Extração, identificação e isomerização de alfa-ácidos em Humulus lupulus L.

Abstract

The application of hops to beer imparts a bitter flavor, characteristic aroma and stability to the beer. With several types of hops grown, it is possible to create a wide variety of beers. Beer, being one of the most consumed drinks today, has a high social and economic character. Aiming for more sustainable ways in its manufacturing and production, a lot of research is done to improve product quality. Hop planting is improving to meet a greater demand for its use. Therefore, research is studying ways of growing this plant in other climates around the world, considering that the ideal climate for planting hops is with well-defined seasons. The subject of hops is diverse in the industrial sector, being used in health, cosmetics and food. In the beer manufacturing process, hops are added at the end of the boiling process and are associated with bitterness and foam stability. When added during the beer cooling stage, it becomes associated with the aroma as well. The alpha-acids present in hops are the classes of compounds that generate bitterness in the drink. Renowned companies in the chemical analysis sector manufacture specific equipment for quantifying iso-alpha-acids. This quantification of bitterness is given in the IBU (International Bitterness Unit), this unit tells us how bitter the beer is. Its value is not given through calculations related to alpha-acids and their isomerization process that occurs in beer during the heating stage. The present study aims to isolate and isomerize alpha-acids, which are the components responsible in hops for imparting the bitter taste. Thus, through procedures such as obtaining hop extract in hexane solvent, separation of alpha-acids by supply and isomerization of alpha-acids when heated with an available solution, it was possible to achieve overwhelming results. Thus, according to the analyzes carried out by HPLC-EM, ¹³C NMR and TLC in the present work were essential to characterize the alpha-acids and iso-alpha-acids by ¹³C NMR, in order to define characteristic peaks that enable the qualification of samples that contain these compounds.