The Book of Cheese.

by Charles Thom and Walter Warner Fisk.

PREFACE

Certain products we a.s.sociate with the manufactures of the household, so familiar and of such long standing that we do not think of them as requiring investigation or any special support of science. The older ones of us look back on cheese as an ancient home product; yet the old-fashioned hard strong kind has given place to many named varieties, some of them bearing little resemblance to the product of the kitchen and the b.u.t.tery. We have a.n.a.lyzed the processes; discovered microorganisms that hinder or help; perfected devices and machines; devised tests of many kinds; studied the chemistry; developed markets for standardized commodities. Here is one of the old established farm industries that within a generation has pa.s.sed from the housewife and the home-made hand press to highly perfected factory processes employing skilled service and handling milk by the many tons from whole communities of cows. This is an example of the great changes in agricultural practice. Cheese-making is now a piece of applied science; many students in the colleges are studying the subject; no one would think of undertaking it in the old way: for these reasons this book is written.

This book is intended as a guide in the interpretation of the processes of making and handling a series of important varieties of cheese. The kinds here considered are those made commercially in America, or so widely met in the trade that some knowledge of them is necessary. The relation of cheese to milk and to its production and composition has been presented in so far as required for this purpose. The principles and practices underlying all cheese-making have been brought together into a chapter on curd-making. A chapter on cla.s.sification then brings together into synoptical form our knowledge of groups of varieties.

These groups are then discussed separately. The problems of factory building, factory organization, buying and testing milk, and the proper marketing of cheese, are briefly discussed.

Such a discussion should be useful to the student, to the beginner in cheese-making, as a reference book on many varieties in the hands of makers who specialize in single varieties, and to the housekeeper or teacher of domestic science. The material has been brought together from the experience of the writers, supplemented by free use of the literature in several languages. Standard references to this literature are added in the text.

No introduction to the subject of cheese should fail to mention the work of J. H. Monrad, who has recently pa.s.sed away. Mr. Monrad never collected his material into a single publication, but his contributions to cheese-making information, scattered widely in trade literature over a period of thirty years, form an encyclopedia of the subject.

Bulletins of the Agricultural Experiment Stations and United States Department of Agriculture have been quoted extensively, with citation of the sources of the material. Personal a.s.sistance from Professor W. A.

Stocking and other members of the Dairy Department of Cornell University, and C. F. Doane of the United States Department of Agriculture, is gladly acknowledged.

Students cannot learn out of books to make cheese. They may, however, be aided in understanding the problems from such study. To make cheese successfully they must have intimate personal touch with some person who knows cheese. Sympathetic relations with such a teacher day by day in the cheese-room are essential to success in making cheese which, at its best, is one of the most attractive of food-products.

THE AUTHORS.

CHAPTER I

_GENERAL STATEMENT ON CHEESE_

Cheese is a solid or semi-solid protein food product manufactured from milk. Its solidity depends on the curdling or coagulation of part or all of the protein and the expulsion of the watery part or whey. The coagulum or curd so formed incloses part of the milk-serum (technically whey) or watery portion of the milk, part of the salts, part or all of the fat, and an aliquot part of the milk-sugar. The loss in manufacture includes a small fraction of the protein and fat, the larger proportion of the water, salts and milk-sugar.

+1. Nature of cheese.+--Milk of itself is an exceedingly perishable product. Cheese preserves the most important nutrient parts of the milk in condition for consumption over a much longer period. The duration of this period and the ripening and other changes taking place depend very closely on the composition of the freshly made cheese. There is an intimate relation between the water, fat, protein and salt-content of the newly made cheese and the ripening processes which produce the particular flavors of the product when it is ready for the consumer.

This relation is essentially biological. A cheese containing 60 to 75 per cent of water, as in "cottage cheese" (the sour-milk cheese so widely made in the homes), must be eaten or lost in a very few days.

Spoilage is very rapid. In contrast to this, the Italian Parmesan, with 30 to 32 per cent of water, requires two to three years for proper ripening.

The cheeses made from soured skim-milk probably represent the most ancient forms of cheese-making. Their origin is lost in antiquity. The makers of Roquefort cheese cite pa.s.sages from Pliny which they think refer to an early form of that product. It is certain that cheese in some form has been familiar to man throughout historic times. The technical literature of cheese-making is, however, essentially recent.

The older literature may be cited to follow the historical changes in details of practice.

+2. Cheese-making as an art+ has been developed to high stages of perfection in widely separate localities. The best known varieties of cheese bear the geographical names of the places of their origin. The practices of making and handling such cheeses have been developed in intimate relation to climate, local conditions and the habits of the people. So close has been this adjustment in some cases, that the removal of expert makers of such cheeses to new regions has resulted in total failure to transplant the industry.

+3. Cheese-making as a science+ has been a comparatively recent development. It has been partly a natural outgrowth of the desire of emigrant peoples to carry with them the arts of their ancestral home, partly the desire to manufacture at home the good things met in foreign travel. Its development has been largely coincident with the development of the agricultural school and the science of dairy biology. Even now we have but a limited knowledge of a few of the 500 or more varieties of cheese named in the literature. It is desirable to bring together the knowledge of underlying principles as far as they are known.

No technical description of a cheese-handling process can replace experience. Descriptions of appearances and textures of curd in terms definite enough to be understood by beginners have been found to be impossible. It is possible, however, to lay down principles and essentials of practice which are common to the industry and form the foundation for intelligent work. Cheese-making will be a science only as we depart from the mere repet.i.tion of a routine or rule-of-thumb practice and understand the underlying principles.

+4. Problems in cheese-making.+--Any understanding of these problems calls for a working knowledge of the very complex series of factors involved. These include the chemical composition of the milk, the nature of rennet and character of its action under the conditions met in cheese-making, the nature of the micro-organisms in milk, and the methods of controlling them, their relation to acidity and to the ripening of the cheese. To these scientific demands must be added acquaintance with the technique of the whole milk industry, from its production and handling on the farm through the multiplicity of details of factory installation and organization, to those intangible factors concerned with the texture, body, odor and taste of the varied products made from it. Some of these factors can be adequately described; others have thus far been handed on from worker to worker but have baffled every effort at standardization or definition.

+5. History.+--The recorded history of the common varieties of cheese is only fragmentary. Practices at one time merely local in origin followed the lines of emigration. Records of processes of manufacture were not kept. The continuance of a particular practice depended on the skill and memory of the emigrant, who called his cheese after the place of origin.

Other names of the same kind were applied by the makers for selling purposes. The widely known names were thus almost all originally geographical. Some of them, such as Gorgonzola, are used for cheeses not now made at the places whose names they bear. Naturally, this method of development has produced national groups of cheeses which have many common characteristics but differ in detail. The English cheeses form a typical group of this kind.

Emigration to America carried English practices across the Atlantic. The story of cheese-making in America has been so closely linked with the development of the American Cheddar process that the historical aspects of the industry in this country are considered under that head in Chapter VIII.

CHAPTER II

_THE MILK IN ITS RELATION TO CHEESE_

The opaque whitish liquid, secreted by the mammary glands of female mammals for the nourishment of their young, is known as milk. The milk of the cow is the kind commonly used for cheese-making in America.

+6. Factors affecting the quality.+--The process of cheese-making begins with drawing the milk from the udder. The care and treatment the milk receives, while being drawn, and its subsequent handling, have a decided influence on its qualities. The process of cheese-making is varied according to the qualities of the milk. There are five factors that influence the quality of the milk for cheese-making: (1) its chemical composition; (2) the flavor of feed eaten by the cow; (3) the absorption of flavors and odors from the atmosphere; (4) the health of the cow; (5) the bacteria present. The first factor is dependent on the breed and individuality of the cow. The other four factors are almost entirely within the control of man. Of these factors, number five is of the most importance, and is the one most frequently neglected.

+7. Chemical composition.+--The high, low and average composition of milk is approximately as follows:

TABLE I

COMPOSITION OF MILK

--------+-------+------+--------+-------+---------+-----

WATER

FAT

CASEIN

SUGAR

ALb.u.mIN

ASH

PER

PER

PER

PER

PER

PER

CENT

CENT

CENT

CENT

CENT

CENT --------+-------+------+--------+-------+---------+----- High

88.90

5.50

3.00

5.00

.72

.73 Low

85.05

3.00

2.10

4.60

.70

.70 Average

87.47

3.80

2.50

4.80

.71

.72 --------+-------+------+--------+-------+---------+-----

+8. Factors causing variation in composition.+--The composition of cow's milk varies according to several factors. The composition of the milk of different breeds differs to such a degree that whole series of factories are found with lower or higher figures than these averages on account of dominant presence of particular kinds of cattle.

The following table shows the usual effect of breed on fat and total solids of milk:

TABLE II

THE USUAL EFFECT OF BREED OF COWS ON FAT AND TOTAL SOLIDS OF MILK

------------------+------------------------

AVERAGES BREED OF COWS +----------+-------------

Fat

Total Solids

Per Cent

Per Cent ------------------+----------+------------- Jersey

5.62

14.74 Guernsey

5.34

14.70 Shorthorn

4.17

13.41 Ayrshire

3.61

12.72 Holstein-Friesian

3.30

11.89 ------------------+----------+-------------

The figures[1] in Tables I and II are compiled and averaged from a large number of a.n.a.lyses made at different agricultural experiment stations.

This variation not only affects the fat, but all const.i.tuents of the milk. While there is a difference in the composition of the milk from cows of different breeds, there is almost as wide variation in the composition of the milk from single cows[2] of the same breed. With the same cow the stage of lactation causes a wide variation in the composition of the milk.[3] As the period of lactation advances, the milk increases in percentage of fat and other solids.

+9. Milk const.i.tuents.+--From the standpoint of the cheese-maker, the significant const.i.tuents of milk are water, fat, casein, milk-sugar, alb.u.min, ash and enzymes. These will be discussed separately.

+10. Water.+--The retention of the solids and the elimination of the water are among the chief considerations in cheese-making. Water forms 84 to 89 per cent of milk. Cheese-making calls for the reduction of this percentage to that typical of the particular variety of cheese desired with the least possible loss of milk solids. This final percentage varies from 30 to 70 per cent with the variety of cheese. The water has two uses in the cheese: (1) It imparts smoothness and mellowness to the body of the cheese; (2) it furnishes suitable conditions for the action of the ripening agents. To some extent the water may supplement or even replace fat in its effect on the texture of the cheese. If the cheese is properly made, the water present is in such combination as to give no suggestion of a wet or "leaky" product.

+11. Fat.+--Fat is present in the milk in the form of suspended small transparent globules (as an emulsion). These globules vary in size with the breed and individuality of the cow and in color from a very light yellow to a deep yellow shade as sought in b.u.t.ter. Milk with small fat globules is preferred for cheese-making, because these are not so easily lost in the process. Milk-fat is made up of several different compounds called glycerids,[4] which are formed by the union of an organic acid with glycerine as a base.

Fat is important in cheese-making for two reasons: (1) Its influence on the yield of cheese; (2) its effect on the quality of the cheese. Many of the details of cheese-making processes have been developed to prevent the loss of fat in manufacture. The yield of cheese is almost directly in proportion to the amount of fat in the milk; nevertheless, because the solids not fat do not increase exactly in proportion to the fat, the cheese yield is not exactly in proportion to the fat. The fat, however, is a good index of the cheese-producing power of the milk.

+12. Casein.+--Cheese-making is possible because of the peculiar properties of casein. This is the fundamental substance of cheese-making because it has the capacity to coagulate or curdle under the action of acid and rennet enzymes. Casein is an extremely complex organic compound.[5] Authorities disagree regarding its exact composition, but it contains varying amounts of carbon, oxygen, nitrogen, hydrogen, phosphorus and sulfur, and it usually is combined with some form of lime or calcium phosphate. It belongs to the general cla.s.s of nitrogen-containing compounds called proteins. It is present in milk in the form of extremely minute gelatinous particles in suspension. Casein is insoluble in water and dilute acids. The acids, when added, cause a heavy, white, more or less flocculent precipitate. Rennet (Chapter III) causes the casein to coagulate (curdle), forming a jelly-like ma.s.s called curd, which is the basis of manufacture in most types of cheese.

In the formation of this coagulum (curd), the fat is imprisoned and held. The casein compounds in the curd hold the moisture and give firmness and solidity of body to the cheese. Casein contains the protein materials in which important ripening changes take place. These changes render the casein more soluble, and are thought to be the source of certain characteristic cheese flavors.