Beer Basics, III

In Beer Basics I, I mentioned wort a couple times.  Wort is the water-based, starch-infused liquid that is the foundation of a beer.  It is the barley-starch tea to which yeast and hops are added, the yeast to convert the sugar to alcohol and the hops to flavor and bitter the beer.  Producing good wort is the important first step in the brewing process.

A grain, traditionally barley, is made to germinate by soaking it in water, and then the newly germinated kernels are quickly dried.  The dried, germinated grain is called malt, and the malted grain is milled/ground to fine particles.  Most brewers buy the milled malt they will use, though some are growing, malting and milling their own grain (and growing their own hops) to create “Estate Ale.”  The milled malt is added to heated water, thereby releasing the sugars from the malt into the water.   That barley-sweetened liquid is the wort.  No alcohol yet – just water sweetened and colored by malted barley.

The color of the wort will be determined by the color of the malt, which in turn is determined by the type of grain(s) used and to what degree the malt was roasted.  The grains most commonly used in craft brewing - barley, wheat, rye and oatmeal - all impart different coloring to the wort, and each grain has lighter and darker varieties as well.  Extensive roasting tends to darken the malt.

A hydrometer is often dropped into the wort to get a reading of its density, which is the first step in determining the amount of sugar in the mixture.  The amount of sugar in the wort prior to fermentation (prior to the addition of yeast) is commonly referred to as Original Gravity (OG) or Original Extract (OE) and is expressed as Degrees Plato (°P).  By knowing how sugary the wort is, the brewer can get an idea of how much alcohol can be produced because it is the sugar that will be converted into alcohol by the yeast.  The higher the Original Gravity, the "bigger" the beer can be (the "size" of a beer is a reference to its alcohol content). In other words, Original Gravity is an indication of the alcoholic potential in the wort.

More technically, Original Gravity, determined by use of a hydrometer, is a measure of the density of the wort, and from that measurement the Original Extract (amount of sugar/potential alcohol) can be calculated.  The Original Extract is the grams of sugar per 100 grams of wort, usually expressed as Degrees Plato (°P).  

Microbreweries often post the "Original Gravity" of their ales, though Original Extract is more likely what they mean.  Check it out next time you are at a microbrewery or reading the label of your favorite bottled brew.  Now you'll know that they are trying to tell you about the sugar content of the wort.  

There will usually be a close correlation between the °P (Original Gravity/Extract) and the Alcohol By Volume (ABV).  But I'm getting ahead of myself.  We'll get to alcohol production - fermentation - in Brew Basics, IV.