This article represents a section of the classic public domain brewing text "American Handy Book of the Brewing, Malting, and Auxiliary Trades" by Robert Wahl and Max Henius.. See the main entry on this book for general information and a complete table of contents.

Utilization of the By-Products of the Brewery

The important by-products of the brewery and malt house are screenings, skimmings, malt sprouts, underdough, spent grains, spent hops, dregs ("Trub"), yeast, carbonic acid.

Screenings and skimmings.

If the screenings from the barley cleaners contain much dust, this is screened out, and the undersized, light and broken kernels, of which the screenings are composed, are sold as chicken or cattle feed, after being mixed with the floaters from the steep tank which are either gathered by skimmers or carried from the steep tank by a current of steep water through an overflow pipe (see "Malt House Outfit") at the top of the tank into a tank provided with a perforated bottom. This wet grain is dried on perforated plates or in a regular kiln.

Malt sprouts.

Malt sprouts contain a very large amount of nutritive substance, and may he considered a concentrated foodstuff for cattle. They are especially valuable as a feed for milch cows on acount of the large amount of easily assimilable nitrogenous substances.

Thausing gives the following analysis of ten samples of sprouts:

The sprouts should be mixed with other feed, like hay, as they are too concentrated a food to be taken alone, and also because they are apt to be refused on account of the bitter taste, to which cattle, however, gradually become accustomed. The value of malt sprouts, as feed, is calculated, on the strength of the analysis, to be about five times as great as that of hay. They are not, however, paid for to the full of their value.

If they cannot be utilized for feeding purposes they may serve as an excellent fertilizer on account of their nitrogenous components, and the ash which is almost entirely made up of phosphoric acid and potash.

The amount of malt sprouts is about 3 per cent of the weight of the malt produced.

Brewers' grains.

Brewers' grains are now recognized as a valuable cattle feed. and are especially appreciated in this respect in Germany, to which country large amounts of the grains from American breweries find their way in a dried condition.

Settegast (Futterungslehre, Breslau) says that brewers' grains take the first place among the feed by-products of agricultural industries, considering their wholesomeness, especially in the case of cattle and swine. They affect to a high degree the flow of milk, on which account they deserve preference for feeding milch stock, and one need not hesitate to cover as much as half of the feed demand by brewers' grains.

In a report of the New Jersey Agricultural Experiment Station, 1893, relating the results of feeding experiments with horses. E. B. and Louis A. Voorhees stati that "by actual trial a pound of dried brewers' grains was shown to be quite as useful as a pound of oats in a ration for workhorses. A comparison of the composition of the feeds indicates that the reason for this result lies in the fact that the dried brewers' grains furnish more of the valuable digestible nutrients than the oats. . . . The substitution of dried brewers' grains for oats resulted not only in a maintenance of the weight of the animals under equivalent work, but in a saving of 4.9 cents per day per horse, or 25 per cent of the cost of the ration." Dried brewers' grains, they say, at $24 a ton would be as cheap a feed as oats at 36 cents a bushel.

Such opinions leave no room for doubt as to the value of brewers' grains, and $10 a ton for the dried product seems to cover only about one-half their intrinsic value.

The brewers' grains as they are discharged from the mash-tun are also fit food for cattle in the wet condition in which they contain from 75 to 81 per cent of water. On account of this high percentage of moisture they are liable to fermentation and putrefaction, in which state they are no longer available for feeding purposes. They cannot be kept for any length of time in this condition, and experiments at ensilage, that is, storing them packed away in bulk, mixed with some salt, have not proven successful, as they have been known to sour quite frequently.

If pressed they will keep somewhat longer in ensilage. Experiments made as between the nutritive value of wet and dried grains have shown that the digestibility is but 'slightly impaired by the drying process, and little differences in milk flow will follow the substitution of the dried grains for the wet.

Dried grains at $15 a ton are equivalent to moist grains at from 10 to ii cents per bushel. One pound of dried grains contains on an average as much nutriment as four pounds of moist grains.

Results with grains driers.

Drying grains is now done regularly in some of our largest brewing plants, and the following information can be given from tests made and figures obtained from a grains drying expert:

A machine with a capacity of 1,500 bushels dry mash per day, floor space 5 feet 2 inches wide by 14 feet high by 22 feet 8 inches long, price $3,500. Power to run, 8 horsepower, took one-quarter to one-third pounds of coal to produce one pound dry grains containing 6 per cent moisture, using new steam made for the purpose specially. Where exhaust steam from a large plant is used this expense is considerably reduced; one man can attend to three machines when doing nothing else.

Steam pressure in upper drums, 10 pounds exhaust steam, or 10 pounds live steam reduced.

In lower drums, full boiler pressure in stirrers, upper stirrers 40 revolutions, lower stirrers 10 revolutions.

One pound dry grains = about four and one-half pounds wet, on an average.

One pound dry grains = about four pounds dry mash (material).

In large plants using this dryer the following was found:

One brewery dries wet grains from 56,000 pounds mash in 24 hours regularly.

Another brewery on a trial run dried 24,800 pounds mash in nine hours, but this amount is not advisable for regular operation. Power, 8 to 10 horsepower to run when properly fed, but there should be at least a is-horsepower capacity of engine, as it has happened that a man filled the machine too full, and it then would require increased power.

A third brewery dries grains from 15,500 lbs. mash in 7 1/2 hours, using power and steam to the value of $2 for that amount. This is figured on a basis of a cost of 10 cents per 1,000 pounds of water evaporated. These 15,500 pounds of mash give 3,800 pounds dry grains. Power to run machine about nine horsepower. They use 13 horsepower, but this includes power to run the blower for the dry grains. The dividing price for wet grains is $1.50 per ton. When the market is higher they sell grains wet, if lower they run the machines.

At a fourth brewery a test was made on an eight-hour run, with steam at 9 1/2 cents per 1,000 pounds water evaporated.

It thus cost $1.90 to produce 4,000 pounds of dry grains. In this plant they used 13% indicated horsepower to operate. This included power necessary to convey the wet grains across an alley to the dryer, and operate a machine for packing the dry grains in sacks. The machine alone used 9 to 10 horsepower.

Brewery No. i dries wet grains from 2,333 pounds dry mash (material) per hour.

Brewery No. 2 dries wet grains from 2,755 pounds dry mash (material) per hour. (Crowding machine.)

Brewery No. 3 dries wet grains from 2,214 pounds dry mash (material) per hour.

Brewery No. 4 produces 500 bushels dry grains = about 2,000 pounds dry mash (material).

Wet grains weigh 60 to 65 pounds per bushel, dry grains 25 to 30 pounds per bushel. It takes 45 minutes to run them through the machine.

The higher percentage of protein or albuminoids contained in American grains, as compared with German, is due to the fact that practically all of the albumen of unmalted cereals, which are used in America to the amount of about 25 to 40 per cent. passes into the grains, whereas of the albumen contained in malt, about one-half is dissolved during mashing.

Analyses of brewers grains.

Relative amounts of brewing materials and wet grains.

The amount of wet grains obtained from a certain amount of material employed in a brew varies somewhat, but is on the average about 16 per cent higher than the weight of the brewing materials.

In two different breweries the following tests were made by Wahl and Henius:

The following table gives the amounts of wet grains actually obtained from the corresponding amounts of brewing material and the increase in per cent:

In another test made the amount of dried grains obtained from 4,400 pounds of grits and 4,400 pounds of malt was 2,017 pounds of dried grains with 5.92 per cent moisture, or about 23 per cent of dried grains. (See G. Thevenot, Drying of Brewers' Grains, American Brewers' Review, IX, page I.)

Underdough.

After removing the grains, the underdough should be taken out as soon as the mash-tun is properly cooled, and mixed with the grains.

Dregs ("Trub or Sediment").

The substance remaining in the sediment bags contains a large quantity of protein. Its proper place after draining the wort from the dregs ("Trub") is in the grains box. It should preferably be thrown into the mash-tun before the grains arr removed, so as to insure proper mixing.

Spent hops.

There seems to be no value attached to spent hops, properly sparged. They contain some nutrient substances, but not in sufficient quantities to warrant drying them. Cattle do not take kindly to them on account of their bitter taste. They have been used with good results, after drying, for horse-bedding, and seem to be preferred by the animals to straw. If not used otherwise they should be disposed of under the boiler as quickly as possible.

Utilization of waste yeast.

Considering that yeast during the process of fermentation, while growing in the wort, takes up such valuable ingredients from the wort as phosphates of potash and other mineral substances, and the amides and peptones of the wort, with which it sustains itself and builds up the body of its progeny, it is rather strange that a substance containing such valuable ingredients should have been allowed to run to waste so long. The crop of yeast that is returned to the brewer during and after the principal fermentation is much larger than the quantity which is added to the wort in the first instance to start fermentation. Allowing for variations due to favorable or unfavorable conditions of growth, it may be assumed that the quantity of yeast which is allowed to run to waste in the brewery will reach, generally speaking, from one to two pounds per barrel of beer brewed.

With a view of recovering the many valuable substances that the yeast contains and making them serviceable for practical uses, R. Wahl and M. Henius of Chicago, during the last ten years, jointly conducted a number of experiments which culminated in the successful extraction of the yeast, ridding it of those foreign substances which impart to the extract a bad flavor or otherwise deteriorate the product. The process consists in washing the yeast with water, heating the cleaned yeast, rupturing the membranes, and bringing into solution the valuable mineral and albuminoid substances of which the protoplasm of the yeast is mainly built up, separating the membranes from the soluble parts by filtration, decantation or otherwise, and condensing the extract to a syrupy or solid form.

Analyses of this extract show that it contains essentially the same substances that are found in meat extract.

Besides serving as a tonic in the place of extract of beef, the new vegetable extract from yeast can be employed with good results in the brewery for nourishing yeast, as it contains the very products that the yeast requires for food, since it is composed of the identical albuminoids and mineral substances which the yeast consumes.

This new yeast product (patented June 4, 1895) can be easily evaporated to a perfectly dry state, in which it is an easily powdered, lustrous mass of a light brown color. This mass readily dissolves in hot water, leaving it perfectly clear, and the solid products as well as the hot aqueous solution have the odor and taste of a freshly prepared extract of meat.

Following is a comparative statement of analyses of the respective substances:

A comparison of these analyses shows that yeast extract contains a higher quantity of the most valuable, readily digestible and nutrient albunioses and peptones, on which the importance of the extracts depend, than even meat extracts. (See Allen, Commercial Organic Analysis, 1898, Vol. IV, page 310.)

Utilization of carbonic acid.

The amount of carbonic acid escaping from the fermenting vats of a brewery during the principal fermentation is very large. For every pound of sugar that ferments one-half pound of carbonic acid is formed. The wort or beer is able to retain only a small fraction of the carbonic acid generated, about three-quarters of a pound per barrel, the remainder escaping. Of the sugar contained in an ordinary wort about 7 per cent ferments, or about 17 1/2 pounds per barrel, producing 8 3/4 pounds carbonic acid, 8 pounds of which escape, or, for every 100 barrels of beer brewed there is a loss of 800 pounds of carbonic acid.

Of late this carbonic acid has been successfully collected in some large brewery plants and is employed for charging the beer of the brewery in its final stages with carbonic acid, or, it is purified and compressed into drums and put on the market for charging beer and other beverages, displacing the liquid carbonic acid produced from other sources, mainly marble dust and sulphuric acid. If properly purified it certainly deserves preference over carbonic acid from chemicals, and is readily distinguishable from such by the mild, "clean" taste of the charged beverage, whereas water charged with marble dust, gas has a peculiar flavor not relished by a sensitive palate.

In order to collect the gas the fermenting vats are provided with hoods. The carbonic acid escapes through a kind of parachute, and is conveyed by means of a pipe that connects with all the hoods, to the purifier, where the gas is washed by means of water and sulphuric acid, which remove all the aromatic ingredients like ethereal oils. It is then passed through a solution of permanganate of potash and carbonate of soda, to remove all traces of acid, and then dried and compressed to a liquid, if desired. In most cases, however, the gas is withdrawn from closed fermenters, washed and compressed.