Tuesday, June 26, 2012

The Ancient Art Of Brewing And The Chemistry Behind It!

According to archaeological evidence, brewing was first done by people living in ancient Mesopotamia around the 5th millennium B.C.  The oldest beer recipe comes from a 3900-year old Sumerian poem honoring the brewing goddess, Ninkasi.  More recent, however, is my summer break which allows me time to experiment with brewing.  This year I decided on a blueberry concoction since I have been seeing fresh fruits all over the place.  As added bonus, my son who loves doing things in the kitchen, assisted me with this endeavor.  Last month we made strawberry ice cream from our excess handpicked strawberries - look for a "chemistry of ice cream post" later in the summer.

The ingredients consist of four main parts:
1) malted grain - barley, wheat, oats, corn, or rice that is soaked with water until germination begins.
2) hops - the flower of the humulus plant that is used for aroma and more importantly adds bitterness which balances the sweetness of the malt.
3) yeast - a type of fungi which converts fermentable sugars into alcohol.
4) water - H2O.

Our Ingredients:
As you can see I cheat a little bit as I brew from a kit (Mr. Beer).  They have numerous recipes and suggestions to choose from.  The brew that we are making is based on the recipe for Jazzberry Ram but we are substituting blueberries in syrup for raspberries in syrup (I like blueberries more).  

Step 1 - Decontamination:
All equipment must be cleaned and sanitized before fermenting.  The cleaner contains sodium percarbonate (2Na2CO3*3H2O2) which is a white solid that releases the oxidizing agent hydrogen peroxide (H2O2when dissolved in water.

Step 2 - Create the Wort:
The wort is the term used for the mixture that is the unfermented beer.  In our case we first boiled water (4 cups) and mixed the Booster from the kit which consists of dextrose (C6H12O6) and maltodextrins (a polysaccharide consisting of multiple dextrose units).  The Booster provided additional fermentable and unfermentable sugars to the wort.  We also added a packet of Saaz Pellet Hops to give a spicy flavor to the wort.  As the powder is added to the water it forms a cool looking soft crystalline mass and before dissolving completely.

After boiling, we added a can of Linebacker Doppel Bock from the kit which is a gooey mixture of already malted grains and hops.  This is the wort.

Step 3 - Final Mixing:

To the decontaminated fermentation chamber (keg) we added cool water (4 quarts) from the faucet.  The water has to be cool as the hot wort could damage the plastic keg.  You might be tempted to use distilled water or water purified by reverse osmosis but it lacks important nutrients for the yeast.  On that note, however, make sure your water is not polluted and tastes good.  We then added the warm wort mixture and the can of blueberries to the keg holding the cool water.  Next we added more water to the mixture until the total volume was 8.5 quarts.  Finally we added the small packet of dry yeast, stirred the wort, and placed it into to the basement so it can ferment.

Fermentation (what's cooking in my basement):
Fermentation is a metabolic (biological) process by which sugars are converted ethanol and carbon dioxide.  The chemical reactions look like this:

1)  C12H22O11    +    H2O    +     Invertase        =>        2C6H12O6
     (sucrose)                        (enzyme in yeast)              (glucose)

2)  2C6H12O6    +    Zymase        =>        4C2H5OH    +    4CO2
     (glucose)        (enzyme in yeast)         (ethanol)         (carbon dioxide)

According the reactions shown above, one mole of sucrose produces four moles of ethanol and carbon dioxide.

The End! Or until bottling...

wikipedia - Good general info for initial an source.
Maltose Express - Good local source for serious brewing.
GlenRo - Good local source for general info.
Mr. Beer - Good source for info and for brewing without leaving your house.

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