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As homebrewers why do we take longer to ferment our beer than what seems like the time-line at the commercial/pro level. Everytime I take a brewery tour or a listen to a podcast that interviews a pro brewer it seems like they ferment for around four days, for example. Then the beer is pushed to a bright tank or through the filter, carbonated and packaged. At home we let it ferment for at least 7 days. I tend to go for 14 days, mostly being lazy.

We all hear about leaving the beer in primary long enough so the yeast can "clean-up" after the ferment.

Any insight into these differences?

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4 Answers 4

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Differences in scale, equipment and in the amount of yeast pitched are the main things I've found. Keep in mind that not everything about commercial brewing translates to homebrewing.

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I know it doesn't all translate. But aren't we pitching at the same rate supposedly, or at least trying to?? 1B cells/L/Plato or something like that. –  brewchez Jun 11 '11 at 19:07
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Larger tanks can ferment at higher temperatures, since the high pressure prevents the yeast from throwing off a lot of esters. So pro-level fermentation is usually faster than home-level. That said, I typically ferment ales for about 5 days, do a diacetyl rest if needed and then keg. Some beers are ready then, others I'll age in the keg. –  Hopwise Jun 11 '11 at 20:18
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I'm curious if anyone has experimented with fermenting under pressure in corny kegs at the homebrew level to replicate pro brewer conditions. –  Graham Jun 17 '11 at 16:59
    
It's a lot more than that. Fermenter geometry plays a large part in the way commercial brewers fermentations react. –  Denny Conn Jun 18 '11 at 23:23
    
Sorry, I don't agree that this is the best answer - and I am not suggesting mine is. Scale and equipment do have their part to play, but the amount of yeast pitched translates straight down to homebrew scales (this is with reference to top fermenting ale yeast as this is my area of experience). Unless you desire the effects of over- or under-pitching I don't believe this is the way to speed up fermentation. –  iWeasel Jun 19 '11 at 8:10

Good question. Hopwise is partially right about the higher temps speeding primary up, but most pro brewers control temp with glycol. Bottom line and beer style is probably the answer to your question. Some beers may not need a longer secondary or extra time to settle out, especially if things are getting run through a filter. So a vigorous, nutrient-rich primary followed by filtration, a spell in the brite tank and some gassing would be the method for some.

I can't speak for other brewers, but I see larger batches of Belgian and American ales no differently than small ones-- a week in primary (plus or minus) and then a secondary that fits the style-- anywhere from 2 weeks to a year. Aroma, flavor, clarity and terminal gravity indicate when it's time to keg or bottle. The nose knows!

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What is a brite tank? Is that analogous to a secondary fermented in home brewing? Or is there more done in the tnk at the commercial level? –  Jerry C. Jun 21 '11 at 22:55

Great question +1. Do we really take longer to ferment our beer? It may seem that way but is it really that different?

Here are my thoughts: The volumes brewed commercially generate far more heat than a homebrew bucket and, inspite of cooling, there must be many more currents self-rousing the beer. Maybe attenuation is faster in the exponential phase of fermentation(can anyone verify?). Commercial brewers in the UK leave their beer in the FVs for 3-5 days then transfer to conditioning tanks.

The conditioning phase is also referred to as the stationary phase of fermentation when the yeast reabsorbs much of the diacetyl and acetaldehyde produced earlier. For UK ale, the slow temperature drop, over a few days, from 21 to 10 degrees with a period of rest at 14 degrees, allows the yeast to 're-use' diacetyl. So, in all, they are probably looking at times of around 7 - 8 days. Not that disimilar to a homebrew fermentation - perhaps with the exception of your 14 day 'lazy' brew. It's just that we don't tend to rack off so early and probably the stationary phase happens in the fermentation bucket.

There was mention of the amount of yeast pitched. I don't think this is used to speed up fermentation, though I agree that not everything commercial translates to homebrewing. I looked into pitching rates and according to Chris White and Jamil Zainasheff (Yeast, The practical guide to beer fermentation pp 121), both over- and under-pitching "...result in a less than ideal fermentation with high levels of diacetyl, acetaldehyde, and low attenuation. Too high a pitching rate can also result in low or unexpected esters, yeast autolysis flavors, and poor head retention."

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As a home brewer you don't have any commercial pressure to get the beer out the door and making money for you. So let it rest as long as it needs to. If you're busy doing other stuff, an extra week won't harm it...

This is why we home-brew!

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