Journal of the Institute of Brewing
MEETING HELD AT THE CRITERION RESTAURANT, W., ON MONDAY, NOVEMBER 11TH, 1907.
Mr. EDWARD FALL LIGHT in the Chair.
The following paper was read and discussed :—
By ALFRED C. CHAPMAN, F.I.C., and F. G. S. BAKER, MA.
A CONSIDERATION of the mode of manufacture and composition of the fermented beverages prepared and drunk by primitive peoples is always interesting, and the examination of such beverages has occasionally yielded scientiﬁc results of importance. We do not, therefore, feel that any apology is necessary for bringing this matter under the notice of the Institute, especially in view of the fact that frequent reference was made to Kaffir beer in connection with the recent unpopular proposal of the Transvaal Government to modify the existing liquor laws.
An interesting paper on this subject was published in January. 1905, in the Agricultural Journal (Cape of Good Hope), by Mr. Charles Juritz, M.A., the Senior Analyst in the Government Analytical Laboratory at Cape Town, who was good enough to send one of us a copy. This led to some correspondence, as a result of which Mr. Juritz most kindly offered to obtain for us samples of some of the materials used in the preparation of Kaffir beer as well as the beers themselves. In due course samples of (a) bark of the Umkwenkwe tree, (b) Kiri Moer, and (c) Kiri plant arrived. These were obtained through the kindness of Mr. Verschuur, the Assistant Resident Magistrate at the New Brighton Native Location, but owing to the stringent measures which had been taken to prevent the introduction of liquor into the Location, that gentleman was unable to get any of the native beers. The above-mentioned materials will be referred to later.
Subsequently a sample of Leting and one of ordinary Kaﬂir beer were received, the former through the instrumentality and courtesy of Mr. Jonas H. Roose, the Resident Magistrate of Matatiele, and the latter through the kindness of Mr. S. Hargreaves, the Assistant Resident Magistrate of Butterworth. To all these gentlemen, as well to Mr. Juritz, we desire to offer our best thanks.
In his letter accompanying the sample Mr. Roose refers to Leling as “the lighter form of Kaffir beer,” and Mr. Orpen, in an interesting paper in a recent number of the Cape Agricultural Journal, speaks of Leting as being something quite distinct from Kaiﬁr beer or Yoala. He mentions that it does not contain any raw meal or ﬂour ﬂoating in it, and says that it has not the alcoholic potentialities of ordinary Kaffir beer. If Mr. Orpen’s remarks on this subject are correct, it would appear that the sample sent by Mr. Roose was not true Leling, but ordinary Kaffir beer, for both contained starchy matter in suspension, and, as will be seen on reference to the following analyses, the Leting sample had the more alcohol of the two.
Total solid matter …………………………………….. 5.19 5.76
Reducing carbohydrates (as maltose) ………. 0.23 0.07
Absolute alcohol (by weight)…………………….. 3.19 2.44
(Proof spirit ……………………………………………… 6.97 5.37
Fixed acidity (as lactic acid) …………………….. 1.26 1.03
Volatile acidity (as acetic acid)……………….. .48 .41
Insoluble matters ……………………………….. — 3.62
Ash …………………………………………………… — 0.38
Present gravity ……………………………….. 1014.4° 1014.4°
These samples resembled one another somewhat closely in appearance, and it will be seen that in chemical composition they were also similar. Both were thick when shaken, owing to the presence of suspended matters, chieﬂy starch, and had a pale brown colour. When allowed to remain undisturbed for some time, a thick greyish coloured sediment settled to the bottom of the bottles, leaving a still turbid, supernatant liquid, of a greenish yellow colour. A considerable amount of fermentation had evidently taken place in the bottles, for on withdrawing the corks there was evidence of great pressure, and the liquid frothed up considerably, owing to the escape of gas. The sediment in both cases consisted of starch granules (many being broken) with some particles of root structure, and some exhausted yeast cells. There were also present some torulae, and innumerable bacteria, these being chiefly represented by short bacilli with some coccus forms. There were also some oily globules. The starch consisted chieﬂy, if not entirely, of maize.
The beers had an acid smell and, as might be expected from the presence of such large proportions of lactic and acetic acids, a very acid ﬂavour. A number of different fermented beverages are prepared by the native tribes of South Africa, and these may be roughly divided into grain beers and sugar beers. Thus Juritz, in his paper, speaks of the following ﬁve native beverages:—
Native name. European equivalent.
- Mqomboti . . . . . . . . . . . . . . . . Kaffir corn beer
- Danti . . . . . . . . . . . . . . . . . . . . .Native hop beer
- Qilika ye Tolofiya . . . . . . . . . .Prickly pear beer
- Qilika no busi . . . . . . . . . . . . . Honey beer
- Qilika ye swekile . . . . . . . . . . Sugar beer
It is the ﬁrst of the above, or Kafﬁr corn beer, with which this paper deals, and it is to be noticed that this is referred to by Mr. Orpen under the name of Yoala. Whether Yoala differs from Mqomboti or not we cannot say, but it seems not unlikely that the same beverage is known under various names in different parts of the country and by different tribes. Several descriptions of the mode of brewing—if that expression may be permitted—of “ Kaffir ” beer have come under our notice, but some are clearly inconsistent with the character of the finished beverage and are obviously incorrect. The following method, which is referred to by Juritz, would appear to agree best with the composition of the beer, and is probably the method generally adopted. The grain (Kaffir corn or maize) after being soaked in water is placed in bags, where it remains until it sprouts, after which it is taken out of the bags and dried in the sun. The malted grain is then thoroughly mixed with a proportion of the unmalted grain, and the whole is roughly ground between stones. The grist is then put into casks with water and allowed to remain for some time. After a while the clear liquid is poured off and the sedimentary matter, having the consistency of dough, is ﬁnely ground between stones. This dough and the liquid from which it was originally taken are next placed in a large pot and boiled until the whole has attained the consistency of porridge. The mixture is then removed from the pot and placed in open vessels to cool, after which it is returned to the cask. A certain proportion of ﬁnely ground malted grain is added and the whole thoroughly mixed. After a time, the contents of the cask become liquid and ferment. When this action has been judged to proceed sufficiently far, the contents of the casks are strained through grass baskets and are ready for consumption. It will be observed that the above description makes no reference either to the use of any matter for flavouring purposes or to the employment of any ferment. In regard to the flavouring, it seems to be tolerably certain that hops are now being very widely used by the Kaffirs, even in beers other than the true hop beer, or DanIi. It seems also to be tolerably certain that before the employment of hops became at all common, the bitter bark of the Umkwenkwe tree was used, and it is to be noted that neither of the samples which we have examined afforded any evidence whatever of the presence of hop, but contained numerous vegetable particles which might possibly have been derived from the Umkwenkwe bark, or more probably from the addition of the kiri root of which we speak below.
In reference to the question of fermentation, an examination of the sediments of the sample submitted to us revealed the presence of numerous yeast cells of various species, and innumerable bacteria of apparently many descriptions. Mr. Juritz states that the sediment of samples examined at the Cape Town Government Laboratory consisted of an agglomeration of yeast cells with small fragments of ground root. It has been ascertained that a plant known as the yeast plant or Koerri plant, was extensively used by natives in many districts as a means of exciting fermentation, and it seems probable that the root fragments we noticed had been derived from that substance. Apparently the Koerri plant is ﬁnely ground, being known in that state as Kiri Moer, and although no mention is made of the addition of this root in the manufacture of Kaffir beer as described above, both the microscopical examination of the sediment and the statement of various authorities regarding the manufacture, render it probable that this plant had been used. We have examined specimens of this plant and also of the ground root, and have been unable to detect any greater number of yeast organisms than might he accidentally present on the surface of any other similar vegetable material. Mr. Lewis has expressed the opinion that Kiri Moer, the ostensible function of which was to supply the yeast needed for the fermentation, in reality supplied no such ferment at all. Mr. Lewis goes on to say that one specimen of Kiri Moer which he examined was mouldy on arrival, and readily caused the sugar solutions to ferment, whilst the freshly-ground root produced no such effect. Taking everything into consideration, it seems probable that the Kaffirs are in the habit of adding some sediment from a previous brew to the cask in order to start the fermentation, but that when such sediment is not available they are compelled to rely upon such yeasts or other organisms as may fall in from the air, or be introduced with the Kiri Moer. In any case, the statement that when the Koerri root alone is used the commencement of the fermentation is much slower than when the sugary liquid is pitched with sediment from a previous brew, is signiﬁcant. It seems very probable that the Kiri Moer is used merely as a vehicle for the collection and transport of the yeast from one liquid to another, the root particles giving to the sediment a greater degree of solidity. Several references have been made to the growth of mould on the Kiri Moer, and we have found that when the root or the Moer is placed in a nutritive solution, such growths invariably occur—aspergilli, penicillia, and mucors growing very freely. Many of these, as is well known, produce diastasc, and it would be interesting to know whether the addition of the Kiri Moer may not sometimes be made with the object of bringing about the conversion of a portion of the starchy matter, as is the case in the manufacture of the well-known Japanese drink, Saké, where the mould, Aspergillus oryzae, is seeded on to the steeped rice. Many species of Mucor, as, for instance, Mucor mouxii, which is made into “ Chinese yeast,” and is a common article of commerce in East Asia, readily change starch into sugar, and some are capable of exciting true fermentation. Whatever may be the function of the moulds which appear to occur invariably on the surface of the Koerri plant, the manufacture of this Kaffir beer affords an interesting example of a process empirically arrived at by a primitive race, which embodies several of the important principles underlying the procedure followed in the brewing of beer in civilised countries. Thus the malting of the grain, and its admixture with the unmalted grain, has its counterpart in the procedure of the majority of our breweries at the present day, whilst the boiling of the starchy matter would appear to indicate that the Kaffirs recognise the necessity for the gelatinisation of the starch, in order that the malted grain, when subsequently added, may bring about mere readily its conversion into sugar.
The lactic, acetic, and other acids present are probably due to the activity of bacteria, of which immense numbers were present, but it is also possible that some of the lactic acid may have been produced by yeast species. Thus the Saccharomyces acidi lactici and the Succharomyces fragilis, which we think we have recognised in this beer, are known to be capable of producing appreciable amounts of lactic acid, simultaneously with the exercise of their ordinary fermentative functions. In respect of its high acidity, this Kaffir beer must be classed with Koumiss, Kephir, and the Belgian Lambick and Faro. It is interesting to note that Mr. Orpen states that the acid, Leling, is a very wholesome beverage, and one which appears most desirable, if not absolutely necessary, for the health of the natives who drink it. It may be pointed out in this connection that Metchnikoff has recently advanced the view, and has supported it experimentally, that certain sporulating acid-producing bacteria perform a very useful function in the human large intestine, inasmuch, as by producing considerable quantities of acid, they inhibit the growth of other intestinal bacteria, and so diminish the amount of poisonous bacterial products passing into the circulation. There can be little doubt that the wholesomencss of (lactic) acid beverages, such as this Kaffir Leting, is to be explained in this manner. In addition to the chemical examination, we have made a very searching biological examination of the sediment, thinking that, possibly we might meet with some new form of organism, such as the Saccharomyces Pombe, which was ﬁrst isolated from negro millet beer. In this, however, we were disappointed. The yeast present consisted almost entirely of small ellipsoidal forms, which were-very closely related to, if not identical with, the ellipsoideus species. In addition to this, we recognised organisms closely resembling, if not identical with, Sascharomyccs fragilis, and one or two schizo-saccharomycetes, which could not, however, be obtained in pure culture, probably on account of their exhausted condition. There were also numerous torulae.
nota bene! The original Kaffir beer was made entirely from germinated Kafﬁr corn (Sorghum vulgare), with the addition of certain herbs, and that the use of honey and sugar was a comparatively modern innovation for the purpose of obtaining a stronger and more intoxicating beverage.