Apart from balancing the sweetness of the malt extract in beer through the contribution of bitterness, hops impart aroma and flavor, reduce the surface tension during the boiling stage, assist in forming a yeast head during ale fermentation and inhibit the growth of bacteria in wort and beer.

Hop plugs are whole flowers that have been dried and compressed into a plug. They are reported to impart a better aroma and flavor than the pelletized hops but you will have to decide that one for yourself. Hop plugs have less surface area exposure to wort and thus are less efficient for bittering, i.e. more of it is required to impart an equal amount of bitterness compared to pellets or extract.

Whole hops are the whole flower dried and uncompressed. They also are reported to impart a better aroma and flavor than the pelletized hops. Again, you will need to make the determination yourself on this one. Whole hops also have less surface area exposure to wort than pellets and are less efficient for bittering, i.e. more of it is required to impart an equal amount of bitterness compared to pellets or extract.

Hop extracts are the liquid bittering essences of hops and are used for convenience in the brewing industry. Some liquid hops extracts are processed with a wide variety of chemical solvents that dissolve the hop resins into solution and chemically "isomerize" alpha acids (to isomerize, means to chemically rearrange the molecular structure of alpha acids so that they are soluble in water and thus impart their bitter qualities.) There are also hop extracts available that are not isomerized. Also the non-isomerized hop extracts do not come into conflict with any German beer purity laws if this is a particular concern of yours. The chief advantage of using the hop extracts, especially for large breweries or where storage space is limited, is that they occupy considerably less space. All hop extracts must be used sparingly and care must be taken that they are well mixed to ensure that they are dissolved.

Hop products keep better when stored in a sealed container (preferably airtight), out of sunlight and at 54 F. Whole hops, hop plugs, and pellets can be put in a mesh bag to avoid the ensuing mess.

AAU stands for Alpha Acid Units and is a measurement of potential bitterness in hops. The percentage of alpha acid in a given sample of hops multiplied by the weight in ounces of that sample. One ounce of hops with an alpha acid content of 1 percent contains 1 AAU, or .01 ounce of alpha acid.

HBU stands for Homebrew Bitterness Units and is another method by which home brewers can determine how much hops to use. Homebrew Bitterness Units equals the percent alpha acid of hops multiplied by the quantity in ounces of hops used. If for example a recipe of a given volume of beer calls for, say 2 ounces of 5 percent alpha acid Cascade hops, it is equal to 10 HBU's.

If your Cascade hops are only 4 percent alpha acid you will know to use: 10 HBU ¸ 4% = 2.5 oz of hops. Or, if you wish to use another variety of hops, say Centennial hops at 10 percent alpha acid, you know to use: 10 HBU ¸ 10% = 1 oz of Centennial hops.

IBU stands for International Bitterness Units. One Bitterness Unit is equal to 1 milligram of isomerized alpha acid in 1 liter of wort or beer or 1 part per million isomerized alpha acid. This is a system of measuring bitterness devised by brewing scientists and is an accepted standard throughout the world. Home brewers usually do not have the sophisticated equipment to measure actual BU's and often use the system of HBU's to closely approximate the desired bitterness in their beer.

The simplest formula for attempting to predict IBU is to use a sliding scale (depending on boil time) as a best-guess for utilization, and use a constant to convert AAU into parts per million. A fairly accurate ballpark figure to use for your homebrewing hop utilization value based on a one-hour boil would be 23-25%, .23-.25 respectively. This translates into: IBU = (AAU x 74.4) ¸ (wort Volume in gallons x Utilization percentage). IBU = (AAU x 74.4) ¸ (V x U). IBU = (5 x 74.4) ¸ (5 x .25) = 18.6 IBU.

Other factors affecting utilization is the pH of the wort. The higher the pH, the greater the isomerization of hop resins. Of course limitations are placed to restrict how high the pH of the wort is in the kettle since we do not want our beer to taste like sh#t. The best flavor is achieved when the wort pH is 5.0 to 5.4. On the other hand a very low wort pH reduces utilization and has other pernicious effects on flavor as well as destroying your chances of forming a good hot break.

From a formulaic or mathematical point of view hop utilization breaks down accordingly: %U(utilization) = (isoalpha acids present ¸ alpha acid used) x 100. If you are following a recipe and the desired bitterness is stated terms of IBU's you can use the following formula to calculate how much bittering hops to use when boiling your wort. (Percentages are expressed as whole numbers, i.e., 15% = 15. Volumes are total volumes for the recipe.) In metric units: Weight(grams) = (Volume in liters x IBU x 10) ¸ (% Utilization x % alpha acid of hops). In English units: Weight(ounces) = (Volume in gallons x IBU x 1.34) ¸ (% Utilization x % alpha acid of hops).

Hop Plugs are whole flowers pressed into ½ oz. plugs. Similar to pellets, these plugs are sealed up immediately, which seals the natural acids and oils. Plugs are generally used as aroma hops and for dry hopping. Dry hopping is adding 1-2 ounces of hops the secondary fermenter. (4-7 days)

Whole Flower Hops are similar to plugs in their use. Hop Flowers are noted for their hop bouquet and are often used in special recipes. All hops sold by Midwest come in oxygen barrier and light barrier bags. All hops are kept refrigerated until the time they are shipped to guarantee maximum freshness.