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.
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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.
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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.
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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.

Is it necessary to remove the cold break? If this is answered in the affirmative, is complete separation recommendable? This paper provides new answers which have been established in commercial brewing tests.

In a first step, hot break was removed. After the wort had been cooled down in the coolship to about 15 - 70°C depending on the season, the hot break was whirled up again and sedimented, precipitating the cold break meantime formed. Hot break is also removed from hot wort in modern plants for wort preparation, mostly in the whirlpool. It is accepted that this is necessary because hot break smears the yeast during fermentation and adversely affects the beer, both in terms of taste and foam properties.g. in the starter vessel.
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As a consequence of redesigning wort boiling, wort and beer quality as well as uniformity of product could be improved. Simultaneously, it was possible to reduce total evaporation, resulting in energy savings.

Before Rosen Brewery in Poessneck/Germany redesigned its brewhouse, wort was boiled atmospherically in an iron kettle. Boiling intensity was a function of atmospheric air pressure. It was thus practically impossible to achieve uniformity of product. Moreover, energy was not recovered.
The Nerb company and Dr.-Ing. Breywisch Engineering (1) were responsible for redesigning wort cooling. An external heating unit or calandria, a flash evaporator with a vacuum pump and an evaporative condenser with hot water reservoir were added to the iron kettle.
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A number of additional items have to be considered when producing wheat beer using bottle fermentation in order to avoid calcium oxalate in the bottle. The basic principle of almost complete precipitation of oxalate by having enough calcium present (as described in part 1) no longer applies here.

Part 1 of this paper described ways of calculating the correct wort calcium concentration required for inducing sufficient precipitation of oxalic acid in the form of calcium oxalate in the beer after storage such that no further precipitation will occur after filtration.
- bottom worts: 45 - 55 mg of calcium/l,
- top worts: 50 - 60 mg of calcium/l.
CaCl2 or CaSO4 can be added to brewing liquor to reach this calcium concentration in the wort. In high-gravity brewing e.g.
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Whenever gushing in beer has been discussed in recent years, the blame was placed mainly on the mould fungi Fusarium graminearum and Fusarium culmorium. When commenting on the phenomenon at the "Gräfelfinger Praxistage" conference in 1999, Dr. Fritz Schur, Managing Director of Doemens Training and Research Institute, made it quite clear that over 99% of gushing is caused by calcium oxalate precipitation in the beer.

What is determining is the solubility product L’ of calcium oxalate
L’ = [Ca++] . [C2O4- -] in mol2/l2
More recent investigations have shown that, owing to the presence in wort and beer of other dissolved substances, e.g. the chelating agents peptides, amino acids, gelatines, etc. But in Dr. "Weizenbier" from bottle fermentation is particularly at risk.
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