The Project Gutenberg EBook of The Bacillus of Long Life, by Loudon Douglas This eBook is for the use of anyone anywhere at no cost and with almost no restrictions whatsoever. You may copy it, give it away or re-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.org Title: The Bacillus of Long Life a manual of the preparation and souring of milk for dietary purposes, together with and historical account of the use of fermente Author: Loudon Douglas Release Date: March 18, 2010 [EBook #31691] Language: English Character set encoding: UTF-8 *** START OF THIS PROJECT GUTENBERG EBOOK THE BACILLUS OF LONG LIFE *** Produced by Peter Vachuska, Turgut Dincer, Chuck Greif and the Online Distributed Proofreading Team at https://www.pgdp.net Putnam's Science Series The Oldest Woman in the World and her Son THE OLDEST WOMAN IN THE WORLD AND HER SON BABA VASILKA IS 126 YEARS OLD, AND HER SON TUDOR IS 101. THEY ARE PEASANTS, AND HAVE LIVED ALL THEIR LIVES IN A LITTLE VILLAGE IN BULGARIA. THEY ARE TYPICAL EXAMPLES OF PEOPLE WHO LIVE TO A GREAT AGE BY THE USE OF SOURED MILK, AS IT HAS BEEN THEIR PRINCIPAL FOOD all their lives. The Bacillus of Long Life A Manual of the Preparation and Souring of Milk for Dietary Purposes, Together with an Historical Account of the Use of Fermented Milks, from the Earliest Times to the Present Day, and Their Wonderful Effect in the Prolonging of Human Existence By Loudon M. Douglas, F.R.S.E. With 62 Illustrations G. P. Putnam's Sons New York and London The Knickerbocker Press 1911 Revised Edition Copyright, 1911 BY G. P. PUTNAM'S SONS The Knickerbocker Press, New York PREFACE This book has been designed with a view to meet an extensive demand for definite data on the subject of Soured Milks. The author has had this matter brought before him, times without number, by those inquiring for authentic information on the subject, and he has therefore considered it desirable to gather together such information as is available in connection with ancient and modern practice. He has endeavoured to present this to the reader in concise form. The author is indebted to many friends for their assistance in getting the book together, and would specially mention Dr. H. B. Hutchinson, Bacteriologist, Rothamsted Experimental Station, for assistance in connection with the bacteriology of fermented milks; Mr. Thomas Douglas, of Wimbledon, who has assisted with the chemistry of the subject; Mr. S. Javrilovitch, of Belgrade, Servia, for local information and illustrations; Dr. Otokar Laxa, Bacteriologist, of Prague, Bohemia, for general assistance; the editor of Bacteriotherapy, New York, U.S.A., for the use of the group of illustrations 30-44; the publishers of the Centralblatt für Bakteriologie, Jena, for the group of illustrations 14-29; and many others, some of whom are referred to in the text. CONTENTS CHAPTER PAGE I.— Introductory—Historical 1 II.— Fermented Milks 15 III.— The Chemistry of Milk 47 IV.— Handling of Milk 68 V.— The Bacteriology of Fermented or Soured Milk 84 VI.— The Preparation of Soured Milk in the House 125 VII.— The Preparation of Soured Milk in the Dairy 139 VIII.— Soured Milk in Health and Disease 151 Index 165 ILLUSTRATIONS FIG. PAGE THE OLDEST WOMAN IN THE WORLD AND HER SON frontispiece THE PASS OF BUKOVA 2 KABYLES SOURING MILK 4 THE HANDLING OF MILK IN THE PYRENEES 8 THE CONSTITUENTS OF MILK 48 1.— MICRO-PHOTOGRAPH OF A DROP OF WHOLE MILK 58 2.— MICRO-PHOTOGRAPH OF SEPARATED MILK 58 3.— MICRO-PHOTOGRAPH OF CREAM 58 4.— PHOTOGRAPH OF TWO PETRI DISHES, WHICH HAVE BEEN INOCULATED WITH ORDINARY MILK 60 5.— THE CREAMOMETER 62 6.— TESTING-GLASS FOR EXTRANEOUS MATTER IN MILK 62 7.— LACTOMETER AND TEST-GLASS 64 iii iv v vi vii 8.— PASTEURISER 78 9.— CONTINUOUS APPARATUS FOR THE PRODUCTION OF LARGE QUANTITIES OF SOURED MILK 82 10.— A MILK-FILLING APPARATUS 90 11.— SECTION THROUGH A KEPHIR GRAIN 94 12.— Streptococcus lacticus (GROTENFELDT) GROWING ON LACTOSE-AGAR, STAINED BY GRAM'S METHOD 96 13.— PHOTO-MICROGRAPH OF PREPARATION FROM ARMENIAN SOURED MILK 106 14.— GRANULE BACILLUS FROM YOGHOURT. SHREDDED PREPARATION OF A FRESH SKIM-MILK CULTURE 110 15.— GRANULE BACILLUS FROM YOGHOURT, CULTIVATED AFTER THE USUAL AGAR METHOD 110 16.— GRANULE BACILLUS FROM YOGHOURT. AGAR MILK SUGAR CULTURE 110 17.— Bacteria W. FROM MILK, CULTIVATED TWENTY-FOUR HOURS 110 18.— AGAR MILK SUGAR CULTURE. FROM THE ORIGINAL BULGARIAN YOGHOURT 112 19.— AGAR MILK SUGAR CULTURE. SURFACE COLONY OF GRANULE BACILLUS FROM CALF'S STOMACH 112 20.— AGAR MILK SUGAR CULTURE. DEEP-LYING COLONY OF GRANULE BACILLUS FROM CALF'S STOMACH 112 21.— AGAR MILK SUGAR. COLONY OF Bacterium W. FROM YOGHOURT 112 22.— TWO COLONIES OF Bacillus Acidophilus FROM CALVES' MANURE 114 23.— BEER-WORT GELATINE 114 24.— SHREDDED PREPARATION OF BULGARIAN ORIGINAL YOGHOURT 114 25.— GRANULE BACILLUS FROM YOGHOURT. CULTIVATED IN SKIM MILK IN TWENTY-FOUR HOURS 114 26.— Bacteria W., AGAR MILK SUGAR CULTURE 116 27.— Bacteria acidophilus FROM CALVES' MANURE 116 28.— MUCUS FROM CALF'S STOMACH INOCULATED INTO MILK AFTER EIGHT TRANSFERRINGS 116 29.— DIPLOSTREPTOCOCCUS FROM YOGHOURT. PURE CULTURE IN SKIM MILK 116 30.— PHOTO-MICROGRAPH OF PREPARATION MADE FROM YOGHOURT, SHOWING YEAST CELLS 118 31.— PHOTO-MICROGRAPH OF SMEAR FROM GREEK CURDLED MILK CALLED "GIAOURTI" 118 32.— PHOTO-MICROGRAPH OF SOURED MILK INOCULATED WITH A TABLET CONTAINING VIABLE AND PURE CULTURES OF Bacillus bulgaricus 120 33.— PHOTO-MICROGRAPH OF MILK INOCULATED WITH A FERMENT TABLE IN WHICH Bacillus bulgaricus IS NO LONGER VIABLE 120 34.— PHOTO-MICROGRAPH OF SMEAR OF CULTURE OF Bacillus bulgaricus 122 35.— Bacillus bulgaricus, SHOWING THE CULTURES IN ENGLISH COW'S MILK 124 36.— PHOTO-MICROGRAPH OF PURE CULTURE OF Bacillus bulgaricus 124 37.— PHOTO-MICROGRAPH OF SMEAR OF COMBINED CULTURE OF Bacillus bulgaricus AND Bacteria paralacticus 124 38.— PHOTO-MICROGRAPH OF SMEAR OF ONE-MONTH CULTURE OF Bacillus bulgaricus 126 39.— PHOTO-MICROGRAPH OF CULTURE OF Bacillus bulgaricus IN MALT 126 40.— PHOTO-MICROGRAPH OF SMEAR FROM MILK THAT HAD BEEN ALLOWED TO SOUR SPONTANEOUSLY 126 41.— PHOTOGRAPH OF AGAR CULTURE, INOCULATED WITH A LACTIC POWDER 128 42.— PHOTOGRAPH OF TEST-TUBES OF STERILE MILK, INOCULATED WITH A TABLET PREPARATION SAID TO CONTAIN PURE CULTURES 128 43.— PHOTOGRAPH OF TEST-TUBES OF STERILE MILK, EACH TUBE HAVING BEEN INOCULATED WITH A TABLET OF A PREPARATION SAID TO CONTAIN PURE CULTURES 128 44.— PHOTOGRAPH OF TEST-TUBES OF STERILE MILK INOCULATED WITH A TABLET OF "LACTOBACILLINE" 130 45.— APPARATUS OF "LE FERMENT" CO. 129 46.— SOURED MILK APPARATUS OF THE MAYA BULGARE COMPANY, LIMITED 130 47.— LACTIC FERMENTS, LIMITED, APPARATUS 131 48.— MESSRS. ALLEN & HANBURY'S SOURED MILK APPARATUS 132 49.— VIRONELLE APPARATUS FOR SOURING MILK, MADE BY MESSRS. CLAY, PAGET & COMPANY, LIMITED 132 50.— .—"LACTOBATOR" MADE BY MESSRS. CHARLES HEARSON & CO., LIMITED 140 51.— MESSRS. HEARSON & COMPANY'S "LACTOBATOR" 142 52.— EDGAR'S "LACTOGENERATOR," SOLD BY THE DAIRY SUPPLY CO., LIMITED 143 53.— APPARATUS OF THE WILLOWS REFRIGERATING CO., LIMITED 144 54.— "LACTO" APPARATUS OF THE DAIRY OUTFIT CO., LIMITED 145 55.— STERILISING APPARATUS FOR STERILISING MILK ON THE LARGE SCALE 146 viii x 56.— ANOTHER METHOD OF STERILISING (DAIRY SUPPLY CO., LTD.). AN AMERICAN APPARATUS FOR PREPARING SOURED MILK 148 57.— AN AMERICAN APPARATUS FOR PREPARING SOURED MILK 149 THE BACILLUS OF LONG LIFE CHAPTER I INTRODUCTORY—HISTORICAL The milk industry is one of the oldest known to mankind, and it is difficult to imagine a time when milk in one way or another did not form a part of the diet of the human race. There is a good deal of evidence to show that in Paleolithic and Neolithic times, cattle were part of the possessions of the nomadic races; and, according to the Vedas, the manufacture of butter was known in India 1500 years B.C. In the eastern part of Europe, milk has always been looked upon as one of the principal kinds of food, but not necessarily the milk of cows, as, from ancient times to the present day, the milk from camels, buffaloes, sheep, and goats has been used indiscriminately throughout the East. According to Layard,1 "the Bedouins do not make cheese. The milk of their sheep and goats is shaken into butter or turned into curds; it is rarely or never drunk fresh, new milk being thought very unwholesome, as soon by experience I found it to be, in the desert. I have frequently had occasion to describe the process of making butter by shaking the milk in skins. This is also an employment confined to women, and one of a very laborious nature. The curds are formed by boiling the milk, and then putting some curds made on the previous day into it and allowing it to stand. When the sheep no longer give milk, some curds are dried, to be used as a leaven on a future occasion. This preparation, called leben, is thick and acid, but very agreeable and grateful to the taste in a hot climate. The sour milk, or sheneena, a universal beverage amongst the Arabs, is either buttermilk pure and diluted, or curds mixed with water. The Pass of Bukova. THE PASS OF BUKOVA.—DURING THE REVOLUTION OF 1904, A NUMBER OF TURKISH SOLDIERS, JUST BEFORE TRAVERSING THIS PASS, WERE GIVEN COFFEE CONTAINING "CAFÉ" BY A BULGARIAN COFFEE-SELLER, OR KEEPER OF A SMALL KHAN. WHILST IN THE PASS THE POISON BEGAN TO TAKE EFFECT, AND THEY REALIZED THAT THEY HAD BEEN POISONED. FORTUNATELY FOR THEM, A PEASANT WITH THREE HORSES LOADED WITH YOGHOURT (SOURED MILK) HAD TAKEN ADVANTAGE OF THEIR ESCORT. THE SOLDIERS ATE FREELY OF THE YOGHOURT, WHICH COUNTERACTED THE effects of the poison. "The camel's milk is drunk fresh. It is pleasant to the taste, rich, and exceedingly nourishing. It is given in large quantities to the horses. The Shammar and Aneyza Bedouins have no cows or oxen, those animals being looked upon as the peculiar property of tribes who have forgotten their independence, and degraded themselves by the cultivation of land. The sheep are milked at dawn, or even before daybreak, and again in the evening on their return from the pastures. The milk is immediately turned into leben, or boiled to be shaken into butter. Amongst the Bedouins and Jebours it is considered derogatory to the character of a man to milk a cow or sheep, but not to milk the camel. The Sheikhs 1 2 3 occasionally obtain dates from the cities. They are eaten dry with bread and leben, or fried in butter, a very favourite dish of the Bedouin...." The practice is now the same as it was in scriptural times, when milk was looked upon as the principal article of diet, and throughout the Scriptures there are copious references to milk in different forms, some of which are of peculiar interest at the present day. It may be noticed, for example, that milk is absent from the sacred offerings amongst the Hebrews, and this was ascribed by the late Professor Robertson Smith to the fact that all ferments were excluded from presentation at the altar,2 it being recognised that, owing to the hot climate, milk of all kinds became rapidly sour, and in this way came to be looked upon as only fit for consumption when in that condition. It has been suggested that the prohibition referred to is on the same level as the prohibition of the use of blood, "as milk has sometimes been regarded as a kind of equivalent for blood, and containing the sacred life."3 To this day the wandering tribes of Arabia consider the milk of their camels and flocks more refreshing when it has been slightly fermented or soured by being poured into a milk-skin on the inside of which are still sticking sour clots from the previous milking, and there shaken for a brief period; but this slightly soured milk (the Oxygala of Pliny) is known widely in the East simply as leben (milk). The name is also applied to what we term buttermilk.4 Kabyles Souring Milk. KABYLES SOURING MILK IN THE NORTH OF AFRICA THE USE OF SOURED MILK IS COMMON, AND THE ILLUSTRATION SHOWS KABYLES SHAKING A SKIN FULL OF MILK SO AS TO SOUR IT. THE SKIN HAS PREVIOUSLY BEEN USED FOR THE SAME OPERATION, AND, AS A CONSEQUENCE, CLOTS OF MILK ARE LEFT FROM THE previous day's use, and thus fermentation is set up. The use of milk-skins for the carrying of milk is not confined to one country, as, while it is common all over the north of Africa, it is also known in the Pyrenees and in some parts of the Balkan Peninsula, the object being identical in each case; and when it is intended to make butter from the milk, the skin is simply rocked between the knees until the butter separates, a process of butter-making which was also used after the introduction of earthenware churns.5 Dried soured milk is also used by the Arabs, and it is reconstituted when required by rubbing it up with a little water, and it is known as Meeresy.6 The ordinary soured milk is the common article of diet, and is looked upon as being necessary at every meal, and travellers frequently refer to the use of this product, as a few references will show. Amongst the peasants at the present day, soured milk is known as _yoghourt_, a word which is spelt differently according to the locality in which it is used. The method of preparation is practically the same everywhere, and a short description of the process as now carried out in one place would, with slight modifications, apply to the general method adopted all over the East. Charles G. Addison states: "A supper was brought in on a round tray. In the centre was a huge pilaff of rice, and around it several small dishes of stewed meats, grilled bones, sour clotted milk called yaoort,7 bits of meat roasted, etc.... "We retired into a tent to breakfast, where we found an immense bowl of delicious fresh camels' milk, with thin hot cakes of unleavened bread, baked upon the ashes, ready prepared for us. The principal food of the Bedouins consists of flour and some camels' milk made into a paste, boiled, and eaten swimming in melted grease and butter; boiled wheat and beans dried in the sun and prepared with butter are a favourite dish. They are all remarkably fond of butter and grease; the butter is made in a goat-skin, suspended to the tent pole, and constantly shaken about by the women."8 Burckhardt9 says: "The provisions of my companion consisted only of flour; besides flour, I carried some butter and dried leben (sour milk), which would dissolve in water. It forms not only a refreshing beverage, but is much to be 4 5 6 recommended as a preservative of health when travelling in summer. These are our only provisions." With regard to the inhabitants of the Houran, Burckhardt relates that the most common dishes of these people are bourgoul and keshk. "In summer they supply the place of the latter by milk, leben, and fresh butter. Of the bourgoul I have spoken on other occasions; there are two kinds of keshk—keshk-hammer and keshk-leben. The first is prepared by putting leaven into the bourgoul and pouring water over it. It is then left until almost putrid, and afterwards spread out in the sun and dried, after which it is pounded, and, when called for, served up mixed with oil or butter. The keshk-leben is prepared by putting leben into the bourgoul instead of leaven; in other respects the process is the same. Keshk and bread are the common breakfasts. Towards sunset a plate of bourgoul, or some Arab dish, forms the dinner." Again, Taylor10 says: "I received a small jug of thick buttermilk, not remarkably clean, but very refreshing." These references particularly refer to the East, from which it would appear that soured milk was universally known in ancient times as it is at the present day, and this remark applies not only to Egypt, Palestine, and Arabia, but throughout Turkey and the Balkan States, where the consumption of soured milk is equally common. It seems curious that the use of this commodity should have been confined for centuries to the East, as we shall see later on that its dietetic value is so great that it is really a wonderful thing that no one has taken the trouble to introduce its use to the Western nations until quite recently. The Handling OF Milk in the Pyrenees THE HANDLING OF MILK IN THE PYRENEES THE HANDLING OF MILK IN THE PYRENEES IS, MORE ESPECIALLY IN THE VILLAGES, CONDUCTED IN GOAT OR SHEEP SKINS, IN A SIMILAR WAY TO THE METHODS WHICH PREVAIL IN EASTERN EUROPE, AND THE PICTURE SHOWS A SKIN OF MILK ON A SMALL FARM IN THE PYRENEES. THE CHURNING IS VERY OFTEN PERFORMED BY SIMPLY ROCKING THE SKIN BETWEEN THE KNEES, ACIDITY BEING INDUCED BY REMNANTS OF THE PREVIOUS DAY'S MILK; SOURING OF MILK IS INDUCED BY THE same method. A curious example of how the virtues of such an article may be independently discovered by another nation is to be found in Lapland, where reindeer's milk is the article used. "The reindeer's milk," says Acerbi,11 "constitutes a principal part of the Laplander's food, and he has two methods of preparing it, according to the season. In summer he boils the milk with sorrel till it arrives to a consistence; in this manner he preserves it for use during that short season. In winter the following is his method of preparation: The milk, which he collects in autumn till the beginning of November, from the reindeer, is put into casks, or whatever vessels he has, in which it soon turns sour, and, as the cold weather comes on, freezes, and in this state it is kept. The milk collected after this time is mixed with cranberries and put into the paunch of the reindeer, well cleaned from filth; thus the milk soon congeals, and it is cut out in slices, together with the paunch, to effect which a hatchet is used, for no smaller instrument would perform the office of dividing that lump of ice. It is then separated into small pieces and eaten throughout the winter every day at noon, which is the Laplander's dinner-hour. It must be presumed, as it is served up without being brought to the fire, that this is ice-cream in the greatest perfection: here are flesh and fruit blended with the richest butyraceous milk that can be drawn from any animal; but, notwithstanding the extraordinary fatness, which may be supposed to resist in a great degree the effect of cold, this preparation, as our good missionary remarks with a degree of feeling, as if his teeth still chattered whilst he delivered the account, chills and freezes the mouth in a violent manner whenever it is taken. The milk which is drawn late in the winter 7 8 9 freezes immediately after being drawn. This is put into small vessels made of birchwood, and is considered by the Laplander as such an extraordinary delicacy, that he reserves it as the most acceptable present he can offer even a missionary. It is placed before the fire and eaten with a spoon as it is thawed. When put by, it is carefully covered up, because if the cold air gets to it afterwards, it turns of a yellow colour and becomes rancid." Amongst the peasants at the present day, soured milk is known as yoghourt, a word which is spelt differently according to the locality in which it is used. The method of preparation is practically the same everywhere, and a short description of the process as now carried out in one place would, with slight modifications, apply to the general method adopted all over the East. "The culture," says a correspondent at Varna, "which is used for the preparation of yogourt, is known as 'Maya' or as 'Bulgarian Maya.' The milk which is to be converted into yogourt must first be freed from all bacteria by boiling and allowed to cool to the temperature of 45° C.; it is then inoculated with maya and maintained at an even temperature of 45° C. during several hours. There are two kinds of maya, or ferment, one known as sour, and the other as sweet maya. "In Europe small stoves, made expressly for the purpose, are used to maintain the milk at the proper temperature. In this country, however, after the milk has been boiled, it is merely poured into a bowl and allowed to cool to approximately 45° C., then a tablespoonful of this tepid milk is well mixed (in a small bowl apart) with a similar quantity of maya, and the mixture, when it has become quite homogeneous, is added to the bowl of tepid milk and stirred slightly. (One tablespoonful of maya is sufficient to ferment one litre of milk.) A cover is then placed on the bowl and the whole is enveloped in flannel and left in a warm place for three hours in summer, and somewhat longer in winter. "The process of preparation is complete when the mixture assumes the appearance of a soft mass somewhat resembling cream cheese, but less solid. The flannel is then removed, the bowl uncovered and placed in a cool spot until needed for consumption. Of the yogourt thus prepared, a tablespoonful is kept to serve as maya for the following day. "The best yogourt is prepared from sheep's milk, the second quality from buffaloes' milk, and the third quality from cows' milk. Yogourt forms an almost daily article of diet with the natives in this country."12 With regard to the time stated for the fermenting process, it must be noted that since the subject has been investigated so thoroughly, the time required for fermentation has been found to be nearer ten than three hours, but this will be dealt with in a subsequent chapter. Historically it may be gleaned from the fragmentary references which we have given, that soured milk has, from time immemorial, formed the principal article of diet of a great many peoples, and the notable feature in connection with it is, that in some countries where it is in daily use, the age limit for human beings seems to be very much extended, and it would appear that there is a direct connection between the use of soured milk and longevity. In Bulgaria, for example, it is stated that the majority of the natives live to an age considerably in excess of what is recognised as the term of life amongst Western nations, and inquiry has shown that in the eastern part of Southern Europe, amongst a population of about three millions, there were more than three thousand centenarians found performing duties which would not be assigned to a man of sixty-five years of age elsewhere. It is quite common to find amongst the peasants who live to such a large extent upon soured milk, individuals of 110 and 120 years of age.13 In the ancient dairy practice, as we have seen, soured milk was the principal product, and the extraordinary ages which are recorded of the patriarchs, if translated into the modern denomination, would not appear to be so imaginary after all, when it is considered that we have thousands of examples at the present day of men and women enjoying quite as long a term of existence. It has been noticed also, that while these very old people are able to perform a certain amount of manual labour, there is not the same tendency to the mental decay which is so prominent and sad a feature amongst Western nations, at a period of about seventy or eighty years of age. It would seem, indeed, as if the habit of living long was well known in ancient times, and that, like many other of the valuable arts and sciences, it fell under a cloud during the Middle Ages, or, perhaps, the significance of the use of soured milk fell into neglect, and, even after the revival of letters in the sixteenth century, still remained obscure. The discovery of micro-organisms in perishable products, which is attributable to Anthony Van Leeuwenhoek, a Dutchman, whose vocation was the polishing of lenses, and who lived between 1632 and 1723, altered our point of view, not only of disease, but of all the functions carried on by the lower organisms. Since Van Leeuwenhoek's time, the germ theory has grown to vast proportions and has more especially been applied with splendid results to the study of milk. As we shall see later, the researches of modern investigators have led them to the conclusion that micro-organisms play such an important part in the milk supply, that it is impossible to carry it on safely without a knowledge of the bacteriology of the subject. This view began to prevail about 1890, some twenty years after Pasteur had shown what fermentation really meant. Since that time, the progress in dairying has been continuous, and, during recent years, attention has been directed to soured milk to such an extent that it has become necessary for all who are interested in the handling of milk and milk products to have a knowledge of the subject, as it seems clearly demonstrated that, under proper direction, there is every possibility of its forming an important element in the prolongation of life. 10 11 12 13 14 15 CHAPTER II FERMENTED MILKS There is considerable variety in the number of soured or fermented milks, and they are known by various names, such as Koumiss or Koomiss, which is prepared from mares' milk; Keffir, which was originally discovered in the mountains of the Caucasus, and which is prepared with Keffir grains; Leben, an Egyptian product prepared from the milk of the buffalo, cow, or goat; Matzoon, a soured milk which is prepared in Armenia from ordinary cows' milk; Dadhi, an Indian preparation from cows' milk. All of these owe their special characteristics to the fact of their having undergone lactic and alcoholic fermentation. "Milk left to itself," says Blyth,14 "at all temperatures above 90° F. begins to evolve carbon dioxide, and this is simply a sign and result of fermentation. If this fermentation is arrested or prevented, the fluid remains perfectly sweet and good for an indefinite time. Besides the production of carbon dioxide during decomposition, a certain portion of milk sugar is converted into lactic acid, some of the casein and albumen are broken up into simpler constituents, and a small proportion of alcohol produced, which by oxidation appears as acetic acid, while the fat is in part separated into free fatty acids, which ultimately unite with the ammonia produced by the breaking up of the albuminoids. The main fermentation of milk is a special kind which of late years has been much studied, and is known as lactic fermentation. Accompanying lactic fermentation there is nearly always a weak butyric and a weak alcoholic fermentation." One of the organisms causing Butyric Acid Fermentation is a bacillus 3 to 10µ in length, and about 1µ in breadth. It has power of movement, and when cultivated in gelatine, liquefies the gelatine, forming a scum on the surface. When the bacillus is sown into sterile milk, the following, according to Hueppe, are the changes: "If the milk thus infected is incubated, on the second day a clear, slightly yellow fluid is seen under the layer of cream; this fluid increases from day to day, so that gradually a column of fluid is formed which is quite clear above, but below is turbid; the casein, at first thrown down in a firm coagulum, in the course of eight days begins to be attacked, and by the end of two or three weeks most of it is dissolved. The filtered fluid gives the biuret reaction; it contains leucin, tyrosin, and ammonia; hence it is clear that the ferment acts to some extent as a digestive of albumen. In advanced butyric acid fermentation, the fluid is most offensive, and may have an alkaline reaction." Lactic acid was first isolated by Scheele in 1780 from soured milk, but its exact constitution was not determined until later by Liebig, Mitscherlich, Gay-Lussac, and Pelouze: "It is widely distributed in nature, occurring in the sap of the vine and in most fermented liquids, especially in soured milk; it is not, however, present in fresh milk."15 In all the Eastern preparations referred to, the lactic fermentation is produced, followed by alcoholic fermentation, which is due to the slow decomposition of the milk sugar, the vinous fermentation being most readily set up in milks which contain a larger relative proportion of milk sugar and water, such as the milk derived from the mare, the sheep, and the camel. As these fermented milks have different characteristics, it is necessary to the thorough understanding of the process of manufacture at the present day, to examine them in some detail. Koumiss.—The greatest of all the fermented milks is koumiss, and it has been celebrated from the most ancient times until the present day, as being the principal food of the wandering tribes of Khirgiz, Bashkirs, Kalmucks, and Tartars, who inhabit the steppes of European Russia and the plains of South, Western, and Central Asia. According to Carrick, who has written an interesting volume on the subject,16 the nomads who inhabit these vast territories are shut up under the most miserable circumstances during the winter time and at the advent of spring they roam over the steppes from morning to night, usually in the saddle. The milk yielded at such time by the mares is carefully collected, and these nomads consume enormous quantities of it in the fermented state, this habit having been in existence amongst them from time immemorial. It is said that the Scythians, long before the Christian era, used fermented mares' milk; and there are ornaments in existence in Russia, of Scythian origin, which exhibit in detail the preparation of koumiss from mares' milk. In historical times, the first mention of koumiss was in the twelfth century, when it is referred to in the Ipatof Chronicles. During the thirteenth century William de Rubruquis, a French missionary, wrote about his travels in Tartary, and he described how he had first become acquainted with koumiss, and how he found it savoury to the palate. Subsequent to this, however, there is very little mention of koumiss in Russian history, or, for that matter, in any other, and the first really scientific contribution on the subject was by Dr. John Grieve, who was a surgeon in the Russian army, and who in the year 1784 sent a description of koumiss to the Royal Society of Edinburgh,17 of which he was a member, and the title of it was, "An Account of the Method of Making Wine called by the Tartars Koumiss, with Observations on its Use as a Medicine." Dr. Grieve strongly advocated the use of koumiss as beneficial in cases of wasting diseases, and subsequently it was adopted by the medical profession, with the result that sanatoria for the treatment of pulmonary consumption were established at Samara and other places in Russia, and met with very great success; and at the present day such sanatoria are carried on, but the bacteriology of the subject now being thoroughly understood, the methods of preparation have been somewhat modified. An interesting account of koumiss is given by Clarke,18 who says: "Everybody has heard of koumiss, and the brandy which the Kalmucks are said to distil from the milk of mares. The manner of preparing these liquids has been differently related, and perhaps is not always the same. They assured us that the brandy was merely distilled from buttermilk. The milk which they collect overnight is churned in the morning into 15 16 17 18 19 20 butter; and the buttermilk is distilled over a fire made with the dung of their cattle, particularly the dromedary, which makes a steady and clear fire like peat. But other accounts have been given both of the koumiss and the brandy. It has been usual to confound them, and to consider the koumiss as their appellation for the brandy so obtained. By other information I could gain, not only here, but in many other camps which we afterwards visited, they are different modifications of the same thing although different liquors; the koumiss being a kind of sour milk, like that so much used by the Laplanders called pina, and which has undergone, in a certain degree, the vinous fermentation; and the brandy an ardent spirit obtained from koumiss by distillation. In making koumiss they sometimes employ the milk of cows, but never if mares' milk can be had, as the koumiss from the latter yields three times as much brandy as that made from cows' milk. "The manner of preparing the koumiss is, by combining one sixth part of warm water with any given quantity of warm mares' milk. To these they add, as a leaven, a little old koumiss, and agitate the mass till fermentation ensues. To produce the vinous fermentation, artificial heat and more agitation is sometimes necessary. This affords what is called koumiss. The subsequent process of distillation afterwards obtains an ardent spirit from the koumiss. They call it vina. In their own language it bears the very remarkable appellation of rack and racky, doubtless nearly allied to the names of our East India spirit rack and arrack. We brought away a quart bottle of it, and considered it very weak bad brandy, not unlike the common spirit distilled by the Swedes and other northern nations. Some of their women were busy making it in an adjoining tent. The simplicity of the operation and their machinery was very characteristic of the antiquity of this chemical process. Their still was constructed of mud, or very coarse clay; and for the neck of the retort they employed a cane. The receiver of the still was entirely covered by a coating of wet clay. The brandy had already passed over. The woman who had the management of the distillery, wishing to give us a taste of the spirit, thrust a stick, with a small tuft of camel's hair at its end, through the external covering of clay, and thus collecting a small quantity of the brandy, she drew out the stick, dropped a portion on the retort, and, waving the instrument above her head, scattered the remaining liquor in the air. I asked the meaning of this ceremony, and was answered that it is a religious custom to give always the first drop of the brandy which they draw from the receiver to their God. The stick having been plunged into the receiver again, she squeezed it into the palm of her dirty and greasy hand, and after tasting the liquor, presented it to our lips." Another interesting account of the preparation of koumiss is given by John M. Wilson in the Rural Encyclopædia,19 and it shows that the methods in use about the middle of last century did not differ materially from those which existed centuries before. Wilson says: "Khoumese is vinously fermented mares' milk. Any quantity of fresh mares' milk is put into wooden vessels; a sixth part of water just off the boil is mixed with it; an eighth part of old khoumese or of the sourest possible cows' milk is added; the mixture is kept from fifteen to twenty-four hours, covered up with several folds of coarse linen cloth and with a very thick board, and without being stirred or in any degree disturbed, in a moderately warm place till it becomes thoroughly sour, and sends up a thick mass to its surface; it is then beaten and pounded and stirred till the curd is not only broken, but so thoroughly mixed with the serum as to form a thick liquid; it next remains covered and at rest during twenty-four hours more, and it is finally put into a common butter churn and beaten and blended into a state of perfect homogeneity. It is now fit for use; yet it acquires an increase of given properties if it be allowed to stand for a few days, and either then or now it would, if distilled, yield nearly one third of its own bulk of a weak spirit which will bear to be rectified. Whenever it is used it must be previously so agitated that its component parts may be well mixed together, and it may be kept either in pans for immediate use or in casks for more remote use; and if placed in a cool cellar it will remain good during three or four months." Mares' milk owes its peculiar fitness for making koumiss to its containing a large proportion of sugar of milk, and readily undergoing the vinous fermentation, and it possesses a general medicinal reputation among the Tartars similar to that which asses' milk has partially acquired in Britain. "That mares' milk will undergo vinous fermentation and yield a certain quantity of spirit," says a writer in the Magazine of Domestic Economy, "is not generally known, and it was reserved for a nation of demi-savages to render this circumstance available as an agent of health, as well as an agreeable and nourishing beverage. Every educated person, however, has heard that the Tartars drink mares' milk, though few know that this milk is taken on account of its specific virtues alone, and not as a substitute for cows' milk, of which they have abundance, and with which they adulterate mares' milk when scarce." But the koumiss is reputed to be much more medicinal than the mares' milk itself; and on account of its being free from all tendency to curdle in the stomach, and of its possessing most of the nutritive power of the milk in combination with native fermented spirit, it has been strongly recommended by some persons as a remedy for most or all cases of general debility, of nervous languor, and even pulmonary disease. "Khoumese is called sometimes koumiss and sometimes milk wine." From these references it will be seen that koumiss is an alcoholic drink made by the fermentation of mares' milk, but it is also frequently prepared from the milk of the camel and cows' milk. It is stated that a similar preparation to Russian koumiss is made in Switzerland from cows' milk simply by the addition of a little sugar and yeast to skim milk; "it contains more sugar and less lactic acid than Russian koumiss, and on account of the much greater proportion of casein contained in cows' milk, differs considerably from that prepared from mares' milk." Suter-Naef gives the composition of a Swiss koumiss20 manufactured at Davos as follows: 21 22 23 24 25 26 In Grams. Per Litre. Per cent. (by weight.) Water 90.346 1019.64 grams. Alcohol 3.210 36.23 " Lactic acid 0.190 2.14 " Sugar 2.105 23.75 " Albuminates 1.860 20.99 " Butter 1.780 20.09 " Inorganic salts 0.509 5.74 " Free carbonic acid 0.177 2.00 " The ferments used in the preparation of koumiss are stated by Carrick to be of two different kinds, artificial and natural. "Of the natural ferments two have been resorted to. One is mentioned by Grieve, which he borrowed from the Bashkirs of Orenbourg, and which simply consists in the addition of one sixth part of water and one eighth of the sourest cows' milk to fresh mares' milk; the other has been employed, and was, if I mistake not, first recommended by Bogoyavlensky. It is a very simple if rather a tedious method. New mares' milk, diluted with one third its bulk of water, is placed in the saba,21 and while allowed to sour spontaneously, is continually beaten up. This milk gradually undergoes the vinous fermentation, and in twenty-four hours is converted into weak koumiss. The disadvantage of this mode of commencing fermentation is obvious—viz., the great waste of time in agitation. Hence it is only employed when no artificial ferment is obtainable. "In starting the process of fermentation in mares' or any other kind of milk, therefore, an artificial ferment is more frequently employed than a natural one. The former is used only for converting the first portion of milk into koumiss; the latter is always resorted to afterwards. "Of artificial ferments the variety is great, for besides all putrefying animal matters which contain nitrogen—such as blood, white of egg, glue, and flesh—certain mineral substances which act by souring the milk are also capable of exciting fermentation. "Now, many of the nomads, whose mares either give no milk or are not milked in winter, commence the preparation of their koumiss in spring by borrowing a ferment from the animal, mineral, or vegetable kingdom. Thus a mixture of honey and flour is the favourite ferment with some races of nomads; a piece of fresh horse-skin or tendon is preferred by others, while a few resort to old copper coins, covered with verdigris, for starting fermentation. In the choice of a ferment they are guided solely by habit and tradition. As it would be useless, almost impossible, to give a list of all the foreign substances that have been employed with the view of converting mares' milk into koumiss, it will be best to consider the simplest artificial ferments, and those most generally in use. "The simplest way is that recommended by Bogoyavlensky, and adopted and modified by Tchembulatof.22 It is prepared thus: 'Take a quarter of a pound of millet-flour, add water to it, and boil it down to the consistence of thick oatmeal porridge. Then heat separately, in another vessel, eleven pints of milk to boiling-point, and allow it to cool down. When its temperature has fallen to 95° F., pour it into a wooden bowl or tub, and add the boiled flour to it. The upper and open part of the vessel is then covered with a piece of coarse linen, and left at rest—at a temperature of about 99° F.—from twenty-four to forty-eight hours. The appearance of small bubbles, which keep bursting on the surface of this liquid, combined with a vinous or acid odour, prove that the ferment is ready. To this fermenting fluid twenty-two quarts of new milk are gradually (i.e., every ten minutes) added, and the whole mass is continuously beaten up for twelve hours. The temperature during stirring should never be higher than 94° F. The whole fluid soon begins to ferment, and after twelve hours a not unpleasant koumiss is ready. This should be filtered through a horse-hair or muslin sieve, after which it is fit for drinking. This liquid is called weak koumiss; but a limited portion of the lactine has undergone the lactuous and vinous fermentations, and thus the percentage of alcohol is small. Koumiss at an ordinary temperature remains weak for twelve hours after it has been beaten up, and then gradually passes into medium.'" Curiously enough, the richness of cows' milk in fat militates against its being a good raw material for the making of koumiss, owing to the production of small quantities of butyric acid, which follows upon the fermentation, so that it is desirable, if koumiss is to be prepared from cows' milk, that the fat should be first of all eliminated, so that the separated milk will then approximate to the composition of mares' milk. "The chemical changes," says Hutchison,23 "which take place in the milk under the double fermentation are not difficult to follow; the lactic ferment simply changes part of the sugar into lactic acid, the vinous ferment eats up a very small part of the proteid of the milk, and, at the same time, produces from the sugar a little alcohol and a good deal of carbon dioxide; the milk thus becomes sour, it effervesces and is weakly alcoholic, but the lactic acid causes the casein to be precipitated just as it does in the ordinary souring of milk, and the casein falls down in flocculi." As will have been noticed, it is an essential part of the process of koumiss-making to keep the milk in a state of agitation during the period of fermentation, a process which is intended to permit of oxygen being taken up by the fermenting fluid, while, at the same time, the casein is broken up into a state of fine division. The casein also, or at least a portion of 27 28 29 30 31 it, becomes very soluble, and after twelve hours of fermentation the taste of the product is only slightly sour, and the milk taste still remains. This taste, however, disappears in twenty-four hours, owing to the rapid development of the lactic acid organisms. After this lapse of time the sugar is entirely destroyed, and the strong koumiss which results is a thin sour fluid which effervesces briskly, and in this condition will keep for an indefinite period. "The net change which has taken place in the original milk may be summed up by saying that the sugar of the milk has been replaced by lactic acid, alcohol, and carbon dioxide, the casein has been partly precipitated in a state of very fine division, and partly pre- digested and dissolved, while the fat and salts have been left much as they were."24 Violent stirring or agitation of the cultures does not seem to work so much by supplying oxygen to the fermenting liquid, as by ensuring a thorough distribution of the micro-organisms throughout the liquid, and thus dividing the casein. The greater number of the organisms are facultative anærobes and oxygen is not necessary. Again, koumiss put up in bottles on the first day is regularly shaken although air is excluded. Keffir.—Keffir is a kind of fermented milk which has been in use in the Caucasus for quite a long time, as koumiss has been in the steppes. It differs from koumiss, however, in this respect, that it is prepared from either sheep's, goats', or cows' milk. The process is started by the addition of keffir grains to the milk, which is contained in leathern bottles. These keffir grains are small solid kernels which are kept in families and handed on from one generation to another.25 The grains are the origin of the ferment, as they disseminate in the milk micro-organisms of a lactic yeast (Saccharomyces kefir Beyerinck and Freudenreich) and also the bacillus Bacterium caucasicum, which develop rapidly and split up the milk sugar into carbon dioxide, alcohol, and lactic acid. Small quantities of glycerine, acetic, succinic, and butyric acids are also formed, the casein and albumen being partly peptonised.26 Keffir becomes slightly effervescent in twenty-four hours, and in that time develops a small quantity of alcohol, but after three days the amount of alcohol and lactic acid is much increased.27 It has been determined that the fermentation of the milk is due to Saccharomyces kefir, and that the Lactobacillus Caucasicus does not take any part in the fermentation, a fact which seems to be supported by the capacity of ordinary keffir for starting the fermentation in fresh milk in the same manner as the keffir grains. The use of this beverage seems to be universal throughout the Caucasus, and travellers in these regions have frequently referred to it. Thus Freshfield28 states in one part of his book of travels as follows: "The pig-faced peasant against whom we had at first sight conceived such an unjust prejudice turned out a capital fellow. He brought us not only fresh milk, but a peculiar species of liquor, something between public-house beer and sour cider, for which we expressed the greatest admiration, taking care at the same time privately to empty out the vessel containing it, on the first opportunity." And again: "The hospitable shepherds regaled us, not only with the inevitable and universal airam or sour milk—if a man cannot reconcile himself to sour milk, he is not fit for the Caucasus—but with a local delicacy that has lately been brought to the knowledge of Europe—kefir. This may best be described as 'effervescing milk.' It is obtained by putting into the liquid some yellow grains, parts of a mushroom which contains a bacillus known to science as Dispora caucasia. The action of the grains is to decompose the sugar in the milk, and to produce carbonic acid and alcohol. The grains multiply indefinitely in the milk; when dried they can be preserved and kept for future use; its results on the digestion are frequently unsatisfactory, as one of my companions learnt to his cost." "It has been supposed," says Metchnikoff, "that the chief merit of kephir was that it was more easy to digest than milk, as some of its casein is dissolved in the process of fermentation. Kephir, in fact, was supposed to be partly digested milk. This view has not been confirmed. Professor Hayem thinks that the good effects of kephir are due to the presence of alcoholic acid, which replaces the acid of the stomach and has an antiseptic effect. The experiments of M. Rovigh, which I speak of in The Nature of Man, have confirmed the latter fact, which now may be taken as certain. The action of kephir in preventing intestinal putrefaction depends on the lactic acid bacillus which it contains. Kephir, although in some cases certainly beneficial, cannot be recommended for the prolonged use necessary, if intestinal putrefaction is to be overcome.... Professor Hayem prohibits its use in the case of persons in whom food is retained for long in the stomach. When it is retained in the stomach, kephir goes on fermenting, and there are developed in the contents butyric and acetic acids, which aggravate the digestive disturbances. Kephir is produced by combined lactic and alcoholic fermentations ... and it is the lactic and not the alcoholic fermentation on which the valuable properties of kephir depend; it is correct to replace it by sour milk, that contains either no alcohol or merely the smallest traces of it. The fact that so many races make sour milk and use it copiously is an excellent testimony of its usefulness." There are two methods given by Flügge29 for the preparation of keffir: "In the first, the dry brown kefir grains of commerce are allowed to lie in water for five or six hours until they swell; they are then carefully washed and placed in fresh milk, which should be changed once or twice a day until the grains become pure white in colour and when placed in fresh milk, quickly mount to the surface—twenty to thirty minutes. One litre of milk is then poured into a flask, and a full tablespoonful of the prepared körner added to it. This is allowed to stand open for five to eight hours; the flask is then closed and kept at 18° C. It should be shaken every two hours. At the end of twenty-four hours the milk is poured through a fine sieve into another flask, which must not be more than four fifths full. This is corked and allowed to stand, being shaken from time to time. At the end of twenty-four hours a drink is obtained which contains but little carbon-dioxide or alcohol....