Day 428

History of Rock & Roll was really far out, man. We had this assignment thing, man, where in groups of 3, we were expected to lay our head space alongside a band manager in 1968. What was the name of our band, what was its groove, its product, its look, its vibe? Then we had to fire one of the band members with a “Dear John” letter. Then we had to convince a promoter to book our band–whose name, btw, was The Blue Cosmic Alliance. Can you dig it? We had a groovy time. Outta sight. Got to split, check you on the flip side. Peace & Love, man. ☮

We returned to 2012 just in time for Business Ethics, where we discussed the ethical implications of pricing your product. What is a fair price? What is predatory pricing? Is price gouging ethical, or are you simply selling what you can?

In FCF, it was carbonation, Part Deux.

In today’s exciting installment, we learned that yeast converts 46 percent of sugar to CO2. Remember that number, we’re going to need it. Likewise, we learned that one litre of CO2 weighs 1.96 grams. While seemingly unimportant, this factoid allows us to do some calculations around the production of CO2, specifically how much sugar we need to add to a given volume of beer in order to carbonate our beer via a a secondary fermentation.

Step 1: Convert the desired volumes of CO2 to grams/L. (A volume of CO2 is exactly what it sounds like–the amount of CO2 at 20°C that would fill a given vessel with 1 atmosphere of pressure.)

The conversion formula is:

volumes per litre desired x 1.96 g/volume (see, I told you we’d use that number) = number of grams/L of CO2

So if we wanted to get a secondary fermentation to produce 2.6 volumes of CO2 in the beer:

2.6 volumes/L  x 1.96 g/vol = 5.069 g/L

Step 2: Determine how much CO2 is already in the beer from primary fermentation.

The temperature at which the beer originally fermented determines how much CO2 was dissolved into the beer during fermentation, so we simply have to look at a number on a chart of fermentation temperatures.  If we assume our beer fermented at 10°C, there is already 2.32 g/L of CO2 dissolved in our beer.

Step 3: How much sugar do we need to add to produce enough CO2?

This actually depends on the sugar’s fermentable factor–that is, how much of the sugar can actually be eaten by the yeast. If it’s all glucose, then it’s 100% fermentable. If it has more complex dextrins, only a certain percentage will be fermentable.

sugar x its fermentable factor = [(CO2 desired – how much CO2 is already dissolved in the beer) x volume of the beer]/0.46 (46% is how much sugar is turned to CO2, remember?)

Using the above example for a 18.9 L pin of beer, and assuming we are using a completely fermentable sugar:

sugar x 100% = [(5.069 g/L – 2.32 g/L) x 18.9 L]/0.46

= [2.749 g/L x 18.9L]/.46 = 112.95 g of sugar required

So, if we add 112.95 grams of sugar to our pin, it should be carbonated with 2.6 volumes of CO2 when we tap it.

One thing to note is that this method assumes the container is completely filled with beer, so no gas is wasted filling empty head space.

We also studied some calculations to determine how much fresh wort to hold back from fermentation in order to add it later and kick-start a secondary fermentation, and also a formula to determine at what point during fermentation you could simply cap a fermentation tank and allow the CO2 to build up and self-carbonate the beer to a desired level.

However, the formulae are long and my candle is burning to a nub…

 

 

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4 Comments on “Day 428”


  1. Saw this article on how microbreweries are “recycling” factories in Toronto and thought, given your field of study, you might enjoy it:

    http://www.thestar.com/news/gta/article/1284619–microbreweries-show-factories-still-have-a-place-in-the-urban-landscape

    • Alan Brown Says:

      At a recent conference of the Ontario Craft Brewers, a representative of VLB Berlin (a very respected brewing school and research centre) indicated that “showcase breweries” like Steam Whistle would be a growing trend in the next few years. The idea is that beer is expensive to ship–not only will the brewery save money by being closer to its market, but by attracting people to the brewery who will then lug away their own beer, the brewery will save even more money.

  2. Ely Says:

    Hello Alan,
    Curious if you have posted those formulae mentioned in the last portion of this post. If so, is there a link to this?
    Thank you,
    Ely


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