The Science of Cheap Beer

Most guys like beer, and many like to brew their own.  Unfortunately, in many countries, beer is heavily taxed.  In the part of Canada where I live, the cheapest beers cost $42 for 24 bottles.  There's a 10c refund for the empty bottles, so after you bring the bottles back the net cost is $39.60, or $1.65 per bottle.  Each bottle is 341ml, making the cost per liter $4.84.  With homebrew kits like Coopers, 23L of beer can be brewed for <$20, or about 1/5th the retail price.  With a little more work, it's even posible to make a brew with the same ingredients as a Coopers kit for about $10, or 1/10th of the retail beer price.

The Coopers kits require adding 1kg of fermentable sugar to the malt extract and water, and the brew shops recommend corn sugar aka dextrose aka glucose, which sells for $5 for a 2kg bag.  Dextrose has about 10% moisture content, so 1kg of fermentable dextrose costs about $2.80.  Cane sugar aka sucrose sells for $2 or less for a 2kg bag, so for my first beer kit brew I tried half dextrose and half glucose.  It turned out fine.

I decided to research some of the science behind the fermentation of different sugars.  I found a paper by Labatt Breweries which shows virtually no difference in the fermentation of glucose vs. sucrose.  Glucose may actually be worse than sucrose, since the paper shows high glucose suppresses fermentation of maltose (fig 4B).  Malt extract is 30-50% maltose, so using sucrose instead of glucose means fermentation will be finished sooner.

Malt extracts are much more expensive than sucrose - about $5/kg for liquid malt extract.  The fermentable sugars do not contribute to the taste, so using a malt with less fermentable solids allows you to use more sucrose while still maintaining flavor. The Coopers kits include 1.7kg of hopped LME and recommend adding 1kg of fermentable sugar.  Using 1.5kg of a darker malt (~$7.50) and a little more than 1kg of sucrose (~$1) should give a flavor profile almost the same as the Coopers kit assuming the same hops.

Dried hops costs about $30/kg, and depending on the recipie, a 23L batch will need 20-50g of hops.  This adds about a dollar to the cost of a batch of beer.  The cheapest source of hops is to grow your own.  One homebrewer I know had a couple varieties of hops growing up a trellis attached to his back deck.

Coopers ale yeast costs just under $2 for a 7g package, but you don't need one for every batch.  I bought a Coopers kit on sale that was missing the yeast pack, and just split a package between 2 batches.  Despite some people that say the amount of yeast you pitch is important, the biochemistry of yeast seems to indicate otherwise.  It might take a bit longer for the brew to ferment, but not that I could notice.   I used 3.5g of yeast for a batch of Cooper's ale, which I uncovered and stirred after a few hours for oxygenation. After three days at 23C there was a full cover of foam from the active yeast.  Yeast from one batch can be re-used multiple times, so is's feasible to use a single 7g package for up to 10 batches.

When it comes time for priming, a number of sources, including this one, say that using sucrose gives a cidery taste to beer.  I've used sucrose and didn't notice a cidery taste.  More likely explanations for a cidery taste in beer is oxidation or incomplete fermentation.  Since only 100 to 150g of priming sugar is needed for a batch, the choice of priming sugar doesn't affect the cost much.

So how do I come up with the $10/batch number I mentioned?  Here's the breakdown:
1.5kg dark LME: 7.50
1.25kg sucrose: 1.25
30g hops:       0.90
yeast:          0.25
total:         $9.90

If you want a lighter tasting beer like mainstream beer buyers (bud light is the top selling beer in the US), then 1kg of dark LME and 1.5kg of sugar should suffice.  If you grow your own hops, then your cost for a homebrew light beer could be as little as 10c per bottle!