BEER BOTTLING There are two main methods of bottling beer. In the first, the older and simpler method, the beer is at a certain age after casking merely run into a bottle, stoppered and stored. During storage a slight fermentation takes place in the bottle and these beers have a sediment due to the yeast thus formed. These are called "naturally conditioned beers." In the second method, beer in bulk is surcharged with carbonic acid gas and filtered into bottle, so that there is no sediment. These are the so-called non-deposit beers ; this latter class now forms the majority of bottled beer.
Naturally Conditioned Beers.—Naturally conditioned beers form the higher class of pale ales and stouts. The beer is matured in cask before bottling, and this, with the subsequent fermentation in bottle, produces a character which is frequently absent from the non-deposit beers. The production of these beers requires more technical skill in obtaining just the right quantity of gas in the beer as sold. They require more careful pouring out and there is a certain amount of waste. These points militate against their popularity.
Non-deposit Beers.—The methods of treating the beer before filtering in order to surcharge it with carbonic acid gas vary widely, but most methods involve chilling the beer to a low point. The three methods most practised are as follows : (1) The beer is run into a tank where wort or sugar solution (priming) is added; the tanks are then sealed so that the gas formed by fermentation of the sugar produces considerable pressure ; the beer is then transferred to other tanks in a cold room, where it can be chilled to about 3o° to 32°, when matter of a proteid nature comes out of solution and most of the carbonic acid gas is entirely dissolved. The beer is then forced, either by means of air or carbonic acid gas pressure or pumps, through a filter of pulp of cotton fibre straight into a bottle filling machine. Instead of forming the carbonic acid gas by fermentation, the beer is chilled and the gas is introduced artificially and mixed with it under pressure ; the beer is then stored for a period of varying length before being passed through the filter and bottled. (3) In this method, the beer is brought to a low temperature rapidly through a tubular or other form of cooler, carbonated, and filtered and bottled at once. There are many variations in details of these methods, but the general opinion is that conditioning in tank by fermentation and long storage after chilling gives rather a better flavour and the beer remains longer in bottle without throwing any deposit.
The lay-out of the bottling plant has to be very skilfully arranged to keep down the number of operators required : three operators for a 120 dozen per hour unit and six for a Soo dozen unit is the minimum that can be attained.
The pasteurizing of bottled beer is common on the Continent with lager, but it is not practised in England to so great an extent; it is, however, gradually coming in. Where it is used the pas teurizer is connected up with the bottling unit between the crowner and labeller. The pasteurizing process consists of heating the bot tled goods up to 140° to 150° for 20 minutes and the process has to be gradual to avoid undue breakage. The simplest form of pasteurizer is a shallow tank of water with a false bottom and heated by steam coils, but tanks in series of increasing tempera tures are used, and also sheet-iron cabinets in which the bottled goods are placed on trays and then submitted to heavy spraying with water gradually heated to the temperature desired.
The tanks used for conditioning and chilling beer are made of glass-lined steel, copper, aluminium or even iron coated with spirit enamel. The first named is the favourite, but when beer is chilled rapidly and in comparatively small quantities, copper is the favourite material. For carbonating, many brewers use the gas collected from their own fermentations which is brought under pressure in large containers made of boiler plate; others buy the gas liquefied in tubes.