Around 65 percent of the worldwide produced hectoliters of beer are produced using the high gravity technology - an impressive percentage for a processing method that to date has been ignored to a great extent e.g. by German brewers, in spite of its capability of fully exploiting the fermentation and storage tank area. It can also frequently have a positive effect on the efficiency of the brewhouse and filtration areas.

The main difference of the high gravity method of brewing as compared to the traditional method of producing beer is that the wort is brewed with an extract concentration greatly exceeding 11 - 12° Plato. This increased concentration of extract is maintained during fermentation and storage. A higher degree of fermentation of high gravity wort is thus attained...

The results presented here indicate that, of itself, intracellular trehalose content of yeast is not intimately related to the survival of cells in physiologically unfavourable situations. It can be shown, on the one hand, that trehalose acts as a reserve carbohydrate in starvation conditions. On the other hand, other parameters such as yeast strain, selection of preserving agent, composition of pre-propagation medium, the movement and aeration of cells during pre-propagation and pre-propagation age are found to be of considerable importance for successful preservation. Future investigations should thus be directed more specifically towards the composition of cell membranes.
The most commonly used yeast strain storage method is still to store them on slant agar.g.

Wort boiling on average accounts for 33 - 50% of total heat requirements in a brewery. Large energy quantities (about 55% primary energy) can be saved by adopting measures such as reducing total evaporation and using heat recovery. This is state-of-the-art.

The various boiling systems operated under atmospheric pressure or a slight overpressure, including heat recovery procedures, are meantime technologically mature. Using current practices, these concepts result in gentle boiling (coagulable nitrogen, foam), low DMS level in pitched wort, low thermal stress (TBI) and further reduction in total evaporation (energy saving). The objectives of wort boiling are well known.Altogether, this already evaporates about 1.5%. This is followed by evaporation using stripping (1%) in a column..

The results of tests carried out in a brewery on a commercial scale are reported in this article. The whirlpool temperature was reduced from 98 to 89°C by cooling during casting, resulting in a noticeable decrease in thermal stress on the wort.

Conditions permitting thermal reactions still exist in the whirlpool during hot break separation and wort cooling. In contrast to wort boiling, due to the absence of convection movement, evaporation of volatile substances formed is minimal. Insufficient thermal cleavage of DMS precursor during wort boiling in particular may cause problems during the subsequent hot holding period. Using this method, unwanted aroma substances are expelled immediately ahead of wort cooling (1). This has been confirmed by casting in by-pass without cooling....

Since development of external and internal boilers, it took until the mid 90’s until new methods of wort boiling established themselves. Since then, there has been a rapid development of novel or upgraded boiling systems and boiling processes.

In recent years, rapid advances have been made in the area of wort boiling. A hundred years ago, total evaporation above 16% and boiling times of more than 120 min were regarded as necessary in order to obtain good beers.g. DMSfree;
- formation of colouring agents and reductones;
- evaporation of water to adjust original gravity. This leads to good colloidal stability and minimised haze problems in beer. Savings arise exclusively as a result of reduced total evaporation.
....

During wort boiling, free DMS in wort can be removed by selective post-evaporation. This has advantages for the boiling process which can be run more flexibly. The present contribution describes a new approach and equipment for selective post-evaporation of wort using an internal boiler.

As in all areas, efforts are being made also in wort boiling to optimise the process further. In this respect, special emphasis is placed on the following objectives:
- Improvement of product quality;
- reduction of production costs by improved utilisation of
- raw materials,
- equipment,
- production time;
- investments required for optimisation should be as low as possible.
When changing one value, another value must not be changed so as to be unacceptable.e. ....

The launching some decades ago of closed wort boiling and, soon afterwards, the introduction of low-pressure boiling with a lower total evaporation rate has rerouted conventional atmospheric wort boiling in breweries onto a new track, initiating a novel approach. This contribution deals with details of low-pressure boiling and describes possibilities for energy storage.

The second oil crisis in 1978/79 caused breweries to look in great detail into possible energy savings potential and heat recovery options. At that time, such techniques became very important. After the first oil crisis in 1973/74, the average market price for light heating oil in Germany between 1975 to 1978 was around 24 DM/hl (= 200 DM/t coal equivalent).08 bar (tb = 102°C) to 1.
....

The gentle boiling process goes as follows: Pfannevoll volume is heated to 98°C in the existing copper or via external heating units. This is followed by hot holding 1°C below boiling temperature, either atmospherically or at a slight pressure. The duration of hot holding is dependent on analytically pre-selected parameters. It can take between 50 and 70 min. Hop additions are adapted to suit the conditions in the particular plant. Intensive convection is important during hot holding in order to achieve the desired changes in the wort. This is done in combined mash and wort coppers using the existing agitator, and by means of a circulation unit in wort coppers. "Evaporation" is between 0.3 - 1% depending on copper type. In recent tests, wort was cooled down to 75°C.
....

The problems associated with wort boiling relate, on the one hand, to the fact that a minimum evaporation of unwanted wort aroma substances sets a lower limit on boiling time and that, on the other hand, in spite of relatively short boiling times, an excessive quantity of proteins having a positive effect on foam are still "boiled off". This paper summarises results obtained with a commercial wort stripping system.

The brewhouse equipment has a very important role to play: Classical boiling of wort takes place in "coppers" where energy input formerly was via double bottom heating and, nowadays, via internal or external boilers. 1. This is simply installed downstream of the existing boiling system and integrated into existing pipework. As such, this arrangement is not new. 2)....

The standards which modern lautering systems have to meet are continuously rising. Some time ago, the main focus was on quantity and quality of worts produced. The emphasis is now also increasingly on an improvement in efficiency and, above all, flexibility.

Currently, the most usual situation is to have lauter tuns running 10 brews/d. 12 brews/d are also state-of-the-art, but with somewhat more elaborate equipment. However, this is oftentimes pushing the limits in terms of peripheral equipment. High yields and a low-maintenance, upset-free operation are the basic prerequisites for meeting the exacting requirements.
The new lauter tun has been named Pegasus, taken from Greek mythology. Pegasus is a winged horse which emerges from the Medusa beheaded by Perseus.
....

More than 100 years ago, when kettles in breweries with direct firing with fuels such as wood or coal were state-of-the-art, the fast-moving process of industrialisation was still in full swing. Seen from this angle, the transition to steam-heated kettles can be understood in principle and has been a logical progression. But discussions among brewmasters about the pros and cons of steam boiling were legion at that time.

To quote Franz Rutschmann who called out (1) "Brewers, back to open hearth boiling if you want to get back to tasty, stable, wholesome beers brimming with drinking pleasure", he felt "surrounded by enemies" who argued against open hearth boiling at the October Meeting of the VLB at the turn of the century. This resulted in inadequate excretion of protein......