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Hydrophobins belong to the most important proteins produced by filamentous fungi. They are surface active and their foaming potential is due to the presence of particular spatial arrangements of hydrophobic and hydrophilic amino acids. However, their presence eventually leads to overfoaming of beers. In beers and other liquids hydrophobin molecules aggregate around hydrophobic carbon dioxide molecules and form nano-structures, containing entrapped carbon dioxide. By pressure release at opening a bottle of beer, the nano-structures behave as nano-bombs. This explosion causes a sudden release of gaseous carbon dioxide, which is gushing. Several solutions to avoid or to reduce gushing, have been proposed, among which beer pasteurization and the effects of hop components have been studied. This review discusses the nature of hydrophobins, the foaming phenomenon and gushing.

Yeast propagation is an old and well established process in breweries. Yet, development is constantly going on and some questions still remain unanswered. The demand for good brewers yeast can be summarized in the following words: A non-stressed, highly vital and viable yeast that is free from infecting organisms. The road to this goes over a carefully designed sanitary propagation plant with an aeration aggregate that is able to supply a sufficient and adequate amount of oxygen to all cells in the propagator without causing mechanical stress to the yeast cells, and an appropriate propagation wort with the right nutrient composition. No matter how much these parameters are optimized it is, however, still only possible to obtain relatively low cell numbers of around 100–200 million cells per millilitre equivalent to approximately 2.5–5 g dry matter per litre. This cell number can be obtained by consuming only a few degrees Plato. In the case of propagation yeast for re-fermentation not only the cell number is essential, but also the fact that the fermentable sugar in the wort is consumed so that an overpressure is not created in the bottle. In order to avoid loosing time while waiting for the yeast to consume all the sugar another process must be used. The only way to do this, is by learning from the baking yeast industry and perform the propagation in a fed batch reactor whereby the sugar concentration is kept constantly low – though not too low in order to avoid that the yeast grows purely aerobic and therefore may loose some of its fermentation characteristics – during propagation. Therefore, a kind of hybrid process between the traditional brewery propagation and a purely aerobic yeast propagation process seems to be the right solution. The feasibility of this process is discussed.

This paper gives an overview of the research performed at KaHo Sint-Lieven in relation to hop α-acids isomerisation kinetics, utilisation, and beer bitterness stability. It is the intention to present an extensive experimental review on α-acids isomerisation in both wort and buffer model solutions, and to provide a clear insight into important developments and recent findings related to this intriguing topic. In addition, hop utilisation and beer bitterness stability are evaluated as a function of current hopping technologies.

In a competitive environment more and more aggressive on the Wines & Spirits Market, cork bottling for beer is a more and more a strong marketing argument because it is synonymous with tradition while consumers are more sensitive to the products environmentally friendly. But for that, cork stoppers should not make any concession quality criteria (absence of cork taint, no loss of pressure, easy opening) because like all other products intended to the food industry, this material must also meet the requirement of “zero defect” to the final consumer. In this article, the basic specifications of a beer closures are first reviewed and commented upon through REFERENCE corks and DIAM of the Diam Bouchage society.