{Reference Type}: Journal Article
{Title}: Comparison of α and β-acid isomerization in hops and beer using HPLC, confocal microscopy, spectrofluorimetry and chemical analysis of metabolites and essential oils in flowers of different hop cultivars produced in Brazil.
{Author}: do Nascimento FMG;Trevisan MTS;Neto MLA;Owen RW;de Brito ES;Alexandre E Silva LM;Rocha KAD;Cesar CL;de Carvalho HF;Pelegati VB;da Silva SA;Marques SPD;
{Journal}: Food Chem
{Volume}: 455
{Issue}: 0
{Year}: 2024 Oct 15
{Factor}: 9.231
{DOI}: 10.1016/j.foodchem.2024.139879
{Abstract}: We used confocal microscopy and spectrofluorescence to characterize the emission spectra in hop flowers, to follow the isomerization processes in different hop preparations, and beers, to compare with HPLC extracted samples. Flowers of different hop cultivars produced in three regions of Brazil, were quantitated by HPLC and GC-MS. The fluorescence spectra showed two characteristic emission bands evaluated from different preparations. The isomerization process leads to a gradual decrease in fluorescence intensity as the reaction progresses. This demonstrates the valuable use of confocal microscopy and fluorescence spectroscopy for analysis of the correlation between bitter acid indices with fluorescence intensity and lifetime microscopy. Such techniques can be used directly in the flowers allowing rapid monitoring of the brewing process. Twenty-nine substances were characterized in the essential oils and some cultivars presented quantities of bitter acids and essential oil levels close to those expected for plants after more than three years of cultivation.