Yeast is a mysterious beast. It reproduces through budding asexually. For this to occur, it must metabolize things like sterols, fatty acids, oxygen, and FAN. Should your wort be lacking in these nutrients, your yeast may stop reproducing, become satiated, and step away from the table. Your yeast is short of breath. There has been quite a bit of discussion on the role of oxygen in healthy fermentation.
Ask about the role of oxygen in a room full of brewing chemists and you'll likely start a brawl. When you pitch your yeast, your wort should have a nice supply of dissolved oxygen in it. The yeast will use this oxygen to be happy. Insufficient oxygen in your wort can lead to sluggish fermentation. Once the fermentation is underway, you should avoid adding any more oxygen or the beer will be prone to becoming stale.
Your yeast has been taken over. If your sanitation isn't up to par, wild yeasts and bacteria may have taken over the feast. This is usually a fatal problem.
Sanitize, sanitize, and sanitize! How to avoid stuck fermentation It follows that you should avoid all the causes listed above. Here's a list of suggestions: Keep your equipment sanitary. Everything that touches the wort below the boiling point should be sanitized well.
Be sure to allow the sanitizer to drain away or rinse it with pre-boiled water or cheap beer. Watch the fermentation temperature. Use a thermometer to check on the fermentation temperature often. Watch out for drafts and maintain the optimum temperature for the yeast you are using. Give your yeast the diet it likes. Brewers of all-grain batches usually have no problem with this. Extract-only brewers should try to use high-quality extracts that are fresh as possible.
Use a commercial yeast energizer in batches. A yeast energizer is like a multi-vitamin, chock full of the stuff your extract wort lacks. Be careful if you re-pitch. Some strains repitch better than others do. Avoid Whitbread and other multi-strain yeasts in favor of single strains. Limit yourself to one repitching. Make a yeast starter. If everyone made a healthy yeast starter, we'd have fewer stuck fermentations.
For a five-gallon batch of beer, you'd like to have at least two fluid ounces of clean, healthy yeast slurry. The only way to generate this much yeast from a pouch of liquid yeast or a packet of dry yeast is to grow up a starter. Aerate your wort. If you are a low-tech brewer, spend ten minutes vigourously shaking out your fermenter before pitching. If you are more high-tech, you can rig an aeration stone to an aquarium pump and HEPA filter and pump air into your wort.
Using a five-second blast of pure oxygen through an aeration stone can make a dramatic difference. How to Fix a Stuck Fermentation Since it's hard to diagnose some fermentation problems, start with the easier solutions first.
One can stir the yeast to complete its work, though I hesitate to encourage it. You must be extremely careful. A yeast nutrient would be a first step. The dense foam had not formed on top, the fermenter did not turn a creamy opaqueness that indicates yeast multiplication and healthy fermentation. Within 12 hours at the most, the yeast should have multiplied to begin its sugar to ethanol conversion.
It does its work slowly, exhibiting a milder, gentler krausen. Lagers may take 15 — 28 days for full fermentation , requiring a well-found patience. Off flavors include index-card, musty, used booky : sounds crazy, but this is what it brings! Another violent result of oxidation is the formation of Acetaldehyde. Acetaldehyde not only forms due to under-pitching and O2 exposure, it will also reconvert your alcohol back into itself, a rancid and villainous contaminating compound.
After cold break solids falling out during cooling and cool-down, stir away! Remembering that all post-boil contact must be sanitary, if stir you must do it in a manner in which the lid keeps the fermenter mostly covered. The stirring introduces O 2 to the wort and mixes the yeast well before its brief pre-fermentation rest. Consider this a preemptive stir allowing the greatest possible success for respiration and cell multiplication. See my article for best handling of pre-pitch yeast: article on hydrating yeast.
Rest it on the floor with a towel underneath for cushion. I don't want to open the lid until cleanup. Hop bag falling into the trub and losing my "clear beer"? Just spit-balling here. I know it's all opinion, but what about hop contact with wort when it's in the bag I've never dry hopped in a bag, only loose? Cheers you helpful brewers! Lukass Meyvn 1, Dec 16, Ohio.
GreenKrusty Initiate 0 Dec 4, Nevada. I've tried dry hopping in the primary three times with a few gravity points left and have concluded it isn't something I need to try a fourth time based on the three strikes rule. Sadly, the so called hop bio-transformation and alleged reduction in oxidation did not produce better results than dry hopping in a keg. Well, yes there are differing opinions, but probably a majority of people Yes, Matt Brynildson gets such "great" results from dry hopping during fermenation that he adds more dry hops after fermentation has ceased and the yeast cake has been dropped.
Meanwhile Brew Betty puts the dry hops in the keg and easily destroys Union Jack with respect to aroma. As always, YMMV. Bell's also adds dry hops to the primary fermenters. At what Plato, I do not know. They do use a shallow cone tank, the bottom cone is only 5 or 10 degrees, I think it does not let the hops to settle into a tight mass like in a 30 degree cone.
Jesse14 Initiate Jul 21, Massachusetts. I try not to touch my fermentor ever. I feel bad moving it to even rack out.
Your head space should be full of C02 not oxygen so no worries there. I will also swirl when I do a big beer.
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