COLUMBIA LIBRARIES OFFSITE HEALTH SCIENCES STANDARD lllllillillllli HX64088880 QP91 5.S7 Ab3 Sugar and its value RECAP Qpqis.si Ab3 Columbia ®nit)ersJftj) College of ^fipsficians! anJi burgeons Digitized by tine Internet Arcinive in 2010 witii funding from Columbia University Libraries http://www.archive.org/details/sugaritsvalueasfOOabel Issued June 7, 1913. Reprinted without change, Jartjary, 1915. U. S. DEPARTMENT OF AGRICULTURE. FARMERS' BULLETIN 535. SUGAR AND ITS VALUE AS FOOD. BY MARY HINMAN ABEL. PREPARED CNDER THE SUPERVISION OP THE NUTRITION INVESTIGATIONS. OFFICE OP EXPERIMENT STATIONS. WASHINGTON: OOVKRNMENT PRINTING OFFICE. J9J5. Q?^(^ LETTER OF TRANSMITTAL. U. S. Department of Agricultube, . Office of Experiment Stations, Washington, D. C, March 19, 1913. Sir : I have the honor to transmit herewith an article on sugar and its value as food, prepared by Mrs. Mary Hinman Abel, who has made an extended study of the subject, taking into account the results of laboratory research- as well as household experience. The work of the Bureau of Chemistry of the department has been drawn upon, and also the results of nutrition investigations of the Office of Experi- ment Stations. Sugar is an important and useful foodstuff, and information regard- ing it is very commonly requested from the department. It is be- lieved that this summary of available information concerning sugar and its value as food will prove useful to housekeepers and othei-s interested in the subject. Tlie bulletin is similar in its general character to other farmers' bulletins on the nature and use of food materials and, like them, has been prepared under the general supervision of C. F. Langworthy, chief of nutrition investigations of the Office of Experiment Stations. In its present form this bulletin is an extension and revision of an earlier farmers' bulletin (Farmers' Bulletin 93, "Sugar as Food"), which it is designed to replace. A. C. True, Director. lion Datid F. Houston, Secretary of Agricyltwre. 536 CONTENTS. Page. Introduction 7 Chemical compoeition of eugare 7 Characteristics of cane sugar 8 Characteristics of other kinde of sugar 9 Dextrose and levulose 9 Milk sugar 9 Honey 10 Japanese ame 10 Malt sugars . 11 Glycogen 11 Sweet materials other than sugar 11 Commercial glucose and other commercial products made from starch 11 Sources of cane sugar 12 Sugar from the sugar cane 12 Sugar from the sugar beet 13 Sugar from the sugar maple 14 Qiiality of sugar from different sources 14 Purity of sugar 16 Food value of sugar 16 Digestion of sugar 17 Sugar as a food for muscular work 17 Sugar as a fat former 20 Sugar as a flavor 20 Food value of table sirups and molasses 21 Nutritive value of sugar cane 23 Practical use of sugar in the ordinary diet 23 Amount and concentration 23 Sugar and the teeth 26 Effect of exercise on the amount of sugar which may be eaten 27 Sugar in cooking, preserving, and confectionery 27 Sugar in fruita 29 Sugar in the dietaries of children 30 Comparative cost of sugar aa food 31 General conclusiona 31 635 5 SUGAR AND ITS VALUE AS FOOD. INTRODUCTION. The pleasant flavor of sugar, together with what is now known of its nutritive value, wiQ account for its great popularity as a food. It may almost be said that people eat as much sugar as they can get, and that the consumption of sugar in different countries is in general proportional to their wealth. The English-speaking people are the largest consumers of sugar. In 1910 England consumed 86.3 pounds per capita and the United States 81.6 pounds, although stUl larger amounts are said to be con- sumed in sugar-growing districts, largely in the form of the ripe cane. Denmark that year consumed 77.7 pounds per capita; Switzerland, 64.3 pounds; and Germany, France, and Holland each about 40 pounds; while in Italy, Greece, and Servia the rate was only about 7 pounds per capita. The consumption of sugar is everywhere increasing. CHEMICAL COMPOSITION OF SUGARS. The term "sugar," as here used without qualification, means the ordinary sugar of commerce, the chemical name of which is sucrose. Because this was first manufactured from sugar cane it is called cane sugar, but the same sugar is manufactured from beets and is known as beet sugar. It is also found in the juice of many other plants. There are other sugars which are also given popular names denoting their origin — ^for instance, mUk sugar, grape sugar, and fruit sugar. The sugars may be conveniently divided chemically into several groups according to the number of carbon atoms which they contain. The most important from the standpoint of food value are the single sugars, grape sugar (dextrose) and fruit sugar (Icvulose), with 6 car- bon atoms; and the double sugars, cane sugar (sucrose), milk sugar (lactose), and maltose (malt sugar), in which the molecule contains 12 carbon atoms, or twice as many as in the single sugars.* 'The brief statement of the chemical nature and names of dilTerent siigaro and other carbohydrates which follows will pcrhai)B make clear to hoiisekecpcrfi, as well aw to othera who are Interested In Hiich qutblUma, tbla interesting part of the chemlMlry of food. Cvbobydratea are oo named becaiine they are composed of the elements, carljon, hydrogen, and oxygen, the hydrogen and oxygen being in theBamoproi)orllonBa.sln water, which incompotiodof 2atonmof hydro- ?€m to each atom of oxygen. '1 iiotigh there are carl>ohydrat<)H with fewer tlian 6 ami with more than 6 carlMn aU^ma, the pirincipal f^rliOhydralcH used as food contain 6 carbon atoms or miilllpl<-« of 0. 1'hese 7 8 SUGAE AND ITS VALUE AS FOOD. By a chemical process called inversion, which may occur in different ways (see pp. 9 and 17), one molecule of the double sugar is made to unite with water and form two molecules of single sugar. In nature two single sugars, dextrose and levulose, often occur in equal pro- portions, and the combination is then referred to as invert sugar. ' vSugar belongs to the important gTOup of food constituents, car- bohydrates, so named because as a whole they contain the element | carbon in chemical combination with oxygen and hydrogen, these ' two elements being in the same proportion as in water. Other car- bohydrates closely related to sugar are starch and crude fiber, or cellulose. Sugars and starches are very important foodstuffs, since j with fat they supply the bulk of the energy of the diet. Crude fiber, ^ usually digested by man in limited quantities only, is, nevertheless, an important foodstuff, since it adds bulk to the diet. CHAUACTEIIISTICS OP CANE SUGAR. Pure cane sugar consists of a mass of white crystals (e. g., the old fashioned "rock candy") easily soluble in about haff their weight of cold, or in a small quantity of hot water. Cane sugar is about two and one-half times as sweet as grape sugar. At 320° F., considerably above the boihng point of water (212° F.), sugar melts into a colorless liquid which rapidly takes on an amber hue. If it is then cooled quickly it hardens into a glassy mass, transparent and brittle, which is called "barley sugar." If heated to a higher temperature it browns, becoming less sweet and acquiring a somewhat bitter flavor. This browned sugar is called caramel. Old-fashioned brown sugar owed its color and flavor, at least partly, to caramel, for the process of manufacture formerly used involved evaporation over an open fire, which caused some of the sugar to become carameHzed or haK burnt, since in the final stages of sugar making the mass became so thick that it could not move about freely, and the layer next to the bottom of the kettle was raised far above the boihng point. are (1) monosaccharids (single sugars), including hexoses (such as dextrose, or grape sugar, and levulose, or fruit sugar), so called because the molecule contains 6 atoms of carbon with 12 atoms of hydrogen and 6 atoms of oxygen; (2) disaccharids (double sugars, such as cane sugar, and lactose, or milk sugar), so called because the molecule contains two of the simple sugar molecules less one molecule of water, namely, 12 atoms of carbon with 22 of hydrogen and 11 of oxygen; and (3) polysaecharids (such as starches), so called because the molecule contains repeated many times the simple sugar molecule minus the molecule of water or 6 atords of carbon, with 10 of hydrogen and 6 of oxygen. When a molecule of water combines chemically with a molecule of the second group, two hexose molecules are formed, and when the neces- sary number of molecules of water combine chemically with a molecule of the thii'd group, two or more hexose molecules are formed. This process, called inversion or hydrolysis, may occur in several different ways. Each group of sugars contains a number of members; for example, grape sugar and fruit sugar have the same chemical formula and the same percentage of carbon, hydrogen, and oxygen, although they are not identical substances. The difference in their properties is due to different groupings of the atoms. This must not be confused with the fact that the same sort of sugar may be obtained from widely different sources. Thus grape sugar is found in grapes and other fruits, and cane sugar is foimd in the juice of the sugar cane, beets, carrots, and other plants. 535 SUGAR AND ITS VALUE AS FOOD. 9 CK A R ACTEBISTIC S OF OTHER KINDS OP SXTGAIL Dextrose and Levulose. / Besides cane sugar, the commonest kinds are dextrose or grape Bugar, very much less sweet than cane sugar, and levulose, very much sweeter than dextrose. These two sugars are usually found together. Dextrose may be seen in yellowish grains in the raisin and other sweet dried fruits. It exists in small quantities. in many fruits, but occurs chiefly as a manufactured product, a result of the hydrolysis of starch, which means causing it to unite chemically with water by heating it with dilute acids or in some other way to induce hydration. By this treatment cane sugar is split up into a mixture of dextrose and levulose known as ''invert " sugar, which is also a commercial product. Honey is practically a natural form of invert sugar in which there is usually more levulose than dextrose. More sugar is supposed to be required to sweeten acid fruits if it is added before cooking than if it is added afterwards, and this is ascribed to the change of the cane sugar into invert sugar under the influence of the acid and heat. Aliss Jennie H. Snow ^ found that the amount of sugar inverted depends upon the length of time it is cooked and the degree of acidity, and her conclusions are borne out by the results of European investigators. She found, however, that loss of sweetness due to cooking sugar with acid fruit is so slight as to be of little prac- tical consequence. The effect of heat and acids in "inverting" cane sugar, as it it is termed, and also in destroying these sugars, has to be kept in view constantly in the manufacture of sugar. By the slow methods formerly in use on the sugar plantations, the juice of the cane soured before it was boiled, and the acids so formed inverted much of the cane sugar under the influence of heat. /This hindered crystallization, as did also the caramel produced by the overheating of a portion of the juice. The hindering of undesired crystallization by inversion with the aid of a little aid is sometimes very important in sugar making. Similarly, manufacturers of candy know that if they wish to prevent crystallization or ''graining'^ of a concentrated solution of sugar, as in making ** fondant" or soft filling, tartaric or other acid must be added to invert some of the sugar. The change of cane sugar in solution to dextrose and levulose men- tioned above may be brought about even in the absence of acid, by the action of heat, or by certain ferments, such as invertase, an enzym of yeast. Milk Sugar. Milk contains from 4 to 5 per cent of anotner important sugar — milk sugar or lactose. When separated and purifled it is a crystalline • Jour. Horn. Boon., 1 (1908), No. 3, pp. 261 306. 7OT23*— Bull. .U'>— 1.5 2 10 SUGAE AND ITS VALUE AS FOOD. product and is sold in that form. It is said to be the most readily digestible sugar and is often found in prepared foods, especially those made for invalids and children. It is much less sweet than cane sugar. Honey. Before sugar was a common commercial product, honey, stored by the honeybee, was very generally used to sweeten foods. Although its use for this purpose is much less common since cane sugar has become so plentiful and cheap, honey is still highly prized as a whole- some sweet food and is used either alone or with other foods in a great many ways. It consists of a natural mixture of dextrose and levu- lose (about 37 per cent of each) and may contain as high as 6 to 8 per cent of sucrose. An average analysk shows 74.41 per cent of reducing sugar calculated as invert sugar, and 1 .98 per cent of sucrose.* It also contains an average of 17.59 per cent of water and 0.23 per cent of mineral matter. Its flavor is due to volatile bodies in the flowers from which it is obtained, some flowers imparting a more agreeable flavor than others to the honey. It was formerly assumed that its composition was practically the same as that of the nectar gathered by the bees, but recent investigation shows that the nectar undergoes certain changes in the honey sack of the bee, and that the chemical properties of honey are not quite like those of the nectar. Its behavior in cooking and storing is different from that of the ordi- nary sugars for reasons not yet thoroughly understood. Honey has been used as a food from the earliest times, and is generally conceded to be wholesome as well as palatable. Prior to the passage of the Federal pure-food law, in 1906, strained honey was very frequently adulterated with commercial glucose (see p- 11) and other materials, such as commercial invert sugar, but since this law went into effect there is little adulteration of this product. Mixtures with glucose and invert sugar are sold, but the law requires that they be so labeled. Japanese Ame. A sweet material called ame has been made in Japan since early times from glutinous rice or glutinous millet, sometimes from com- mon rice and rarely from Indian corn or sweet potatoes, by converting the starch they contain into maltose (a double sugar similar to su- crose, lactose, etc.) by the action of an unorganized ferment called diastase. Malt or sprouted barley is generally used to furnish the ferment. The cleaned grain or other material is soaked in water and steamed until the starch grains are broken open and made easily accessible to the ferment. Powdered malt and water in proper pro- portions are added, and in six or eight hours the diastase converts the starch very largely into dextrin and maltose. The liquid is then filtered and evaporated to the desired consistency, which varies 1 U. S. Dept. Agr., Bur. Chem. Bui. 110. 535 SUGAR AND ITS VALUE AS FOOD. 11 according to the season. One of the forms is a dense, clear, light- colored amber liquid not unlike the best commercial glucose in some of its physical properties. Another form is hard and not unlike a white candy in appearance. Ame has been manufactured in Japan for at least two thousand years, and long before sugar was known it was a favorite flavoring. Even at the present time it is sometimes used instead of sugar in cooking, and it is also a favorite food adjunct for invalids. Malt Sugars. Several malt preparations, some of them thick like sirup and others more of the consistency of candy, are on the market. These are mixtures of dextrin and maltose coming from the action of diastase on starchy materials. Many commercial products, so-caUed "pre- digested" and "malted" products and similar goods, have this material as their basis. Glycogen. Glycogen or "animal sugar" is a carbohydrate of the same chem- ical composition as starch, but with different chemical properties. It is found in smaU amounts in muscular tissue, and more abundantly in the liver, where it may exist in considerable quantities. It has an important function in nutrition, being stored as a reserve source of energy for the body. SWEET MATEEIAIS OTHER THAN SUGAR. Saccharin, an extremely sweet material, is not a sugar, but is of an entirely different chemical structure, boiag a benzene compound. Its use in food products was forbidden under the Federal pure-food law,' It is quite commonly prescribed in cases of diabetes to satisfy the craving for sweets, as it is believed to be less harmful in such cases than the sugar, the flavor of which it replaces. There are other chemical substances which are not sugars, but which have a marked sweet flavor. They, like saccharin, are in no sense foodstuffs. COMMERCIAL GLUCOSE AND OTHER COMMERCIAL PRODUCTS MADE FROM STARCH. "Commercial glucose," "40 sugar," "80 sugar," and "commercial ilcxtrose" are commercial products of the hydrolysis of starch. The first is a thick liquid, runJy showing crystallization, havhig a coiii- position of between 30 and 39 per cent dextrose, 40 to 53 per cent dextrin, and about 0.5 per cent ash. The others are solid protlucts varying in percentag(5 of U. 8. Dept. Agr., Farmen' Ilul. 62. > ealifornia SU. (ire. .3S. »8fi 16 SUGAK AND ITS VALUE AS FOOD. PURITY OF SUGAE. Of 500 samples of sugar examined several years ago by the Bureau of Chemistry of this department/ not one was found to be adulterated. The low price of cane sugar, in comparison with the price of substances that might be used for adulteration, protects it from such attempts. A more recent publication of the Bureau of Chemistry ^ states that sugars as a class, both the high and low grades as now found on the market, are practically free from adulteration. This is par- ticularly true since the Federal pure-food law of 1906 went into effect. There is a popular belief that granulated sugar is often adulterated with white sand or finely ground rock, and that pulverized sugar is commonly adulterated with starch or lime dust. Cases of such adulteration, however, have rarely been found by the Bureau of Chemistry, though starch has been detected in a very few samples of powdered sugar. It is a very simple matter to test suspicious sugar for the presence of such materials. Sugar is readily soluble in water, and the sand and mineral adulterants are insoluble. If a spoonful of sugar is added to a glass of water and stbred, it will com- pletely dissolve, while any sand or similar material will remain un- dissolved. If the water is warm the sugar will dissolve more quickly than otherwise, and care must be taken to continue the stirring for considerable time, as some of the very dry crystallme sugars dissolve rather slowly. FOOD VALUE OF SUGAR. The most interesting use of sugar is as a food for the animal body. Within certain limits, sugar may be considered as the equivalent of starch that has been digested and made ready for absorption. A mealy boiled potato, like all forms of starchy food, must be largely converted into some kind of sugar by the digestive juices before it can be absorbed as food. It is commonly stated that the food eaten by the average adult is at least one-half of vegetable origin, and analyses show that the nutrients of vegetable foods are very largely starch. The average of 400 dietary studies made in the United States shows about 40 per cent animal food and 60 per cent vegetable food. Starch in cereal grains and other foods, and separated as cornstarch, etc., furnishes a considerable part of the heat and muscular power of the body. The summary of data regarding the American diet quoted above shows that sugar constitutes 5.4 per cent of the average diet and furnishes 17.5 per cent of the total energy in it. It is clear that starch, sugar, or any food that will serve the same purpose is of great importance. To understand the utilization of such foods ia the body better, the process of carbohydrate digestion may be considered. When a » U. S. Dept. Agr., Div. Chem. Bui, 13, pt. 6. a U. S. Dept. Agr., Bur. Chem. Bid. 100. 535 SUGAR AND ITS VALUE AS FOOD. 17 starchy food, such as boiled potato, is taken into the month, it is at once acted upon more or less by a ferment contained in the saliva, and this action is continued by a ferment contained in the intestines. It is broken up into simpler chemical compounds, and it finally reaches the blood and muscles as dextrose, a form of sugar which can be burned in the body to yield muscular energy and heat. "When an excess of carbohydrates (sugar or starch) is consumed, the dextrose in the digestive tract is converted in the- liver to glycogen and stored until required, being then, it is believed, reconverted into dextrose. More complex changes may take place which convert carbohydrates consumed in excess into fat, wliich is also stored as a reserve material. Some recent German investigations indicate that the different kinds of sugar are not equally well adapted to increasing the supply of glycogen in the body. In experiments with dogs, sucrose and dextrose proved the most valuable in this respect. DIGESTION OF SUGAR. When sugar is eaten it is changed in the digestive tract before it is taken up in the blood and carried where it is needed. If a solution of cane sugar be injected directly into the blood, it is passed out by the kidneys unchanged, showing that it is not fitted for assimilation until it has been changed, as it is in normal digestion. The change needed is slight compared with that required for the digestion of starch, sugar being "inverted" or changed into the simpler sugars as already described (see p. 9), and this change is brought about in the digestive tract by the agency of enzyms or ferments regard- ing the nature of which little is known. When thus changed into the simpler sugars, its function in the body is similar to that of starch after it has reached the analogous stage in digestion. At the Minnesota Experiment Station^ the thorouglmess of diges- tion of sugar was studied with healthy men, 5 ounces per day being consumed as part of a simple mixed diet. The sugar showed a high digastibility, 98.9 per cent of its total energy being available to the body, on the average. In general, it increased the available energy of the whole ration 25 per cent and did not aflFect the digestibility of the foods with which it was combined. Tho protein of the ration was more economically used than commonly, the nitrogen retention being increased 25 per cent. It was pointed out in discussing these experiments that "the value of sugar in a ration depends upon its judicious use and combination with otlier foods." SUGAR AS A FOOD FOR MUSCULAR WORK. Food must supply enough protein or nitrogenous material for the formation and ro[)air of tissues and for c(U'tain other uses in tlio body, and in addition suflicient oth(»r material to make up the amount of > HlnnoMta Bta. Rpt. 190S-4. 6.^5 18 SUGAE AND ITS VALUE AS FOOD, energy necessary for heat and muscular work. The nitrogen-free nutrients are fats and carbohydrates. In the ordinary diet the rela- tive amount of fat and carbohydrates, is usually regulated by per- sonal preference. Fat will furnish two and one-fourth times as much energy per pound as carbohydrates. Taking account of this fact it is immaterial on chemical grounds which of these nutrients supplies the necessary energy, although this is not the case from the stand- point of hygiene. The main function of sugar as found in the blood, whether result- ing from the digestion of sugar or of starch, is believed to be the production of energy for internal and external muscular work, and, as a necessary accompaniment, body heat. This has been amply demonstrated by experiment. By ingenious devices the blood going to and from a muscle of a living animal may be analyzed, and it is thus shown that more blood traverses an active or working muscle and more sugar disappears from it than is the case with a muscle at rest. To decide the question of the value of sugar as a source of energy for the working muscle, much careful laboratory work has been car- ried on. It has been found that an increase in the sugar content of the diet, when not too great and when the sugar is not too concen- trated, lessens or delays fatigue and increases working power. In- creased amounts of sugar were found to increase the ability to perform muscular work to such an extent that on a ration of 500 grams (17.5 ounces) of sugar alone a man was able to do 61 to 76 per cent more work than on a fasting diet, or almost as much as on a full ordinary diet. The addition of about half this quantity of sugar to an ordi- nary or to a meager diet also considerably increased the capacity for work, the effect of the sugar being felt about a half hour after eating it, and its maximum effect showing itself about two hours after eating. The coming of fatigue was also found to be considerajbly delayed on this diet, and taking 3 or 4 ounces of sugar a short time before the usual time for the occurrence of fatigue prevented the ap- pearance of it. Lemonade, or other similar refreshing drink, and chocolate have been suggested as mediums for supplying in small doses an extra amount of sugar to men called upon to perform extraordinary muscular labor. The application of these results to the food .of soldiers who may be called upon for extraordinary exertion in marching or fighting is very evident. Practical tests of the value of sugar in preventing or delaying fatigue, made in both the German and French armies, indicate the value of sugar in the ration when the men are subjected to great exertion. It is believed that more decisive results may be obtained by tests with men and animals in which the effects of given quantities of sugar in the diet are compared with those obtained with starch and other food materials. Such experiments have been made 535 SUGAK AND ITS VALUE AS FOOD. 19 under the auspices of this department with men iq the respiration calorimeter. This apparatus makes it possible to measure with great accuracy the relation between the material consumed and the muscular work done. In experiments planned to test the value of carbohydratie foods as a source of energy during severe muscular work, the subjects were able to include 350 grams, or about three- quarters of a pound, of cane sugar in then* daily diet without any deleterious effects.^ According to our present knowledge the value of sugar as a food for muscular work may be briefly summarized as follows: Wlien the organism is adapted to the digestion of starch, and there is sufl&cient time for its utilization, sugar has no advantage over starch as a food for muscular work. Id small quantities and in not too concentrated form sugar will take the place, practically weight for weight, of starch as a food for muscular work, barring the difference in energy and in time required to digest them, sugar having the advantage in these respe.cts. It furnishes the needed carbohydrate material to organisms that have httle or no power to digest starch. Thus, milk sugar is part of the natural f ootl of the infant whose digestive organs are, as yet, un- able to convert starch into an assimilable form. In times of great exertion or exhausting labor, the rapidity with which it is assimilated gives sugar certain advantages over starch and makes it prevent fatigue. This latter quality, which renders it more rapidly available for mus- cular power, may account for the fact that sugar is so rehshed by people who are doing muscular work, and by those of very active habits, such as children. The American farmer ranks high among agriculturists as a rapid and enduring worker, and his consumption of sweets is known to be very large. The same is true of lumbermen and others who work hard in the open air; sugar and sweet cakes are favorite foods with them. Dietary studies carried on in the winter lumber camps of Maine showed that largo quantities of cookies, cakes, molasses, and sugar were eaten, sugar of aU sorts supplying on an average 10 per cent of the total energy of the diet. The value of sugar in cold climates, whcr foods containing starch are not available, is evident, and in the outfit of polar expeditions sugar is now given an important place. Oriental races are very fond of sweets, as often noted l^y travelers. Certain forms of confectionery are very popular in Turkey and other regions of the East, and in tropical lands the consumption of dates, figs, and oth(;r sweet fruits is very large. In a discussion ^ of the food of the natives of India the great value set on sweetmeats or sugar » U. 8. Dept. Agr., Omoe Kxnt. Htos. BuL 17«. » Jour. Trop. Med. [I/ondonl, (1906), p. 310. 635 20 SUGAE AND ITS VALUE AS FOOD. by the Hindoo population of all classes is pointed out. Large quan- tities of brown or white sugar are used to sweeten the boiled milk, which is a common article of diet, and sugar is also used with sour milk, rice, cheese, and other foods. It has also been said that the employer who wUl not furnish the native laborers with the large amounts of sugar they desire in their daily ration must expect to lose his workmen. Certain rowmg clubs in Holland have reported very beneficial results from the use of large amounts of sugar in training. Pfliiger, who devoted so much attention to glycogen and other carbohydrates, says that undoubtedly sugar in the blood is heavily drawn on during violent exercise; hence the longiug for it in a form that can be rapidly assimilated. Its use by mountain climbers is well known. The Swiss guide con- siders lump sugar and highly sweetened chocolate an indispensable part of his outfit. This brief summary serves to show the use which is made of sugar when severe work is performed, and some of the experimental data which indicate that this custom is justified. SUGAE AS A FAT FORMER. Sugar, like starch, is fattening; that is, when taken in excess it may be transformed into fat and stored as reserve material. On this account physicians commonly advise that sugar be sparingly used by the corpulent. This advice is given because sugar in the form of candy or other sweets is often taken as an accessory to an already abundant diet. A practical illustration of the use of sugar as a fattening food is found in the use of both sugar and molasses in fattening farm animals, the fat so produced being found firm and of good quality. In sugar- producing regions it is a common constituent of the rations of horsea and mules, and it is fed to dairy cattle and to fattening steers. In Louisiana, for example, it is the usual practice to feed ''black strap" molasses to plantation horses and mules at the rate of 8 to 12 pounds per head per day. So common has its use become for farm animals in general that many mixed rations are now on the market which contain molasses as one of their chief constituents. Sometimes the materials added are used principally to absorb the molasses and make it more convenient to feed. The molasses, of course, contains prac- tically no protein, the body-building material, and frequently materials are mixed with it which are rich in this constituent in order that the mixed feed may constitute a well-balanced ration. SUGAR AS A FLAVOR. In addition to its value as a food, sugar is important in the diet as a flavor, one which the cook could not easily spare, as it now enters into 535 SUGAR AND ITS VALUE AS FOOD. 21 a great variety of dishes. Indeed its agreeable flavor has always constituted one of the chief reasons for its use, and will continue to do so, even though we make use of the abundance of relatively cheap starchy materials we possess which theoretically may readily take the place of sugar as a food. In some dietary studies made under the auspices of this department with a club of students at the University of Elaine, an investigation was made of the effect of supplying a liberal amount of maple sirup in a diet which contained an abundance of nutrients. The snup was e^'idently relished, and considerable amounts were eaten. However, there was not a corresponding decrease in other foods; on the contrary, the amount of flour was in excess of the amount ordinarily consumed. It would seem that the maple s:rup, and flour in the form of griddlecakes, were consumed simply on account of their agreeable flavor. Provided the diet contained sufficient nutrients in the first place, this increase was not desirable on the ground of econ- omy, and it may be questioned whether it was desii*able from the standpoint of health. When a similar comparison was made of the addition to the diet of liberal quantities of milk, which has a much less distinctive flavor, there was a corresponding decrease in the amount of other foods consumed. This would indicate that much of the sugar used is consumed for its agreeable flavor and not because it is recognized as a food which is required to satisfy body needs. FOOD VAI.TJE OF TABLE SIBUPS AND MOLASSES. Sirups of various kinds and molasses have always been used to a large extent in the United States as articles of diet and for cookery. There are several forms in common use. Of these, maple sirup, which is obtained by evaporating tlie sap of the sugar maple, commands the highest price. Cane sirup made from the expressed juice of the sugar cane is another important sirup, as is also tlie sirup made from sorghum by methods very much lUvo tliose used in the manufacture of sirup from sugar cane. Very much used, too, are the homemade sirups obtained hj boiling sugar, either white or brown, with water. A little caramel made by burning sugar in a frying pan and dissolving it in water may be added to the sirup to give both color and flavor. Some housekeepers add a little vinegar to homemade sirup, wliich imparts a flavor and inverts more or less of the sugar. Sometimes water in which several corncobs have been boiled is used in making homemade sugar sirups, the cobs imparting a flavor which many relish and which Is said to suggest maple. In Europe a simp called " whey honey " is made by boiling doAvn, with sugar, the whey drained from rottage (sour milk) rhccse until it is thick as honey, the propor- tions boing 1 pound of sugar to a quart of whey. This has a pleasant and distinctive flavor. S3S 22 SUGAR AND ITS VALUE AS FOOD. An interesting example of the use of molasses in quantity is fur- nished by the negroes in some regions of the Southern States. Dietary studies in the Black Belt of Alabama showed that the diet was made up almost entirely of molasses, frequently homemade, com meal, and fat pork. The different grades of molasses obtained as by-products in the manufacture of sugar from sugar cane have always been po'pular as table sirups and for cookery. Molasses produced by the open-kettle process of boiling is the most highly appreciated, and for a long time was a staple article for both purposes. Generally speaking, it can now be obtained only in the Southern States and there m small quantities only, since the modern process of sugar making has prac- tically eliminated this open-kettle molasses from the market. To supply its place, the manufacture of sirup directly from the sugar cane and without the separation of any kind of sugar has come to be practiced extensively in the South, particularly in Georgia, Florida, Alabama, Mississippi, and Louisiana. According to an early publi- cation of this department, ^'this sirup forms a delicious, wholesome, and valuable condimental food substance, the use of which is rapidly extending; and, because of its merits, it appears destined to become a very important food." For some reason the public has come to judge sirup largely Oy its color. Many prefer a dark product for cooking, partly because it colors the material with which it is mixed, and partly because the dark color is still associated in their minds with the flavor of old- fashioned molasses. For table use, however, a light-colored sirup is usually preferred. In this case the fact has apparently been over- looked that if properly manufactured good sirup must possess some color, since in the evaporation of the sugar juice in an open kettle or pan a high temperature is employed, which causes an inversion of some of the sugar, and also has a tendency to produce caramel which imparts a color to the sirup. Though a light-colored sirup is popular, a brown color does not mean that the sirup is not of good quality. There are also in use in this country quantities of table sirups which are simple mixtures, the chief ingredient of which is commer- cial glucose, and the flavor of which comes very largely from some of the sirups and molasses mentioned above. In certain of -these mixtures which owe their flavor and color to "refining sirup," a by-product of the sugar refinery, the content of soluble salts is large enough to impart a distinct saline flavor. The bone black used in purifying the sugar also affects the flavor of "refining sirup." Since the Federal pure-food law was enacted such mixtures bear a label showing the constituents. Sugar-beet molasses is not used for table purposes, as no way has been found to free it commercially from objectionable impurities. 536 SUGAR AND ITS VALUE AS FOOD. 23 NTJTEITIVE VALUE OF SUGAR CANE. The entire juice of the ripened sugar cane is, of course, more nearly a complete food than its crystallized sugar, for it contains other con- stituents besides carbohydrates. It is elaborated by the plant as a rich food for building up young leaves and buds. In sugar-producing countries the cane is regarded as a staple food during its season. All classes of people chew the ripe cane freed from its hard rind, incredible quantities being consumed in this waj^. Shiploads are brought daily to the markets of Rio Janeiro and West Indian towns. For months the chief food of the negro laborers on the plantations is said to be the sugar cane, and they are seen to grow strong and fat as the harvesting season advances, although they may begin it weak and half-starved. PRACTICAL USE OF SUGAR IN THE ORDINARY DIET. Sugar was formerly regarded as a condiment and valued chiefly for its pleasant taste, but its food value has been fully established and, considering the immense quantities at present consumed, it is very important to determine the extent of its usefulness in dietaries. It has been ascertained that in large numbers of well-to-do families in this country about 2 pounds per week per person are consumed. It would seem that this amount, or about one-fourth of a pound daily, taken in addition to other food, is well utilized by the system. There is some question regarding the desirability of using larger quan- tities. The use of sugar it would seem should be limited in two ways: (1) The amount consumed should not be greater than may be readily assimilated, else it would overload the stomach and bring on diges- tive disturbances and in some cases might produce pathological con- ditions in the excretory organs; and, (2) the sugar should not be taken in a solution or other form so concentrated that it causes a burning sensation or other digestive disturbance (see p. 24). The question f'f possible permanent injury from the use of fairl}^ large amounts of ii;rar seems to be an open one, and certainly the extreme views which are sometimes found in popular ^vritings do not seem to be entertained by well-informed physiologists, the conclusion generally accepted being that used in reasonable amounts sugar is both wholesome and nutritious. AMOUNT AND CONCENTRATION. Sugar differs greatly from starch in the amount that can be properly used in the system. Starchy foods, such as potatoes, bread, etc., can be digested and utilized in very large quantities. As much as 600 grams (1 .3 pounds) of starch per day may be digested for many days without difficulty. This amount of starch is contained in 2.5 or 3 pounds of bread, or in 6 or 7 pounds of potatoes. Fewer tests have 530 24 SUGAR AND ITS VALUE AS FOOD. been made regarding the maximum amount of sugar that may be used by the system. Vaughan Harley used large quantities of sugar in some of his experiments on himself, but 400 grams (nearly a pound) daily for some time very much affected his digestion. Since, as scientific investigators seem agreed, the digestion of sugar is relatively so rapid, assimilation and storage in the liver can not keep pace with its absorption from the intestines if it is taken in large quantities. In this case, part of the sugar will be excreted unchanged. Not only is this excess of sugar wasted, but such an unnatural tax on the excretory organs, if constant and long con- tinued, might end in disease. It is also a matter of common obser- vation that large amounts of sugar and sweetened food are apt to be accompanied by undue fermentation in the stomach and intestines. If this occurs it shows that the quantity of sugar eaten is too great. In this regard, investigators have pointed out that sugar bears much the same relation to starch that peptone, one of the products of meat digestion, does to meat. Both sugar and peptone are very diffusible, and thus enter rapidly into the circulation, strong solutions at the same time irritating the mucous membrane with which they come iato contact by virtue of their water-abstracting power. The ''furry " feeling noticed when a piece of hard candy is held in the mouth for some time against the cheek is a familiar example of the effect pro- duced on sensitive membrane by a concentrated solution of sugar, which is undoubtedly due to the fact that equilibrium of density is not readily established between the liquid of the two sides of the membrane. The digestive disturbances noted when very concen- trated solutions of sugar or other substances are taken into the stomach are attributed to similar causes; that is, to differences in the density of solutions on the two sides of the livLag membrane. Doubtless because sugar is commonly excluded from the diet of diabetics the statement has been made that eating sugar is the cause of this disease, which of course does not follow. Such an opinion is not entertained by physiologists, as is apparent from the statement in a recent report ^ of the Connecticut State Agricultural Experi- ment Station, which shows the fallacy of such a belief. That sugar, honey, sirup, etc., "produce diabetes" would, according to the report, be "startling if true." It is sometimes said that sugar produces gout. There seems to be no proof of this theory. Sugar seems iU adapted to the sick, except when used in very small quantities as a flavor. Jacobi^ remarks that the absorption of sugar is slower by sick than by healthy children, and that in such 535 1 Connecticut State Sta. Rpt. 1911, pt. 2, p. 161. 2 Therapeutics of Infancy and Childhood. Philadelphia, 1896, p. 16. SUGAR AND ITS VALUE AS FOOD. 25 cases only a little should be given and never in concentrated form. He also states that the conversion of milk sugar into lactic acid takes place very rapidly, while cane sugar is not so readily trans- formed, and accordingly he insists that the latter be added to the food of infants and children. When any bad effects can be ascribed to sugar they are usually due to its use in larger quantities than the 3 or 4 ounces a day which seem to be digested by the healthy adult without difficulty. The conclusion to be drawn from such experimental work as that referred to is that overeating with sugar is to be avoided, not, as has sometimes been stated, that sugar is other than a useful foodstuff. The statement is sometimes made that sugar is unwholsome because it has been separated from the plant and is therefore "artificial." Like a host of other statements of similar popular origin, this is based on belief rather than experience and evidence and is not the view generally held. Bimge^ has called attention to the lack of calcium (lime) and iron in sugar as compared with honey and sweet fruits. His contention that this might be a possible soiu"ce of danger does not seem probable when one considers the varied character of our diet and its abundant supply of fruits and vegetables, milk products, and other foods which contain calcium and iron. The object sought is, of course, to supply in the diet all the substances which the body needs, and if this is done by the foods as a whole, the possible lack of a con- stituent or constituents in some single food which forms a part of the diet is not of importance. If for any reason calcium is lacking in the diet, the deficiency may be easily made good by increasiug the amomit of milk and milk products. Similarly, iron may be increased, if this is desirable, by taking more fruits, green vegetables, and the coarser milling products of the cereal grains, foods which are within the reach of practically everyone. It will be noticed that sugar as it exists in nature — e. g., in the sugar cane, in milk, and in most fruits — is not higlily concentrated. In mUk it constitutes from 4 to 6 per cent. It would seem that the animal organism is best adapted to the utilization of food principles in the somewhat dilute or bulky form in wliich they occur in the commonly accepted foods — protein as found in meat, mUk, etc., starch in grains, and sugar in small quantities at a time as found in vegetable juices and milk and in combination with other foods — and that it does not readUy accept unlimited amounts of chemically iso- lated and, purified food princii)les. Most of the statements wiiich have been made regarding tlio amounts of sugar which are well toler- ated depend upon evidence obtained in experiments in which the sugar > Ztscbr. BioL, 61 (1901), p. IfiS. 68C 26 SUGAK AND ITS VALUE AS FOOD. was used dissolved in liquid, as in tea, coffee, or some similar way, or from experience of the results which sometimes follow when a large quantity of sirup or candy or some similar product rich in sugar is taken. How far the conclusions drawn would apply to sugar taken in cake, pastry, custards, and other cooked foods can not be stated definitely, as few tests have been made upon the digestibility of such foods. With the exception of thick preserves and some similar foods, in which sugar is used as a preservative as well as a flavor, most cakes, custards, and other foods flavored with sugar contain it in moderate amounts, which means that the sugar is diluted or extended by a considerable quantity of other material. In this connection it may be said that it is the usual custom to take sugar in dilute form, as, for instance, when we add it to tea or coffee, sprinkle it on fruit, add it with milk or cream to breakfast cereals, or use it in other similar ways. SUGAR AND THE TEETH. It is often said that sugar is harmful to the teeth, but the facts seem to be as follows: According to the theory universally accepted, the decay of the teeth, technically called caries, is caused by bacteria, such as are found in every mouth, entering the soft portions of the teeth through defects in the hard outer covering. If acid is present in the mouth, and especially in the interstices of the teeth, it tends to eat into the enamel and thus provide an entrance for the caries- producing bacteria. Ordinarily, saliva is alkahne and protects the teeth against this danger, but when it is in contact with sugar or starch, acid is produced, hence a carbohydrate material lodged upon the teeth may be the indirect cause of caries. Some authorities hold that certain forms of sugar cause the flow of a less alkaline saliva, but this point is not fully estabhshed. In general, it is believed that starch is just as dangerous as sugar, and that the form and man- ner in which the material is eaten is a more important consideration than its exact chemical structure. Soft foods are especially hkely to cause trouble^ both because bits of them may remain on the teeth where they form "plaques" which are centers of bacterial action so long as they remain, and because they are swallowed without much chewing and thus do not rub the food "plaques" or other deposits from the teeth. Modern speciahsts consider that the cleansing action of proper mastication is as important for the preservation of the teeth as the regular use of a toothbrush, important as this last is. Any soft carbohydrate food eaten alone is much more likely to leave a deposit on the teeth than if it is eaten in combination with other foods. If candies are eaten by themselves, they are more likely to cause the development of acid in the mouth than if they are taken 535 SUGAR AND ITS VALUE AS FOOD. 27 during a meal. Some physicians advise finishing the meal with acid fruit for the sake of lessening the chances of carbohydrate material clinging to the teeth. While soft foods may possibly cause trouble, the hard ones may also be dangerous, especially to diseased teeth, as the effort to crush them may tend to increase flaws in the enamel. Such things as hard crusty food, hard candies such as lemon drops, stick candy, etc., may be dangerous in this respect, though invest!-' gations by G. V. Black ^ on the crushing force of the teeth have proved that sound teeth are capable of crushing much harder sub- stances than these without injury. EFFECT OF EXERCISE ON THE AMOUNT OF SUGAR WHICH MAY BE EATEN. The amount of sugar that may be eaten without bad effects depends much on the amount of exercise taken. It has been observed that a man doing hard work in the open air can easily assimilate large quantities of sugar, while the same quantity would cause indigestion if eaten when Uving indoors and taking httle exercise. This is what might be expected, as the active outdoor hfe means much physical work or exercise, either of which involves much muscular energy. Sugar, as has been pointed out, is a valuable energy-yielding food. SUGAR IN COOKING, PRESERVING, AND CONFECTIONERY. Sugar is used in cookery, in the manufacture of confectionery, which is almost entirely sugar, and as an addition to a great variety of foods. It is almost always used with cooked fruit, cakes, pastry, and, in general, food made with eggs and flour, and very rarely with meat dishes in modern cookery, though often added in earher times, as old recipe books show, to meat pies, which were heavily seasoned with sugar and spice. Mince pie is one of the very few surviving representatives of such foods. Sugar and fat are often cooked together, and many " foods, butter-scotch for example, owe their pleasing flavor to this combination. Sugar and suet are often used, as in puddings, but leas often now than formerly. Sugar added in cakes and pastry affects the texture as well as the composition and flavor, as any cook knows. A special form of cookery is the making of preserves, jams, jellies, etc., and in those sugar in thick, heavy solution not only adds to the palatability and character of the flavor, but it also acts as a preservative. On the contrary, thin solutions of sugar alone or with fruit juices, etc., are very readily sub- ject to dec<^miposition by microorganisms. Hence, in order that it may act as a preservative, a solution of sugar must be concentrated. Without doubt more sugar is used in cookery and in making jams, » A work on operative dentistry, Chicago and I/ondon, 1008, Vol. I, p. 101. 28 SUGAE AND ITS VALUE AS POOD. jellies, and preserves, and in making confectionery (which is a special form of cookery) than in any other way. In general it may be said that for ordinary cakes the proportion of sugar is not usually greater than one part by measure to two parts of flour, and that too much sugar should not be used in making puddings, cakes, etc., since oversweetening, like other forms of overflavoring, is regarded as a mark of unskilled cookery. In the case of canned fruits a common proportion is one part of sugar to two parts of fruit by weight; for preserves, equal parts of sugar and fruit; and for jellies, three- quarters to one part by weight of sugar to one part of juice. Detailed recipes for making preserves, jellies, and similar articles are given in earher buUetias ^ in this series. Directions for making cakes, pies, puddings, and other such dishes in which sugar is an important part can be found in cookbooks and similar publications. Candy of the better grade is very largely made up of sugar, with the addition of various coloring matters and flavors, nuts, fruit, etc., and sometimes fat, starch, and commercial glucose. The food value of most candies may be expressed by the amount of the sugar contaiaed (72 to 96 per cent), but as regards wholesomeness the other in- gredients must be taken into account. The coloring matters used in cheap candies are nearly all compounds of anilin or other coal-tar products, some of which are thought to be harmless. Some of the coloring matters and flavors used, however, have been shown to be harmful. Ordinary caution would suggest that children, at least, be allowed to partake very sparingly of such unknown compounds. Two hundred and fifty samples of cheap candy examined by the Bureau of Chemistry of this department a few years ago were found to be made up largely of commercial glucose with a little sugar and starch. Candies are often exposed to the dust and dirt in stores and booths, taken out of jars and boxes by dirty hands, or weighed in scales of questionable cleanHness. Dangerous microorganisms such as are frequently present in dust may thus lodge on them and be eaten with the candy. Cleanliness in the marketing of this class of goods is just as necessary as in the case of fruits or vegetables, per- haps more so, as the others can be washed if they are to be eaten raw, and candies would not be washed. Studies recently made in Pennsylvania ^ show that while there has been marked improvement in the quality of cheap candies during the last few years, there is room for still greater improvement in the form of these candies and the method of marketing them. Many are made in the form of whistles, marbles, belts, and necklaces, which the children often play with and which become very dirty before they 1 U. S. Dept. Agr., Farmers' Bills. 203, Canned Fruit, Preserves, and Jellies— Household Methods of Preparation; 359, Canning Vegetables in the Home; and 426, Canning Peaches on the Farm. 2 Pennsylvania Dent. A.gr., Dairy and Food Div. Bui. 216. 535 SUGAB AND ITS VALUE AS FOOD. 29 are eaten. The desirabilit}' of having candies wrapped or at least protected from dust and dirt while exposed for sale is evident. The custom of marketing candies wrapped or of packing them in boxes, etc., at the factory is a growing one, particularly with the more expensive sorts, and is certainly a measure which makes for cleanli- ness. With respect to the candies themselves, manufacturers who realize their responsibility endeavor to insure sanitary conditions in their manufactories. In a number of States the candy factories, like hke other food manufactories, are inspected under State auspices. SUGAB IN FRUITS. A large number of studies of fruits and fruit products by the Cali- fornia experiment station indicate that the food value of fruits is largely due to the various sugars they contain, the ones most com- monly found being cane sugar, grape sugar or dextrose, and fruit sugar or levulose, the last two usually present together in equal quantities, in which case they are collectively knoAvn as invert sugar, though sometimes not in equal quantities, in which case they are called reducing sugar. The stage of^rowth and the degree of ripeness have a very decided effect on the kind and amount of sugar present in fruits, and it is therefore difficult to give average figures which will f ahly represent the quantities present. According to figures published several yeara ago, invert sugar ranges from about 2 per cent in large early apricots to 15 per cent in grapes and a variety of sweet cherries, while straw- berries, gooseberries, raspberries, and apples contain about half the latter quantity. The cane sugar ranges from less than 1 per cent in lemons to 14 per cent in a variety of plums. Ripe bananas were also found to contain a fairly high percentage, namely, 11 per cent. Dried fruits, like figs, dates, and raisins, which have been con- centrated by evaporation, naturally contain much greater propor- tions of sugar than fresh fruits, the amount of levulose reported bcmg •-Mmctimes over 50 per cent. The use of such sweet fruits for swoet- ling cooked breakfast cereals and other dishes is by no means un- (oinmon. The question of the sugar content of fresh fruits and dried f 1 uits and their value as food has been discussed in earlier })ublications.* Jams, jellies, and similar products almost always contain added sugar, and hence their nutritive vahn? may ])o considerable. Home- made jams are often cooked l(jngor than the commercial ones, and tlieroforc may contain a larger proportion of invert sugar. On the other hand, commercial brands ar(i often made with glucose, but the law requires that the fact bo stated on the label, along with the i)ro- portions of chemical preservatives, etc., if present. (See also p. 12.) ' U. 8. Dcpt. Art., rarm'-n' IJul. 283, Uao of FruJt as Food; V. B. Dopt. Agr., Yearbook »»2, p. 606, Haislaa, Fign, and Otbcr J;rli;