; THE CHEMISTEY OF BKEADMAKING BY JAMES GRANT, M.Sc.Tech., F.I.C., F.C.S. U Head of the Fermentation Industries Department in the Municipal School of Technology, Manchester Examiner in Chemical Technology in the Victoria University, Manchester WITH PLATES SECOND EDITION LONDON EDWARD ARNOLD 1917 All rights reserved PREFACE TO THE SECOND EDITION In sending out a second edition of this little volume, the author wishes to express his acknowledgments of the very kindly reception accorded to the first. He has corrected a few errors which occurred in the original volume, and has added some pages at the end of this book in the form of addenda, hoping thereby to increase its efficiency. The author would strongly advocate more strenuous efforts on the part of all bakery students to persevere in the pursuit of scientific knowledge to a much greater extent than hitherto, in order to become more successful in their business, and endeavour to place the trade on a higher level than it at present occupies. J. G. Manchester, November 1916. 9 The Reference Numbers 1-14 in the text are to the ' Addenda on pp. 219 et seq. — PKEEACE This volume, on the application of science to the very important industry of Breadmaking, is put forward in the hope that it may fill in a gap which undoubtedly exists in the literature and text-books on this subject. It does not lay claim to any literary merit, but should rather be looked upon as an honest endeavour to assist learners who are groping in some amount of obscurity or darkness, with the dawn only Just beginning to break. The majority of earnest students in breadmaking and there are many—have not the same opportunities that are enjoyed by their fellows in other industries, in most of which there is a plethora of books, many of a very excellent character. For books the breadmaking industry at the moment is dependent upon the efforts of Mr. William Jago of Brighton, and Mr. John Kirkland of the School of Baking and Confectionery in the London Borough Polytechnic, in addition, of course, to several useful trade papers. This book is not intended to be a text-book on either chemistry or physics, but rather on the application of these and the kindred science of technical mycology to the subject of Breadmaking. It is advised that all who study its contents should do so in conjunction with some simple text-books on chemistry, physics, mechanics, and the elements of biology and botany. Eecourse has been had in a few instances to chemical equations, and whenever they have been used, the names V vi CHEMISTRY OF BREADMAKING of all substances taking part in the reactions have been inserted immediately below. As years advance, and a scientific education is given to the members of the trade generally, such an arrangement will become as unneces- sary as it is in many other technical sciences dependent on a working knowledge of chemistry. A large number of analytical figures are included in the little volume, which are quite original, and have not before been published. In other instances the sources of the information have been acknowledged. This has been considered advisable for reference sake, as very few of such exist to assist the student in his analytical studies. If the book merits and receives the favourable con- sideration of the trade and allied industries, it is hoped that in future editions any imperfections may be eradi- cated, whilst its scope and usefulness may be greatly enlarged. The author's thanks are due to his colleagues, Messrs. F. G. Richards, F.C.S., and Abraham Flatters, F.R.M.S., to the former for assistance in analytical work and proof- reading, and to the latter for kindly help in preparing many of the illustrations ; also to his student, Mr. F. Robinson, B.Sc. Tech., for aid in the illustrations for the technical mycology portion of the work. J. G. Manchester. CONTENTS CHAP. PAOB I. INTRODUCTORY ... 1 II. THE ATMOSPHERE. WATER 10 III. ACIDS, ALKALIES AND SALTS 22 IT. BAKERY PHYSICS I THERMOMETERS, BAROMETERS, AND CALCULATIONS 30 V. HEAT AND PHYSICAL PROBLEMS 42 VI. THE ORGANIC CONSTITUENTS OF THE CEREALS . 55 VII. THE CEREALS AND THEIR COMPOSITION ... 91 VIII. MILLING, MEALS, FLOURS, MALTS AND EXTRACTS . 102 IX. FERMENTS, YEASTS, MOULDS, BACTERIA AND BARMS . 125 X. BREADMAKING PROCESSES AND BREADS . .153 XI. ANTISEPTICS AND BAKEHOUSE HYGIENE . , 172 XII. FUELS AND OVENS 178 XIII. THE ANALYSIS OF CEREAL FOODS .... 186 BIBLIOGBAPHY 217 ADDENDA .... 219 index # 225 LIST OF PLATES I. Starches at page 72 II. Starches ,, 73 III. (i.) Wheat Flower, (ii.) Section of Wheat Berry „ 92 IV. (i.) Section of a Wheat Endosperm, (ii.) Section through Aleurone Cells, (iii.) Section of Wheat Germ ....,»•„ 98 CHEMISTRY OF BREADMAKING CHAPTER I INTRODUCTORY Breadmaking and the kindred fermentation industry of brewing have been known and practised from the remotest ages of mankind. Long ages before the Christian era, the growing of wheat and other cereals, the preparation of the grain for the mill, the milling of the cleaned and prepared grain, and the conversion of the meal into cakes or bread both leavened and unleavened, have occupied the attention of mankind. To the German, French, and English ex- plorers of the ruins of ancient Troy we are indebted for accounts of the wheat and barley growing in those early times and the certain knowledge that these cereals were used for the preparation of foods. The pyramids of Egypt, the mound tombs in North Africa and Asia, and the lake dwellings of Switzerland have all furnished evidence of the uses of wheat and barley, as the starting points for making bread and fermented liquids for the inhabitants of those ancient places. In the early chapters of the book of Genesis, an interesting account is given of the proclivities of one of the earliest Hebrews in making a corner in corn, and afterwards in selling the corn from his granaries to the famine-stricken nations around Egypt at enhanced prices. Early Greek and Roman writers appear to have been intimately acquainted with both breadmaking and brew- ing. For example, the elder Pliny in his writings makes a statement to the effect that flour yielded one and a third times its weight of bread. A — 2 CHEMISTRY OF BREADMAKING In our own country, the Anglo-Saxons were adepts in the art of making cakes and mead. In all cases, in these c early times, the word flour ' refers to meal, and this was produced by crushing the wheat in hand-stone mills or ' querns.' The evolution of the present-day white loaf has been a question of time like that of any other important industry, and to trace it step by step would be a study of considerable interest, but entirely outside the scope of this work. In order to produce bread of great food value, a loaf pleasing to the sight, palatable, easy of digestion and assimilation, and, above all, composed of three out of the four proximate principles of foods, is a work requiring much skill and manipulative power in addition to a general knowledge of flours and other raw materials. This implies that the modern, scientific baker should possess a working knowledge of such sciences as those of chemistry, physics, biology, botany, mechanics, and mathematics. Chemistry is that branch of physical science which has for its chief object the study of the composition of matter. For convenience sake the study of chemistry is divided into two parts inorganic and organic. The former deals with the forms of matter known as the non-metals or metalloids and the metallic bodies, together with the derivatives of both ; organic chemistry has for its object the consideration of the carbon compounds and their derivatives. The same laws of combination, the same forces and all other influences affect the compounds of both groups equally, but as there are so many thousands of the carbon bodies it is better to consider them separately. Matter is made up of almost infinitely small particles, the atoms and molecules. An atom is generally defined to be the smallest quantity of matter that can enter into chemical combination and can rarely exist in the free state ; whilst a molecule is composed of two or more atoms and is the smallest quantity of matter that can exist in the free state. Matter under different conditions of temperature ,and pressure exists in three states : gaseous, liquid, and — INTRODUCTORY 3 solid. Each of these three may be either elementary or compound matter. An element or elementary matter is that which is composed of particles all of the same kind, as, for example, sulphur, iron, oxygen, etc., while a compound or chemical compound is composed of two or more elements in a state of chemical combination, as, for example, water, sugar, butyrin, gypsum, etc. At the present time there are about eighty so-called elements recognised, but this number is not by any means a fixed one, for almost every year fresh additions are made to the list. The elements are divided into two groups : the non-metals or metalloids, and the metals. The metals are characterised by possessing some of the following properties : They possess a bright shining surface or lustre when seen in the lump ; they are of high specific gravity or are said to be dense compared with the non-metals ; are good conductors of heat and electricity ; possess ductility, malleability and tenacity ; form alloys or mixtures of metals which contain not only the properties of the con- stituent metals as enumerated above, but in addition certain special ones ; and in most cases they have a char- acteristic appearance or fracture when broken across or torn apart.