Μεταβολή χρώματος και πικράδας κατά την παλαίωση του ζύθου

Abstract

In recent years, the brewing industry has focused on continuous research and development related to the improvement of bitterness, colour and the aromatic profile of the products produced. The main objective of this research is to revuew the raw materials used in beer which through various processes it is possible to give multiple combinations of organoleptic characteristics. As a result, there are several different products that can even satisfy the most demanding consumer. In the present study, the change of colour and bitterness of beer was observed during the aging process of the beer. One of the most basic ingredients of beer is hops. Hops is a herb consisted of several components which are gradually released upon boiling and are therefore responsible for the bitterness of beer. However, during the aging of beer, hops are affected due to oxidation during storage and has a direct impact on its shelf life due to the oxidation of acid bonds which in the case of aged hops, leads to a cheesy odour. As beer matures and depending on its storage conditions, it undergoes through many changes. Most of these changes are related to the deterioration of sensory characteristics, especially in its taste or aroma. These changes as well as the appearance of opaqueness reduce the overall shelf life of the beer. Most of these factors have been taken into account: opacity, for example, occurs in beer that is high in protein and tannins. Moreover, another important ingredient for the production of beer is malt. Malt consists of starch, which during the mashing process releases sugars due to the enzymatic breakdown. During this process, an extract is retrieved which ranges from light blonde to dark brown. This extract is what can determine the colour of the beer. This prementioned malt extract consists of invert sugars, glucose, maltose, fructose and amino acids, peptides and proteins. During the boiling process of the malt extract, pigments (melanoidins) are formed mainly due to the Maillard reaction, where the carbonyl group reacts with the amino acids that form a complex mixture of molecules which therefore give the dark colour and aroma.