BJCP Exam Study Group Tech Article: Yeast And Fermentation

This is the Tech Article I wrote on Yeast and Fermentation for our BJCP Exam study group earlier this week.  It is long, but not overly technical:

FERMENTATION

Pitch Rate & Health

Yeast Cells

• Most of the off flavors/flaws in a beer are directly connected to yeast health and pitching rates (as well as fermentation temperatures), making yeast care and fermentation the most important factors in brewing aside from sanitation. In order to properly ferment a beer wort and avoid all the flaws associated with poor fermentation you need to ensure that your yeast are healthy and that you have the proper amount of them, as well as the ability to control the temperature of the fermenting beer. Old yeast will not be sufficient to fully ferment a beer and clean up after itself; neither will pitching too low of a cell count. Yeast should be pitched at a rate of 0.75 million cells of viable yeast, for every milliliter of wort, for every degree plato, 1.5 million for a lager (Jamil Z, Mr Malty.com) As the gravity of the beer increases so does the amount of healty cells required, as with volume as well. In order to achieve the correct amount of healthy cells you have a number of options. You can brew a low gravity beer such as a Mild, Bitter, or APA, then use some or all of the yeast cake for the larger beer. You can also make a starter by fermenting a mini-batch (1 pint to 1 gallon based on the beer to be fermented) then use that yeast to ferment the main beer (a stirred starter of roughly 1.040 OG works best). Or you can go to a local brewery that has a yeast which matches your needs and ask for a pitch of their slurry. Consult an online pitch rate calculator for the proper amount of yeast to pitch as well as the best way to achieve this.

• You should have enough fresh yeast to not only finish the job properly but to start it quickly to avoid contamination from bacteria, wild yeast, or molds which all want at your sugary goodness as well.

• In order for yeast to have the optimal health and ability to reproduce it requires nutrients which are typically found in standard beer wort but can be added through using commercially available nutrient blends. It also requires oxygen for reproduction which the beer wort is highly deprived of as it has been driven off in the boil. Oxygen should be added to the beer prior to fermentation for proper yeast growth.

Review: Gummy Bears - Simple Saison

I love Saisons. Real ones. Light, refreshing, rustic, big spices and big fruits, dry, hoppy, packed with flavor and aroma, with a clean finish that draws you back for more. I love them made with the 3724 DuPont strain, not so much on the French Saison yeast that so many use to avoid the care needed for the DuPont. Enter the 3726 Farmhouse Ale strain that Wyeast releases only every 3 years. On this beer I had to try it before it left. And I was not disappointed. 1 week fermentation took the beer to 1.008, no stalling, no problems, 76*F controlled fermentation, great Saison. This beer is a simple recipe, 41% Great Western Pale Malt, 41% Weyermann Pils, 18% German Dark Wheat Malt, 147*F mash for 75 minutes, 1 tsp Gypsum and 1 tsp Calcium Chloride (split 3/8 each in mash, 5/8 each in boil). Bittered with 0.4 oz of Seuz at 45 minutes, 0.6 oz Styrian Bobek at 10 minutes, and a blend of 0.4 oz Bobek, 0.5 oz German Saphir, and 0.5 oz Hallertau Mittelfruh at FO for a total of 20 IBUs. The beer didn’t finish as low as I had hoped, but with the combination of the tartness of the yeast, the bitterness, and the acidic bite from the high carbonation, along with the sulfates, it turned out perfect.

Look: Pours a deep gold w/ rustic orange burnish, big frothy pure white head that fades slow to a whispy layer atop and a thin ring along the sides. Nice bubbly carbonation. Decent lacing.

Aroma: Lots of fruits, pears, bananas, strawberries, apples, white pepper, cloves, ginger, grass, hay,

floral, rosemary.

Taste: Pepper, fruity, lychee, rosemary, ginger, spicy bite, lite floral, refreshing and crisp, grainy, yeasty.

Mouthfeel: Fizzy, dry, light acidic bite, spicy finish, bitterness is there, but not overly done, balanced between bitter, dry, acidic, and sweet.

Overall: Very good Saison, big fruits and spices. Herbs and florals from the hops shine. Very dry and light, bitterness and carbonic acid play well together for a perfect finish. Lacing and head retention could be boosted some, but very well crafted Farmhouse Ale. Rustic, fruity, spicy, floral, dry, bitter, hoppy, grainy, light, crisp, tart, refreshing, as it should be.

Spontaneous Fermentation Update

Awhile back I did a time line blog of the yeast starters I was making from the wild yeast and bacteria living on the skins of wild blackberries living in my neighbor's yard and from locally grown organic peaches. The brew day has come and gone, and I thought I would fill in the specifics and update on how the beer has progressed thus far.

The recipe:
6.25# Pilsner Malt (54%)
2.25# Vienna Malt (20%)
2.00# Flaked Wheat (17%)
1.00# Caravienne (9%)

90 minute boil
FW Hops 0.4oz Styrian Bobek 3.8AA pellets
15 min 0.6oz Styrian Bobek 3.8AA pellets

10 min 1.50z Cake Flour
5 min 1tsp Coriander, Crushed

Mashed 60 mins @ 152*F
Sparged w/ Boiling water

5.25 gals
OG 1.057
FG 1.002
IBU 10
ABV 7.2%

I mashed at 152*F, I was shooting for 154, but added too much cold water when I was too hot, and it cooled it down too much. I sparged with boiling water to try to extract as much sugar as possible and even some tannins as well. At the end of the 90 minute boil I added some cake flour for extra dextrins and starches for the Brett to chew on over the long fermentation. I cooled it as usual and ran it into the fermenter. I added the 2 starters to it whole, all the wort, fruit, bacteria, yeast, a couple ants, everything. I didn't aerate it since oxygen feeds bad bacteria, and inhibits Lacto growth. It looked kind of stratified until the next day as the different parts were layered, wort, trub, break material, fruit, starter, etc.

After a few days I noticed some odd activity. There was no krausen, but I had used S-Foam, and foam inhibitor, so it is quite possible that it was fermenting and not putting up a krausen. I did notice lots of little tiny bubbles shooting up and feeding a fluffy foam at the top though, and I assume this was from the Lacto working since it releases CO2. Another day later and I saw the wort churning away like any other beer fermentation, so things were going good.

I let it go for a few weeks with out tasting it, and finally on week 3 I gave it a taste. Nice, light, clean tartness, clean fermentation, no off flavors, mild funkiness, slightly fruity, not much oak character, gravity was 1.005. Quite happy with it. I tasted it again 1 week later and the oak is starting to show some; I will be watching this since I don't want it to be too oaky. If it gets where I want it I am going to rack the beer off, remove the oak, and add the beer back to the trub, yeast, and fruit for longer conditioning and funkdifying. So far I am very pleased. I even used the yeast to ferment a cider.

NOTE: This beer took 1st place in Sour Beers and won BEST OF SHOW in February 2014 at the KLCC BJCP comp.