The study of biofilms in breweries and beverage operations has been carried out systematically worldwide over a period of about 15 years. In the study, swab samples together with NBB broth (more recently with NBB-AM broth) were used in all operational areas. Direct and indirect contact points and/or operational weak points were the main focus.

Direct contact points involve continuous or frequent contact with beer or beverage. As a result, potential beverage-spoilage organisms may adapt to the beverage and, over time, take on an obligate harmful character. Biofilms in such areas contain predominantly mucigenous acetic acid bacteria. Indirect contact points or weak points without contact with beverages show mainly concentrations or biofilms with ubiquitary slime-forming agents (e.g.

One of the most important pre-requisites for food processing operations in production of high-quality products in perfect condition is strict compliance with good hygiene practice and a tightly organised quality assurance system. By specifying, executing, achieving compliance as well as monitoring all safety measures or monitoring "critical quality aspects" during the whole production process, the consumer is assured of having food which can be enjoyed without reservation. Modern methods involving preventive measures to avoid mistakes are given priority.

In practice, visual and microbiological checks are used to evaluate the effectiveness of cleaning and disinfection routines. Visual checks suffer oftentimes from the disadvantage that they are not sufficiently accurate. 1). 2). ..

The influence of various yeast preservation methods on vitality and beer quality has been investigated. It was found that no relationship exists between survival rates after preservation and vitality of yeasts during fermentation. This is a convincing argument to support the clear distinction between the concepts of viability and vitality.

After it has been observed that the lyophilisation preservation method was unsuitable due to its negative effects on brewing-related yeast characteristics, the practicable method of partial desiccation of yeasts on filter paper is examined in more detail in terms of its influence on taste and taste stability of beers. However, in the case of weizen beers, the tendency was more in favour of the reference beer.

It is important that all direct and indirect factors are taken into account for improving the flavour stability of pale beers on a sustainable basis. These factors range from processing of barley to the cast wort, to fat oxidation and Strecker degradation. In the main, it is also a question of utilising natural malt-based antioxidants, radical scavengers and LOX inhibitors as well as hop-based inhibitors of fat oxidation. The author highlights the most important aspects, also including recent research results.

Reactions and raw materials - this might be a heading describing the two main influences on flavour stability of a beer. Strecker aldehydes can be determined more simply and in larger quantities in aged beer than aldehydes of fat oxidation such as e.g. trans-2-nonenal.g.g...

For the brewer, an important quality characteristic of beer is taste stability (Back et al., 1997). Dalgliesh (1977) spoke of a taste instability as every beer is subject to a natural staling process. As a result of having special constituents, beers are, however, capable of reducing staling processes which are mainly oxidative in nature. Furthermore, brewers are nowadays in a position to keep beer largely oxygen-free right up to the filling stage. This manifests itself in significantly improved taste stabilities.

The discovery of free radicals in beer (Kaneda et al., 1988) was a further contribution to the staling theory of beer. As a result of endogenous antioxidative activity, beers are in a position to prevent formation of radicals. Production of SO2 can be purposely raised.g.

Corrosion effects and deformation related to excess pressure in beer and beverage cans as well as slime or biofilm formation in the pasteuriser can be typical problems arising in the pasteurisation process of cans. Frequently, such problems are a direct consequence of unsuitable water quality and/or wrong process parameters not in accordance with specifications. Very often, they lead to upsets in the filling process.

This was the reason why the VMV Technical Working Group Beverage Cans organised this workshop. Manufacturers of beverage cans, tunnel pasteurisers and producers of water treatment chemicals came with the objective of letting operators in filling operations know the causes for these types of upsets and to contribute to decisions about preventive measures....

A constant supply of recently propagated yeast of uniform consistency and quality is key to maintaining quality in the modern brewing process.

Yeast is produced through a process known as propagation. In its generic sense, propagation simply refers to breeding or multiplying but, in a brewing context, its meaning is much more specific. Here, propagation is the creation of large quantities of yeast culture ready for the fermentation process and, more specifically still, the production of yeast from a single culture rather than a selection of different cultures.
In modern breweries, the accepted best practice is to propagate fresh yeast every max. 10 fermenting cycles. Any and all of these can affect the yeast and, ultimately, the quality of the beer.

Following a brief historic review of stabilisation techniques and the biochemical reaction of haze formation, the pros and cons of various treatment techniques are discussed. Nephelometric titration for predicting stability is also covered. Apart from the stabilisation effect, filtration characteristics and particle size distribution of silica gels in particular are described.

The title of this paper is meant to underline the idea that past experiences shape ideas for the future or, in the words of a former French foreign minister André Malraux, one should remember: "If you want to read into the future, you must leaf through the past."

The past
In addition to smell and taste, the optical impression i.e. Simple clarity was replaced by brilliance. This was in 1983. 4.

The novel Lg-Foam-Tester is an addition to the many possibilities of objectively measuring foam stability of beer. Designed for laboratories, the instrument has now undergone first inter-laboratory tests, the results of which are reproduced below. The instrument offers ease of operation similar to other modern systems while simultaneously being reminiscent of the well-proven Ross & Clark method.

eople in most beer-drinking civilisations regard the foam on a freshly dispensed beer as one of the important external quality characteristics of their favourite drink.

Once the transport (pressure) container has been opened, pressure release causes carbon dioxide dissolved in beer to be set free, and foam is formed prior to or during dispensing.

Taste stability of beer has been and continues to be a topical issue. This is due to the fact that this important quality parameter is still in the optimisation phase, both in terms of analysis and technology.

Taste stability (TS) is seen as the property of a beer to maintain, to the greatest possible extent, the quality characteristics present immediately after filling unchanged up to the point of consumption. As during storage of beer, not only are limited numbers of chemical reactions taking place but complex processes are in train, one is faced here with a dynamic process. A number of substances involved in the process are known which are responsible for an aged flavour. As the term TS has become established, we will continue to use it in this article.

At the 34th Technological Seminar in Weihenstephan, a measuring system was presented designed to provide an insight into the fundamental rheological properties of mash. The measurement arrangement and latest test results are described and discussed. Based on starch breakdown as the basic hydrolysis process during mashing, the gelatinisation and dissolution phases of polymers are visualised with the measuring system as a function of time and temperature. A wet sieve stack for measuring particle size distribution of the grist in suspended state is presented.

Mash is a mixture of soluble and insoluble solid components and water. In the presence of solids, the flow behaviour of mash changes. These changes are a function of, i.a. This is the liquid in which the solids are dispersed.

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