Particular Features of Hop-Derived Compounds and Beer Quality

Beer quality can be defined in many ways. Combining consumer liking data and trained panel sensory descriptive data, this presentation will present a case study whereby the importance of hops on beer quality is demonstrated. Hop-related descriptive attributes such as "grapefruit" and "piney" aromas as well as bitterness intensity were positively correlated with consumer liking. Furthermore, "DMS" and "sulfide" aroma were significantly, inversely correlated with liking. Having demonstrated the importance of hops on consumer liking, and in turn on beer quality, this presentation turns to where and how hops influence beer flavor quality with an emphasis on bitterness. Naturally, the amount and timing of hops additions during brewing and fermenting influence the intensities of the aromatic and taste contributors from hops which in turn controls the trueness-to-type and the balance/complexity aspects of beer quality. Iso-alpha-acid concentration and, to a lesser degree, analogous types are responsible for the bitterness intensity in beer. Beyond intensity, the nature of the bitterness (for example, fine and fleeting versus coarse and lingering) may also significantly impact beer quality. This is apparent when comparing iso-alpha-acids with rho-iso-alpha-acids or tetrahydroiso-alpha-acids, and may also be important when comparing these compounds against alpha and beta acid degradation products. In addition to alpha-acid-derived bitterness, hop polyphenols contribute their own bitterness, albeit at much lower intensities, plus they contribute to the physical and flavor stability/instability of beer.