( Beer r...)HPLC/MS/MS Analysis of Bitter Acids in Hops and Beer

Beer represents one of the most widely consumed beverages in the world. Its annual worldwide production, measured in hundreds of millions of hectoliters, is a testimony to its popularity. While there are many different types of beer, all share one underlying characteristic taste, bitterness. Beer derives its bitter taste from bitter acids present in hops that undergo isomerization during the brewing process. In contrast to old traditional processes modern brewing techniques may use hop products such as extracts to achieve greater production volumes and improved batch consistency. In this study, bitter acid composition of different types of beers is presented. The results are grouped by beer type and geographical location. Beer taste degradation with extended exposure to air is correlated to its reduction of bitter acid content. A reversed phase chromatography has been used to separate the hop alpha acids from their isomerized products in beer, API 3000 LC/MS/MS System triple quadrupole mass spectrometer was then used to determine the bitter acid contents. API 3000 system mass spectrometer and a high mass accuracy hybrid QqTOF instrument, QSTAR LC/MS/MS System, have been used to generate fragmentation spectra for structural elucidation of the acids.

Introduction

Hop cones, a crop harvested from a hop plant, contain the bitter alpha and beta acids; n-, co-, and ad- humulones and lupulones respectively. The humulones in particular are widely used in the brewing process to provide bitterness to beer. During traditional brewing, hops are added to a waterextracted barley malt and the mixture is boiled. This process causes the largely insolubl
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