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The Influence of Hop Harvest Date on Hop Aroma in Dry-Hopped Beers

MBAA TQ doi:10.1094/TQ-46-2-0409-01  |  VIEW ARTICLE

Benjamin Bailey (1), Christina Sch�nberger (2), Georg Drexler (2), Andreas Gahr (3), Rebecca Newman (4), Moritz P�schl (5), and Eberhard Geiger (5). 1. MillerCoors, 2525 Wayne Madison Rd., Trenton, OH 45067-9760. 2. Joh. Barth und Sohn, Freiligrathstr. 7/9, 90482 N�rnberg, Germany. 3. Hopfenveredlung St. Johann, Mainburgerstrasse 15, 93358 St. Johann, Germany. 4. Boston Beer Company, One Design Center Place, Ste. 850, Boston, MA 02130-2315. 5. Lehrstuhl f�r Technologie der Brauerei II, Alte Akademie 3, 85350 Freising-Weihenstephan, Germany.

Abstract
The aim of this work was to investigate the influence of hop harvest date on the sensory properties of a dry-hopped lager. The selected harvest dates encompassed a period of 24 days, from a very early (date 1) to a very late (date 5) harvesting date. Analysis of the hop samples confirmed an increase in hop oil and alpha-acids over the harvest season. On average, the alpha-acids contents of hop samples from date 5 were 28% higher than those from date 1. The hop oil contents of hops harvested on date 5 were on average 30% higher than those harvested on date 1. This increase over the harvest season is not only of importance for brewing and dry hopping but is also an economic factor for breweries. Not only were the late-harvested hops rated better in aroma quality, the beers brewed from them were also rated better when late-harvested hops were used. Profiling of the beers showed that some hop characters developed with later harvest dates, while other characters decreased with later harvest dates. The beers containing hops harvested at later dates were also rated better when using a modified version of the DLG tasting scheme, which did not focus on hop characters but on the fulfillment of general beer parameters, including aroma, taste, body, and bitterness. Triangle tests of the beers revealed that not only the harvest date was a significant influence on sensory distinguishability but also the crop location. This was proven for all four crop locations, although the distance among the locations was only 1.2�24 km. These findings reveal the sensitivity of dry-hopped beers, as many of the characteristics of the raw hops used were transferred to the finished beers.

Keywords: dry-hopping, hop harvest date, hops, sensory evaluation 

S�ntesis
Se investig� la influencia de la fecha de cosechar el l�pulo sobre las propiedades sensoriales de un �lager� con lupulado seco. Las fechas de la cosecha estuvieron separadas por 21 d�as, desde una fecha tempranera (d�a 1) a una fecha tard�a (d�a 5). Los an�lisis de las muestras de l�pulo confirmaron que los alfa-�cidos y los aceites del l�pulo aumentan durante la �poca de la cosecha. El contenido de alfa-�cidos de las muestras del d�a 5 fue, en promedio, 28% mayor que el del d�a 1, mientras que el contenido de aceites en el d�a 5 fue 30% mayor que en las muestras del d�a 1. Este aumento durante la �poca de la cosecha es de gran importancia para cervecer�as en general, y especialmente para el caso de un lupulado seco, por ser adem�s un factor econ�mico. No s�lo se obtuvo un aroma de mejor calidad en las muestras tard�as, sino que tambi�n se evalu� mejor a las cervezas con l�pulo tard�o. Los perfiles sensoriales de las cervezas mostraron que algunas caracter�sticas del l�pulo aumentaron mientras m�s tarde la cosecha, mientras que otras caracter�sticas disminuyeron. Las cervezas con l�pulo tard�o tambi�n fueron evaluadas m�s alto cuando se us� una versi�n modificada del esquema sensorial DLG; este esquema no se enfoca en las caracter�sticas del l�pulo en la cerveza sin� en la buena realizaci�n de par�metros generales de la cerveza, tales como aroma, sabor, cuerpo y amargor. Las pruebas triangulares mostraron que no s�lo la fecha de la cosecha afecta la capacidad de distinguir entre cervezas, sino que tambi�n influye el sitio de la recolecta. Los cuatro sitios de recolecta mostraron diferencias aun cuando s�lo se distanciaban por 1,2�24 km. Este estudio demuestra la alta sensibilidad de cervezas con lupulado seco, puesto que muchas de las caracter�sticas del l�pulo crudo fueron transferidas a la cerveza final.

Palabras claves: evaluaci�n sensorial, fecha de cosechar el l�pulo, lupulado en seco, l�pulo

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