Determination of α- and β-acids in hops by liquid chromatography or electromigration techniques: A critical review

Hop plays an essential role in brewing beer and its study and analysis is of paramount importance. - and -acids are considered two of the most important hop components. While -acids are associated with the bitter flavor, -acids have antimicrobial effects. This work aims to critically review the published analytical methods for - and -acids determination in hops employing separation methods in liquid medium: liquid chromatography (LC) and capillary electrophoresis (CE). The types of hop samples, the optimized protocols to extract the hop acids, and the main instrumental conditions for both LC and CE techniques are highlighted and discussed. Specific and critical aspects of the - and β-acids separation by LC and CE and some challenges in this field are raised. Several key aspects discussed in this review may be of practical importance for brewers, whether in the microbrewery or industry and for researchers in the brewing field.

Evaluation of craft beers through the direct determination of amino acids by capillary electrophoresis and principal component analysis

The composition of beer wort in terms of amino acid (AA) content affects the final product quality, once it is related to the vitality of yeast during the initial exponential growth phase and throughout fermentation. The objective of this work was the use of a capillary zone electrophoresis method with UV-vis detection in association with Principal Component (Data) Analysis for craft beer classification. Cysteine, histidine, phenylalanine, lysine, tryptophan and arginine were the monitored AAs in wort and finished beer, which were extracted through cation exchange resin. Good differentiation among samples according to their production was obtained, showing a profile of AAs (<LQ-99 µg mL^-1) for each wort, which can be used as indicator of the quality of a beer. One of the samples had the mashing step monitored, showing an increasing profile in the concentrations of AAs (6.5-55 µg mL^-1), which can be explained by the protein cleavage.