There are many different varieties of hops available to the brewer. In addition, hops come in many different forms including leaf hops, pellets, powder, oils, and extract to name a few. Different forms of hops vary with regards to their use and performance in the brewhouse.
Whole Leaf Hops
When hops (i.e., cone hops) are used in their raw or unprocessed form, directly from the bale, they are designated as whole, raw, or leaf hops (Figure 3.3) Although whole hops are not as popular today as in the past, some of the world’s major brewers, as well as some craft brewers, use them in the belief that whole hops provide the best aroma. Brewers who use only whole hops believe hop products cause unacceptable flavor change in the beer. Processing the hops is believed to change the chemical composition and, therefore, the nature of the product.
Hop plugs are used in the United Kingdom as a convenient means of dry hopping cask-conditioned ales and by brewers with traditional hop backs who cannot use powder pellets (Figure 3.4). The production of hop plugs merely involves the breaking up of baled hops, pushing into a die producing a loose, large pellet usually weighing either approximately 14 or 28 grams (0.5 and 1.0 ounces), and packing into vacuum packs to preserve the oil content.
Hop pellets are nothing more than whole hops mechanically processed by removing foreign material, milling in a hammer mill, blending batches of hops together for product consistency, pelleting through a standardized pellet die, cooling, and packing in aluminum-based foil packs (Figure 3.5). The pellets are held together naturally by their own oils, resins, and moisture content. The alpha acid rating (and, if available, the oil content rating) is determined after the pelletizing process. Craft brewers commonly use hop pellets to the exclusion of hop extracts.se, in some products, polyphenols may be reduced or removed completely.
Lupulin powder (pronounced loop-you-lin) is the yellow gland of a hop plant in which the hop acids and the essential oils can be found (Figure 3.6). Lupulin is a fine yellow powder that can be separated out from the green leaves of the hop itself, sort of like pollen from a flower. Lupulin powder produces flavors in beer indistinguishable from those of leaf hops. Lupulin powder provides bitterness and aroma to the beer. The flavor depends on the variety, quantity and time of the addition. Lupulin powder is added to the wort kettle during the boiling process.
Hop extract is a concentrated hop resin that contains alpha acids, beta acids, and essential oils. It’s used throughout the brewing process in place of traditional whole-leaf or pellet hops. One major advantage in using hop extract is improved hop utilization. In the traditional brewing process, where dried hops are added directly to the kettle during boiling, only about 25 to 35 percent of the alpha-acids contained in the hops are utilized as iso-alpha-acids. In the modern brewing process on an industrial scale, the application of hop extracts and their isomers has become more popular. The use of hop extracts allows one to increase the utilization of the alpha-acids to 45 percent, whereas with isomerized extract to 45 to 60 percent utilization occurs.
Hop Oil Products
Pure hop oils usually have a very pale green/yellow appearance. They have been on the market for many years, and give beer hop aroma without imparting any bitterness. Traditionally, hop oils are added to the kettle late in the boil, which is known as “late hopping,” or they are used for dry hopping. Hop oils allow the brewer to reduce the amount of waste products and trub during the boil.
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