is that the open fermentation saison has a less intense yeast character than the traditional closed fermentation saison. It is also noted that the open fermentation beer finished a half of a gravity point lower than the close fermentation beer. This makes sense as the open fermentation is assumed to have more available oxygen for yeast due to the lack of airlock. Another potential possibility of the lower gravity is that the yeast in the open fermentation experienced less CO2 toxicity as the CO2 was allowed to escape out of the top of the fermentor. Regardless of the explanation, the result is that the yeast esters and phenols of the open fermentation are more delicate and allow the malt and hops to shine through. 

So what exactly would I use open fermentation for? If I were wanting to brew a saison with new world hops such as Citra or Amarillo (Farmhouse Pale Ale?) I would definitely use open fermentation. The less intrusive yeast character would allow the hops to shine. I am also thinking that open fermentation will be something that I explore for my next batch of Belgian-style Dark Strong Ale to help ensure that the beer fully attenuates and keep the yeast character from getting too dominant. Or how about open an open fermented lager? Conversely, what would I used closed fermentation for? I would use closed fermentation for beers where I really want an obvious yeast character. I will continue to use closed fermentation for my table saison as I feel that the low gravity beer really needs to have substantial yeast character to keep it from becoming boring. In my experience, the yeast character of WY3726 is less intense than the standard WY3724 so reducing the yeast character further is not something I am looking for in a low OG saison. 

What else would I change about this recipe? I think for what I am looking for in a saison, this beer is lacking hop bitterness as well as hop flavor. Next time I will probably increase the late addition to be 2.0oz instead of 1.2oz and increase the bittering addition to a calculated IBU of 20. I entered this beer in two different competitions and the judges agreed that the bitterness was low. However, I did win two bronze medals with the closed fermentation beer.