MEETING OF THE SCOTTISH SECTION HELD AT THE CALEDONIAN HOTEL, EDINBURGH, On Tuesday, 18th January, 1938
The following paper was road and discussed:—
FEATURES OF BREWING SYSTEMS OBSERVED IN AMERICA
By Prof. R. H. Hopkins, D.Sc, F.I.C.
Brewing, as practised in post-prohibition times in the United States, has been described
by Gusmer and Hind (this Journ., 1937,415). This communication is not to be regarded
as other than supplementary to that paper.
American ale brewers have to supply a product differing somewhat from the ales brewed in this country and they have been forced to pay special attention to certain parts of their processes, such as the carbonation and filtration of the ale. Inasmuch as this is so, the efforts of the American brewers and plant manufacturers to meet the exacting standards of the consumer in certain respects are, or should be, of considerable interest to the British brewer. It is, however, mainly in the realm of plant and equipment that there is most to be learnt.
The American brewer in the Eastern and Middle Western States has at his disposal, for his main domestic supply, two raw materials which differ considerably from those used by the British brewer. Firstly, his barley is of the Manchurian six rowed type and contains upwards of 2 per cent, of nitrogen. Thus the average figures for mid-western grown barleys of the 1935 and 1936 crops were 203 and 2·06 per cent, respectively, whereas the corresponding figures for Californian barleys were 1·41 and 1·44 respectively. These are official figures and presumably refer to the normal (not moisture-free) samples. Secondly, his hops possess in varying degrees well known characteristics such as are associated particularly with Oregons. With these materials constituting by far his cheapest and most available supplies he has to furnish the consumer with products which differ from those normally in demand in Europe. The American beer drinker requires above all an ice-cold, thirst-quenching beverage of mildly stimulating character, which must also be perfectly brilliant. It must therefore be chilled virtually to freezing-point before filtration and carbonated under pressure. Conditioning as we know it is inadequate and artificial carbonation essential.
An all-malt brew with richly nitrogenous malt would yield a beer with a satiating flavour and difficult to obtain brilliant when, served ice-cold. The use of a high proportion of maize or rice is the means adopted of overcoming this difficulty, although sugars (glucose and invert) are used in some cases. The exceedingly high diastatic powers of the malts used, varying from 80° to 180° Lintner are of no disadvantage, being associated with the high nitrogen-content of the barley rather than under-curing or defects in malting. The starch conversion in mashing is most probably not much affected thereby, and even if there are formed a little more maltose and less of the type of “malto-dextrins” which are fermented during conditioning, this is of no account since condition almost always depends on carbonation.
Californian barley is not liked and its malt is considered not to blend with ordinary American malt.
Malt is in some cases conveyed to the brewery in large cylindrical drums mounted on lorries, it having been introduced pneumatically by means of a pump affixed to the front of the drum. The malt is sucked into the drum at the back, the drum sealed, and on its arrival at the brewery the process is reversed and the malt forced to the conveyor.
Mashing. Infusion mashing as practiced in Great Britain, i.e., one temperature being
maintained more or less exactly throughout the mash, is comparatively rare. For bottom
fermentation beer naturally a decoction mash is employed. For ale, if a genuine ale brewing is performed, it is usual to proceed by infusion at a low temperature followed by raising the temperature by means of steam coils or by running in the contents of the maize cooker. A stand for “protein rest” or peptonisation is often made. However, in one or more cases in which the infusion is performed at one temperature only, the liquor was preheated to the desired mashing temperature, about 150° F., and maintained at this in a “Lauter tube” by blowing steam through it whilst the grist was introduced without an external masher.
In one brewery malt conveying, weighing, grinding, dust collecting, and decoction mashing and mash filter operations were subject to an impressive system of centralized control. Operations are confined to pushing buttons or turning switches mounted on a single control panel. Capacity gauges for liquor backs are read on this board for control of mashing. Pilot lights and “blinkers” indicate which vessels or parts of plant are in use. It compares with the Institute of Brewing’s Experimental brewery on a large scale. It was installed by Shock of Shock, Gusmer Inc. He was indebted to that firm for the film of cask-washing, and also for the photos of lauter tubs, which show the series of knives suspended from rotating arms of the machine. These knives are set at right-angles to the line of the arm for stirring operations and in line with the arm for sweeping out the spent grains, the respective motors driving at appropriate rates for these purposes.
Boiling is usually performed in a closed copper (“kettle”) heated by a central coil or calorifier, which in some cases is rotated, supplemented by either fixed coils up the walls or a steam jacket. The latter serve to keep the wort at a simmer while the vessel is filling up. The central coil is put into action when violent boiling is desired, and may be turned off at the time of the last addition of hops about twenty minutes from the time of discharging the copper. The idea, of course, is to withhold some of the hop oil. In one brewery the last hops to be added are previously broken in a machine, the seeds and stalks being removed. In the Bureau of Plant Industry, U.S. Department of Agriculture at Washington, Babak has been investigating the contribution made to the wort by the various parts of the hop. Seeds contribute useless extractive matters, and a little of the fatty oil which constitutes about 24 per cent, of the seed is liable to gain access to the wort. It has a “rancid odour and an extremely unpalatable and persistent bitter taste.” The leaves and stems also contain soluble extractive matter which enters the wort and is of undesirable flavour. Samples of commercial seeded hops from Europe and America were analysed for the proportions of seeds, stems and leaves, and whilst inevitably great variations were found, the proportion of seeds averaged 10 per cent., of leaves 4 per cent., and of stems 1 per cent, for American hops, but European hops contained less leaves and more stems. Machine picked hops were markedly superior to hand-picked, containing 1·37 per cent, of leaves plus stems, whereas European hand-picked hops contained 3 per cent, and American hand-picked over 4 per cent.
The separation of the hops from the wort is sometimes effected by the hop back, but often a hop strainer is employed. This is either a vertical or horizontal cylindrical vessel, steel or copper, within which fits a basket made of slotted metal. Often the latter rotates. As compared with a hop back, the wort passes much more rapidly through the strainer, and is considered to extract less bitters, but on the other hand carries with it through the side walls fragments of hops, coagulum, etc. Only experiment can decide how far, if at all, this rapid removal of hops is of advantage, and most British brewers will, no doubt, prefer a good filtration at this stage. Many factors are affected, not only extraction of bitters from the hops, but of tannin which helps to form sludge and later, haze; the carrying forward of more cooler sludge to the fermenters with its attendant effects on the flocculation of the cold coagulum, on adsorption of hop bitters and on the progress of fermentation. In one brewery, however, the wort was later passed through a fine strainer at the bottom of the deep wort receiver. In some breweries a hop strainer is used which squeezes and ejects the spent hops to a conveyor. Power driven scrapers do away with the necessity of men entering the hot vessel.
Cooling. Either shallow open coolers or deep wort receivers are used. In one brewery seen the wort passed directly from the hop strainer to the refrigerator. The refrigerators are of two types. Firstly the Baudelot or Morton type. In lager breweries the lower pipes are cooled by direct ammonia expansion, not by brine. The straight type is preferred to the wavy one. New patterns are appearing, in one of these a number of vertical refrigerators are disposed as the leaves of a book, being hinged to a heavy strong vertical suspension member, or wall supported. When the wings are “closed,” as in use, they stand over the wort-collecting trough, and are surmounted by a distributing trough and double inclined strainer which feed the wort evenly to each cooling surface. Thus the wort is roughly filtered through the strainer, this removing coarse particles which might block the grooves which feed the cooling surfaces, and giving aeration. It then passes on to the flat distributing trough, through the perforated grooves set in line with the refrigerator surfaces. The spacing of the wings is designed to give currents of air rising between them. For cleaning, the distributing trough and strainer are removed and the wings opened. The whole is made of stainless steel.
Secondly, the wort may be cooled in an “enclosed cooler ” which closely resembles the counter current chiller employed in Great Britain for chilling beer. The internal pipes through which the wort passes are roughly 2 in. in diameter, the jacket, containing in the respective parts cooler water and ammonia, is about half an inch or so in width making about 3 in. in all. Apparently flocculation is as good in the enclosed cooler as on the open vertical refrigerator, but definite experimental evidence was not available.
Fermentation. In lager and sometimes in ale brewing, the fermentation is started in one vessel and the wort run or pumped into another (the fermenter) at a suitable stage, leaving the sludge and some yeast behind. This—with ale—is virtually the dropping system. Pure yeast plants are maintained and resort mode to them from time to time even in many ale breweries. Fermenting vessels for ale are often made of wood. Gloss enameled vessels, linings of aluminium, patent enamels, mammut, waxes and the copper silicon alloy “Everdure” were seen.
One wax did not stand high enough temperatures for effective sterilisation, whilst it exhibited scratches from the cleaning brushes. The ale yeasts always looked exceedingly healthy, and no complaints of “yeast weakness” were encountered. A large aluminium skimming board, which could be lifted by two men, with small wheels which run on a flange at the sides of the vessel with a frictionless action, was able in one case to skim a very large vessel in twenty-five minutes.
Storage Vessels. The fermented ale or beer is run into large storage vessels with or without some cooling and a primary carbonation. These vessels were often of concrete and often have cork layers outside to insulate. The preparation and lining of concrete vessels has developed considerably in recent years. The application of a mixture of, for instance, cement and powdered glass followed by “Rostock” of thin consistency was followed by scraping off, leaving a rough surface to which a subsequent layer of the same materials would adhere more closely. Slow cooling after this treatment was necessary to avoid cracking of the vessel. Alternatively “Ebon” is applied hot to the roughened prepared surface. Another device is the use of “tar” paper to prevent the alkali from the cement from attacking the layer of resinous preparation of one half inch thickness or more which is applied afterwards.
In two breweries seen the working aisles were separated from the remainder of the storage tank cellar by walls enclosing the spaces between the tanks, thus exposing only the parts outside the head joints. These walls were tile faced. Cleaning is reduced, the unexposed portion need not be cleaned in the normal routine, and the aisle needs less refrigeration than the rest of the cellar.
Filtration.—For filtration the use of diatomaceous silica is being developed as an improvement on ordinary commercial kieselguhr. This takes out much of the hazy matter and greatly lengthens the life of the pulp filter which follows it. Diatomaceous silica is the fossil remains of diatoms, minute marine plants, the particles being like tiny sponges. It is pre-coated on the filter cloth or fine metal screen, and as filtration proceeds, more of it is continually injected and mixed into some beer which is by-passed through a slurry tank. This is to prevent the filter surface from becoming plugged by slimy matter. Thus while the beer filters the filter cake grows and the slimy matter is kept dispersed through the porous cake. About 10 lb. of material is required for pre-coating 100 square feet of filter area, and the system can be operated in a number of types of filter already on the market.
In bottling there are appearing an increasing number of devices designed to secure the minimum of air in the bottle or can at the time of sealing. These include injection of gas into the beer just below the surface, or tapping the side of the bottle or can, either of which causes the foam to rise, this being timed so that the foam is just exuding from the neck when the crown-stopper is forced on. Bottles or cans contain normally less than 2·5 c.c. of air per standard 12 oz. of beer. Such resist haze formation and pasteurisation flavour fairly successfully.
The short bottle “steinie” (but not the “stubby”) will, according to some, ultimately beat the can; but others hold that as the lining of cans continues to improve, canned beer automatically packed and sealed in cardboard cartons will prevail in America, and that wooden boxes for beer will soon cease to exist. Much the same view is expressed regarding the steel or metal keg, lined with pitch or resin for the cask trade.
In a paper read before the Master Brewers’ Association in October, 1937, H. S. Ellington mentioned some interesting trends in brewery design and construction. Of these the use of glass bricks in structural parts where the introduction of diffused light would be of advantage, and of ceramic glazed blocks or wall units to cover old rubble walls instead of plaster or painting were of note. Improved cement compositions for floors required to bear heavy loads, aluminium bronze or other metal window frames to replace wood have made their appearance.
To sum up, the main problem of producing a beer or ale capable of being served at 40° F. or lower whilst in a brilliant and gassy condition has been solved by paying attention to the following points: the use of maize or rice as malt adjuncts to the highly nitrogenous malt, peptonisation during the mash, successive carbonations after fermentation, these also helping to eliminate oxygen, the use of carbon dioxide counter pressure in storage, filtration and bottling, new devices for nitration, chill proofing treatments, and lastly, improved devices for air elimination at bottling or canning.
The paper was illustrated by numerous lantern slides. A film showing a new cask washing plant employed in America was exhibited. The main feature, of the plant is that it takes casks, or kegs of all sizes and shapes at random.
British School of Malting and Brewing,
University of Birmingham.
Crescent City Brew Talk 