Effects of Dry-Hopping on Beer Chemistry and Sensory Properties-A Review

Abstract

Dry-hopping is the addition of hops to the wort on the cold side of the brewing process. Unlike standard hop additions, its main purpose is not to produce a characteristic bitterness but to extract as much of the hop essential oils as possible, which are largely lost in the standard hopping process. When dry-hopped, it is possible to obtain a beer with an aroma that is difficult to achieve when hops are used on the hot side of the brewing process. As a result, this process has become very popular in recent years, particularly in beers that belong to the 'craft beer revolution' trend. In addition, the usefulness of this process is increasing with the development of new hop varieties with unique aromas. This article presents the main components of hops, focusing on those extracted during the process. Changes in the composition of beer bittering compounds and essential oils resulting from this process are discussed. This paper presents the current state of the knowledge on the factors affecting the degree of extraction, such as hop dosage, the time, and temperature of the process. Issues such as process-related physicochemical changes, hop creep, low flavor stability, haze formation, and green flavor are also discussed.

Keywords: beer; dry-hopping; essential oils; hop creep; hop resins.

Figure 1

Schema of the oxidation of α-bitter acids and β-bitter acids to humulinones and hulupones, respectively [20,26]. Prefixes n-, co-, ad-, pre-, and post- are identical for various analogs of both humulones and lupulones and are determined by the structure of the acyl side chain (R), which is presented below the figure.

Figure 2

Chemical structure of the most important compounds present in hops [26,37,38,39,40].

Figure 3

Chemical structure of the most important esters present in hops [40] PubChem database.

Figure 4

Chemical structure of the most important esters present in hops [37,38,39,40].