Difference between revisions of "Blending"

Blending (or High Gravity Brewing) is a technique that allows you to brew a larger end-batch volume without buying larger fermentation equipment. A higher specific gravity beer (strong beer)is first fermented and then blended with water to create a lower alcohol beer with less IBU, SRM and final gravity than the originally fermented beverage.

Blending can also mean the mixing of two independently fermented beverages. This can be the same beer or different beers combined for a different flavor. Commercial examples include Newcastle (two differently fermented beers blended for a consistant flavor), Budweiser-Coors-Miller (the same beer fermented in different tanks and then blended for a consistant taste), and finally bartender-mixed blends such as Black & Tan (Guiness Stout and Bass Ale) or Half & Half (Guniess Stout and Harp Lager), which are two different beers mixed after the serving container for a differently tasting beverage.

Blending (or high gravity brewing) is a technique the big US brewers use. American Pilsners are brewed with an original gravity (OG) around 14–16 °Plato (SG 1.056–1.064). After fermentation, the strong beer is diluted to a virtual OG of around 10–11 °Plato (1.040–1.044). The big breweries brew this way because they can produce more beer with high-gravity brewing than if they brewed it all at working strength. A fermenter that holds 500 barrels of beer will end up producing 700 barrels of beer. For home brewers, a 5-gallon (19-L) batch of strong beer can easily be diluted to yield 6–6.5 gallons (23–25 L) of finished beer, more if you’re careful.[Colby,2004]

Recipe Formulation

The easiest way to formulate a "blending" brewing recipe is to take a recipe for one volume and expand it to the larger target volume. However, you should brew the beer at the original volume. To calculate how much to expand the recipe, divide the larger volume of target beer by the smaller volume of strong beer.

For example let’s say you have a 5-gallon (19 L) pale ale recipe with:

• 10 lbs. (4.5 kg) pale malt
• 1 lb. (0.45 kg) crystal malt
• 2 oz. (56 g) of bittering hops

If you want to end up with 6 gallons (23 L) of beer, multiply all the ingredients by 6 divided by 5, or 1.2. You’d end up with the following amounts which you can then use to brew 5 Gallons (19L) and dilute to 6 Gallons (23L).

• 12 lbs. (5.4 kg) pale malt
• 1.2 lbs (0.54 kg)
• 2.4 oz (68 g) of hops

A drawback to this simple calculation method is that hop utilization slightly decreases at higher wort gravities. Thus using proportionally more hops in your high-gravity base beer may lead to an under-hopped diluted beer. However, in most cases, this discrepancy will be minimal. To completely master high-gravity brewing calculations, all you need to know is one simple formula

(C1V1 = C2V2), where C is concentration and V is volume.

The subscripts refer to the initial strong beer and resulting blended beer.[Colby,2004]

Brewing the Strong Beer

At higher water dilution/blending rates, you may notice that your finished beer is a bit more estery than it would have been had you brewed it normally. Esters and higher alcohols, byproducts of fermentation, are produced at non-linearly higher rates in more dense worts than in less dense ones. Taking into effect the higher specific gravity and lower hop utilization, you are going to want to brew your base beer as you would brew any beer and ferment it to completion. You have to have a good base beer to produce a good final blended beer.

If your final beer tastes too estery, has fusel notes or other unwanted fermentation byproducts, you’ve pushed the technique too far. At higher dilution rates, you may also need to tinker with your recipe a bit to get the beer to taste as you want it. The big breweries typically do not exceed 16 °Plato (SG 1.064) when brewing their strong beer for dilution. Above this gravity and the resulting blended lager is too estery. For most lagers to be blended, 16 °Plato (SG 1.064) is a reasonable maximum starting gravity for the strong base beer.[Colby,2004]

Blending/Dilution Water

Any dilution/blending water used should be of the same quality as the water you brewed with. It should taste/smell good and be free of contaminants such as heavy minerals or chlorine. Carbon filtering your tap water, buying spring water, or using RO/distilled water should all get you more-than-acceptable dilution/blending water.

Under most normal circumstances, water has some oxygen dissolved in it. At 68 °F (20 °C), pure water that is exposed to air will have 9.0 parts per million (ppm) oxygen at equilibrium. This amount decreases at higher temperatures. When you dilute your beer, you don’t want to introduce oxygen into it. Oxygen will cause the beer to go stale faster than it normally would, resulting in cardboard-like aromas or sherry-like flavors. So, you need to remove the oxygen from your dilution water.[Colby,2004]

Boil your dilution/blending water for 15-20 minutes, and then cool it very fast (without splashing) to reduce the oxygen content to around 1 ppm oxygen content. You should measure out the amount of water you will need for dilution/blending, plus 5-10% to take in account evaporation. You should use your prepared dilution/blending water immediately unless you can store it under CO2.

Sources

[Colby,2004] Chris Colby editor of BYO magazine,"Blending for volume: Techniques", Jan,2004

--By WortMonger, member of HBT.com 15:34, 19 August 2008 (CDT)