Vintage Beer Brewing

Introduction

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in the modern acceptation of the term, a series of operations the object of which is to prepare an alcoholic beverage of a certain kind—to wit, beer—mainly from cereals (chiefly malted barley), hops and water. Although the art of preparing beer or ale is a very ancient one, there is very little information in the literature of the subject as to the apparatus and methods employed in early times. It seems fairly certain, however, that up to the 18th century these were of the most primitive kind.

With regard to materials, we know that prior to the general introduction of the hop as a preservative and astringent, a number of other bitter and aromatic plants had been employed with this end in view. Thus J.L. Baker (The Brewing Industry) points out that the Cimbri used the Tamarix germanica, the Scandinavians the fruit of the sweet gale (Myrica gale), the Cauchi the fruit and the twigs of the chaste tree (Vitex agrius castus), and the Icelanders the yarrow (Achillea millefolium).

The preparation of beer on anything approaching to a manufacturing scale appears, until about the 12th or 13th century, to have been carried on in England chiefly in the monasteries; but as the brewers of London combined to form an association in the reign of Henry IV., and were granted a charter in 1445, it is evident that brewing as a special trade or industry must have developed with some rapidity. After the Reformation the ranks of the trade brewers were swelled by numbers of monks from the expropriated monasteries. Until the 18th century the professional brewers, or brewers for sale, as they are now called, brewed chiefly for the masses, the wealthier classes preparing their own beer, but it then became gradually apparent to the latter (owing no doubt to improved methods of brewing, and for others reasons) that it was more economical and less troublesome to have their beer brewed for them at a regular brewery. The usual charge was 30s. per barrel for bitter ale, and 8s. or so for small beer.

This tendency to centralize brewing operations became more and more marked with each succeeding decade. Thus during 1895-1905 the number of private brewers declined from 17,041 to 9930. Of the private brewers still existing, about four-fifths were in the class exempted from beer duty, i.e. farmers occupying houses not exceeding £10 annual value who brew for their labourers, and other persons occupying houses not exceeding £15 annual value. The private houses subject to both beer and licence duty produced less than 20,000 barrels annually.

There are no official figures as to the number of "cottage brewers," that is, occupiers of dwellings not exceeding £8 annual value; but taking everything into consideration it is probable that more than 99% of the beer produced in the United Kingdom is brewed by public brewers (brewers for sale). The disappearance of the smaller public brewers or their absorption by the larger concerns has gone hand-in-hand with the gradual extinction of the private brewer. In the year 1894-1895 8863 licences were issued to brewers for sale, and by 1904-1905 this number had been reduced to 5164. There are numerous reasons for these changes in the constitution of the brewing industry, chief among them being (a) the increasing difficulty, owing partly to licensing legislation and its administration, and partly to the competition of the great breweries, of obtaining an adequate outlet for retail sale in the shape of licensed houses; and (b) the fact that brewing has continuously become a more scientific and specialized industry, requiring costly and complicated plant and expert manipulation.

It is only by employing the most up-to-date machinery and expert knowledge that the modern brewer can hope to produce good beer in the short time which competition and high taxation, etc., have forced upon him. Under these conditions the small brewer tends to extinction, and the public are ultimately the gainers. The relatively non-alcoholic, lightly hopped and bright modern beers, which the small brewer has not the means of producing, are a great advance on the muddy, highly hopped and alcoholized beverages to which our ancestors were accustomed.

Brewing Operations

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The general scheme of operations in an English brewery will be readily understood if reference be made to fig. 1, which represents an 8-quarter brewery on the gravitation system, the principle of which is that all materials to be employed are pumped or hoisted to the highest point required, to start with, and that subsequently no further pumping or hoisting is required, the materials (in the shape of water, malt, wort or hops, &c.) being conveyed from one point to another by the force of gravity.

The malt, which is hoisted to the top floor, after cleaning and grading is conveyed to the Malt Mill, where it is crushed. Thence the ground malt, or "grist" as it is now called, passes to the Grist Hopper, and from the latter to the Mashing Machine, in which it is intimately mixed with hot water from the Hot Liquor Vessel. From the mashing machine the mixed grist and "liquor" pass to the Mash-Tun, where the starch of the malt is rendered soluble. From the mash-tun the clear wort passes to the Copper, where it is boiled with hops. From the copper the boiled wort passes to the Hop Back, where the insoluble hop constituents are separated from the wort. From the hop back the wort passes to the Cooler, from the latter to the Refrigerator, thence (for the purpose of enabling the revenue officers to assess the duty) to the Collecting Vessel,[4] and finally to the Fermenting Vessels, in which the wort is transformed into "green" beer. The latter is then cleansed, and finally racked and stored.

It will be seen from the above that brewing consists of seven distinct main processes, which may be classed as follows: (1) Grinding; (2) Mashing; (3) Boiling; (4) Cooling; (5) Fermenting; (6) Cleansing; (7) Racking and Storing.

Beer Brewing: Grinding

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In most modern breweries the malt passes, on its way from the bins to the mill, through a cleaning and grading apparatus, and then through an automatic measuring machine. The mills, which exist in a variety of designs, are of the smooth roller type, and are so arranged that the malt is crushed rather than ground. If the malt is ground too fine, difficulties arise in regard to efficient drainage in the mash-tun and subsequent clarification. On the other hand, if the crushing is too coarse the subsequent extraction of soluble matter in the mash-tun is incomplete, and an inadequate yield results.

Mashing

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Mashing is a process which consists mainly in extracting, by means of water at an adequate temperature, the soluble matters pre-existent in the malt, and in converting the insoluble starch and a great part of the insoluble nitrogenous compounds into soluble and partly fermentable products. Mashing is, without a doubt, the most important of the brewing processes, for it is largely in the mash-tun that the character of the beer to be brewed is determined. In modern practice the malt and the mashing "liquor" (i.e. water) are introduced into the mash-tun simultaneously, by means of the mashing machine (fig. 2, A). This is generally a cylindrical metal vessel, commanding the mash-tun and provided with a central shaft and screw. The grist (as the crushed malt is called) enters the mashing machine from the grist case above, and the liquor is introduced at the back. The screw is rotated rapidly, and so a thorough mixture of the grist and liquor takes place as they travel along the mashing machine. The mash-tun (fig. 2) is a large metal or wooden vessel, fitted with a false bottom composed of plates perforated with numerous small holes or slits (C). This arrangement is necessary in order to obtain a proper separation of the "wort" (as the liquid portion of the finished mash is called) from the spent grains. The mash-tun is also provided with a stirring apparatus (the rakes) so that the grist and liquor may be intimately mixed (D), and an automatic sprinkler, the sparger (fig. 2, B, and fig. 3), which is employed in order to wash out the wort remaining in the grains. The sparger consists of a number of hollow arms radiating from a common centre and pierced by a number of small perforations. The common central vessel from which the sparge-arms radiate is mounted in such a manner that it rotates automatically when a stream of water is admitted, so that a constant fine spray covers the whole tun when the sparger is in operation. There are also pipes for admitting "liquor" to the bottom of the tun, and for carrying the wort from the latter to the "underback" or "copper."

The grist and liquor having been introduced into the tun (either by means of the mashing machine or separately), the rakes are set going, so that the mash may become thoroughly homogeneous, and after a short time the rakes are stopped and the mash allowed to rest, usually for a period of about two hours. After this, "taps are set"—i.e. communication is established between the mash-tun and the vessel into which the wort runs—and the sparger is started. In this manner the whole of the wort or extract is separated from the grains. The quantity of water employed is, in all, from two to three barrels to the quarter (336 lb) of malt.

In considering the process of mashing, one might almost say the process of brewing, it is essential to remember that the type and quality of the beer to be produced depends almost entirely (a) on the kind of malt employed, and (b) on the mashing temperature. In other words, quality may be controlled on the kiln or in the mash-tun, or both. Viewed in this light, the following theoretical methods for preparing different types of beer are possible:—(1) high kiln heats and high mashing temperatures; (2) high kiln heats and low mashing temperatures; (3) low kiln heats and high mashing temperatures; and (4) low kiln heats and low mashing temperatures. In practice all these combinations, together with many intermediate ones, are met with, and it is not too much to say that the whole science of modern brewing is based upon them.

It is plain, then, that the mashing temperature will depend on the kind of beer that is to be produced, and on the kind of malt employed. For stouts and black beers generally, a mashing temperature of 148° to 150° F. is most usual; for pale or stock ales, 150° to 154° F.; and for mild running beers, 154° to 149° F. The range of temperatures employed in brewing English beers is a very limited one as compared with foreign mashing methods, and does not range further, practically speaking, than from 140° to 160° F. The effect of higher temperatures is chiefly to cripple the enzyme or "ferment" diastase, which, as already said, is the agent which converts the insoluble starch into soluble dextrin, sugar and intermediate products. The higher the mashing temperature, the more the diastase will be crippled in its action, and the more dextrinous (non-fermentable) matter as compared with maltose (fermentable sugar) will be formed. A pale or stock ale, which is a type of beer that must be "dry" and that will keep, requires to contain a relatively high proportion of dextrin and little maltose, and, in its preparation, therefore, a high mashing temperature will be employed. On the other hand, a mild running ale, which is a full, sweet beer, intended for rapid consumption, will be obtained by means of low mashing temperatures, which produce relatively little dextrin, but a good deal of maltose, i.e. sweet and readily fermentable matter.

Diastase is not the only enzyme present in malt. There is also a ferment which renders a part of the nitrogenous matter soluble. This again is affected by temperature in much the same way as diastase. Low heats tend to produce much non-coagulable nitrogenous matter, which is undesirable in a stock beer, as it tends to produce fret and side fermentations. With regard to the kind of malt and other materials employed in producing various types of beer, pale ales are made either from pale malt (generally a mixture of English and fine foreign, such as Smyrna, California) only, or from pale malt and a little flaked maize, rice, invert sugar or glucose. Running beers (mild ale) are made from a mixture of pale and amber malts, sugar and flaked goods; stout, from a mixture of pale, amber and roasted (black) malts only, or with the addition of a little sugar or flaked maize.

When raw grain is employed, the process of mashing is slightly modified. The maize, rice or other grain is usually gelatinized in a vessel (called a converter or cooker) entirely separated from the mash-tun, by means of steam at a relatively high temperature, mostly with, but occasionally without, the addition of some malt meal. After about half an hour the gelatinized mass is mixed with the main mash, and this takes place shortly before taps are set. This is possible inasmuch as the starch, being already in a highly disintegrated condition, is very rapidly converted. By working on the limited-decoction system (see below), it is possible to make use of a fair percentage of raw grain in the mash-tun proper, thus doing away with the "converter" entirely.

Beer Brewing: Filter Press

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The ordinary mash-tun process, as described above, possesses the disadvantage that only coarse grists can be employed. This entails loss of extract in several ways. To begin with, the sparging process is at best a somewhat inefficient method for washing out the last portions of the wort, and again, when the malt is at all hard or "steely," starch conversion is by no means complete. These disadvantages are overcome by the filter press process, which was first introduced into Great Britain by the Belgian engineer P. Meura. The malt, in this method of brewing, is ground quite fine, and although an ordinary mash-tun may be used for mashing, the separation of the clear wort from the solid matter takes place in the filter press, which retains the very finest particles with ease. It is also a simple matter to wash out the wort from the filter cake in the presses, and experience has shown that markedly increased yields are thus obtained. In the writer's opinion, there is little doubt that in the future this, or a similar process, will find a very wide application.

Boiling

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From the mash-tun the wort passes to the copper. If it is not possible to arrange the plant so that the coppers are situated beneath the mash-tuns (as is the case in breweries arranged on the gravitation system), an intermediate collecting vessel (the underback) is interposed, and from this the wort is pumped into the copper. The latter is a large copper vessel heated by direct fire or steam. Modern coppers are generally closed in with a dome-shaped head, but many old-fashioned open coppers are still to be met with, in fact pale-ale brewers prefer open coppers. In the closed type the wort is frequently boiled under slight pressure. When the wort has been raised to the boil, the hops or a part thereof are added, and the boiling is continued generally from an hour to three hours, according to the type of beer. The objects of boiling, briefly put, are: (1) sterilization of the wort; (2) extraction from the hops of substances that give flavour and aroma to the beer; (3) the coagulation and precipitation of a part of the nitrogenous matter (the coagulable albuminoids), which, if left in, would cause cloudiness and fret, &c., in the finished beer; (4) the concentration of the wort. At least three distinct substances are extracted from the hops in boiling. First, the hop tannin, which, combining with a part of the proteids derived from the malt, precipitates them; second, the hop resin, which acts as a preservative and bitter; third, the hop oil, to which much of the fine aroma of beer is due. The latter is volatile, and it is customary, therefore, not to add the whole of the hops to the wort when it commences to boil, but to reserve about a third until near the end of the copper stage. The quantity of hops employed varies according to the type of beer, from about 3 lb to 15 lb per quarter (336 lb) of malt. For mild ales and porters about 3 to 4 lb, for light pale ales and light stouts 6 to 10 lb, and for strong ales and stouts 9 to 15 lb of hops are employed.

Cooling

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When the wort has boiled the necessary time, it is turned into the hop back to settle. A hop back is a wooden or metal vessel, fitted with a false bottom of perforated plates; the latter retain the spent hops, the wort being drawn off into the coolers. After resting for a brief period in the hop back, the bright wort is run into the coolers. The cooler is a very shallow vessel of great area, and the result of the exposure of the hot wort to a comparatively large volume of air is that a part of the hop constituents and other substances contained in the wort are rendered insoluble and are precipitated. It was formerly considered absolutely essential that this hot aeration should take place, but in many breweries nowadays coolers are not used, the wort being run direct from the hop back to the refrigerator. There is much to be said for this procedure, as the exposure of hot wort in the cooler is attended with much danger of bacterial and wild yeast infection, but it is still a moot point whether the cooler or its equivalent can be entirely dispensed with for all classes of beers. A rational alteration would appear to be to place the cooler in an air-tight chamber supplied with purified and sterilized air. This principle has already been applied to the refrigerator, and apparently with success. In America the cooler is frequently replaced by a cooling tank, an enclosed vessel of some depth, capable of artificial aeration. It is not practicable, in any case, to cool the wort sufficiently on the cooler to bring it to the proper temperature for the fermentation stage, and for this purpose, therefore, the refrigerator is employed. There are several kinds of refrigerators, the main distinction being that some are vertical, others horizontal; but the principle in each case is much the same, and consists in allowing a thin film or stream of wort to trickle over a series of pipes through which cold water circulates. Fig. 5, Plate I., shows refrigerators, employed in Messrs Allsopp's lager beer brewery, at work.

Fermenting

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By the process of fermentation the wort is converted into beer. By the action of living yeast cells, the sugar contained in the wort is split up into alcohol and carbonic acid, and a number of subsidiary reactions occur. There are two main systems of fermentation, the top fermentation system, which is that employed in the United Kingdom, and the bottom fermentation system, which is that used for the production of beers of the continental ("lager") type. The wort, generally at a temperature of about 60° F. (this applies to all the systems excepting B [see below], in which the temperature is higher), is "pitched" with liquid yeast (or "barm," as it is often called) at the rate of, according to the type and strength of the beer to be made, 1 to 4 lb to the barrel.

After a few hours a slight froth or scum makes its appearance on the surface of the liquid. At the end of a further short period this develops into a light curly mass (cauliflower or curly head), which gradually becomes lighter and more solid in appearance, and is then known as rocky head. This in its turn shrinks to a compact mass—the yeasty head—which emits great bubbles of gas with a hissing sound.

At this point the cleansing of the beer—i.e. the separation of the yeast from the liquid—has fairly commenced, and it is let down (except in the skimming and Yorkshire systems) into the pontos or unions, as the case may be. During fermentation the temperature rises considerably, and in order to prevent an excessive temperature being obtained (70-75° F. should be the maximum) the fermenting vessels are fitted with "attemperators," i.e. a system of pipes through which cold water may be run.

Cleansing

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In England the methods of applying the top fermentation system may be classified as follows: (A) The Cleansing System: (a) Skimming System, (b) Dropping System (pontos or ordinary dropping system), (c) Burton Union System. (B) The Yorkshire Stone Square System.

(A) In (a) the Skimming System the fermentation from start to finish takes place in wooden vessels (termed "squares" or "rounds"), fitted with an attemperator and a parachute or other similar skimming device for removing or "skimming" the yeast at the end of the fermentation. The principle of (b) the Dropping System is that the beer undergoes only the main fermentation in the "round" or "square," and is then dropped down into a second vessel or vessels, in which fermentation and cleansing are completed. The ponto system of dropping, which is now somewhat old-fashioned, consists in discharging the beer into a series of vat-like vessels, fitted with a peculiarly-shaped overflow lip. The yeast works its way out of the vessel over the lip, and then flows into a gutter and is collected. The pontos are kept filled with beer by means of a vessel placed at a higher level. In the ordinary dropping system the partly fermented beer is let down from the "squares" and "rounds" into large vessels, termed dropping or skimming "backs." These are fitted with attemperators, and parachutes for the removal of yeast, in much the same way as in the skimming system. As a rule the parachute covers the whole width of the back. (c) The Burton Union System is really an improved ponto system. A series of casks, supplied with beer at the cleansing stage from a feed vessel, are mounted so that they may rotate axially. Each cask is fitted with an attemperator, a pipe and cock at the base for the removal of the finished beer and "bottoms," and lastly with a swan neck fitting through a bung-hole and commanding a common gutter. This system yields excellent results for certain classes of beers, and many Burton brewers think it is essential for obtaining the Burton character.

(B) The Stone Square System, which is only used to a certain extent (exclusively in the north of England), practically consists in pumping the fermenting wort from one to the other of two superimposed square vessels, connected with one another by means of a man-hole and a valve. These squares are built of stone and kept very cool. At the end of the fermentation the yeast (after closing the man-hole) is removed from the top square.

Racking

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After the fermentation and cleansing operations are completed, the beer is racked off (sometimes after passing a few hours in a settling tank) into storage vessels or trade casks. The finest "stock" and "pale" ales are stored from six weeks to three months prior to going out, but "running" beers (mild ales, &c.) are frequently sent out of the brewery within a week or ten days of mashing. It is usual to add some hops in cask (this is called dry hopping) in the case of many of the better beers. Running beers, which must be put into condition rapidly, or beers that have become flat, are generally primed. Priming consists in adding a small quantity of sugar solution to the beer in cask. This rapidly ferments and so produces "condition."

Fining

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As a very light article is desired nowadays, and this has to be provided in a short time, artificial means must be resorted to, in order to replace the natural fining or brightening which storage brings about. Finings generally consist of a solution or semi-solution of isinglass in sour beer, or in a solution of tartaric acid or of sulphurous acid. After the finings are added to the beer and the barrels have been well rolled, the finings slowly precipitate (or work out through the bung-hole) and carry with them the matter which would otherwise render the beer turbid.

Bottling

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Formerly it was the general custom to brew a special beer for bottling, and this practice is still continued by some brewers. It is generally admitted that the special brew, matured by storage and an adequate secondary fermentation, produces the best beer for bottling, but the modern taste for a very light and bright bottled beer at a low cost has necessitated the introduction of new methods. The most interesting among these is the "chilling" and "carbonating" system. In this the beer, when it is ripe for racking, is first "chilled," that is, cooled to a very low temperature. As a result, there is an immediate deposition of much matter which otherwise would require prolonged time to settle. The beer is then filtered and so rendered quite bright, and finally, in order to produce immediate "condition," is "carbonated," i.e. impregnated under pressure with carbon dioxide (carbonic acid gas).

Decoction

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The method pursued in the decoction system is broadly as follows. After the grist has been mashed with cold water until a homogeneous mixture ensues, sufficient hot water is introduced into the mash-tun to raise the temperature to 85-100° F., according to circumstances. Thereupon, about one-third of the mash (including the "goods") is transferred to the Maisch Kessel (mash copper), in which it is gradually brought to a temperature of (about) 165° F., and this heat is maintained until the mash becomes transparent. The Dickmaische, as this portion is called, is then raised to the boil, and the ebullition sustained between a quarter and three-quarters of an hour. Just sufficient of the Dickmaische is returned to the mash-tun proper to raise the temperature of the whole to 111-125° F., and after a few minutes a third is again withdrawn and treated as before, to form the second "thick mash." When the latter has been returned to the mash-tun the whole is thoroughly worked up, allowed to stand in order that the solids may deposit, and then another third (called the Läutermaische or "clear mash") is withdrawn, boiled until the coagulable albuminoids are precipitated, and finally reconveyed to the mash-tun, where the mashing is continued for some time, the final heat being rather over 160° F. The wort, after boiling with hops and cooling, much as in the English system, is subjected to the peculiar system of fermentation called bottom fermentation. In this system the "pitching" and fermentation take place at a very low temperature and, compared with the English system, in very small vessels. The fermenting cellars are maintained at a temperature of about 37-38° F., and the temperature of the fermenting wort does not rise above 50° F. The yeast, which is of a different type from that employed in the English system, remains at the bottom of the fermenting tun, and hence is derived the name of "bottom fermentation" (see Fermentation). The primary fermentation lasts about eleven to twelve days (as compared with three days on the English system), and the beer is then run into store (lager) casks where it remains at a temperature approaching the freezing-point of water for six weeks to six months, according to the time of the year and the class of the beer.

Japanese Method

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The preparation of the Japanese beer saké (q.v.) is of interest. The first stage consists in the preparation of Koji, which is obtained by treating steamed rice with a culture of Aspergillus oryzae. This micro-organism converts the starch into sugar. The Koji is converted into moto by adding it to a thin paste of fresh-boiled starch in a vat. Fermentation is set up and lasts for 30 to 40 days. The third stage consists in adding more rice and Koji to the moto, together with some water. A secondary fermentation, lasting from 8 to 10 days, ensues. Subsequently the whole is filtered, heated and run into casks, and is then known as saké. The interest of this process consists in the fact that a single micro-organism—a mould—is able to exercise the combined functions of saccharification and fermentation. It replaces the diastase of malted grain and also the yeast of a European brewery. Another liquid of interest is Weissbier. This, which is largely produced in Berlin (and in some respects resembles the wheat-beer produced in parts of England), is generally prepared from a mash of three parts of wheat malt and one part of barley malt. The fermentation is of a symbiotic nature, two organisms, namely a yeast and a fission fungus (the lactic acid bacillus) taking part in it. The preparation of this peculiar double ferment is assisted by the addition of a certain quantity of white wine to the yeast prior to fermentation.

Chemistry

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The principles of brewing technology belong for the most part to physiological chemistry, whilst those of the cognate industry, malting, are governed exclusively by that branch of knowledge. Alike in following the growth of barley in field, its harvesting, maturing and conversion into malt, as well as the operations of mashing malt, fermenting wort, and conditioning beer, physiological chemistry is needed. On the other hand, the consideration of the saline matter in waters, the composition of the extract of worts and beers, and the analysis of brewing materials and products generally, belong to the domain of pure chemistry. Since the extractive matters contained in wort and beer consist for the most part of the transformation products of starch, it is only natural that these should have received special attention at the hands of scientific men associated with the brewing industry.

It was formerly believed that by the action of diastase on starch the latter is first converted into a gummy substance termed dextrin, which is then subsequently transformed into a sugar—glucose. F.A. Musculus, however, in 1860, showed that sugar and dextrin are simultaneously produced, and between the years 1872 and 1876 Cornelius O'Sullivan definitely proved that the sugar produced was maltose. When starch-paste, the jelly formed by treating starch with boiling water, is mixed with iodine solution, a deep blue coloration results. The first product of starch degradation by either acids or diastase, namely soluble starch, also exhibits the same coloration when treated with iodine. As degradation proceeds, and the products become more and more soluble and diffusible, the blue reaction with iodine gives place first to a purple, then to a reddish colour, and finally the coloration ceases altogether. In the same way, the optical rotating power decreases, and the cupric reducing power (towards Fehling's solution) increases, as the process of hydrolysis proceeds. C. O'Sullivan was the first to point out definitely the influence of the temperature of the mash on the character of the products.

The work of Horace T. Brown (with J. Heron) extended that of O'Sullivan, and (with G.H. Morris) established the presence of an intermediate product between the higher dextrins and maltose. This product was termed maltodextrin, and Brown and Morris were led to believe that a large number of these substances existed in malt wort. They proposed for these substances the generic name "amyloins." Although according to their view they were compounds of maltose and dextrin, they had the properties of mixtures of these two substances. On the assumption of the existence of these compounds, Brown and his colleagues formulated what is known as the maltodextrin or amyloin hypothesis of starch degradation. C.J. Lintner, in 1891, claimed to have separated a sugar, isomeric with maltose, which is termed isomaltose, from the products of starch hydrolysis. A.R. Ling and J.L. Baker, as well as Brown and Morris, in 1895, proved that this isomaltose was not a homogeneous substance, and evidence tending to the same conclusion was subsequently brought forward by continental workers. Ling and Baker, in 1897, isolated the following compounds from the products of starch hydrolysis—maltodextrin-α, C36H62O31, and maltodextrin-β, C24H42O21 (previously named by Prior, achroodextrin III.). They also separated a substance, C12H22O11, isomeric with maltose, which had, however, the characteristics of a dextrin. This is probably identical with the so-called dextrinose isolated by V. Syniewski in 1902, which yields a phenylosazone melting at 82-83° C. It has been proved by H. Ost that the so-called isomaltose of Lintner is a mixture of maltose and another substance, maltodextrin, isomeric with Ling and Baker's maltodextrin-β.