The bitterness and sweetness balance of a beer is a complicated balance to achieve. While these two tastes are each perceived by different receptors on the tongue, the careful combination of these two create a balance. Too much sweetness without bitter will be perceived and cloying, and too much bitterness without sweetness will taste soapy. Yet balance these two perfectly on the teeter-tottering see-saw that is beer and the two will be better than either on its own.
Adding high dextrin malts like Caramel or Crystal malts will leave the beer with a higher final gravity. Steeping crystal malt after the mash will produce 25% less ferment-able sugars. (1) This not only give the beer a thicker mouth feel, but also adds to the final sweetness of the beer. High final gravity can also be achieved by mashing at higher temperatures. For every degree Fahrenheit above 155 the final attenuation of the beer is lowered about 2 percent. (2) In general 1%-2% is normal to add color to a beer. 5% will add noticeable sweetness and caramel taste. 10% can easily be too much if not balanced with hops, or keeping the Chlorine ions low.
On the bitterness side the most apparent factor is the hop level measured in IBU's. The bitterness from hops can easily be adjusted during the boil of the brewing processes by changing boil time and amount of the hops. After the wort has cooled, the gravity sample can be tasted and dry hops can be added to further adjust the flavor, but because the wort will be high in sugar content at this time it may be hard to judge if more bitterness is needed. Keeping the IBU’s around 20 will make most people happy although light beer drinkers may prefer less than eight. If less sulfates are in the brewing water the IBU value can be higher without tasting harsh.
After fermentation is complete most of the sugar will have changed to alcohol. Higher alcohol content will mask some of the sweetness of the beer. Have you ever tasted a cocktail mix without the alcohol? They are extremely sweet, yet when the alcohol is added they taste much less sweet. The ABV to sweetness balance works it’s self out pretty well in beer because the alcohol content is directly proportional to the amount of sugar that is converted. So bigger beers have more final sugar, but also have more alcohol to balance it.
Before bottling the bitter sweet balance can be adjusted using salts. It's very easy to overdo it here. Remember these are called brewing SALTS, and if overused you will have beer that tastes … well… salty! One half a teaspoon of salt in a five gallon batch is normally plenty. Sulfates (SO4) will enhance the bitterness while chlorates (Cl) and sodium (Na) will enhance the sweetness. Sodium can often cause a metallic taste in the beer so common table salt (NaCl) is often not used in beer. There are a number of good sources online that can be found by searching for “brewing water chemistry.”
The final adjustment to balance is carbonation. The higher the volume of CO2 dissolved in the beer the more bitter the beer will taste. If you compare a flat soda to a carbonated soda the difference in taste is very apparent. Although CO2 content does play into the bitter sweet balance it is likely the least noticeable. Considering it for taste should be secondary to mouth feel and style.
Finding this balance can take time. If you are starting a recipe from scratch it is easy to miss your mark by a mile. If you start with a reliable recipe you are bound to get good results.
(1) See post from nilo on Homebrewtalk.com 03-09-2011, 11:55 PM http://www.homebrewtalk.com/
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